Faculty Publications: March, 2014
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Abstract
We report TimeDomain ThermoReflectance experiments measuring the Thermal Boundary Conductance (TBC) of interfaces between diamond and metal surfaces, based on samples consisting of [111]oriented diamond substrates with hydrogen or with sp2 carbon surface terminations created using plasma treatments. In a concurrent theoretical study, we calculate the work of adhesion between Ni, Cu, and diamond interfaces with (111) surface orientation, with or without hydrogen termination of the diamond surface, using firstprinciples electronic structure calculations based on density functional theory (DFT). We find a positive correlation between the calculated work of adhesion and the measured conductance of these interfaces, suggesting that DFT could be used as a screening tool to identify metal/dielectric systems with high TBC. We also explain the negative effect of hydrogen on the thermal conductance of metal/diamond interfaces.
Title:  Quantum hexatic order in twodimensional dipolar and charged fluids  
Authors:  Bruun, Georg M.; Nelson, David R.  
Publication:  Physical Review B, Volume 89, Issue 9, id.094112 (PhRvB Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Static properties of condensates, thermodynamical statistical and structural properties, Quantum statistical mechanics, General studies of phase transitions, Ultracold gases trapped gases  
Abstract Copyright:  2014: American Physical Society  
DOI:  10.1103/PhysRevB.89.094112  
Bibliographic Code:  2014PhRvB..89i4112B 
Abstract
Recent advances in cold atom experimentation suggest that studies of quantum twodimensional melting of dipolar molecules, with dipoles aligned perpendicular to ordering plane, may be on the horizon. An intriguing aspect of this problem is that twodimensional classical aligned dipoles (already studied in great detail in soft matter experiments on magnetic colloids) are known to melt via a twostage process, with an intermediate hexatic phase separating the usual crystal and isotropic fluid phases. We estimate here the effect of quantum fluctuations on this hexatic phase, for both dipolar systems and charged Wigner crystals. Our approximate phase diagrams rely on a pair of Lindemann criteria, suitably adapted to deal with the effects of thermal fluctuations in two dimensions. As part of our analysis, we determine the phonon spectra of quantum particles on a triangular lattice interacting with repulsive 1/r3 and 1/r potentials. A large softening of the transverse and longitudinal phonon frequencies, due to both lattice effects and quantum fluctuations, plays a significant role in our analysis. The hexatic phase is predicted to survive down to very low temperatures.
Title:  Scaleinvariant hyperscalingviolating holographic theories and the resistivity of strange metals with randomfield disorder  
Authors:  Lucas, Andrew; Sachdev, Subir; Schalm, Koenraad  
Publication:  Physical Review D, Volume 89, Issue 6, id.066018 (PhRvD Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Gauge/string duality, Disordered solids  
Abstract Copyright:  2014: American Physical Society  
DOI:  10.1103/PhysRevD.89.066018  
Bibliographic Code:  2014PhRvD..89f6018L 
Abstract
We compute the directcurrent resistivity of a scaleinvariant, ddimensional strange metal with dynamic critical exponent z and hyperscalingviolating exponent θ, weakly perturbed by a scalar operator coupled to randomfield disorder that locally breaks a Z2 symmetry. Independent calculations via EinsteinMaxwell dilaton holography and memory matrix methods lead to the same results. We show that randomfield disorder has a strong effect on resistivity and leads to a short relaxation time for the total momentum. In the course of our holographic calculation, we use a nontrivial dilaton coupling to the disordered scalar, allowing us to study a strongly coupled scaleinvariant theory with θ ≠0. Using holography, we are also able to determine the disorder strength at which perturbation theory breaks down. Curiously, for locally critical theories, this breakdown occurs when the resistivity is proportional to the entropy density, up to a possible logarithmic correction.
Title:  Degreescale Cosmic Microwave Background Polarization Measurements from Three Years of BICEP1 Data  
Authors:  Barkats, D.; Aikin, R.; Bischoff, C.; Buder, I.; Kaufman, J. P.; Keating, B. G.; Kovac, J. M.;... and 27 coauthors  
Publication:  The Astrophysical Journal, Volume 783, Issue 2, article id. 67, 18 pp. (2014). (ApJ Homepage)  
Publication Date:  03/2014  
Origin:  IOP  
Astronomy Keywords:  cosmic background radiation, cosmology: observations, gravitational waves, inflation, polarization  
DOI:  10.1088/0004637X/783/2/67  
Bibliographic Code:  2014ApJ...783...67B 
Abstract
BICEP1 is a millimeterwavelength telescope designed specifically to measure the inflationary Bmode polarization of the cosmic microwave background at degree angular scales. We present results from an analysis of the data acquired during three seasons of observations at the South Pole (20062008). This work extends the twoyear result published in Chiang et al., with additional data from the third season and relaxed detectorselection criteria. This analysis also introduces a more comprehensive estimation of band power window functions, improved likelihood estimation methods, and a new technique for deprojecting monopole temperaturetopolarization leakage that reduces this class of systematic uncertainty to a negligible level. We present maps of temperature, E and Bmode polarization, and their associated angular power spectra. The improvement in the map noise level and polarization spectra error bars are consistent with the 52% increase in integration time relative to Chiang et al. We confirm both selfconsistency of the polarization data and consistency with the twoyear results. We measure the angular power spectra at 21 <= l <= 335 and find that the EE spectrum is consistent with Lambda cold dark matter cosmology, with the first acoustic peak of the EE spectrum now detected at 15σ. The BB spectrum remains consistent with zero. From Bmodes only, we constrain the tensortoscalar ratio to r = 0.03^{+0.27}_{0.23}, or r < 0.70 at 95% confidence level.
Title:  Measuring Distances and Reddenings for a Billion Stars: Toward a 3D Dust Map from PanSTARRS 1  
Authors:  Green, Gregory Maurice; Schlafly, Edward F.; Finkbeiner, Douglas P.; Jurić, Mario; Rix, HansWalter; Burgett, Will; Chambers, Kenneth C.; Draper, Peter W.; Flewelling, Heather; Kudritzki, Rolf Peter; Magnier, Eugene; Martin, Nicolas; Metcalfe, Nigel; Tonry, John; Wainscoat, Richard; Waters, Christopher  
Publication:  The Astrophysical Journal, Volume 783, Issue 2, article id. 114, 16 pp. (2014). (ApJ Homepage)  
Publication Date:  03/2014  
Origin:  IOP  
Astronomy Keywords:  dust, extinction, Galaxy: structure, ISM: structure, methods: statistical, stars: distances  
DOI:  10.1088/0004637X/783/2/114  
Bibliographic Code:  2014ApJ...783..114G 
Abstract
We present a method to infer reddenings and distances to stars based only on their broadband photometry, and show how this method can be used to produce a threedimensional (3D) dust map of the Galaxy. Our method samples from the full probability density function of distance, reddening, and stellar type for individual stars, as well as the full uncertainty in reddening as a function of distance in the 3D dust map. We incorporate prior knowledge of the distribution of stars in the Galaxy and the detection limits of the survey. For stars in the PanSTARRS 1 (PS1) 3π survey, we demonstrate that our reddening estimates are unbiased and accurate to ~0.13 mag in E(B  V) for the typical star. Based on comparisons with mock catalogs, we expect distances for mainsequence stars to be constrained to within ~20%60%, although this range can vary, depending on the reddening of the star, the precise stellar type, and its position on the sky. A later paper will present a 3D map of dust over the three quarters of the sky surveyed by PS1. Both the individual stellar inferences and the 3D dust map will enable a wealth of Galactic science in the plane. The method we present is not limited to the passbands of the PS1 survey but may be extended to incorporate photometry from other surveys, such as the Two Micron All Sky Survey, the Sloan Digital Sky Survey (where available), and in the future, LSST and Gaia.
Title:  Chargeexchange Coupling between Pickup Ions across the Heliopause and its Effect on Energetic Neutral Hydrogen Flux  
Authors:  Zirnstein, E. J.; Heerikhuisen, J.; Zank, G. P.; Pogorelov, N. V.; McComas, D. J.; Desai, M. I.  
Publication:  The Astrophysical Journal, Volume 783, Issue 2, article id. 129, 8 pp. (2014). (ApJ Homepage)  
Publication Date:  03/2014  
Origin:  IOP  
Astronomy Keywords:  ISM: atoms, ISM: bubbles, methods: numerical, solar wind, Sun: heliosphere  
DOI:  10.1088/0004637X/783/2/129  
Bibliographic Code:  2014ApJ...783..129Z 
Abstract
Pickup ions (PUIs) appear to play an integral role in the multicomponent nature of the plasma in the interaction between the solar wind (SW) and local interstellar medium (LISM). Threedimensional (3D) MHD simulations with a kinetic treatment for neutrals and PUIs are currently still not viable. In light of recent energetic neutral atom (ENA) observations by the Interstellar Boundary EXplorer, the purpose of this paper is to illustrate the complex coupling between PUIs across the heliopause (HP) as facilitated by ENAs using estimates of PUI properties extracted from a 3D MHD simulation of the SWLISM interaction with kinetic neutrals. First, we improve upon the multicomponent treatment of the inner heliosheath (IHS) plasma from Zank et al. by including the extinction of PUIs through chargeexchange. We find a significant amount of energy is transferred away from hot, termination shockprocessed PUIs into a colder, "freshly injected" PUI population. Second, we extend the multicomponent approach to estimate ENA flux from the outer heliosheath (OHS), formed from chargeexchange between interstellar hydrogen atoms and energetic PUIs. These PUIs are formed from ENAs in the IHS that crossed the HP and experienced chargeexchange. Our estimates, based on plasmaneutral simulations of the SWLISM interaction and a postprocessing analysis of ENAs and PUIs, suggest the majority of flux visible at 1 AU from the front of the heliosphere, between ~0.02 and 10 keV, originates from OHS PUIs, indicating strong coupling between the IHS and OHS plasmas through chargeexchange.
Title:  Improving dopant incorporation during femtosecondlaser doping of Si with a Se thinfilm dopant precursor  
Authors:  Smith, Matthew J.; Sher, MengJu; Franta, Benjamin; Lin, YuTing; Mazur, Eric; Gradečak, Silvija  
Publication:  Applied Physics A, Volume 114, Issue 4, pp.10091016 (ApPhA Homepage)  
Publication Date:  03/2014  
Origin:  SPRINGER  
Abstract Copyright:  (c) 2014: SpringerVerlag Berlin Heidelberg  
DOI:  10.1007/s0033901376738  
Bibliographic Code:  2014ApPhA.114.1009S 
Abstract
We study the dopant incorporation processes during thinfilm fslaser doping of Si and tailor the dopant distribution through optimization of the fslaser irradiation conditions. Scanning electron microscopy, transmission electron microscopy, and profilometry are used to study the interrelated dopant incorporation and surface texturing mechanisms during fslaser irradiation of Si coated with a Se thinfilm dopant precursor. We show that the crystallization of Sedoped Si and micrometerscale surface texturing are closely coupled and produce a doped surface that is not conducive to device fabrication. Next, we use this understanding of the dopant incorporation process to decouple dopant crystallization from surface texturing by tailoring the irradiation conditions. A lowfluence regime is identified in which a continuous surface layer of doped crystalline material forms in parallel with laserinduced periodic surface structures over many laser pulses. This investigation demonstrates the ability to tailor the dopant distribution through a systematic investigation of the relationship between fslaser irradiation conditions, microstructure, and dopant distribution.
Title:  Deformations with Maximal Supersymmetries Part 1: Onshell Formulation  
Authors:  Chang, ChiMing; Lin, YingHsuan; Wang, Yifan; Yin, Xi  
Publication:  eprint arXiv:1403.0545  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  High Energy Physics  Theory, Mathematical Physics  
Comment:  58 pages, new references are added  
Bibliographic Code:  2014arXiv1403.0545C 
Abstract
We study deformations of maximally supersymmetric gauge theories by higher dimensional operators in various spacetime dimensions. We classify infinitesimal deformations that preserve all 16 supersymmetries, while allowing the possibility of breaking either Lorentz or Rsymmetry, using an onshell algebraic method developed by Movshev and Schwarz. We also consider the problem of extending the deformation beyond the first order.
Title:  Dark Matter as a Trigger for Periodic Comet Impacts  
Authors:  Randall, Lisa; Reece, Matthew  
Publication:  eprint arXiv:1403.0576  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Astrophysics  Galaxy Astrophysics, Astrophysics  Earth and Planetary Astrophysics  
Comment:  Accepted by Physical Review Letters. 4 figures, no dinosaurs  
Bibliographic Code:  2014arXiv1403.0576R 
Abstract
Although statistical evidence is not overwhelming, possible support for an approximately 35 million year periodicity in the crater record on Earth could indicate a nonrandom underlying enhancement of meteorite impacts at regular intervals. A proposed explanation in terms of tidal effects on Oort cloud comet perturbations as the Solar System passes through the galactic midplane is hampered by lack of an underlying cause for sufficiently enhanced gravitational effects over a sufficiently short time interval and by the time frame between such possible enhancements. We show that a smooth dark disk in the galactic midplane would address both these issues and create a periodic enhancement of the sort that has potentially been observed. Such a disk is motivated by a novel dark matter component with dissipative cooling that we considered in earlier work. We show how to evaluate the statistical evidence for periodicity by input of appropriate measured priors from the galactic model, justifying or ruling out periodic cratering with more confidence than by evaluating the data without an underlying model. We find that, marginalizing over astrophysical uncertainties, the likelihood ratio for such a model relative to one with a constant cratering rate is 3.0, which moderately favors the dark disk model. Our analysis furthermore yields a posterior distribution that, based on current crater data, singles out a dark matter disk surface density of approximately 10 solar masses per square parsec. The geological record thereby motivates a particular model of dark matter that will be probed in the near future.
Title:  Interferometric probes of manybody localization  
Authors:  Serbyn, M.; Knap, M.; Gopalakrishnan, S.; Papić, Z.; Yao, N. Y.; Laumann, C. R.; Abanin, D. A.; Lukin, M. D.; Demler, E. A.  
Publication:  eprint arXiv:1403.0693  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Condensed Matter  Disordered Systems and Neural Networks, Condensed Matter  Quantum Gases, Condensed Matter  Statistical Mechanics  
Comment:  5 pages, 4 figures  
Bibliographic Code:  2014arXiv1403.0693S 
Abstract
We propose a method for detecting manybody localization (MBL) in disordered spin systems. The method involves pulsed, coherent spin manipulations that probe the dephasing of a given spin due to its entanglement with a set of distant spins. It allows one to distinguish the MBL phase from a noninteracting localized phase and a delocalized phase. In particular, we show that for a properly chosen pulse sequence the MBL phase exhibits a characteristic powerlaw decay reflecting its slow growth of entanglement. We find that this powerlaw decay is robust with respect to thermal and disorder averaging, provide numerical simulations supporting our results, and discuss possible experimental realizations in solidstate and cold atom systems.
Title:  Deformations with Maximal Supersymmetries Part 2: Offshell Formulation  
Authors:  Chang, ChiMing; Lin, YingHsuan; Wang, Yifan; Yin, Xi  
Publication:  eprint arXiv:1403.0709  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  High Energy Physics  Theory  
Comment:  36 pages, new references are added  
Bibliographic Code:  2014arXiv1403.0709C 
Abstract
Continuing our exploration of maximally supersymmetric gauge theories (MSYM) deformed by higher dimensional operators, in this paper we consider an offshell approach based on pure spinor superspace and focus on constructing supersymmetric deformations beyond the first order. In particular, we give a construction of the BatalinVilkovisky action of an allorder nonAbelian BornInfeld deformation of MSYM in the nonminimal pure spinor formalism. We also discuss subtleties in the integration over the pure spinor superspace and the relevance of BerkovitsNekrasov regularization.
Title:  Combined analysis of $\nu_{\mu}$ disappearance and $\nu_{\mu} \rightarrow \nu_{e}$ appearance in MINOS using accelerator and atmospheric neutrinos  
Authors:  MINOS Collaboration; Adamson, P.; Anghel, I.; Aurisano, A.;... Feldman, G. J.;... ; and 109 coauthors  
Publication:  eprint arXiv:1403.0867  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  High Energy Physics  Experiment, High Energy Physics  Phenomenology  
Comment:  6 pages, 2 figures  
Bibliographic Code:  2014arXiv1403.0867M 
Abstract
We report on a new analysis of neutrino oscillations in MINOS using the complete set of accelerator and atmospheric data. The analysis combines the $\nu_{\mu}$ disappearance and $\nu_{e}$ appearance data using the threeflavor formalism. We measure $\Delta m^{2}_{32}=[2.282.46]\times10^{3}\mbox{\,eV}^{2}$ (68% C.L.) and $\sin^{2}\theta_{23}=0.350.65$ (90% C.L.) in the normal hierarchy, and $\Delta m^{2}_{32}=[2.322.53]\times10^{3}\mbox{\,eV}^{2}$ (68% C.L.) and $\sin^{2}\theta_{23}=0.340.67$ (90% C.L.) in the inverted hierarchy. The data also constrain $\delta_{CP}$, the $\theta_{23}$ octant degeneracy and the mass hierarchy; we disfavor 36% (11%) of this threeparameter space at 68% (90%) C.L.
Title:  Effective field theory and keV lines from dark matter  
Authors:  Krall, Rebecca; Reece, Matthew; Roxlo, Thomas  
Publication:  eprint arXiv:1403.1240  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  High Energy Physics  Phenomenology  
Bibliographic Code:  2014arXiv1403.1240K 
Abstract
We survey operators that can lead to a keV photon line from dark matter decay or annihilation. We are motivated in part by recent claims of an unexplained 3.5 keV line in galaxy clusters and in Andromeda, but our results could apply to any hypothetical line observed in this energy range. We find that given the amount of flux that is observable, explanations in terms of decay are more plausible than annihilation, at least if the annihilation is directly to Standard Model states rather than intermediate particles. The decay case can be explained by a scalar or pseudoscalar field coupling to photons suppressed by a scale not far below the reduced Planck mass, which can be taken as a tantalizing hint of highscale physics. The scalar case is particularly interesting from the effective field theory viewpoint, and we discuss it at some length. Because of a quartically divergent mass correction, naturalness strongly suggests the theory should be cut off at or below the 1000 TeV scale. The most plausible such natural UV completion would involve supersymmetry. These bottomup arguments reproduce expectations from topdown considerations of the physics of moduli. A keV line could also arise from the decay of a sterile neutrino, in which case a renormalizable UV completion exists and no direct inference about highscale physics is possible.
Title:  Extremal Bundles on CalabiYau Threefolds  
Authors:  Gao, Peng; He, YangHui; Yau, ShingTung  
Publication:  eprint arXiv:1403.1268  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  High Energy Physics  Theory, Mathematics  Algebraic Geometry  
Comment:  49 pages, 24 figures; minor errors corrected  
Bibliographic Code:  2014arXiv1403.1268G 
Abstract
We study constructions of stable holomorphic vector bundles on CalabiYau threefolds, especially those with exact anomaly cancellation which we call extremal. By going through the known databases we find that such examples are rare in general and can be ruled out for the spectral cover construction for all elliptic threefolds. We then introduce a generalized version of HartshorneSerre construction and use it to yield extremal bundles of general ranks and study their geometry. In light of this probing the geometry of the space of stable vector bundles, we revisit the DRY conjecture on stable reflexive sheaves while focusing on the distribution of Chern numbers to use both theoretical and statistical ideas to provide evidence for DRY.
Title:  Tunable Fractional Quantum Hall Phases in Bilayer Graphene  
Authors:  Maher, Patrick; Wang, Lei; Gao, Yuanda; Forsythe, Carlos; Taniguchi, Takashi; Watanabe, Kenji; Abanin, Dmitry; Papić, Zlatko; CaddenZimansky, Paul; Hone, James; Kim, Philip; Dean, Cory R.  
Publication:  eprint arXiv:1403.2112  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Condensed Matter  Mesoscale and Nanoscale Physics  
Bibliographic Code:  2014arXiv1403.2112M 
Abstract
Symmetry breaking in a quantum system often leads to complex emergent behavior. In bilayer graphene (BLG), an electric field applied perpendicular to the basal plane breaks the inversion symmetry of the lattice, opening a band gap at the charge neutrality point. In a quantizing magnetic field electron interactions can cause spontaneous symmetry breaking within the spin and valley degrees of freedom, resulting in quantum Hall states (QHS) with complex order. Here we report fractional quantum Hall states (FQHS) in bilayer graphene which show phase transitions that can be tuned by a transverse electric field. This result provides a model platform to study the role of symmetry breaking in emergent states with distinct topological order.
Title:  Measurement of the ZZ production cross section using the full CDF II data set  
Authors:  CDF Collaboration; Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... Guimaraes da Costa, J.;... and 402 coauthors  
Publication:  eprint arXiv:1403.2300  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  High Energy Physics  Experiment  
Comment:  13 pages, 7 figures. To be submitted to Phys. Rev. D  
Bibliographic Code:  2014arXiv1403.2300C 
Abstract
We present a measurement of the ZZ bosonpair production cross section in 1.96 TeV centerofmass energy ppbar collisions. We reconstruct final states incorporating four charged leptons or two charged leptons and two neutrinos from the full data set collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.7 fb1 of integrated luminosity. Combining the results obtained from each final state, we measure a cross section of 1.04(+0.32)(0.25) pb, in good agreement with the standard model prediction at nexttoleading order in the stronginteraction coupling.
Title:  Revealing topological superconductivity in extended quantum spin Hall Josephson junctions  
Authors:  Lee, ShuPing; Michaeli, Karen; Alicea, Jason; Yacoby, Amir  
Publication:  eprint arXiv:1403.2747  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Condensed Matter  Superconductivity, Condensed Matter  Mesoscale and Nanoscale Physics  
Comment:  8 pages, 6 figures  
Bibliographic Code:  2014arXiv1403.2747L 
Abstract
Quantum spin Hallsuperconductor hybrids are promising sources of topological superconductivity and Majorana modes, particularly given recent progress on HgTe and InAs/GaSb. We propose a new method of revealing topological superconductivity in extended quantum spin Hall Josephson junctions supporting `fractional Josephson currents'. Specifically, we show that as one threads magnetic flux between the superconductors, the critical current traces an interference pattern featuring sharp fingerprints of topological superconductivityeven when noise spoils parity conservation.
Title:  Gravity Waves from ExtremeMassRatio Plunges into Kerr Black Holes  
Authors:  Hadar, Shahar; Porfyriadis, Achilleas P.; Strominger, Andrew  
Publication:  eprint arXiv:1403.2797  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  High Energy Physics  Theory, General Relativity and Quantum Cosmology  
Comment:  20 pages, 1 figure  
Bibliographic Code:  2014arXiv1403.2797H 
Abstract
Massive objects orbiting a nearextreme Kerr black hole quickly plunge into the horizon after passing the innermost stable circular orbit. The plunge trajectory is shown to be related by a conformal map to a circular orbit. Conformal symmetry of the nearhorizon region is then used to compute the gravitational radiation produced during the plunge phase.
Title:  Atomically thin pn junctions with van der Waals heterointerfaces  
Authors:  Lee, ChulHo; Lee, GwanHyoung; van der Zande, Arend M.; Chen, Wenchao; Li, Yilei; Han, Minyong; Cui, Xu; Arefe, Ghidewon; Nuckolls, Colin; Heinz, Tony F.; Guo, Jing; Hone, James; Kim, Philip  
Publication:  eprint arXiv:1403.3062  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Condensed Matter  Mesoscale and Nanoscale Physics  
Comment:  29 pages, 3 figures in main & 10 figures in supplementary information  
Bibliographic Code:  2014arXiv1403.3062L 
Abstract
Semiconductor pn junctions are essential building blocks for modern electronics and optoelectronics. In conventional semiconductors, a pn junction produces depletion regions of free charge carriers at equilibrium and builtin potentials associated with uncompensated dopant atoms. Carrier transport across the junction occurs by diffusion and drift processes defined by the spatial extent of this region. With the advent of atomically thin van der Waals (vdW) materials and their heterostructures, we are now able to realize a pn junction at the ultimate quantum limit. In particular, vdW junctions composed of p and ntype semiconductors each just one unit cell thick are predicted to exhibit completely different charge transport characteristics than bulk junctions. Here we report the electronic and optoelectronic characterization of atomically thin pn heterojunctions fabricated using vdW assembly of transition metal dichalcogenides (TMDCs). Across the pn interface, we observe gatetuneable diodelike current rectification and photovoltaic response. We find that the tunnellingassisted interlayer recombination of the majority carriers is responsible for the tunability of the electronic and optoelectronic processes. Sandwiching an atomic pn junction between graphene layers enhances collection of the photoexcited carriers. The atomically scaled vdW pn heterostructures presented here constitute the ultimate quantum limit for functional electronic and optoelectronic components.
Title:  A Large Catalog of Accurate Distances to Molecular Clouds from PS1 Photometry  
Authors:  Schlafly, E. F.; Green, G.; Finkbeiner, D. P.; Rix, H.W.; Bell, E. F.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Hodapp, K. W.; Kaiser, N.; Magnier, E. A.; Martin, N. F.; Metcalfe, N.; Price, P. A.; Tonry, J. L.  
Publication:  eprint arXiv:1403.3393  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Astrophysics  Galaxy Astrophysics  
Comment:  16 pages, 4 figures  
Bibliographic Code:  2014arXiv1403.3393S 
Abstract
Distance measurements to molecular clouds are important, but are often made separately for each cloud of interest, employing very different different data and techniques. We present a large, homogeneous catalog of distances to molecular clouds, most of which are of unprecedented accuracy. We determine distances using optical photometry of stars along lines of sight toward these clouds, obtained from PanSTARRS1. We simultaneously infer the reddenings and distances to these stars, tracking the full probability distribution function using a technique presented in Green et al. (2014). We fit these starbystar measurements using a simple dust screen model to find the distance to each cloud. We thus estimate the distances to almost all of the clouds in the Magnani et al. (1985) catalog, as well as many other wellstudied clouds, including Orion, Perseus, Taurus, Cepheus, Polaris, California, and Monoceros R2, avoiding only the inner Galaxy. Typical statistical uncertainties in the distances are 5%, though the systematic uncertainty stemming from the quality of our stellar models is about 10%. The resulting catalog is the largest catalog of accurate, directlymeasured distances to molecular clouds. Our distance estimates are generally consistent with available distance estimates from the literature, though in some cases the literature estimates are off by a factor of more than two.
Title:  Are nonFermiliquids stable to Cooper pairing?  
Authors:  Metlitski, Max A.; Mross, David F.; Sachdev, Subir; Senthil, T.  
Publication:  eprint arXiv:1403.3694  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Condensed Matter  Strongly Correlated Electrons  
Comment:  16 pages, 7 figures  
Bibliographic Code:  2014arXiv1403.3694M 
Abstract
States of matter with a sharp Fermisurface but no welldefined Landau quasiparticles arise in a number of physical systems. Examples include: ${\it (i)}$ quantum critical points associated with the onset of order in metals; ${\it (ii)}$ spinon Fermisurface (U(1) spinliquid) state of a Mott insulator; ${\it (iii)}$ HalperinLeeRead composite fermion charge liquid state of a halffilled Landau level. In this work, we use renormalization group techniques to investigate possible instabilities of such nonFermiliquids in two spatial dimensions to Cooper pairing. We consider the Isingnematic quantum critical point as an example of a phase transition in a metal, and demonstrate that the attractive interaction mediated by the order parameter fluctuations always leads to a superconducting instability. Moreover, in the regime where our calculation is controlled, superconductivity preempts the destruction of electronic quasiparticles. On the other hand, the spinon Fermisurface and the HalperinLeeRead states are stable against Cooper pairing for a sufficiently weak attractive shortrange interaction; however, once the strength of attraction exceeds a critical value, pairing sets in. We describe the ensuing quantum phase transition between ${\it (i)}$ $U(1)$ and $Z_2$ spinliquid states; ${\it (ii)}$ HalperinLeeRead and MooreRead states.
Title:  BICEP2 I: Detection Of Bmode Polarization at Degree Angular Scales  
Authors:  BICEP2 Collaboration; Ade, P. A. R; Aikin, R. W.; Barkats, D.; Benton, S. J.;... Kovac, J. M.;... and 43 coauthors  
Publication:  eprint arXiv:1403.3985  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Astrophysics  Cosmology and Extragalactic Astrophysics, General Relativity and Quantum Cosmology, High Energy Physics  Phenomenology, High Energy Physics  Theory  
Comment:  19 pages, 14 figures  
Bibliographic Code:  2014arXiv1403.3985B 
Abstract
We report results from the BICEP2 experiment, a Cosmic Microwave Background (CMB) polarimeter specifically designed to search for the signal of inflationary gravitational waves in the Bmode power spectrum around l=80. The telescope comprised a 26 cm aperture allcold refracting optical system equipped with a focal plane of 512 antenna coupled transition edge sensor (TES) 150 GHz bolometers each with temperature sensitivity of approx. 300 uk.sqrt(s). BICEP2 observed from the South Pole for three seasons from 2010 to 2012. A lowforeground region of sky with an effective area of 380 square degrees was observed to a depth of 87 nKdegrees in Stokes Q and U. In this paper we describe the observations, data reduction, maps, simulations and results. We find an excess of Bmode power over the base lensedLCDM expectation in the range 30<l<150, inconsistent with the null hypothesis at a significance of $>5\sigma$. Through jackknife tests and simulations based on detailed calibration measurements we show that systematic contamination is much smaller than the observed excess. We also estimate potential foreground signals and find that available models predict these to be considerably smaller than the observed signal. These foreground models possess no significant crosscorrelation with our maps. Additionally, crosscorrelating BICEP2 against 100 GHz maps from the BICEP1 experiment, the excess signal is confirmed with $3\sigma$ significance and its spectral index is found to be consistent with that of the CMB, disfavoring synchrotron or dust at $2.3\sigma$ and $2.2\sigma$, respectively. The observed Bmode power spectrum is wellfit by a lensedLCDM + tensor theoretical model with tensor/scalar ratio $r=0.20^{+0.07}_{0.05}$, with r=0 disfavored at $7.0\sigma$. Subtracting the best available estimate for foreground dust modifies the likelihood slightly so that r=0 is disfavored at $5.9\sigma$.
Title:  Kramers Pairs of Majorana Fermions and Parafermions in Fractional Topological Insulators  
Authors:  Klinovaja, Jelena; Yacoby, Amir; Loss, Daniel  
Publication:  eprint arXiv:1403.4125  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Condensed Matter  Mesoscale and Nanoscale Physics  
Bibliographic Code:  2014arXiv1403.4125K 
Abstract
We propose a scheme based on topological insulators to generate Kramers pairs of Majorana fermions or parafermions in the complete absence of magnetic fields. Our setup consists of two topological insulators whose edge states are brought close to an swave superconductor. The resulting proximity effect leads to an interplay between a nonlocal crossed Andreev pairing, which is dominant in the strong electronelectron interaction regime, and usual superconducting pairing, which is dominant at large separation between the two topological insulator edges. As a result, there are zeroenergy bound states localized at interfaces between spatial regions dominated by the two different types of pairing. Due to the preserved timereversal symmetry, the bound states come in Kramers pairs. If the topological insulators carry fractional edge states, the zeroenergy bound states are parafermions, otherwise, they are Majorana fermions.
Title:  Multiepoch spectropolarimetry of SN 2009ip: direct evidence for aspherical circumstellar material  
Authors:  Mauerhan, Jon C.; Williams, G. Grant; Smith, Nathan; Smith, Paul S.; Filippenko, Alexei V.; Hoffman, Jennifer L.; Leonard, Douglas C.; Milne, Peter; Clubb, Kelsey I.; Fox, Ori D.; Kelly, Patrick L.  
Publication:  eprint arXiv:1403.4240  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Astrophysics  Solar and Stellar Astrophysics, Astrophysics  Galaxy Astrophysics  
Comment:  submitted to MNRAS 2014 March 16. 15 pages, 10 figures  
Bibliographic Code:  2014arXiv1403.4240M 
Abstract
We present spectropolarimetry of SN 2009ip throughout the evolution of its 2012 explosion. During the initial 2012a phase, when the source spectrum exhibits broad PCygni lines, we measure a Vband polarization of P~0.9% at a position angle of ~166 deg, indicating substantial asphericity for the 2012a outflow. Near the subsequent peak of the 2012b phase, when the spectrum shows signs of intense interaction with circumstellar material (CSM), we measure P~1.7% at a position angle of 72 deg, indicating a separate physical component of polarization, which has a higher degree of asphericity than the 2012a outflow and an orthogonal axis of symmetry on the sky. Around 30 days past peak, which is coincident with a bump in the declining light curve, we measure P~0.7% and significant variations in P across some broad lines, particularly HeI/NaI. By 60 days past peak the source appears to be approaching a low value of interstellar polarization (P<0.2%). The results are consistent with a scenario in which a potentially bipolar explosion during 2012a impacts a toroidal distribution of CSM, thereby causing the 2012b brightening. Orthogonality between the 2012a and 2012b geometries is inconsistent with the hypothesis that the 2012a event launched the CSM that was hit 40 days later by material from the 2012b event. Rather, the aspherical CSM probably has a separate origin associated with the outbursts of the stellar progenitor during prior years. Previous calculations that assumed spherical symmetry for the CSM have underestimated the required explosion energy, as the results suggest that <10% of the fast SN ejecta participated in strong CSM interaction during the 2012b phase. In light of the spectropolarimetric results, a kinetic energy of 1e51 erg for the ejecta is difficult to avoid, supporting the interpretation that the 2012 outburst was the result of a corecollapse supernova explosion (abridged).
Title:  Stabilizing the false vacuum: Mott skyrmions  
Authors:  KanászNagy, Márton; Dóra, Balázs; Demler, Eugene A.; Zaránd, Gergely  
Publication:  eprint arXiv:1403.4242  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Condensed Matter  Quantum Gases, Physics  Atomic Physics, Quantum Physics  
Comment:  11 pages, 6 figures  
Bibliographic Code:  2014arXiv1403.4242K 
Abstract
Topological excitations keep fascinating physicists since many decades. While individual vortices and solitons emerge and have been observed in many areas of physics, their most intriguing higher dimensional topological relatives, skyrmions (smooth, topologically stable textures) and magnetic monopoles  emerging almost necessarily in any grand unified theory and responsible for charge quantization  remained mostly elusive. Here we propose that loading a threecomponent nematic superfluid such as $^{23}$Na into a deep optical lattice and thereby creating an insulating core, one can create topologically stable skyrmion textures and investigate their properties in detail. We show furthermore that the spectrum of the excitations of the superfluid and their quantum numbers change dramatically in the presence of the skyrmion, and they reflect the presence of a trapped monopole, as imposed by the skyrmion's topology.
Title:  BICEP2 II: Experiment and ThreeYear Data Set  
Authors:  BICEP2 Collaboration; Ade, P. A. R; Aikin, R. W.; Amiri, M.;... Kovac, J. M.;... and 47 coauthors  
Publication:  eprint arXiv:1403.4302  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Astrophysics  Cosmology and Nongalactic Astrophysics, Astrophysics  Instrumentation and Methods for Astrophysics  
Comment:  29 pages, 24 figures  
Bibliographic Code:  2014arXiv1403.4302B 
Abstract
The BICEP2 instrument was designed to measure the polarization of the cosmic microwave background (CMB) on angular scales of 1 to 5 degrees ($\ell$=40200), near the expected peak of the Bmode polarization signature of primordial gravitational waves from cosmic inflation. Measuring Bmodes requires dramatic improvement in sensitivity combined with exquisite control of systematics. We have built on the successful strategy of BICEP1, which achieved the most sensitive limit on Bmodes at these scales. The telescope had a 26 cm aperture and cold, onaxis, refractive optics, and it observed from a threeaxis mount at the South Pole. BICEP2 adopted a new detector design in which beamdefining slot antenna arrays couple to transitionedge sensor (TES) bolometers, all fabricated monolithically on a common substrate. BICEP2 took advantage of this design's scalable fabrication and multiplexed SQUID readout to field more detectors than BICEP1, improving mapping speed by more than a factor of ten. In this paper we report on the design and performance of the instrument and on the threeyear data set. BICEP2 completed three years of observation with 500 detectors at 150 GHz. After optimization of detector and readout parameters BICEP2 achieved an instrument noise equivalent temperature of 15.8 $\mu$K sqrt(s) and the full data set reached Stokes Q and U map depths of 87.8 nK in squaredegree pixels (5.3 $\mu$K arcmin) over an effective area of 390.3 square degrees within a 1000 square degree field. These are the deepest CMB polarization maps at degree angular scales.
Title:  Multiple Scattering and Plasmon Resonance in the Intermediate Regime  
Authors:  Liu, Bo; Heller, Eric J.  
Publication:  eprint arXiv:1403.4310  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Condensed Matter  Mesoscale and Nanoscale Physics, Physics  Optics  
Bibliographic Code:  2014arXiv1403.4310L 
Abstract
The collective excitation of the conduction electrons in subwavelength structures gives rise to the Localized Surface Plasmon(LSP). The system consisting of two such LSPs, known as the dimer system,is of fundamental interest and is being actively investigated in the literature. Three regimes have been previously identified and they are the photonic regime, the strong coupling regime and the quantum tunneling regime. In this Letter, we propose a new regime for this intriguing systems, the intermediate regime. In this new regime, the quasistatic approximation, which is widely used to study such LSP systems, fails to capture the main physics: the multiple scattering of the electromagnetic waves between the two LSPs, which significantly modifies the properties of the resonant modes in the system. This intermediate regime provides a new route to explore in plasmonics, where controlling both the excited plasmon modes and the damping rates are of paramount significance.
Title:  Phase diagram and excitations of a Shiba molecule  
Authors:  Yao, N. Y.; Moca, C. P.; Weymann, I.; Sau, J. D.; Lukin, M. D.; Demler, E. A.; Zaránd, G.  
Publication:  eprint arXiv:1403.4611  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Condensed Matter  Superconductivity, Condensed Matter  Mesoscale and Nanoscale Physics, Condensed Matter  Strongly Correlated Electrons  
Comment:  13 pages, 7 figures  
Bibliographic Code:  2014arXiv1403.4611Y 
Abstract
We analyze the phase diagram associated with a pair of magnetic impurities trapped in a superconducting host. The natural interplay between Kondo screening, superconductivity and exchange interactions leads to a rich array of competing phases, whose transitions are characterized by discontinuous changes of the total spin. Our analysis is based on a combination of numerical renormalization group techniques as well as semiclassical analytics. In addition to the expected screened and unscreened phases, we observe a new molecular doublet phase where the impurity spins are only partially screened by a single extended quasiparticle. Direct signatures of the various Shiba molecule states can be observed via RF spectroscopy.
Title:  Bright and fast voltage reporters across the visible spectrum via electrochromic FRET (eFRET)  
Authors:  Zou, Peng; Zhao, Yongxin; Douglass, Adam D.; Hochbaum, Daniel R.; Brinks, Daan; Werley, Christopher A.; Jed Harrison, D.; Campbell, Robert E.; Cohen, Adam E.  
Publication:  eprint arXiv:1403.4636  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Quantitative Biology  Biomolecules, Physics  Biological Physics, Quantitative Biology  Neurons and Cognition  
Comment:  * Denotes equal contribution. For correspondence regarding the library screen: robert.e.campbell@ualberta.ca; For other correspondence: cohen@chemistry.harvard.edu  
Bibliographic Code:  2014arXiv1403.4636Z 
Abstract
We present a palette of brightly fluorescent genetically encoded voltage indicators (GEVIs) with excitation and emission peaks spanning the visible spectrum, sensitivities from 6  10% Delta F/F per 100 mV, and halfmaximal response times from 1  7 ms. A fluorescent protein is fused to an Archaerhodopsinderived voltage sensor. Voltageinduced shifts in the absorption spectrum of the rhodopsin lead to voltagedependent nonradiative quenching of the appended fluorescent protein. Through a library screen, we identified linkers and fluorescent protein combinations which reported neuronal action potentials in cultured rat hippocampal neurons with a singletrial signaltonoise ratio from 6.6 to 11.6 in a 1 kHz imaging bandwidth at modest illumination intensity. The freedom to choose a voltage indicator from an array of colors facilitates multicolor voltage imaging, as well as combination with other optical reporters and optogenetic actuators.
Title:  Nonglobal Logarithms at 3 Loops, 4 Loops, 5 Loops and Beyond  
Authors:  Schwartz, Matthew D.; Zhu, Hua Xing  
Publication:  eprint arXiv:1403.4949  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  High Energy Physics  Phenomenology, High Energy Physics  Theory  
Comment:  42 pages, 6 figures  
Bibliographic Code:  2014arXiv1403.4949S 
Abstract
We calculate the coefficients of the leading nonglobal logarithms for the hemisphere mass distribution analytically at 3, 4, and 5 loops at large Nc . We confirm that the integrand derived with the strongenergyordering approximation and fixedorder iteration of the BanfiMarchesiniSyme (BMS) equation agree. Our calculation exploits a hidden PSL(2,R) symmetry associated with the jet directions, apparent in the BMS equation after a stereographic projection to the Poincare disk. The required integrals have an iterated form, leading to functions of uniform transcendentality. This allows us to extract the coefficients, and some functional dependence on the jet directions, by computing the symbols and coproducts of appropriate expressions involving classical and Goncharov polylogarithms. Convergence of the series to a numerical solution of the BMS equation is also discussed.
Title:  Measurements of Direct CPViolating Asymmetries in Charmless Decays of Bottom Baryons  
Authors:  CDF Collaboration; Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... Guimaraes da Costa, J.;... and 402 coauthors  
Publication:  eprint arXiv:1403.5586  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  High Energy Physics  Experiment  
Comment:  8 pages, 2 figures, 1 table. Submitted to Phys.Rev.Lett  
Bibliographic Code:  2014arXiv1403.5586C 
Abstract
We report final measurements of direct $\mathit{CP}$violating asymmetries in charmless decays of neutral bottom hadrons to pairs of charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using the complete $\sqrt{s}=1.96$ TeV protonantiproton collisions data set, corresponding to \mbox{9.3 fb$^{1}$} of integrated luminosity, we measure $\mathcal{A}(\Lambda^0_b \rightarrow p\pi^{}) = +0.06 \pm 0.07\mathrm{(stat)} \pm 0.03\mathrm{(syst)}$ and $\mathcal{A}(\Lambda^0_b \rightarrow pK^{}) = 0.10 \pm 0.08\mathrm{(stat)} \pm 0.04\mathrm{(syst)}$, compatible with no asymmetry. In addition we measure the $\mathit{CP}$violating asymmetries in $B^0_s \rightarrow K^{}\pi^{+}$ and $B^0 \rightarrow K^{+}\pi^{}$ decays to be $\mathcal{A}(B^0_s \rightarrow K^{}\pi^{+}) = +0.22 \pm 0.07\mathrm{stat)} \pm 0.02\mathrm{(syst)}$ and $\mathcal{A}(B^0 \rightarrow K^{+}\pi^{}) = 0.083\pm 0.013 \mathrm{(stat)} \pm 0.004\mathrm{(syst)}$, respectively, which are significantly different from zero and consistent with current world averages.
Title:  HardSoftCollinear Factorization to All Orders  
Authors:  Feige, Ilya; Schwartz, Matthew D.  
Publication:  eprint arXiv:1403.6472  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  High Energy Physics  Phenomenology  
Bibliographic Code:  2014arXiv1403.6472F 
Abstract
We provide a precise statement of hardsoftcollinear factorization of scattering amplitudes and prove it to all orders in perturbation theory. Factorization is formulated as the equality at leading power of scattering amplitudes in QCD with other amplitudes in QCD computed from a product of operator matrix elements. The equivalence is regulator independent and gauge independent. As the formulation relates amplitudes to the same amplitudes with additional soft or collinear particles, it includes as special cases the factorization of soft currents and collinear splitting functions from generic matrix elements, both of which are shown to be process independent to all orders. We show that the overlapping softcollinear region is naturally accounted for by vacuum matrix elements of kinked Wilson lines. Although the proof is selfcontained, it combines techniques developed for the study of pinch surfaces, scattering amplitudes, and effective field theory.
Title:  Poisson metrics on flat vector bundles over noncompact curves  
Authors:  Collins, Tristan C.; Jacob, Adam; Yau, ShingTung  
Publication:  eprint arXiv:1403.7825  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  Mathematics  Differential Geometry  
Comment:  55 pages  
Bibliographic Code:  2014arXiv1403.7825C 
Abstract
Let (E,D,P) be a flat vector bundle with a parabolic structure over a punctured Riemann surface, (M,g). We consider a deformation of the harmonic metric equation which we call the Poisson metric equation. This equation arises naturally as the dimension reduction of the HermitianYangMills equation for holomorphic vector bundles on K3 surfaces in the large complex structure limit. We define a notion of slope stability, and show that if the flat connection D has regular singularities, and the Riemannian metric g has finite volume then E admits a Poisson metric with asymptotics determined by the parabolic structure if and only if (E,D,P) is slope polystable.
Title:  Mass and lifetime measurements of bottom and charm baryons in $p\bar p$ collisions at $\sqrt{s}= 1.96 TeV  
Authors:  CDF Collaboration; Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... Guimaraes da Costa, J.;... and 402 coauthors  
Publication:  eprint arXiv:1403.8126  
Publication Date:  03/2014  
Origin:  ARXIV  
Keywords:  High Energy Physics  Experiment  
Bibliographic Code:  2014arXiv1403.8126C 
Abstract
We report on mass and lifetime measurements of several ground state charmed and bottom baryons, using a data sample corresponding to 9.6 $\textrm{fb}^{1}$ from $p\bar p$ collisions at $\sqrt{s}=1.96$ TeV, and recorded with the Collider Detector at Fermilab. Baryon candidates are reconstructed from data collected with an online event selection designed for the collection of longlifetime heavyflavor decay products and a second event selection designed to collect $J/\psi \rightarrow \mu^+ \, \mu^$ candidates. First evidence for the process $\Omega_b^ \rightarrow \Omega_c^0 \, \pi^$ is presented with a significance of $3.3\sigma$. We measure the following baryon masses: \begin{eqnarray} M(\Xi_c^{0}) = 2470.85\pm0.24(stat)\pm0.55(syst) \, MeV/c^2, \nonumber M(\Xi_c^{+}) = 2468.00\pm0.18(stat)\pm0.51(syst) \, MeV/c^2, \nonumber \\ M(\Lambda_b) = 5620.15\pm0.31(stat)\pm0.47(syst) \, MeV/c^2, \nonumber \\ M(\Xi_b^) = 5793.4\pm1.8(stat)\pm0.7(syst) \, MeV/c^2, \nonumber \\ M(\Xi_b^0) = 5788.7\pm4.3(stat)\pm1.4(syst) \, MeV/c^2, \, and \nonumber \\ M(\Omega_b^) = 6047.5\pm3.8(stat)\pm0.6(syst) \, MeV/c^2. \nonumber \end{eqnarray} The isospin splitting of the $\Xi_b^{,0}$ states is found to be $M(\Xi_b^)M(\Xi_b^0)=4.7\pm4.7(stat)\pm0.7(syst)$ MeV/$c^2$. The isospin splitting of the $\Xi_c^{0,+}$ states is found to be $M(\Xi_c^0)M(\Xi_c^+)$ = $2.85\pm0.30(stat)\pm0.04(syst)$ MeV/$c^2$. The following lifetime measurements are made: \begin{eqnarray} \tau(\Lambda_b) = 1.565\pm0.035(stat)\pm0.020(syst) \, ps, \nonumber \\ \tau(\Xi_b^) = 1.32\pm0.14(stat)\pm0.02(syst) \, ps, \nonumber \\ \tau(\Omega_b^) = 1.66^{+0.53}_{0.40}(stat)\pm0.02(syst) \, ps. \nonumber \end{eqnarray}.
Title:  Generalized Cohomologies and Supersymmetry  
Authors:  Tseng, LiSheng; Yau, ShingTung  
Publication:  Communications in Mathematical Physics, Volume 326, Issue 3, pp.875885  
Publication Date:  03/2014  
Origin:  SPRINGER  
Abstract Copyright:  (c) 2014: SpringerVerlag Berlin Heidelberg  
DOI:  10.1007/s0022001418952  
Bibliographic Code:  2014CMaPh.326..875T 
Abstract
We show that the complex cohomologies of Bott, Chern, and Aeppli and the symplectic cohomologies of Tseng and Yau arise in the context of type II string theory. Specifically, they can be used to count a subset of scalar moduli fields in Minkowski compactification with RR fluxes in the presence of either O5/ D5 or O6/ D6 brane sources, respectively. Further, we introduce a new set of cohomologies within the generalized complex geometry framework which interpolate between these known complex and symplectic cohomologies. The generalized complex cohomologies play the analogous role for counting massless fields for a general supersymmetric Minkowski type II compactification with RamondRamond flux.
Title:  Harmonically trapped twoatom systems: Interplay of shortrange swave interaction and spinorbit coupling  
Authors:  Yin, X. Y.; Gopalakrishnan, S.; Blume, D.  
Publication:  Physical Review A, Volume 89, Issue 3, id.033606 (PhRvA Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Multicomponent condensates, spinor condensates, Fermion systems and electron gas, Boson systems, Multicomponent condensates, spinor condensates  
Abstract Copyright:  2014: American Physical Society  
DOI:  10.1103/PhysRevA.89.033606  
Bibliographic Code:  2014PhRvA..89c3606Y 
Abstract
The coupling between the spin degrees of freedom and the orbital angular momentum has a profound effect on the properties of nuclei, atoms, and condensedmatter systems. Recently, synthetic gauge fields have been realized experimentally in neutral coldatom systems, giving rise to a spinorbit coupling term with "strength" kso. This paper investigates the interplay between the singleparticle spinorbit coupling term of Rashba type and the shortrange twobody swave interaction for cold atoms under external confinement. Specifically, we consider two different harmonically trapped twoatom systems. The first system consists of an atom with spinorbit coupling that interacts with a structureless particle through a shortrange twobody potential. The second system consists of two atoms that both feel the spinorbit coupling term and that interact through a shortrange twobody potential. Treating the spinorbit term perturbatively, we determine the correction to the groundstate energy for various generic parameter combinations. Selected excited states are also treated. An important aspect of our study is that the perturbative treatment is not limited to small swave scattering lengths but provides insights into the system behavior over a wide range of scattering lengths, including the strongly interacting unitary regime. We find that the interplay between the spinorbit coupling term and the swave interaction generically enters, depending on the exact parameter combinations of the swave scattering lengths, at order kso2 or kso4 for the ground state and leads to a shift of the energy of either sign. While the absence of a term proportional to kso follows straightforwardly from the functional form of the spinorbit coupling term, the absence of a term proportional to kso2 for certain parameter combinations is unexpected. The wellknown fact that the spinorbit coupling term couples the relative and centerofmass degrees of freedom has interesting consequences for the trapped twoparticle systems. For example, we find that, for certain parameter combinations, the spinorbit coupling term turns sharp crossings into avoided crossings with an energy splitting proportional to kso. Our perturbative results are confirmed by numerical calculations that expand the eigenfunctions of the twoparticle Hamiltonian in terms of basis functions that contain explicitly correlated Gaussians.
Title:  Variational polaron method for BoseBose mixtures  
Authors:  Benjamin, David; Demler, Eugene  
Publication:  Physical Review A, Volume 89, Issue 3, id.033615 (PhRvA Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Multicomponent condensates, spinor condensates, Atoms in optical lattices, Polarons and electronphonon interactions  
Abstract Copyright:  2014: American Physical Society  
DOI:  10.1103/PhysRevA.89.033615  
Bibliographic Code:  2014PhRvA..89c3615B 
Abstract
We study degenerate mixtures of heavy bosons and light superfluid bosons using a variational polaron transformation. We consider the Mottinsulatorsuperfluid transition of the heavy species and find that at T =0 interaction favors the superfluid phase of the heavy species. Our analytic results agree well with numerically exact quantum Monte Carlo simulations in two dimensions. We then show that in three dimensions the variational polaron transformation can be combined with a Gutzwiller approximation to give good results.
Title:  Evidence for the decay B0→ωω and search for B0→ωϕ  
Authors:  Lees, J. P.; Poireau, V.; Tisserand, V.;... Morii, M.;... and 327 coauthors (Babar Collaboration)  
Publication:  Physical Review D, Volume 89, Issue 5, id.051101 (PhRvD Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Decays of bottom mesons, Charge conjugation parity time reversal and other discrete symmetries, Determination of KobayashiMaskawa matrix elements  
Abstract Copyright:  2014: American Physical Society  
DOI:  10.1103/PhysRevD.89.051101  
Bibliographic Code:  2014PhRvD..89e1101L 
Abstract
We describe searches for B meson decays to the charmless vectorvector final states ωω and ωϕ with 471×106BB stretchy="false">¯ pairs produced in e+e annihilation at √s =10.58 GeV using the BABAR detector at the PEPII collider at the SLAC National Accelerator Laboratory. We measure the branching fraction B(B0→ωω)=(1.2±0.30.2+0.3)×106, where the first uncertainty is statistical and the second is systematic, corresponding to a significance of 4.4 standard deviations. We also determine the upper limit B(B0→ωϕ)<0.7×106 at 90% confidence level. These measurements provide the first evidence for the decay B0→ωω, and an improvement of the upper limit for the decay B0→ωϕ.
Title:  Measurement of the inclusive isolated prompt photons cross section in pp collisions at √s =7 TeV with the ATLAS detector using 4.6 fb1  
Authors:  Aad, G.; Abajyan, T.; Abbott, B.;... ; Franklin, M.;... Guimarães da Costa, J.;... Huth, J.;...; Morii, M.; and 2910 coauthors  
Publication:  Physical Review D, Volume 89, Issue 5, id.052004 (PhRvD Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Inclusive production with identified leptons photons or other nonhadronic particles, Experimental tests  
Abstract Copyright:  2014: CERN  
DOI:  10.1103/PhysRevD.89.052004  
Bibliographic Code:  2014PhRvD..89e2004A 
Abstract
A measurement of the cross section for the production of isolated prompt photons in pp collisions at a centerofmass energy √s =7 TeV is presented. The results are based on an integrated luminosity of 4.6 fb1 collected with the ATLAS detector at the LHC. The cross section is measured as a function of photon pseudorapidity ηγ and transverse energy ETγ in the kinematic range 100≤ETγ<1000 GeV and in the regions ηγ<1.37 and 1.52≤ηγ<2.37. The results are compared to leadingorder partonshower Monte Carlo models and nexttoleadingorder perturbative QCD calculations. Nexttoleadingorder perturbative QCD calculations agree well with the measured cross sections as a function of ETγ and ηγ.
Title:  Selfcalibration of BICEP1 threeyear data and constraints on astrophysical polarization rotation  
Authors:  Kaufman, J. P.; Miller, N. J.; Shimon, M.; Barkats, D.; Bischoff, C.; Buder, I.; Keating, B. G.; Kovac, J. M.;... and 28 coauthors  
Publication:  Physical Review D, Volume 89, Issue 6, id.062006 (PhRvD Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Background radiations  
Abstract Copyright:  2014: American Physical Society  
DOI:  10.1103/PhysRevD.89.062006  
Bibliographic Code:  2014PhRvD..89f2006K 
Abstract
Cosmic microwave background (CMB) polarimeters aspire to measure the faint Bmode signature predicted to arise from inflationary gravitational waves. They also have the potential to constrain cosmic birefringence, rotation of the polarization of the CMB arising from parityviolating physics, which would produce nonzero expectation values for the CMB's temperature to Bmode correlation (TB) and Emode to Bmode correlation (EB) spectra. However, instrumental systematic effects can also cause these TB and EB correlations to be nonzero. In particular, an overall miscalibration of the polarization orientation of the detectors produces TB and EB spectra which are degenerate with isotropic cosmological birefringence, while also introducing a small but predictable bias on the BB spectrum. We find that Bicep1 threeyear spectra, which use our standard calibration of detector polarization angles from a dielectric sheet, are consistent with a polarization rotation of α =2.77°±0.86°(statistical)±1.3°(systematic). We have revised the estimate of systematic error on the polarization rotation angle from the twoyear analysis by comparing multiple calibration methods. We also account for the (negligible) impact of measured beam systematic effects. We investigate the polarization rotation for the Bicep1 100 GHz and 150 GHz bands separately to investigate theoretical models that produce frequencydependent cosmic birefringence. We find no evidence in the data supporting either of these models or Faraday rotation of the CMB polarization by the Milky Way galaxy's magnetic field. If we assume that there is no cosmic birefringence, we can use the TB and EB spectra to calibrate detector polarization orientations, thus reducing bias of the cosmological Bmode spectrum from leaked Emodes due to possible polarization orientation miscalibration. After applying this "selfcalibration" process, we find that the upper limit on the tensortoscalar ratio decreases slightly, from r<0.70 to r<0.65 at 95% confidence.
Title:  First Results from the LUX Dark Matter Experiment at the Sanford Underground Research Facility  
Authors:  Akerib, D. S.; Araújo, H. M.; Bai, X.;... Morii, M.;... and 99 coauthors  
Publication:  Physical Review Letters, Volume 112, Issue 9, id.091303 (PhRvL Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Dark matter, Tracking and positionsensitive detectors, Neutrino muon pion and other elementary particle detectors, cosmic ray detectors  
Abstract Copyright:  2014: American Physical Society  
DOI:  10.1103/PhysRevLett.112.091303  
Bibliographic Code:  2014PhRvL.112i1303A 
Abstract
The Large Underground Xenon (LUX) experiment is a dualphase xenon timeprojection chamber operating at the Sanford Underground Research Facility (Lead, South Dakota). The LUX cryostat was filled for the first time in the underground laboratory in February 2013. We report results of the first WIMP search data set, taken during the period from April to August 2013, presenting the analysis of 85.3 live days of data with a fiducial volume of 118 kg. A profilelikelihood analysis technique shows our data to be consistent with the backgroundonly hypothesis, allowing 90% confidence limits to be set on spinindependent WIMPnucleon elastic scattering with a minimum upper limit on the cross section of 7.6×1046 cm2 at a WIMP mass of 33 GeV/c2. We find that the LUX data are in disagreement with lowmass WIMP signal interpretations of the results from several recent direct detection experiments.
Title:  Search for Quantum Black Hole Production in HighInvariantMass Lepton+Jet Final States Using pp Collisions at √s =8 TeV and the ATLAS Detector  
Authors:  Aad, G.; Abajyan, T.; Abbott, B.;... ; Franklin, M.;... Guimarães da Costa, J.;... Huth, J.;...; Morii, M.; and 2903 coauthors  
Publication:  Physical Review Letters, Volume 112, Issue 9, id.091804 (PhRvL Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Inclusive production with identified leptons photons or other nonhadronic particles, KaluzaKlein theories, Higherdimensional black holes black strings and related objects  
Abstract Copyright:  2014: CERN  
DOI:  10.1103/PhysRevLett.112.091804  
Bibliographic Code:  2014PhRvL.112i1804A 
Abstract
This Letter presents a search for quantum blackhole production using 20.3 fb1 of data collected with the ATLAS detector in pp collisions at the LHC at √s =8 TeV. The quantum black holes are assumed to decay into a final state characterized by a lepton (electron or muon) and a jet. In either channel, no event with a leptonjet invariant mass of 3.5 TeV or more is observed, consistent with the expected background. Limits are set on the product of cross sections and branching fractions for the lepton+jet final states of quantum black holes produced in a search region for invariant masses above 1 TeV. The combined 95% confidence level upper limit on this product for quantum black holes with threshold mass above 3.5 TeV is 0.18 fb. This limit constrains the threshold quantum blackhole mass to be above 5.3 TeV in the model considered.
Title:  Spatial Propagation of Protein Polymerization  
Authors:  Cohen, S. I. A.; Rajah, L.; Yoon, C. H.; Buell, A. K.; White, D. A.; Sperling, R. A.; Vendruscolo, M.; Terentjev, E. M.; Dobson, C. M.; Weitz, D. A.; Knowles, T. P. J.  
Publication:  Physical Review Letters, vol. 112, Issue 9, id. 098101 (PhRvL Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Fibrils, Aggregation, Polymerization, Diffusion  
DOI:  10.1103/PhysRevLett.112.098101  
Bibliographic Code:  2014PhRvL.112i8101C 
Abstract
We consider the spatial dependence of filamentous protein selfassembly. Through studying the cases where the spreading of aggregated material is dominated either by diffusion or by growth, we derive analytical results for the spatial evolution of filamentous protein aggregation, which we validate against Monte Carlo simulations. Moreover, we compare the predictions of our theory with experimental measurements of two systems for which we identify the propagation as either growth or diffusion controlled. Our results connect the macroscopic observables that characterize the spatial propagation of protein selfassembly with the underlying microscopic processes and provide physical limits on spatial propagation and prionlike behavior associated with protein aggregation.
Title:  First Search for Exotic Z Boson Decays into Photons and Neutral Pions in Hadron Collisions  
Authors:  Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... ; Guimaraes da Costa, J.;... and 403 coauthors  
Publication:  Physical Review Letters, Volume 112, Issue 11, id.111803 (PhRvL Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Decays of Z bosons, Models beyond the standard model, Z bosons  
Abstract Copyright:  2014: American Physical Society  
DOI:  10.1103/PhysRevLett.112.111803  
Bibliographic Code:  2014PhRvL.112k1803A 
Abstract
A search for forbidden and exotic Z boson decays in the diphoton mass spectrum is presented for the first time in hadron collisions, based on data corresponding to 10.0 fb1 of integrated luminosity from protonantiproton collisions at √s =1.96 TeV collected by the CDF experiment. No evidence of signal is observed, and 95% credibility level Bayesian upper limits are set on the branching ratios of decays of the Z boson to a photon and neutral pion (which is detected as a photon), a pair of photons, and a pair of neutral pions. The observed branching ratio limits are 2.01×105 for Z→π0γ, 1.46×105 for Z→γγ, and 1.52×105 for Z→π0π0. The Z→π0γ and Z→γγ limits improve the most stringent results from other experiments by factors of 2.6 and 3.6, respectively. The Z→π0π0 branching ratio limit is the first experimental result on this decay.
Title:  Magnetic Trapping of Molecules via Optical Loading and Magnetic Slowing  
Authors:  Lu, HsinI.; Kozyryev, Ivan; Hemmerling, Boerge; Piskorski, Julia; Doyle, John M.  
Publication:  Physical Review Letters, Volume 112, Issue 11, id.113006 (PhRvL Homepage)  
Publication Date:  03/2014  
Origin:  APS  
PACS Keywords:  Slowing and cooling of molecules, Trapping of molecules, Mechanical effects of light on atoms molecules and ions  
Abstract Copyright:  2014: American Physical Society  
DOI:  10.1103/PhysRevLett.112.113006  
Bibliographic Code:  2014PhRvL.112k3006L 
Abstract
Calcium monofluoride (CaF) is magnetically slowed and trapped using optical pumping. Starting from a collisionally cooled slow beam, CaF with an initial velocity of ˜30 m/s is slowed via magnetic forces as it enters a 800 mK deep magnetic trap. Employing twostage optical pumping, CaF is irreversibly loaded into the trap via two scattered photons. We observe a trap lifetime exceeding 500 ms limited by background collisions. This method paves the way for cooling and magnetic trapping of chemically diverse molecules without closed cycling transitions.
Title:  Quantum Field Theory and the Standard Model  
Authors:  Schwartz, Matthew D.  
Publication:  Quantum Field Theory and the Standard Model, by Matthew D. Schwartz, Cambridge, UK: Cambridge University Press, 2014  
Publication Date:  03/2014  
Origin:  CUP  
Bibliographic Code:  2014qfts.book.....S 
Abstract
Part I. Field Theory: 1. Microscopic theory of radiation; 2. Lorentz invariance and second quantization; 3. Classical Field Theory; 4. Oldfashioned perturbation theory; 5. Cross sections and decay rates; 6. The Smatrix and timeordered products; 7. Feynman rules; Part II. Quantum Electrodynamics: 8. Spin 1 and gauge invariance; 9. Scalar QED; 10. Spinors; 11. Spinor solutions and CPT; 12. Spin and statistics; 13. Quantum electrodynamics; 14. Path integrals; Part III. Renormalization: 15. The Casimir effect; 16. Vacuum polarization; 17. The anomalous magnetic moment; 18. Mass renormalization; 19. Renormalized perturbation theory; 20. Infrared divergences; 21. Renormalizability; 22. Nonrenormalizable theories; 23. The renormalization group; 24. Implications of Unitarity; Part IV. The Standard Model: 25. Yang–Mills theory; 26. Quantum YangMills theory; 27. Gluon scattering and the spinorhelicity formalism; 28. Spontaneous symmetry breaking; 29. Weak interactions; 30. Anomalies; 31. Precision tests of the standard model; 32. QCD and the parton model; Part V. Advanced Topics: 33. Effective actions and Schwinger proper time; 34. Background fields; 35. Heavyquark physics; 36. Jets and effective field theory; Appendices; References; Index.
Title:  Teaching and physics education research: bridging the gap  
Authors:  Fraser, James M.; Timan, Anneke L.; Miller, Kelly; Dowd, Jason E.; Tucker, Laura; Mazur, Eric  
Publication:  Reports on Progress in Physics, Volume 77, Issue 3, article id. 032401 (2014).  
Publication Date:  03/2014  
Origin:  IOP  
DOI:  10.1088/00344885/77/3/032401  
Bibliographic Code:  2014RPPh...77c2401F 
Abstract
Physics faculty, experts in evidencebased research, often rely on anecdotal experience to guide their teaching practices. Adoption of researchbased instructional strategies is surprisingly low, despite the large body of physics education research (PER) and strong dissemination effort of PER researchers and innovators. Evidencebased PER has validated specific nontraditional teaching practices, but many faculty raise valuable concerns toward their applicability. We address these concerns and identify future studies required to overcome the gap between research and practice.
Title:  Boosted objects and jet substructure at the LHC. Report of BOOST2012, held at IFIC Valencia, 23rd27th of July 2012  
Authors:  Altheimer, A.; Arce, A.; Asquith, L.;... Schwartz, M. D.;... ... and 84 coauthors  
Publication:  The European Physical Journal C, Volume 74, article id. #2792 (EPJC Homepage)  
Publication Date:  03/2014  
Origin:  SPRINGER  
Abstract Copyright:  (c) 2014: The Author(s)  
DOI:  10.1140/epjc/s1005201427928  
Bibliographic Code:  2014EPJC...74.2792A 
Abstract
This report of the BOOST2012 workshop presents the results of four working groups that studied key aspects of jet substructure. We discuss the potential of firstprinciple QCD calculations to yield a precise description of the substructure of jets and study the accuracy of stateoftheart Monte Carlo tools. Limitations of the experiments' ability to resolve substructure are evaluated, with a focus on the impact of additional (pileup) proton proton collisions on jet substructure performance in future LHC operating scenarios. A final section summarizes the lessons learnt from jet substructure analyses in searches for new physics in the production of boosted top quarks.
Title:  Ultrathin Shell Double Emulsion Templated Giant Unilamellar Lipid Vesicles with Controlled Microdomain Formation  
Authors:  Arriaga, L.R.; Datta, S.S.; ShinHyun Kim; Amstad, E.; Kodger, T.E.; Monroy, F.; Weitz, D.A.  
Publication:  Small 12 March 2014, vol.10, no.5, pp. 9506. ISSN: 16136810  
Publication Date:  03/2014  
Publisher:  WileyVCH  
Database:  Inspec  
Inspec Headings:  biomembranes; cellular biophysics; emulsions; lipid bilayers; microfluidics 

DOI:  10.1002/smll.201301904 
Abstract
A microfluidic approach is reported for the highthroughput, continuous production of giant unilamellar vesicles (GUVs) using waterinoilinwater double emulsion drops as templates. Importantly, these emulsion drops have ultrathin shells; this minimizes the amount of residual solvent that remains trapped within the GUV membrane, overcoming a major limitation of typical microfluidic approaches for GUV fabrication. This approach enables the formation of microdomains, characterized by different lipid compositions and structures within the GUV membranes. This work therefore demonstrates a straightforward and versatile approach to GUV fabrication with precise control over the GUV size, lipid composition and the formation of microdomains within the GUV membrane.
Title:  Precision astronomy with imperfect fully depleted CCDs  an introduction and a suggested lexicon  
Authors:  Stubbs, C.W.  
Publication:  Journal of Instrumentation, vol.9, no.3, C03032 (11 pp.). ISSN: 17480221  
Publication Date:  03/2014  
Publisher:  IOP  
Database:  Inspec  
Inspec Headings:  astronomical image processing; astronomical instruments; CCD image sensors  
DOI:  10.1088/17480221/9/03/C03032 
Abstract
This paper summarizes the introductory presentation for a workshop (held Nov 18, 19 2013 at Brookhaven National Laboratory) that explored the challenges associated with making precision astronomical measurements using deeply depleted = 'thick' = 'highρ'' CCDs. While thick CCDs do provide definite advantages in terms of increased quantum efficiency at wavelengths 700 nm < λ < 1.1 μm and reduced fringing from atmospheric emission lines, these devices also exhibit undesirable features that pose a challenge to precision determination of the positions, fluxes, and shapes of astronomical objects, and for the precision extraction of features in astronomical spectra. For example, the assumptions of a perfectly rectilinear pixel grid and of an intensityindependent point spread function become increasingly invalid as we push to higher precision measurements. Many of the effects seen in these devices arise from lateral electrical fields within the detector, that produce charge transport anomalies that have been previously misinterpreted as quantum efficiency variations. Performing simplistic flatfielding therefore introduces systematic errors in the image processing pipeline. One measurement challenge we face is devising a combination of calibration methods and algorithms that can distinguish genuine quantum efficiency variations from charge transport effects. These device imperfections also confront spectroscopic applications, such as line centroid determination for precision radial velocity studies. Given the scientific benefits of improving both the precision and accuracy of astronomical measurements, we need to identify, characterize, and overcome these various detector artifacts. In retrospect, many of the detector features first identified in thick CCDs also afflict measurements made with more traditional CCD detectors, albeit often at a reduced level since the photocharge is subject to the perturbing influence of lateral electric fields for a shorter time interval. I provide a qualitative overview of the physical effects we think are responsible for the observed device properties, and provide some perspective for the work that lies ahead. Finally, I take this opportunity to make a plea for establishing a clear and consistent vocabulary when describing these various detector features, and make some suggestions for a standard lexicon based on discussions at the workshop. A more refined understanding of the device imperfections we are working to circumvent lies ahead, and this workshop was convened to help us find our way.
Title:  Plasmonics with twodimensional conductors  
Authors:  Hosang Yoon; Yeung, K.Y.M.; Kim, P.; Ham, D.  
Publication:  Philosophical Transactions of the Royal Society A (Mathematical, Physical & Engineering Sciences) 28 March 2014, vol.372, no.2012, 20130104 (12 pp.). ISSN: 1364503X  
Publication Date:  03/2014  
Publisher:  Royal Society (UK)  
Database:  Inspec  
Inspec Headings:  plasmonics; twodimensional conductors; surface; threedimensional bulk metals; semiconductor heterojunction; graphene; terahertz frequency; infrared frequency; ultrasubwavelength plasmonic circuits; metamaterials  
DOI:  10.1098/rsta.2013.0104 
Abstract
A wealth of effort in photonics has been dedicated to the study and engineering of surface plasmonic waves in the skin of threedimensional bulk metals, owing largely to their trait of subwavelength confinement. plasmonic waves in twodimensional conductors, such as semiconductor heterojunction and graphene, contrast the surface plasmonic waves on bulk metals, as the former emerge at gigahertz to terahertz and infrared frequencies well below the photonics regime and can exhibit far stronger subwavelength confinement. This review elucidates the machinery behind the unique behaviours of the twodimensional plasmonic waves and discusses how they can be, engineered to create ultrasubwavelength plasmonic circuits and metamaterials for infrared and gigahertz to terahertz integrated electronics.
Title:  Microfluidic assembly of multistage porous siliconlipid vesicles for controlled drug release  
Authors:  HerranzBlanco, B.; Arriaga, L.R.; Mäkila, E.; Correia, A.; Shrestha, N.; Mirza, S.; Weitz, D.A.; Salonen, J.; Hirvonen, J.; Santos, H.A.  
Publication:  Lab on a Chip 21 March 2014, vol.14, no.6, pp. 10836. ISSN: 14730197  
Publication Date:  03/2014  
Publisher:  Royal Society of Chemistry  
Database:  Inspec  
Inspec Headings:  biomedical materials; biomembrane transport; drops; drug delivery systems; drugs; emulsions; hydrophobicity; porous materials; silicon  
DOI:  10.1039/c3lc51260f 
Abstract
A reliable microfluidic platform for the generation of stable and monodisperse multistage drug delivery systems is reported. A glasscapillary flowfocusing droplet generation device was used to encapsulate thermally hydrocarbonized porous silicon (PSi) microparticles into the aqueous cores of double emulsion drops, yielding the formation of a multistage PSilipid vesicle. This composite system enables a large loading capacity for hydrophobic drugs.