Faculty Publications: May, 2015

Query Results from the Smithsonian/NASA Astrophysics Data System (ADS)

The following are Harvard Physics faculty members' publications, added to the ADS database last month. Please note that some publications which appeared in print last month may not be included in the database (and therefore may not appear on this list) until the following month.

see also:
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Title:
Electrical pulse fabrication of graphene nanopores in electrolyte solution
Authors:
Kuan, Aaron T.; Lu, Bo; Xie, Ping; Szalay, Tamas; Golovchenko, Jene A.
Publication:
Applied Physics Letters, Volume 106, Issue 20, id.203109 (ApPhL Homepage)
Publication Date:
05/2015
Origin:
AIP
Abstract Copyright:
2015: AIP Publishing LLC
DOI:
10.1063/1.4921620
Bibliographic Code:
2015ApPhL.106t3109K

Abstract

Nanopores in graphene membranes can potentially offer unprecedented spatial resolution for single molecule sensing, but their fabrication has thus far been difficult, poorly scalable, and prone to contamination. We demonstrate an in-situ fabrication method that nucleates and controllably enlarges nanopores in electrolyte solution by applying ultra-short, high-voltage pulses across the graphene membrane. This method can be used to rapidly produce graphene nanopores with subnanometer size accuracy in an apparatus free of nanoscale beams or tips.

 

Title:
Measurement of the top-quark mass in the ${t\bar{t}}$ dilepton channel using the full CDF Run II data set
Authors:
CDF Collaboration; Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... Guimaraes da Costa, J.; and 397 coauthors
Publication:
eprint arXiv:1505.00500
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
High Energy Physics - Experiment
Comment:
Submitted to Phys. Rev. D, 11 pages, 5 figures and 2 tables
Bibliographic Code:
2015arXiv150500500C

Abstract

We present a measurement of the top-quark mass in events containing two leptons (electrons or muons) with a large transverse momentum, two or more energetic jets, and a transverse-momentum imbalance. We use the full proton-antiproton collision data set collected by the CDF experiment during the Fermilab Tevatron Run~II at center-of-mass energy $\sqrt{s} = 1.96$ TeV, corresponding to an integrated luminosity of 9.1 fb$^{-1}$. A special observable is exploited for an optimal reduction of the dominant systematic uncertainty, associated with the knowledge of the absolute energy of the hadronic jets. The distribution of this observable in the selected events is compared to simulated distributions of ${t\bar{t}}$ dilepton signal and background.We measure a value for the top-quark mass of $171.5\pm 1.9~{\rm (stat)}\pm 2.5~{\rm (syst)}$ GeV/$c^2$.

 

Title:
Optimizing a Dynamical Decoupling Protocol for Solid-State Electronic Spin Ensembles in Diamond
Authors:
Farfurnik, Demitry; Jarmola, Andrey; Pham, Linh M.; Wang, Zhi-Hui; Dobrovitski, Viatcheslav V.; Walsworth, Ronald L.; Budker, Dmitry; Bar-Gill, Nir
Publication:
eprint arXiv:1505.00636
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Quantum Physics
Bibliographic Code:
2015arXiv150500636F

Abstract

We demonstrate significant improvements of the spin coherence time of a dense ensemble of nitrogen-vacancy (NV) centers in diamond through optimized dynamical decoupling (DD). Cooling the sample down to $77$ K suppresses longitudinal spin relaxation $T_1$ effects and DD microwave pulses are used to increase the transverse coherence time $T_2$ from $\sim 0.7$ ms up to $\sim 30$ ms. We extend previous work of single-axis (CPMG) DD towards the preservation of arbitrary spin states. Following a theoretical and experimental characterization of pulse and detuning errors, we compare the performance of various DD protocols. We identify that the optimal control scheme for preserving an arbitrary spin state is a recursive protocol, the concatenated version of the XY8 pulse sequence. The improved spin coherence might have an immediate impact on improvements of the sensitivities of AC magnetometry. Moreover, the protocol can be used on denser diamond samples to increase coherence times up to NV-NV interaction time scales, a major step towards the creation of quantum collective NV spin states.

 

Title:
Low-noise optical lattices for ultracold $^6$Li
Authors:
Blatt, S.; Mazurenko, A.; Parsons, M. F.; Chiu, C. S.; Huber, F.; Greiner, M.
Publication:
eprint arXiv:1505.00758
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Physics - Atomic Physics, Condensed Matter - Quantum Gases, Quantum Physics
Comment:
4 pages, 4 figures, 4 pages supplemental material
Bibliographic Code:
2015arXiv150500758B

Abstract

We demonstrate stable, long-term trapping of fermionic $^6$Li atoms in an optical lattice with MHz trap frequencies for use in a quantum gas microscope. Adiabatic release from the optical lattice in the object plane of a high-numerical-aperture imaging system allows a measurement of the population distribution among the lowest three bands in both radial directions with atom numbers as low as $7\times 10^2$. We measure exponential ground band heating rates as low as 0.014(1) s$^{-1}$ corresponding to a radial ground state $1/e$ lifetime of 71(5) s, fundamentally limited by scattering of lattice photons. For all lattice depths above 2 recoil, we find radial ground state lifetimes $\ge 1.6 \times 10^6$ recoil times.

 

Title:
Measurement of the production and differential cross sections of $W^{+}W^{-}$ bosons in association with jets 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 397 coauthors
Publication:
eprint arXiv:1505.00801
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
High Energy Physics - Experiment
Comment:
Submitted to PRD-RC
Bibliographic Code:
2015arXiv150500801C

Abstract

We present a measurement of the $W$-boson-pair production cross section in $p\bar{p}$ collisions at 1.96 TeV center-of-mass energy and the first measurement of the differential cross section as a function of jet multiplicity and leading-jet energy. The $W^{+}W^{-}$ cross section is measured in the final state comprising two charged leptons and neutrinos, where either charged lepton can be an electron or a muon. Using data collected by the CDF experiment corresponding to $9.7~\rm{fb}^{-1}$ of integrated luminosity, a total of $3027$ collision events consistent with $W^{+}W^{-}$ production are observed with an estimated background contribution of $1790\pm190$ events. The measured total cross section is $\sigma(p\bar{p} \rightarrow W^{+}W^{-}) = 14.0 \pm 0.6~(\rm{stat})^{+1.2}_{-1.0}~(\rm{syst})\pm0.8~(\rm{lumi})$ pb, consistent with the standard model prediction.

 

Title:
Results from the Wide-field Infrared Survey Explorer (WISE) Future Uses Session at the WISE at 5 Meeting
Authors:
Faherty, Jacqueline K.; Alatalo, K.; Anderson, L. D.;... Finkbeiner, Douglas P.;... and 44 coauthors
Publication:
eprint arXiv:1505.01923
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Comment:
10 pages, 6 figures
Bibliographic Code:
2015arXiv150501923F

Abstract

During the "WISE at 5: Legacy and Prospects" conference in Pasadena, CA -- which ran from February 10 - 12, 2015 -- attendees were invited to engage in an interactive session exploring the future uses of the Wide-field Infrared Survey Explorer (WISE) data. The 65 participants -- many of whom are extensive users of the data -- brainstormed the top questions still to be answered by the mission, as well as the complementary current and future datasets and additional processing of WISE/NEOWISE data that would aid in addressing these most important scientific questions. The results were mainly bifurcated between topics related to extragalactic studies (e.g. AGN, QSOs) and substellar mass objects. In summary, participants found that complementing WISE/NEOWISE data with cross-correlated multiwavelength surveys (e.g. SDSS, Pan-STARRS, LSST, Gaia, Euclid, etc.) would be highly beneficial for all future mission goals. Moreover, developing or implementing machine-learning tools to comb through and understand cross-correlated data was often mentioned for future uses. Finally, attendees agreed that additional processing of the data such as co-adding WISE and NEOWISE and extracting a multi-epoch photometric database and parallax and proper motion catalog would greatly improve the scientific results of the most important projects identified. In that respect, a project such as MaxWISE which would execute the most important additional processing and extraction as well as make the data and catalogs easily accessible via a public portal was deemed extremely important.

 

Title:
The Organization and Control of an Evolving Interdependent Population
Authors:
Vural, Dervis Can; Isakov, Alexander; Mahadevan, L.
Publication:
eprint arXiv:1505.02195
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Quantitative Biology - Populations and Evolution
Comment:
To download simulation code cf. article in Proceedings of the Royal Society, Interface
Bibliographic Code:
2015arXiv150502195V

Abstract

Starting with Darwin, biologists have asked how populations evolve from a low fitness state that is evolutionarily stable to a high fitness state that is not. Specifically of interest is the emergence of cooperation and multicellularity where the fitness of individuals often appears in conflict with that of the population. Theories of social evolution and evolutionary game theory have produced a number of fruitful results employing two-state two-body frameworks. In this study we depart from this tradition and instead consider a multi-player, multi-state evolutionary game, in which the fitness of an agent is determined by its relationship to an arbitrary number of other agents. We show that populations organize themselves in one of four distinct phases of interdependence depending on one parameter, selection strength. Some of these phases involve the formation of specialized large-scale structures. We then describe how the evolution of independence can be manipulated through various external perturbations.

 

Title:
Higher Derivative Terms, Toroidal Compactification, and Weyl Anomalies in Six-Dimensional (2,0) Theories
Authors:
Cordova, Clay; Dumitrescu, Thomas T.; Yin, Xi
Publication:
eprint arXiv:1505.03850
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
High Energy Physics - Theory
Comment:
48 pages + appendix, 3 figures
Bibliographic Code:
2015arXiv150503850C

Abstract

We systematically analyze the effective action on the moduli space of (2,0) superconformal field theories in six dimensions, as well as their toroidal compactification to maximally supersymmetric Yang-Mills theories in five and four dimensions. We present a streamlined approach to non-renormalization theorems that constrain this effective action. The first several orders in its derivative expansion are determined by a one-loop calculation in five-dimensional Yang-Mills theory. This fixes the leading higher-derivative operators that describe the renormalization group flow into theories residing at singular points on the moduli space of the compactified (2,0) theories. This understanding allows us to compute the a-type Weyl anomaly for all (2,0) superconformal theories. We show that it decreases along every renormalization group flow that preserves (2,0) supersymmetry, thereby establishing the a-theorem for this class of theories. Along the way, we encounter various field-theoretic arguments for the ADE classification of (2,0) theories.

 

Title:
Coulomb bound states of strongly interacting photons
Authors:
Maghrebi, M. F.; Gullans, M. J.; Bienias, P.; Choi, S.; Martin, I.; Firstenberg, O.; Lukin, M. D.; Büchler, H. P.; Gorshkov, A. V.
Publication:
eprint arXiv:1505.03859
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Quantum Physics, Physics - Atomic Physics
Comment:
10 pages, 5 figures
Bibliographic Code:
2015arXiv150503859M

Abstract

We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasi-bound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wavefunction resembles that of a diatomic molecule in which the two polaritons are separated by a finite "bond length." These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.

 

Title:
Specular Interband Andreev Reflections in Graphene
Authors:
Efetov, D. K.; Wang, L.; Handschin, C.; Efetov, K. B.; Shuang, J.; Cava, R.; Taniguchi, T.; Watanabe, K.; Hone, J.; Dean, C. R.; Kim, P.
Publication:
eprint arXiv:1505.04812
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science, Condensed Matter - Superconductivity
Bibliographic Code:
2015arXiv150504812E

Abstract

Electrons incident from a normal metal onto a superconductor are reflected back as holes - a process called Andreev reflection. In a normal metal where the Fermi energy is much larger than a typical superconducting gap, the reflected hole retraces the path taken by the incident electron. In graphene with ultra low disorder, however, the Fermi energy can be tuned to be smaller than the superconducting gap. In this unusual limit, the holes are expected to be reflected specularly at the superconductor-graphene interface due to the onset of interband Andreev processes, where the effective mass of the reflected holes change sign. Here we present measurements of gate modulated Andreev reflections across the low disorder van der Waals interface formed between graphene and the superconducting NbSe2. We find that the conductance across the graphene-superconductor interface exhibits a characteristic suppression when the Fermi energy is tuned to values smaller than the superconducting gap, a hallmark for the transition between intraband retro- and interband specular- Andreev reflections.

 

Title:
Gravitational Waves and Their Memory in General Relativity
Authors:
Bieri, Lydia; Garfinkle, David; Yau, Shing-Tung
Publication:
eprint arXiv:1505.05213
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
General Relativity and Quantum Cosmology, 83C35, 83C05
Comment:
To be published in the volume "The Centenary of General Relativity", volume 20 of "Surveys in Differential Geometry"
Bibliographic Code:
2015arXiv150505213B

Abstract

General relativity explains gravitational radiation from binary black hole or neutron star mergers, from core-collapse supernovae and even from the inflation period in cosmology. These waves exhibit a unique effect called memory or Christodoulou effect, which in a detector like LIGO or LISA shows as a permanent displacement of test masses and in radio telescopes like NANOGrav as a change in the frequency of pulsars' pulses. It was shown that electromagnetic fields and neutrino radiation enlarge the memory. Recently it has been understood that the two types of memory addressed in the literature as `linear' and `nonlinear' are in fact two different phenomena. The former is due to fields that do not and the latter is due to fields that do reach null infinity.

 

Title:
Negative Holomorphic curvature and positive canonical bundle
Authors:
Wu, Damin; Yau, Shing-Tung
Publication:
eprint arXiv:1505.05802
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Mathematics - Differential Geometry, Mathematics - Algebraic Geometry, 32Q05, 32Q15, 14E30, 32Q45, 32W20
Bibliographic Code:
2015arXiv150505802W

Abstract

In this note we show that if a projective manifold admits a K\"ahler metric with negative holomorphic sectional curvature then the canonical bundle of the manifold is ample. This confirms a conjecture of the second author.

 

Title:
Supervertices and Non-renormalization Conditions in Maximal Supergravity Theories
Authors:
Wang, Yifan; Yin, Xi
Publication:
eprint arXiv:1505.05861
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
High Energy Physics - Theory
Comment:
52 pages, 6 figures, reference added, section 3 expanded and section 5 restructured
Bibliographic Code:
2015arXiv150505861W

Abstract

We construct higher derivative supervertices in an effective theory of maximal supergravity in various dimensions, in the super spinor helicity formalism, and derive non-renormalization conditions on up to 14-derivative order couplings from supersymmetry. These non-renormalization conditions include Laplace type equations on the coefficients of $R^4$, $D^4R^4$, and $D^6R^4$ couplings. We also find additional constraining equations, which are consistent with previously known results in the effective action of toroidally compactified type II string theory, and elucidate many features thereof.

 

Title:
Fluctuating orders and quenched randomness in the cuprates
Authors:
Nie, Laimei; Hayward Sierens, Lauren E.; Melko, Roger G.; Sachdev, Subir; Kivelson, Steven A.
Publication:
eprint arXiv:1505.06206
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Comment:
13 pages, 10+2 figures
Bibliographic Code:
2015arXiv150506206N

Abstract

We study a quasi-2D classical Landau-Ginzburg-Wilson effective field theory in the presence of quenched disorder in which incommensurate charge-density wave and superconducting orders are intertwined. The disorder precludes long-range charge-density wave order, but not superconducting or nematic order. We select three representative sets of input parameters and compute the corresponding charge-density wave structure factors using both large-$N$ techniques and classical Monte Carlo simulations. Where nematicity and superconductivity coexist at low temperature, the peak height of the charge-density wave structure factor decreases monotonically as a function of increasing temperature, unlike what is seen in X-ray experiments on YBa$_2$Cu$_3$O$_{6+x}$. Conversely, where the thermal evolution of the charge-density wave structure factor qualitatively agrees with experiments, the nematic correlation length, computed to one-loop order, is shorter than the charge-density wave correlation length.

 

Title:
Activity driven fluctuations in living cells
Authors:
Fodor, É.; Guo, M.; Gov, N. S.; Visco, P.; Weitz, D. A.; van Wijland, F.
Publication:
eprint arXiv:1505.06489
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Physics - Biological Physics, Condensed Matter - Soft Condensed Matter, Quantitative Biology - Cell Behavior
Comment:
6 pages, 4 figures
Bibliographic Code:
2015arXiv150506489F

Abstract

We propose a model for the dynamics of a probe embedded in a living cell, where both thermal fluctuations and nonequilibrium activity coexist. The model is based on a confining harmonic potential describing the elastic cytoskeletal matrix, which undergoes random active hops as a result of the nonequilibrium rearrangements within the cell. We describe the probe's statistics and we bring forth quantities affected by the nonequilibrium activity. We find an excellent agreement between the predictions of our model and experimental results for tracers inside living cells. Finally, we exploit our model to arrive at quantitative predictions for the parameters characterizing nonequilibrium activity, such as the typical time scale of the activity and the amplitude of the active fluctuations.

 

Title:
Elastohydrodynamics and kinetics of protein patterning in the immunological synapse
Authors:
Carlson, Andreas; Mahadevan, L.
Publication:
eprint arXiv:1505.07133
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Physics - Biological Physics, Quantitative Biology - Subcellular Processes
Bibliographic Code:
2015arXiv150507133C

Abstract

The cellular basis for the adaptive immune response during antigen recognition relies on a specialized protein interface known as the immunological synapse (IS). Understanding the biophysical basis for protein patterning by deciphering the quantitative rules for their formation and motion is an important aspect of characterizing immune cell recognition and thence the rules for immune system activation. We propose a minimal mathematical model for the physical basis of membrane protein patterning in the IS, which encompass membrane mechanics, protein binding kinetics and motion, and fluid flow in the synaptic cleft. Our theory leads to simple predictions for the spatial and temporal scales of protein cluster formation, growth and arrest as a function of membrane stiffness, rigidity and kinetics of the adhesive proteins, and the fluid in the synaptic cleft. Numerical simulations complement these scaling laws by quantifying the nucleation, growth and stabilization of proteins domains on the size of the cell. Direct comparison with experiment shows that passive elastohydrodynamics and kinetics of protein binding in the synaptic cleft can describe the short-time formation and organization of protein clusters, without evoking any active processes in the cytoskeleton. Despite the apparent complexity of the process, our analysis highlights the role of just two dimensionless parameters that characterize the spatial and temporal evolution of the protein pattern: a ratio of membrane elasticity to protein elasticity, and the ratio of a hydrodynamic time scale for fluid flow relative to the protein binding rate, and we present a simple phase diagram that encompasses the variety of patterns that can arise.

 

Title:
Exact CNOT Gates with a Single Nonlocal Rotation for Quantum-Dot Qubits
Authors:
Pal, Arijeet; Rashba, Emmanuel I.; Halperin, Bertrand I.
Publication:
eprint arXiv:1505.07847
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Condensed Matter - Mesoscale and Nanoscale Physics, Quantum Physics
Comment:
11 pages, 4 figures, Added 2 references
Bibliographic Code:
2015arXiv150507847P

Abstract

We investigate capacitively coupled two-qubit quantum gates based on quantum dots. For exchange-only coded qubits electron spin $S$ and its projection $S_z$ are exact quantum numbers. Capacitive coupling between qubits, as distinct from interqubit exchange, preserves these quantum numbers. We prove, both analytically and numerically, that conservation of the spins of individual qubits has dramatic effect on performance of two-qubit gates. By varying the level splittings of individual qubits, $J_a$ and $J_b$, and the interqubit coupling time $t$, we can find an infinite number of triples $(J_a, J_b, t)$ for which the two-qubit entanglement, in combination with appropriate single-qubit rotations, can produce an exact CNOT gate. This statement is true for practically arbitrary magnitude and form of capacitive interqubit coupling. Our findings promise a large decrease in the number of nonlocal (two-qubit) operations in quantum circuits.

 

Title:
Homogeneous dust emission and jet structure near active cometary nuclei: the case of 67P/Churyumov-Gerasimenko
Authors:
Kramer, Tobias; Noack, Matthias; Baum, Daniel; Hege, Hans-Christian; Heller, Eric J.
Publication:
eprint arXiv:1505.08041
Publication Date:
05/2015
Origin:
ARXIV
Keywords:
Astrophysics - Earth and Planetary Astrophysics
Comment:
11 pages, with figures
Bibliographic Code:
2015arXiv150508041K

Abstract

We compute trajectories of dust grains starting from a homogeneous surface activity-profile. Despite the homogeneous initial distribution a collimation in jet-like structures becomes visible. The fine structure is caused by topographical features with similar bundles of normal vectors. Gravitational forces are accurately determined from the triangular surface mesh. For the comet 67P/Churyumov-Gerasimenko, we find several areas of good agreement between the homogeneous dust emission model and Rosetta observation of dust jets.

 

Title:
Complete cscK Metrics on the Local Models of the Conifold Transition
Authors:
Fu, Jixiang; Yau, Shing-Tung; Zhou, Wubin
Affiliation:
AA(Institute of Mathematics, Fudan University), AB(Department of Mathematics, Harvard University), AC(Shanghai Center for Mathematical Sciences)
Publication:
Communications in Mathematical Physics, Volume 335, Issue 3, pp.1215-1233
Publication Date:
05/2015
Origin:
SPRINGER
Abstract Copyright:
(c) 2015: Springer-Verlag Berlin Heidelberg
DOI:
10.1007/s00220-015-2337-5
Bibliographic Code:
2015CMaPh.335.1215F

Abstract

In this paper, we construct complete constant scalar curvature Kähler (cscK) metrics on the complement of the zero section in the total space of over , which is biholomorphic to the smooth part of the cone C 0 in defined by equation . On its small resolution and its deformation, we also consider complete cscK metrics and find that if the cscK metrics are homogeneous, then they must be Ricci-flat.

 

Title:
Invariant Solutions to the Strominger System on Complex Lie Groups and Their Quotients
Authors:
Fei, Teng; Yau, Shing-Tung
Publication:
Communications in Mathematical Physics, Online First
Publication Date:
05/2015
Origin:
SPRINGER
Abstract Copyright:
(c) 2015: Springer-Verlag Berlin Heidelberg
DOI:
10.1007/s00220-015-2374-0
Bibliographic Code:
2015CMaPh.tmp..130F

Abstract

Using canonical 1-parameter family of Hermitian connections on the tangent bundle, we provide invariant solutions to the Strominger system on certain complex Lie groups and their quotients. Both flat and non-flat cases are discussed in detail. This paper answers a question proposed by Andreas and Garcia-Fernandez in Comm Math Phys 332(3):1381-1383, 2014.

 

Title:
Fluid-driven fingering instability of a confined elastic meniscus
Authors:
Biggins, John S.; Wei, Z.; Mahadevan, L.
Publication:
Europhysics Letters, Volume 110, Issue 3, article id. 34001 (2015).
Publication Date:
05/2015
Origin:
IOP
DOI:
10.1209/0295-5075/110/34001
Bibliographic Code:
2015EL....11034001B

Abstract

When a fluid is pumped into a cavity in a confined elastic layer, at a critical pressure, destabilizing fingers of fluid invade the elastic solid along its meniscus (Saintyves B. et al., Phys. Rev. Lett., 111 (2013) 047801). These fingers occur without fracture or loss of adhesion and are reversible, disappearing when the pressure is decreased. We develop an asymptotic theory of pressurized highly elastic layers trapped between rigid bodies in both rectilinear and circular geometries, with predictions for the critical fluid pressure for fingering, and the finger wavelength. Our results are in good agreement with recent experimental observations of this elastic interfacial instability in a radial geometry. Our theory also shows that, perhaps surprisingly, this lateral-pressure--driven instability is analogous to a transverse-displacement--driven instability of the elastic layer. We verify these predictions by using non-linear finite-element simulations on the two systems which show that in both cases the fingering transition is first order (sudden) and hence has a region of bistability.

 

Title:
Search for direct pair production of a chargino and a neutralino decaying to the 125 GeV Higgs boson in TeV collisions with the ATLAS detector
Authors:
Aad, G.; Abbott, B.; Abdallah, J.;... Barreiro Guimarães da Costa, J.;... Franklin, M.;... Huth, J.;... Morii, M.;... and 2817 coauthors
Publication:
The European Physical Journal C, Volume 75, article id. #208, 31 pp. (EPJC Homepage)
Publication Date:
05/2015
Origin:
SPRINGER
Abstract Copyright:
(c) 2015: CERN for the benefit of the ATLAS collaboration
DOI:
10.1140/epjc/s10052-015-3408-7
Bibliographic Code:
2015EPJC...75..208A

Abstract

A search is presented for the direct pair production of a chargino and a neutralino , where the chargino decays to the lightest neutralino and the boson, , while the neutralino decays to the lightest neutralino and the 125 GeV Higgs boson, . The final states considered for the search have large missing transverse momentum, an isolated electron or muon, and one of the following: either two jets identified as originating from bottom quarks, or two photons, or a second electron or muon with the same electric charge. The analysis is based on 20.3 of proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with the Standard Model expectations, and limits are set in the context of a simplified supersymmetric model.

 

Title:
Search for production of resonances decaying to a lepton, neutrino and jets in collisions at TeV with the ATLAS detector
Authors:
Aad, G.; Abbott, B.; Abdallah, J.;... Barreiro Guimarães da Costa, J.;... Franklin, M.;... Huth, J.;... Morii, M.;... and 2825 coauthors
Publication:
The European Physical Journal C, Volume 75, article id. #209, 20 pp. (EPJC Homepage)
Publication Date:
05/2015
Origin:
SPRINGER
Abstract Copyright:
(c) 2015: CERN for the benefit of the ATLAS collaboration
DOI:
10.1140/epjc/s10052-015-3425-6
Bibliographic Code:
2015EPJC...75..209A

Abstract

A search is presented for narrow diboson resonances decaying to or in the final state where one boson decays leptonically (to an electron or a muon plus a neutrino) and the other boson decays hadronically. The analysis is performed using an integrated luminosity of 20.3 fb of collisions at TeV collected by the ATLAS detector at the large hadron collider. No evidence for resonant diboson production is observed, and resonance masses below 700 and 1490 GeV are excluded at 95 % confidence level for the spin-2 Randall-Sundrum bulk graviton with coupling constant of 1.0 and the extended gauge model boson respectively.

 

Title:
Graphene-templated directional growth of an inorganic nanowire
Authors:
Lee, Won Chul; Kim, Kwanpyo; Park, Jungwon; Koo, Jahyun; Jeong, Hu Young; Lee, Hoonkyung; Weitz, David A.; Zettl, Alex; Takeuchi, Shoji
Publication:
Nature Nanotechnology, Volume 10, Issue 5, pp. 423-428 (2015).
Publication Date:
05/2015
Origin:
NATURE
Abstract Copyright:
(c) 2015: Nature Publishing Group
DOI:
10.1038/nnano.2015.36
Bibliographic Code:
2015NatNa..10..423L

Abstract

Assembling inorganic nanomaterials on graphene is of interest in the development of nanodevices and nanocomposite materials, and the ability to align such inorganic nanomaterials on the graphene surface is expected to lead to improved functionalities, as has previously been demonstrated with organic nanomaterials epitaxially aligned on graphitic surfaces. However, because graphene is chemically inert, it is difficult to precisely assemble inorganic nanomaterials on pristine graphene. Previous techniques based on dangling bonds of damaged graphene, intermediate seed materials and vapour-phase deposition at high temperature, have only formed randomly oriented or poorly aligned inorganic nanostructures. Here, we show that inorganic nanowires of gold(I) cyanide can grow directly on pristine graphene, aligning themselves with the zigzag lattice directions of the graphene. The nanowires are synthesized through a self-organized growth process in aqueous solution at room temperature, which indicates that the inorganic material spontaneously binds to the pristine graphene surface. First-principles calculations suggest that this assembly originates from lattice matching and pi interaction to gold atoms. Using the synthesized nanowires as templates, we also fabricate nanostructures with controlled crystal orientations such as graphene nanoribbons with zigzag-edged directions.

 

Title:
Protein mediated membrane adhesion
Authors:
Carlson, Andreas; Mahadevan, L.
Publication:
Physics of Fluids, Volume 27, Issue 5, id.051901 (PhFl Homepage)
Publication Date:
05/2015
Origin:
AIP
Abstract Copyright:
2015: AIP Publishing LLC
DOI:
10.1063/1.4919777
Bibliographic Code:
2015PhFl...27e1901C

Abstract

Adhesion in the context of mechanical attachment, signaling, and movement in cellular dynamics is mediated by the kinetic interactions between membrane-embedded proteins in an aqueous environment. Here, we present a minimal theoretical framework for the dynamics of membrane adhesion that accounts for the kinetics of protein binding, the elastic deformation of the membrane, and the hydrodynamics of squeeze flow in the membrane gap. We analyze the resulting equations using scaling estimates to characterize the spatiotemporal features of the adhesive patterning and corroborate them using numerical simulations. In addition to characterizing aspects of cellular dynamics, our results might also be applicable to a range of phenomena in physical chemistry and materials science where flow, deformation, and kinetics are coupled to each other in slender geometries.

 

Title:
Search for a CP-odd Higgs boson decaying to Zh in pp collisions at &surd;{ s} = 8 TeV with the ATLAS detector
Authors:
Aad, G.; Abbott, B.; Abdallah, J.;... Barreiro Guimarães da Costa, J.;... Franklin, M.;... Huth, J.;... Morii, M.;... and 2820 coauthors
Publication:
Physics Letters B, Volume 744, p. 163-183.
Publication Date:
05/2015
Origin:
ELSEVIER
Keywords:
BSM Higgs boson, ATLAS
Abstract Copyright:
(c) 2015 Elsevier Science B.V. All rights reserved.
DOI:
10.1016/j.physletb.2015.03.054
Bibliographic Code:
2015PhLB..744..163A

Abstract

A search for a heavy, CP-odd Higgs boson, A, decaying into a Z boson and a 125 GeV Higgs boson, h, with the ATLAS detector at the LHC is presented. The search uses proton-proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb-1. Decays of CP-even h bosons to tautau or bb pairs with the Z boson decaying to electron or muon pairs are considered, as well as h --> bb decays with the Z boson decaying to neutrinos. No evidence for the production of an A boson in these channels is found and the 95% confidence level upper limits derived for sigma (gg --> A) × BR (A --> Zh) × BR (h --> f f bar) are 0.098-0.013 pb for f = tau and 0.57-0.014 pb for f = b in a range of mA = 220- 1000 GeV. The results are combined and interpreted in the context of two-Higgs-doublet models.

 

Title:
Topological bands with a Chern number C =2 by dipolar exchange interactions
Authors:
Peter, David; Yao, Norman Y.; Lang, Nicolai; Huber, Sebastian D.; Lukin, Mikhail D.; Büchler, Hans Peter
Publication:
Physical Review A, Volume 91, Issue 5, id.053617 (PhRvA Homepage)
Publication Date:
05/2015
Origin:
APS
PACS Keywords:
Ultracold gases trapped gases, Boson systems, Atoms in optical lattices, Theory and modeling
Abstract Copyright:
2015: American Physical Society
DOI:
10.1103/PhysRevA.91.053617
Bibliographic Code:
2015PhRvA..91e3617P

Abstract

We demonstrate the realization of topological band structures by exploiting the intrinsic spin-orbit coupling of dipolar interactions in combination with broken time-reversal symmetry. The system is based on polar molecules trapped in a deep optical lattice, where the dynamics of rotational excitations follows a hopping Hamiltonian which is determined by the dipolar exchange interactions. We find topological bands with Chern number C =2 on the square lattice, while a very rich structure of different topological bands appears on the honeycomb lattice. We show that the system is robust against missing molecules. For certain parameters we obtain flat bands, providing a promising candidate for the realization of hard-core bosonic fractional Chern insulators.

 

Title:
Publisher's Note: Scattering resonances and bound states for strongly interacting Rydberg polaritons [Phys. Rev. A 90, 053804 (2014)]
Authors:
Bienias, P.; Choi, S.; Firstenberg, O.; Maghrebi, M. F.; Gullans, M.; Lukin, M. D.; Gorshkov, A. V.; Büchler, H. P.
Publication:
Physical Review A, Volume 91, Issue 5, id.059903 (PhRvA Homepage)
Publication Date:
05/2015
Origin:
APS
PACS Keywords:
Quantum optical phenomena in absorbing dispersive and conducting media, Rydberg states, Interatomic potentials and forces, Effects of atomic coherence on propagation absorption and amplification of light, electromagnetically induced transparency and absorption, Publisher's note
DOI:
10.1103/PhysRevA.91.059903
Bibliographic Code:
2015PhRvA..91e9903B

Abstract

Not Available

 

Title:
Memory matrix theory of magnetotransport in strange metals
Authors:
Lucas, Andrew; Sachdev, Subir
Publication:
Physical Review B, Volume 91, Issue 19, id.195122 (PhRvB Homepage)
Publication Date:
05/2015
Origin:
APS
PACS Keywords:
Transport properties and hydrodynamics
Abstract Copyright:
2015: American Physical Society
DOI:
10.1103/PhysRevB.91.195122
Bibliographic Code:
2015PhRvB..91s5122L

Abstract

We model strange metals as quantum liquids without quasiparticle excitations, but with slow momentum relaxation and with slow diffusive dynamics of a conserved charge and energy. General expressions are obtained for electrical, thermal, and thermoelectric transport in the presence of an applied magnetic field using the memory matrix formalism. In the appropriate limits, our expressions agree with previous hydrodynamic and holographic results. We discuss the relationship of such results to thermoelectric and Hall transport measurements in the strange-metal phase of the hole-doped cuprates.

 

Title:
Exploring dynamical phase transitions and prethermalization with quantum noise of excitations
Authors:
Smacchia, Pietro; Knap, Michael; Demler, Eugene; Silva, Alessandro
Publication:
Physical Review B, Volume 91, Issue 20, id.205136 (PhRvB Homepage)
Publication Date:
05/2015
Origin:
APS
PACS Keywords:
Boson systems, Dynamic properties of condensates, collective and hydrodynamic excitations superfluid flow, Ultracold gases trapped gases
Abstract Copyright:
2015: American Physical Society
DOI:
10.1103/PhysRevB.91.205136
Bibliographic Code:
2015PhRvB..91t5136S

Abstract

Dynamical phase transitions can occur in isolated quantum systems that are brought out of equilibrium by sudden parameter changes. We discuss the characterization of such dynamical phase transitions based on the statistics of produced excitations. We consider both the O (N ) model in the large-N limit and a spin model with long-range interactions and show that the dynamical criticality of their prethermal steady states manifests most dramatically not in the average number of excitations but in their higher moments. We argue that the growth of defect fluctuations carries unique signatures of the dynamical criticality, irrespective of the precise details of the model. Our theoretical results should be relevant to quantum quench experiments with ultracold bosonic atoms in optical lattices.

 

Title:
Combined Measurement of the Higgs Boson Mass in p p Collisions at &surd;{s }=7 and 8 TeV with the ATLAS and CMS Experiments
Authors:
Aad, G.; Abbott, B.; Abdallah, J.;... Barreiro Guimarães da Costa, J.;... Franklin, M.;... Huth, J.;... Morii, M.;... and 5148 coauthors
Publication:
Physical Review Letters, Volume 114, Issue 19, id.191803 (PhRvL Homepage)
Publication Date:
05/2015
Origin:
APS
PACS Keywords:
Standard-model Higgs bosons, Inclusive production with identified leptons photons or other nonhadronic particles
Abstract Copyright:
2015: CERN
DOI:
10.1103/PhysRevLett.114.191803
Bibliographic Code:
2015PhRvL.114s1803A

Abstract

A measurement of the Higgs boson mass is presented based on the combined data samples of the ATLAS and CMS experiments at the CERN LHC in the H -->gamma gamma and H -->Z Z -->4 l decay channels. The results are obtained from a simultaneous fit to the reconstructed invariant mass peaks in the two channels and for the two experiments. The measured masses from the individual channels and the two experiments are found to be consistent among themselves. The combined measured mass of the Higgs boson is mH=125.09 ±0.21 (stat)±0.11 (syst) GeV .

 

Title:
High efficiency positron accumulation for high-precision magnetic moment experiments
Authors:
Fogwell Hoogerheide, S.; Dorr, J. C.; Novitski, E.; Gabrielse, G.
Publication:
Review of Scientific Instruments, Volume 86, Issue 5, id.053301 (RScI Homepage)
Publication Date:
05/2015
Origin:
AIP
Abstract Copyright:
2015: AIP Publishing LLC
DOI:
10.1063/1.4919413
Bibliographic Code:
2015RScI...86e3301F

Abstract

Positrons are accumulated within a Penning trap designed to make more precise measurements of the positron and electron magnetic moments. The retractable radioactive source used is weak enough to require no license for handling radioactive material, and the radiation dosage 1 m from the source gives an exposure several times smaller than the average radiation dose on the earth's surface. The 100 mK trap is mechanically aligned with the 4.2 K superconducting solenoid that produces a 6 T magnetic trapping field with a direct mechanical coupling.

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