Faculty Publications: November, 2013

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Title:
How a blister heals
Authors:
Longley, Jonathan E.; Mahadevan, L.; Chaudhury, Manoj K.
Publication:
Europhysics Letters, Volume 104, Issue 4, article id. 46002 (2013).
Publication Date:
11/2013
Origin:
IOP
DOI:
10.1209/0295-5075/104/46002
Bibliographic Code:
2013EL....10446002L

Abstract

We use experiments to study the dynamics of the healing of a blister, a localized bump in a thin elastic layer that is adhered to a soft substrate everywhere except at the bump. We create a blister by gently placing a glass cover slip on a PDMS substrate. The pressure jump across the elastic layer drives fluid flow through micro-channels that form at the interface between the layer and the substrate; these channels coalesce at discrete locations as the blister heals and eventually disappear at a lower critical radius. The spacing of the channel follows a simple scaling law that can be theoretically justified, and the kinetics of healing is rate limited by fluid flow, but with a non-trivial dependence on the substrate thickness that likely arises due to channelization. Our study is relevant to a variety of soft adhesion scenarios.

 

Title:
Measurement of the top quark charge in pp collisions at TeV with the ATLAS detector
Authors:
Aad, G.; Abajyan, T.; Abbott, B.;...... Barreiro Guimarães da Costa, J.; ... Franklin, M.; ... Huth, J.; ... Morii, M.; ... ; and 2907 coauthors
Publication:
Journal of High Energy Physics, Volume 2013, article id. #31
Publication Date:
11/2013
Origin:
SPRINGER
Keywords:
Hadron-Hadron Scattering, Top physics
Abstract Copyright:
(c) 2013: CERN, for the benefit of the ATLAS collaboration
DOI:
10.1007/JHEP11(2013)031
Bibliographic Code:
2013JHEP...11..031A

Abstract

A measurement of the top quark electric charge is carried out in the ATLAS experiment at the Large Hadron Collider using 2.05 fb-1 of data at a centre-of-mass energy of 7 TeV. In units of the elementary electric charge, the top quark charge is determined to be 0.64 ± 0.02 (stat.) ± 0.08 (syst.) from the charges of the top quark decay products in single lepton candidate events. This excludes models that propose a heavy quark of electric charge -4/3, instead of the Standard Model top quark, with a significance of more than 8 σ. [Figure not available: see fulltext.]

 

Title:
Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at = 2.76 TeV with the ATLAS detector at the LHC
Authors:
Aad, G.; Abajyan, T.; Abbott, B.;...... Barreiro Guimarães da Costa, J.; ... Franklin, M.; ... Huth, J.; ... Morii, M.; ... ; and 2910 coauthors
Publication:
Journal of High Energy Physics, Volume 2013, article id. #183
Publication Date:
11/2013
Origin:
SPRINGER
Keywords:
Heavy-ion collision, harmonic flow, event-by-event fluctuation, unfolding, Hadron-Hadron Scattering
Abstract Copyright:
(c) 2013: CERN, for the benefit of the ATLAS collaboration
DOI:
10.1007/JHEP11(2013)183
Bibliographic Code:
2013JHEP...11..183A

Abstract

The distributions of event-by-event harmonic flow coefficients v n for n = 2- 4 are measured in = 2 .76 TeV Pb + Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum p T > 0 .5 GeV and in the pseudorapidity range | η| < 2 .5 in a dataset of approximately 7 μb-1 recorded in 2010. The shapes of the v n distributions suggest that the associated flow vectors are described by a two-dimensional Gaussian function in central collisions for v 2 and over most of the measured centrality range for v 3 and v 4. Significant deviations from this function are observed for v 2 in mid-central and peripheral collisions, and a small deviation is observed for v 3 in mid-central collisions. In order to be sensitive to these deviations, it is shown that the commonly used multi-particle cumulants, involving four particles or more, need to be measured with a precision better than a few percent. The v n distributions are also measured independently for charged particles with 0 .5 < p T < 1 GeV and p T > 1 GeV. When these distributions are rescaled to the same mean values, the adjusted shapes are found to be nearly the same for these two p T ranges. The v n distributions are compared with the eccentricity distributions from two models for the initial collision geometry: a Glauber model and a model that includes corrections to the initial geometry due to gluon saturation effects. Both models fail to describe the experimental data consistently over most of the measured centrality range. [Figure not available: see fulltext.]

 

Title:
Chemically synthesized nanowire TiO2/ZnO core-shell p-n junction array for high sensitivity ultraviolet photodetector
Authors:
Dao, T. D.; Dang, C. T. T.; Han, G.; Hoang, C. V.; Yi, W.; Narayanamurti, V.; Nagao, T.
Publication:
Applied Physics Letters, Volume 103, Issue 19, id. 193119 (4 pages) (2013). (ApPhL Homepage)
Publication Date:
11/2013
Origin:
AIP
PACS Keywords:
Photodetectors, Chemical synthesis methods, Sol-gel processing precipitation, Liquid phase epitaxy, deposition from liquid phases
Abstract Copyright:
(c) 2013: American Institute of Physics
DOI:
10.1063/1.4826921
Bibliographic Code:
2013ApPhL.103s3119D

Abstract

A sol-gel-based ultrathin TiO2 lamination coating was adapted to a hydrothermally grown ZnO nanowire array to realize an all-oxide ultra-sensitive p-n photodiode. The core-shell heterojunction--the key component of the device--is composed of a 5-10 nm thick p-type Cr-doped TiO2 nanoshell and n-type single-crystalline ZnO nanowires (50 nm radius). Owing to the enhanced light scattering and carrier separation in the core-shell architecture, this device exhibits the highest performance among the ZnO nanowire-based photodetectors. At a moderate reverse bias of -5 V and under ultraviolet light illumination at 104 μW, it shows a switch current ratio of 140 and a responsivity as large as 250 A/W, while it shows nearly no response to the infrared and visible light.

 

Title:
A precise measurement of the $W$-boson mass with the Collider Detector at Fermilab
Authors:
Aaltonen, T.; Amerio, S.; Amidei, D.;... Guimaraes da Costa, J.;... Franklin, M.;... and 405 coauthors
Publication:
eprint arXiv:1311.0894
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
High Energy Physics - Experiment
Comment:
Submitted to Phys. Rev. D
Bibliographic Code:
2013arXiv1311.0894A

Abstract

We present a measurement of the $W$-boson mass, $M_W$, using data corresponding to 2.2/fb of integrated luminosity collected in ppbar collisions at $\sqrt{s}$ = 1.96 TeV with the CDF II detector at the Fermilab Tevatron. The selected sample of 470126 $W\to e\nu$ candidates and 624708 $W\to\mu\nu$ candidates yields the measurement $M_W = 80387\pm 12$ (stat) $\pm 15$ (syst)$ = 80387 \pm 19$ MeV$/c^2$ . This is the most precise single measurement of the $W$-boson mass to date.

 

Title:
Imaging the Nanoscale Band Structure of Topological Sb
Authors:
Soumyanarayanan, Anjan; Yee, Michael M.; He, Yang; Lin, Hsin; Gardner, Dillon R.; Bansil, Arun; Lee, Young S.; Hoffman, Jennifer E.
Publication:
eprint arXiv:1311.1758
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Strongly Correlated Electrons
Comment:
10 pages, 5 figures
Bibliographic Code:
2013arXiv1311.1758S

Abstract

Many promising building blocks of future electronic technology - including non-stoichiometric compounds, strongly correlated oxides, and strained or patterned films - are inhomogeneous on the nanometer length scale. Exploiting the inhomogeneity of such materials to design next-generation nanodevices requires a band structure probe with nanoscale spatial resolution. To address this demand, we report the first simultaneous observation and quantitative reconciliation of two candidate probes - Landau level spectroscopy and quasiparticle interference imaging - which we employ here to reconstruct the multi-component surface state band structure of the topological semimetal antimony(Sb). We thus establish the technique of band structure tunneling microscopy (BSTM), whose unique advantages include nanoscale access to non-rigid band structure deformation, empty state dispersion, and magnetic field dependent states. We use BSTM to elucidate the relationship between bulk conductivity and surface state robustness in topological materials, and to quantify essential metrics for spintronics applications.

 

Title:
All-optical sensing of a single-molecule electron spin
Authors:
Sushkov, A. O.; Chisholm, N.; Lovchinsky, I.; Kubo, M.; Lo, P. K.; Bennett, S. D.; Hunger, D.; Akimov, A.; Walsworth, R. L.; Park, H.; Lukin, M. D.
Publication:
eprint arXiv:1311.1801
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Atomic Physics, Physics - Biological Physics, Quantum Physics
Bibliographic Code:
2013arXiv1311.1801S

Abstract

We demonstrate an all-optical method for magnetic sensing of individual molecules in ambient conditions at room temperature. Our approach is based on shallow nitrogen-vacancy (NV) centers near the surface of a diamond crystal, which we use to detect single paramagnetic molecules covalently attached to the diamond surface. The manipulation and readout of the NV centers is all-optical and provides a sensitive probe of the magnetic field fluctuations stemming from the dynamics of the electronic spins of the attached molecules. As a specific example, we demonstrate detection of a single paramagnetic molecule containing a gadolinium (Gd$^{3+}$) ion. We confirm single-molecule resolution using optical fluorescence and atomic force microscopy to co-localize one NV center and one Gd$^{3+}$-containing molecule. Possible applications include nanoscale and in vivo magnetic spectroscopy and imaging of individual molecules.

 

Title:
Snowmass 2013 Top quark working group report
Authors:
Agashe, K.; Erbacher, R.; Gerber, C. E.;... Reece, M.;... and 160 coauthors
Publication:
eprint arXiv:1311.2028
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
High Energy Physics - Phenomenology, High Energy Physics - Experiment
Bibliographic Code:
2013arXiv1311.2028A

Abstract

This report summarizes the work of the Energy Frontier Top Quark working group of the 2013 Community Summer Study (Snowmass).

 

Title:
Elastic proton-proton scattering from ISR to LHC energies, focusing on the dip region
Authors:
Csorgo, T.; Glauber, R. J.; Nemes, F.
Publication:
eprint arXiv:1311.2308
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
High Energy Physics - Phenomenology, High Energy Physics - Experiment, Nuclear Experiment
Comment:
13 pages, 6 figures, invited talk of T. Csorgo at the Low x workshop, May 30 - June 4 2013, Rehovot and Eilat, Israel
Bibliographic Code:
2013arXiv1311.2308C

Abstract

The differential cross-section of elastic proton-proton collisions is studied at ISR and LHC energies, utilizing a quark-diquark model, that generalizes earlier models of Bialas and Bzdak, and, in addition, a model of Glauber and Velasco. These studies suggest that the increase of the total pp cross-section is mainly due to an increase of the separation of the quark and the diquark with increasing energies. Within the investigated class of models, two simple and model-independent phenomenological relations were found, that connect the total pp scattering cross-section to the effective quark, diquark size and their average separation, on one hand, and to the position of the dip of the differential cross-section, on the other hand. The latter t(dip) sigma(tot) ~ const relation can be used to predict t(dip), the position of the dip of elastic pp scattering for future colliding energies, and for other reactions, where sigma(tot) is either known or can be reliably estimated.

 

Title:
Spatial population expansion promotes the evolution of cooperation in an experimental Prisoner's Dilemma
Authors:
Van Dyken, J. David; Muller, Melanie J. I.; Mack, Keenan M. L.; Desai, Michael M.
Publication:
eprint arXiv:1311.2646
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
Quantitative Biology - Populations and Evolution, Physics - Biological Physics
Comment:
Curr Biol 23, 919-923, 2013 Export Citation Permissions Current Biology, Volume 23, Issue 10, 919-923; doi:10.1016/j.cub.2013.04.026
Bibliographic Code:
2013arXiv1311.2646V

Abstract

Cooperation is ubiquitous in nature, but explaining its existence remains a central interdisciplinary challenge. Cooperation is most difficult to explain in the Prisoner's Dilemma game, where cooperators always lose in direct competition with defectors despite increasing mean fitness. Here we demonstrate how spatial population expansion, a widespread natural phenomenon, promotes the evolution of cooperation. We engineer an experimental Prisoner's Dilemma game in the budding yeast Saccharomyces cerevisiae to show that, despite losing to defectors in nonexpanding conditions, cooperators increase in frequency in spatially expanding populations. Fluorescently labeled colonies show genetic demixing of cooperators and defectors, followed by increase in cooperator frequency as cooperator sectors overtake neighboring defector sectors. Together with lattice-based spatial simulations, our results suggest that spatial population expansion drives the evolution of cooperation by (1) increasing positive genetic assortment at population frontiers and (2) selecting for phenotypes maximizing local deme productivity. Spatial expansion thus creates a selective force whereby cooperator-enriched demes overtake neighboring defector-enriched demes in a "survival of the fastest". We conclude that colony growth alone can promote cooperation and prevent defection in microbes. Our results extend to other species with spatially restricted dispersal undergoing range expansion, including pathogens, invasive species, and humans.

 

Title:
Boosted objects and jet substructure at the LHC
Authors:
participants-A. Altheimer, BOOST2012; Arce, A.; Asquith, L.; Backus Mayes, J.;... Schwartz, M. D.;...; and 82 coauthors
Publication:
eprint arXiv:1311.2708
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
High Energy Physics - Experiment, High Energy Physics - Phenomenology
Comment:
Report of BOOST2012, held at IFIC Valencia, 23$^{rd}$-27$^{th}$ of July 2012
Bibliographic Code:
2013arXiv1311.2708P

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 the description of jet substructure in first-principle QCD calculations and study the accuracy of state-of-the-art Monte Carlo tools. Experimental limitations of the ability to resolve substructure are evaluated, with a focus on the impact of additional proton proton collisions on jet substructure performance in future LHC operating scenarios. A final section summarizes the lessons learnt during the deployment of substructure analyses in searches for new physics in the production of boosted top quarks.

 

Title:
Precision Spectroscopy of Polarized Molecules in an Ion Trap
Authors:
Loh, Huanqian; Cossel, Kevin C.; Grau, Matt; Ni, Kang-Kuen; Meyer, Edmund R.; Bohn, John L.; Ye, Jun; Cornell, Eric A.
Publication:
eprint arXiv:1311.3165
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
Physics - Atomic Physics
Comment:
Accepted to Science; Science 342, 1220-1222 (2013); doi:10.1126/science.1243683
Bibliographic Code:
2013arXiv1311.3165L

Abstract

Polar molecules are desirable systems for quantum simulations and cold chemistry. Molecular ions are easily trapped, but a bias electric field applied to polarize them tends to accelerate them out of the trap. We present a general solution to this issue by rotating the bias field slowly enough for the molecular polarization axis to follow but rapidly enough for the ions to stay trapped. We demonstrate Ramsey spectroscopy between Stark-Zeeman sublevels in 180Hf19F+ with a coherence time of 100 ms. Frequency shifts arising from well-controlled topological (Berry) phases are used to determine magnetic g-factors. The rotating-bias-field technique may enable using trapped polar molecules for precision measurement and quantum information science, including the search for an electron electric dipole moment.

 

Title:
Mean field theory of competing orders in metals with antiferromagnetic exchange interactions
Authors:
Deep Sau, Jay; Sachdev, Subir
Publication:
eprint arXiv:1311.3298
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Comment:
10 pages, 8 figures; (v2) added refs
Bibliographic Code:
2013arXiv1311.3298D

Abstract

It has long been known that two-dimensional metals with antiferromagnetic exchange interactions have a weak-coupling instability to the superconductivity of spin-singlet, d-wave electron pairs. We examine additional possible instabilities in the spin-singlet particle-hole channel, and study their interplay with superconductivity. We perform an unrestricted Hartree-Fock-BCS analysis of bond order parameters in a single band model on the square lattice with nearest-neighbor exchange and repulsion, while neglecting on-site interactions. The dominant particle-hole instability is found to be an incommensurate, bi-directional, bond density wave with wavevectors along the (1,1) and (1,-1) directions, and an internal d-wave symmetry. The magnitude of the ordering wavevector is close to the separation between points on the Fermi surface which intersect the antiferromagnetic Brillouin zone boundary. The temperature dependence of the superconducting and bond order parameters demonstrates their mutual competition. We also obtain the spatial dependence of the two orders in a vortex lattice induced by an applied magnetic field: "halos" of the bond order appear around the cores of the vortices.

 

Title:
Building Blocks for Generalized Heterotic/F-theory Duality
Authors:
Heckman, Jonathan J.; Lin, Hai; Yau, Shing-Tung
Publication:
eprint arXiv:1311.6477
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
High Energy Physics - Theory
Comment:
37 pages, 3 figures
Bibliographic Code:
2013arXiv1311.6477H

Abstract

In this note we propose a generalization of heterotic/F-theory duality. We introduce a set of non-compact building blocks which we glue together to reach compact examples of generalized duality pairs. The F-theory building blocks consist of non-compact elliptically fibered Calabi-Yau fourfolds which also admit a K3 fibration. The compact elliptic model obtained by gluing need not have a globally defined K3 fibration. By replacing the K3 fiber of each F-theory building block with a T^2, we reach building blocks in a heterotic dual vacuum which includes a position dependent dilaton and three-form flux. These building blocks are glued together to reach a heterotic flux background. We argue that in these vacua, the gauge fields of the heterotic string become localized, and remain dynamical even when gravity decouples. This enables a heterotic dual for the hyperflux GUT breaking mechanism which has recently figured prominently in F-theory GUT models. We illustrate our general proposal with some explicit examples.

 

Title:
Many-body Localization with Dipoles
Authors:
Yao, Norman Y.; Laumann, Chris R.; Gopalakrishnan, Sarang; Knap, Michael; Mueller, Markus; Demler, Eugene A.; Lukin, Mikhail D.
Publication:
eprint arXiv:1311.7151
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
Condensed Matter - Statistical Mechanics, Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Quantum Gases, Condensed Matter - Strongly Correlated Electrons, Quantum Physics
Comment:
8 pages, 5 figures
Bibliographic Code:
2013arXiv1311.7151Y

Abstract

Systems of strongly interacting dipoles offer an attractive platform to study many-body localized phases, owing to their long coherence times and strong interactions. We explore conditions under which such localized phases persist in the presence of power-law interactions and supplement our analytic treatment with numerical evidence of localized states in one dimension. We propose several experimental systems that can be used for the observation of such states, including ultracold polar molecules and solid-state magnetic spin impurities.

 

Title:
The Monge-Ampere constrained elastic theories of shallow shells
Authors:
Lewicka, Marta; Mahadevan, L; Pakzad, Mohammad Reza
Publication:
eprint arXiv:1312.0050
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
Mathematics - Analysis of PDEs
Bibliographic Code:
2013arXiv1312.0050L

Abstract

Motivated by the degree of smoothness of constrained embeddings of surfaces in $\mathbb{R}^3$, and by the recent applications to the elasticity of shallow shells, we rigorously derive the $\Gamma$-limit of 3-dimensional nonlinear elastic energy of a shallow shell of thickness $h$, where the depth of the shell scales like $h^\alpha$ and the applied forces scale like $h^{\alpha+2}$, in the limit when $h\to 0$. The main analytical ingredients are two independent results: a theorem on approximation of $W^{2,2}$ solutions of the Monge-Amp\`ere equation by smooth solutions, and a theorem on the matching (in other words, continuation) of second order isometries to exact isometries.

 

Title:
Evidence for the decay B0 --> omega omega and search for B0 --> omega phi
Authors:
The BABAR Collaboration; Lees, J. P.; Poireau, V.; Tisserand, V.;... Morii, M.;... and 332 coauthors
Publication:
eprint arXiv:1312.0056
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
High Energy Physics - Experiment
Comment:
7 pages, 2 postscript figures, submitted to Phys. Rev. Lett
Bibliographic Code:
2013arXiv1312.0056T

Abstract

We describe searches for B meson decays to the charmless vector-vector final states omega omega and omega phi with 471 x 10^6 B Bbar pairs produced in e+ e- annihilation at sqrt(s) = 10.58 GeV using the BABAR detector at the PEP-II collider at the SLAC National Accelerator Laboratory. We measure the branching fraction B(B0 --> omega omega) = (1.2 +- 0.3 +0.3-0.2) x 10^-6, 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 --> omega phi) < 0.7 x 10^-6 at 90% confidence level. These measurements provide the first evidence for the decay B0 --> omega omega, and an improvement of the upper limit for the decay B0 --> omega phi.

 

Title:
An explicit formula of hitting times for random walks on graphs
Authors:
Xu, Hao; Yau, Shing-Tung
Publication:
eprint arXiv:1312.0065
Publication Date:
11/2013
Origin:
ARXIV
Keywords:
Mathematics - Combinatorics
Comment:
to appear in Pure Appl. Math. Q
Bibliographic Code:
2013arXiv1312.0065X

Abstract

We prove an explicit formula of hitting times in terms of enumerations of spanning trees for random walks on general connected graphs. We apply the formula to improve Lawler's bound of hitting times for general graphs, prove a sharp bound of hitting times for adjacent vertices and derive closed formulas of hitting times for some special graphs.

 


Title:
BPS Quivers and Spectra of Complete Quantum Field Theories
Authors:
Alim, Murad; Cecotti, Sergio; Córdova, Clay; Espahbodi, Sam; Rastogi, Ashwin; Vafa, Cumrun
Publication:
Communications in Mathematical Physics, Volume 323, Issue 3, pp.1185-1227
Publication Date:
11/2013
Origin:
SPRINGER
Abstract Copyright:
(c) 2013: Springer-Verlag Berlin Heidelberg
DOI:
10.1007/s00220-013-1789-8
Bibliographic Code:
2013CMaPh.323.1185A

Abstract

We study the BPS spectra of complete quantum field theories in four dimensions. For examples that can be described by a pair of M5 branes on a punctured Riemann surface we explain how triangulations of the surface fix a BPS quiver and superpotential for the theory. The BPS spectrum can then be determined by solving the quantum mechanics problem encoded by the quiver. By analyzing the structure of this quantum mechanics we show that all asymptotically free examples, Argyres-Douglas models, and theories defined by punctured spheres and tori have a chamber with finitely many BPS states. In all such cases we determine the spectrum.

 

Title:
Intermodal energy transfer in a tapered optical fiber: optimizing transmission
Authors:
Ravets, S.; Hoffman, J. E.; Kordell, P. R.; Wong-Campos, J. D.; Rolston, S. L.; Orozco, L. A.
Publication:
Journal of the Optical Society of America A, vol. 30, issue 11, p. 2361
Publication Date:
11/2013
Origin:
CROSSREF
DOI:
10.1364/JOSAA.30.002361
Bibliographic Code:
2013JOSAA..30.2361R

Abstract

We present an experimental and theoretical study of the energy transfer between modes during the tapering process of an optical nanofiber through spectrogram analysis. The results allow optimization of the tapering process, and we measure transmission in excess of 99.95% for the fundamental mode. We quantify the adiabaticity condition through calculations and place an upper bound on the amount of energy transferred to other modes at each step of the tapering, giving practical limits to the tapering angle.

 

Title:
Fast compressed sensing analysis for super-resolution imaging using L1-homotopy
Authors:
Babcock, Hazen P.; Moffitt, Jeffrey R.; Cao, Yunlong; Zhuang, Xiaowei
Publication:
Optics Express, vol. 21, issue 23, p. 28583
Publication Date:
11/2013
Origin:
CROSSREF
DOI:
10.1364/OE.21.028583
Bibliographic Code:
2013OExpr..2128583B

Abstract

Not Available

 

Title:
Robustness of quantum memories based on Majorana zero modes
Authors:
Mazza, L.; Rizzi, M.; Lukin, M. D.; Cirac, J. I.
Publication:
Physical Review B, vol. 88, Issue 20, id. 205142 (PhRvB Homepage)
Publication Date:
11/2013
Origin:
APS
PACS Keywords:
Quantum error correction and other methods for protection against decoherence, Quantum computation, Quantum wires
DOI:
10.1103/PhysRevB.88.205142
Bibliographic Code:
2013PhRvB..88t5142M

Abstract

We analyze the rate at which quantum information encoded in zero-energy Majorana modes is lost in the presence of perturbations. We show that information can survive for times that scale exponentially with the size of the chain both in the presence of quenching and time-dependent quadratic dephasing perturbations, even when the latter have spectral components above the system's energy gap. The origin of the robust storage, namely the fact that a sudden quench affects in the same way both parity sectors of the original spectrum, is discussed, together with the memory performance at finite temperatures and in the presence of particle exchange with a bath.

 

Title:
Search for the production of ZW and ZZ boson pairs decaying into charged leptons and jets in pp¯ collisions at s=1.96TeV
Authors:

Aaltonen, T.; Amerio, S.; Amidei, D.;...; Franklin, M.;... Guimaraes da Costa, J.;... ; and 402 coauthors

Publication:
Physical Review D, vol. 88, Issue 9, id. 092002 (PhRvD Homepage)
Publication Date:
11/2013
Origin:
APS
PACS Keywords:
Gauge bosons, Electroweak interactions
DOI:
10.1103/PhysRevD.88.092002
Bibliographic Code:
2013PhRvD..88i2002A

Abstract

We present a measurement of the production cross section for ZW and ZZ boson pairs in final states with a pair of charged leptons, from the decay of a Z boson, and at least two jets, from the decay of a W or Z boson, using the full sample of proton-antiproton collisions recorded with the CDF II detector at the Tevatron, corresponding to 8.9fb-1 of integrated luminosity. We increase the sensitivity to vector-boson decays into pairs of quarks using a neural-network discriminant that exploits the differences between the spatial spread of energy depositions and charged-particle momenta contained within the jet of particles originating from quarks and gluons. Additionally, we employ new jet energy corrections to Monte Carlo simulations that account for differences in the observed energy scales for quark and gluon jets. The number of signal events is extracted through a simultaneous fit to the dijet mass spectrum in three classes of events: events likely to contain jets with a heavy-quark decay, events likely to contain jets originating from light quarks, and events that fail these identification criteria. We determine the production cross section to be σZW+ZZ=2.5-1.0+2.0pb (<6.1pb at the 95% confidence level), consistent with the standard model prediction of 5.1 pb.

 

Title:
Search for a dijet resonance in events with jets and missing transverse energy in pp¯ collisions at s=1.96TeV
Authors:
Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... Guimaraes da Costa, J.;... and 402 coauthors
Publication:
Physical Review D, vol. 88, Issue 9, id. 092004 (PhRvD Homepage)
Publication Date:
11/2013
Origin:
APS
PACS Keywords:
Applications of electroweak models to specific processes, Experimental tests, Gauge bosons, Other particles
DOI:
10.1103/PhysRevD.88.092004
Bibliographic Code:
2013PhRvD..88i2004A

Abstract

We report on a search for a dijet resonance in events with only two or three jets and a large imbalance in the total event transverse momentum. This search is sensitive to the possible production of a new particle in association with a W or Z boson, where the boson decays leptonically with one or more neutrinos in the final state. We use the full data set collected by the CDF II detector at the Tevatron collider at a proton-antiproton center-of-mass energy of 1.96 TeV. These data correspond to an integrated luminosity of 9.1fb-1. We study the invariant mass distribution of the two jets with highest transverse energy. We find good agreement between data and standard model background expectations and measure the combined cross section for WW, WZ, and ZZ production to be 13.8-2.7+3.0pb. No significant anomalies are observed in the mass spectrum, and 95% credibility level upper limits are set on the production rates of a potential new particle in association with a W or Z boson.

 

Title:
Production of KS0, K(892) and ϕ0(1020) in minimum bias events and KS0 and Λ0 in jets in pp¯ collisions at s=1.96TeV
Authors:
Aaltonen, T.; Albrow, M.; Amerio, S.;... Franklin, M.;... Guimaraes da Costa, J.;... and 402 coauthors
Publication:
Physical Review D, vol. 88, Issue 9, id. 092005 (PhRvD Homepage)
Publication Date:
11/2013
Origin:
APS
PACS Keywords:
Decays of other mesons, Hadronic decays, Inelastic scattering: many-particle final states, Fragmentation into hadrons
DOI:
10.1103/PhysRevD.88.092005
Bibliographic Code:
2013PhRvD..88i2005A

Abstract

We report measurements of the inclusive transverse momentum (pT) distribution of centrally produced KS0, K⋆±(892), and ϕ0(1020) mesons up to pT=10GeV/c in minimum bias events, and KS0 and Λ0 particles up to pT=20GeV/c in jets with transverse energy between 25 and 160 GeV in pp¯ collisions. The data were taken with the CDF II detector at the Fermilab Tevatron at s=1.96TeV. We find that as pT increases, the pT slopes of the three mesons (KS0, K⋆±, and ϕ) are similar. And using our previous Λ0 results from minimum bias events, we show that the ratio of Λ0 to KS0 as a function of pT in minimum bias events becomes similar to the fairly constant ratio in jets at pT˜5GeV/c. This suggests that the particles with pT≳5GeV/c in minimum bias events are from “soft” jets, and that the pT slope of particles in jets is insensitive to light quark flavor (u, d, or s) and to the number of valence quarks. We also find that for pT≲4GeV relatively more Λ0 baryons are produced in minimum bias events than in jets.

 

Title:
1/16 BPS states in N=4 super-Yang-Mills theory
Authors:
Chang, Chi-Ming; Yin, Xi
Publication:
Physical Review D, vol. 88, Issue 10, id. 106005 (PhRvD Homepage)
Publication Date:
11/2013
Origin:
APS
PACS Keywords:
Gauge/string duality, Quantum aspects of black holes evaporation thermodynamics
DOI:
10.1103/PhysRevD.88.106005
Bibliographic Code:
2013PhRvD..88j6005C

Abstract

We investigate the problem of counting 1/16 Bogomol’nyi-Prasad-Sommerfield (BPS) operators in N=4 super-Yang-Mills theory at weak coupling. We present the complete set of 1/16 BPS operators in the infinite-N limit, which agrees with the counting of free BPS multigraviton states in the gravity dual AdS5×S5. Further, we conjecture that all 1/16 BPS operators in N=4 super-Yang-Mills theory are of the multigraviton form, and give numerical evidence for this conjecture. We discuss the implication of our conjecture and the seeming failure in reproducing the entropy of large 1/16 BPS black holes in AdS5.

 

Title:
Direct Measurement of the Total Decay Width of the Top Quark
Authors:
Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;...; Guimaraes da Costa, J.; ;... and 402 coauthors
Publication:
Physical Review Letters, vol. 111, Issue 20, id. 202001 (PhRvL Homepage)
Publication Date:
11/2013
Origin:
APS
PACS Keywords:
Top quarks, Quark and lepton masses and mixing, Inclusive production with identified hadrons, Inclusive production with identified leptons photons or other nonhadronic particles
DOI:
10.1103/PhysRevLett.111.202001
Bibliographic Code:
2013PhRvL.111t2001A

Abstract

We present a measurement of the total decay width of the top quark using events with top-antitop quark pair candidates reconstructed in the final state with one charged lepton and four or more hadronic jets. We use the full Tevatron run II data set of s=1.96TeV proton-antiproton collisions recorded by the CDF II detector. The top quark mass and the mass of the hadronically decaying W boson are reconstructed for each event and compared with distributions derived from simulated signal and background samples to extract the top quark width (Γtop) and the energy scale of the calorimeter jets with in situ calibration. For a top quark mass Mtop=172.5GeV/c2, we find 1.10<Γtop<4.05GeV at 68% confidence level, which is in agreement with the standard model expectation of 1.3 GeV and is the most precise direct measurement of the top quark width to date.

 

Title:
Realizing a Kondo-Correlated State with Ultracold Atoms
Authors:
Bauer, Johannes; Salomon, Christophe; Demler, Eugene
Publication:
Physical Review Letters, vol. 111, Issue 21, id. 215304 (PhRvL Homepage)
Publication Date:
11/2013
Origin:
APS
PACS Keywords:
Mixtures of Bose and Fermi gases, Scattering by point defects dislocations surfaces and other imperfections, Scattering mechanisms and Kondo effect, Local moment in compounds and alloys, Kondo effect valence fluctuations heavy fermions
DOI:
10.1103/PhysRevLett.111.215304
Bibliographic Code:
2013PhRvL.111u5304B

Abstract

We propose a novel realization of Kondo physics with ultracold atomic gases. It is based on a Fermi sea of two different hyperfine states of one atom species forming bound states with a different species, which is spatially confined in a trapping potential. We show that different situations displaying Kondo physics can be realized when Feshbach resonances between the species are tuned by a magnetic field and the trapping frequency is varied. We illustrate that a mixture of K40 and Na23 atoms can be used to generate a Kondo-correlated state and that momentum resolved radio frequency spectroscopy can provide unambiguous signatures of the formation of Kondo resonances at the Fermi energy. We discuss how tools of atomic physics can be used to investigate open questions for Kondo physics, such as the extension of the Kondo screening cloud.


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