Faculty Publications: January, 2013

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Title:   Rolling particle lithography by soft polymer microparticles
Authors:   Di Benedetto, Francesca; Fasano, Vito; Persano, Luana; Maruccio, Claudio; Mele, Elisa; Potente, Giovanni; Weitz, David A.; De Lorenzis, Laura; Pisignano, Dario
Publication:   Soft Matter, vol. 9, issue 7, p. 2206
Publication Date:   01/2013
Origin:   CROSSREF
DOI:   10.1039/c2sm27327f
Bibliographic Code:   2013SMat....9.2206D

Abstract

Not Available
 

Title:   Chiroptical hot spots in twisted nanowire plasmonic oscillators
Authors:   Tang, Yiqiao; Sun, Li; Cohen, Adam E.
Publication:   Applied Physics Letters, Volume 102, Issue 4, id. 043103 (4 pages) (2013). (ApPhL Homepage)
Publication Date:   01/2013
Origin:   AIP
Keywords:   chirality, circular dichroism, nanophotonics, nanowires, optical metamaterials, plasmonics
PACS Keywords:   Optical elements, devices, and systems, Optical materials
Abstract Copyright:   (c) 2013: American Institute of Physics
DOI:   10.1063/1.4789529
Bibliographic Code:   2013ApPhL.102d3103T

Abstract

We image the chiroptical response of crossed nanowire junctions as a function of the vertical offset between the nanowires and the incident wavelength. These samples show chiroptical ``hot spots'' with strongly localized circular differential scattering at the nanowire crossing points. These chiroptical hot spots are not apparent in the spatially averaged spectra. The sign and magnitude of the chiroptical enhancement show a complex dependence on sample geometry, which we reproduce with a fully retarded analytical scattering model. These results suggest strategies for engineering devices with enhanced chiral light-matter interactions.
 

Title:   Flagellar Motor Remodeling and Filament Growth
Authors:   Berg, Howard
Publication:   Biophysical Journal, vol. 104, issue 2, p. 533a
Publication Date:   01/2013
Origin:   CROSSREF
DOI:   10.1016/j.bpj.2012.11.2947
Bibliographic Code:   2013BpJ...104..533B

Abstract

Not Available
 

Title:   Reductive Caging enables Ultra-Bright Photoactivatable Fluorophores for Superresolution Imaging
Authors:   Vaughan, Joshua; Jia, Shu; Zhuang, Xiaowei
Publication:   Biophysical Journal, vol. 104, issue 2, p. 534a
Publication Date:   01/2013
Origin:   CROSSREF
DOI:   10.1016/j.bpj.2012.11.2956
Bibliographic Code:   2013BpJ...104..534V

Abstract

Not Available
 

Title:   Single-Molecule Studies of Nucleosome Translocation by the ACF Chromatin Remodeling Complex
Authors:   Hwang, William L.; Deindl, Sebastian; Blosser, Timothy R.; Zhuang, Xiaowei
Publication:   Biophysical Journal, vol. 104, issue 2, p. 541a
Publication Date:   01/2013
Origin:   CROSSREF
DOI:   10.1016/j.bpj.2012.11.2995
Bibliographic Code:   2013BpJ...104..541H

Abstract

Not Available
 

Title:   Catsper Channel Organizes and Regulates Calcium Signaling Molecules in Spermatozoa
Authors:   Chung, Jean-Ju; Shim, Sang-Hee; Zhuang, Xiaowei; Clapham, David E.
Publication:   Biophysical Journal, vol. 104, issue 2, p. 633a
Publication Date:   01/2013
Origin:   CROSSREF
DOI:   10.1016/j.bpj.2012.11.3501
Bibliographic Code:   2013BpJ...104..633C

Abstract

Not Available
 

Title:   Compliant Or Stiff: Two Differing Mechanisms of Actin Network Stabilization by Calponin and Tropomyosin
Authors:   Jensen, Mikkel H.; Morris, Eliza J.; Gallant, Cynthia; Graceffa, Philip; Leavis, Paul; Morgan, Kathleen G.; Weitz, David A.; Moore, Jeffrey R.
Publication:   Biophysical Journal, vol. 104, issue 2, p. 647a
Publication Date:   01/2013
Origin:   CROSSREF
DOI:   10.1016/j.bpj.2012.11.3572
Bibliographic Code:   2013BpJ...104..647J

Abstract

Not Available
 

Title:   Mechanics and Structure of Fibrin Networks Polymerized under Oscillatory Shear Perturbations
Authors:   Münster, Stefan; Jawerth, Louise M.; Weitz, David A.; Fabry, Ben
Publication:   Biophysical Journal, vol. 104, issue 2, p. 142a
Publication Date:   01/2013
Origin:   CROSSREF
DOI:   10.1016/j.bpj.2012.11.807
Bibliographic Code:   2013BpJ...104..142M

Abstract

Not Available
 

Title:   Isotropic 3D Super Resolution Imaging with Self-Bending Point Spread Function
Authors:   Jia, Shu; Vaughan, Joshua C.; Zhuang, Xiaowei
Publication:   Biophysical Journal, vol. 104, issue 2, p. 668a
Publication Date:   01/2013
Origin:   CROSSREF
DOI:   10.1016/j.bpj.2012.11.3687
Bibliographic Code:   2013BpJ...104..668J

Abstract

Not Available
 

Title:   Wide-Field Magnetic Imaging using Nitrogen-Vacancy Color Centers in Diamond
Authors:   Arai, Keigo; Le Sage, David; DeVience, Stephen J.; Glenn, David R.; Pham, Linh M.; Rahn-Lee, Lilah; Lukin, Mikhail D.; Yacoby, Amir; Komeili, Arash; Walsworth, Ronald L.
Publication:   Biophysical Journal, vol. 104, issue 2, p. 193a
Publication Date:   01/2013
Origin:   CROSSREF
DOI:   10.1016/j.bpj.2012.11.1088
Bibliographic Code:   2013BpJ...104Q.193A

Abstract

Not Available
 

Title:   The Mechanical Mechanism of Platelet Induced Clot Stiffening
Authors:   Jawerth, Louise; Muenster, Stefan; Weitz, David A.
Publication:   Biophysical Journal, vol. 104, issue 2, p. 150a
Publication Date:   01/2013
Origin:   CROSSREF
DOI:   10.1016/j.bpj.2012.11.851
Bibliographic Code:   2013BpJ...104R.150J

Abstract

Not Available
 

Title:   Note: A three-dimensional calibration device for the confocal microscope
Authors:   Jensen, K. E.; Weitz, D. A.; Spaepen, F.
Publication:   Review of Scientific Instruments, Volume 84, Issue 1, pp. 016108-016108-3 (2013). (RScI Homepage)
Publication Date:   01/2013
Origin:   AIP
Keywords:   calibration, image processing, micrometry
PACS Keywords:   Imaging and optical processing, Standards and calibration, Spatial dimensions
Abstract Copyright:   (c) 2013: American Institute of Physics
DOI:   10.1063/1.4776672
Bibliographic Code:   2013RScI...84a6108J

Abstract

Modern confocal microscopes enable high-precision measurement in three dimensions by collecting stacks of 2D (x-y) images that can be assembled digitally into a 3D image. It is difficult, however, to ensure position accuracy, particularly along the optical (z) axis where scanning is performed by a different physical mechanism than in x-y. We describe a simple device to calibrate simultaneously the x, y, and z pixel-to-micrometer conversion factors for a confocal microscope. By taking a known 2D pattern and positioning it at a precise angle with respect to the microscope axes, we created a 3D reference standard. The device is straightforward to construct and easy to use.
 

Title:   Visualizing multiphase flow and trapped fluid configurations in a model three-dimensional porous medium
Authors:   Krummel, Amber T.; Datta, Sujit S.; Münster, Stefan; Weitz, David A.
Publication:   eprint arXiv:1301.4883
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   Physics - Fluid Dynamics, Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Materials Science, Condensed Matter - Soft Condensed Matter, Condensed Matter - Statistical Mechanics
Comment:   Published in AIChE Journal (2013); doi:10.1002/aic.14005
Bibliographic Code:   2013arXiv1301.4883K

Abstract

We report an approach to fully visualize the flow of two immiscible fluids through a model three-dimensional (3D) porous medium at pore-scale resolution. Using confocal microscopy, we directly image the drainage of the medium by the non-wetting oil and subsequent imbibition by the wetting fluid. During imbibition, the wetting fluid pinches off threads of oil in the narrow crevices of the medium, forming disconnected oil ganglia. Some of these ganglia remain trapped within the medium. By resolving the full 3D structure of the trapped ganglia, we show that the typical ganglion size, and the total amount of residual oil, decreases as the capillary number Ca increases; this behavior reflects the competition between the viscous pressure in the wetting fluid and the capillary pressure required to force oil through the pores of the medium. This work thus shows how pore-scale fluid dynamics influence the trapped fluid configurations in multiphase flow through 3D porous media.
 

Title:   Nanoscale Surface Element Identification and Dopant Homogeneity in the High-$T_c$ Superconductor Pr$_x$Ca$_{1-x}$Fe$_2$As$_2$
Authors:   Zeljkovic, Ilija; Huang, Dennis; Song, Can-Li; Lv, Bing; Chu, Ching-Wu; Hoffman, Jennifer E.
Publication:   eprint arXiv:1301.4942
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Comment:   5 pages, 4 figures
Bibliographic Code:   2013arXiv1301.4942Z

Abstract

We use scanning tunneling microscopy to determine the surface structure and dopant distribution in Pr$_x$Ca$_{1-x}$Fe$_2$As$_2$, the highest-$T_c$ member of the 122 family of iron-based superconductors. We identify the cleaved surface termination by mapping the local tunneling barrier height, related to the work function. We image the individual Pr dopants responsible for superconductivity, and show that they do not cluster, but in fact repel each other at short length scales. We therefore suggest that the low volume fraction high-$T_c$ superconducting phase is unlikely to originate from Pr inhomogeneity.
 

Title:   Drainage in a model stratified porous medium
Authors:   Datta, Sujit S.; Weitz, David A.
Publication:   eprint arXiv:1301.5253
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   Physics - Fluid Dynamics, Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Soft Condensed Matter
Comment:   EPL 101, 14002 (2013); doi:10.1209/0295-5075/101/14002
Bibliographic Code:   2013arXiv1301.5253D

Abstract

We show that when a non-wetting fluid drains a stratified porous medium at sufficiently small capillary numbers Ca, it flows only through the coarsest stratum of the medium; by contrast, above a threshold Ca, the non-wetting fluid is also forced laterally, into part of the adjacent, finer strata. The spatial extent of this partial invasion increases with Ca. We quantitatively understand this behavior by balancing the stratum-scale viscous pressure driving the flow with the capillary pressure required to invade individual pores. Because geological formations are frequently stratified, we anticipate that our results will be relevant to a number of important applications, including understanding oil migration, preventing groundwater contamination, and sub-surface CO$_{2}$ storage.
 

Title:   One-Particle Measurement of the Antiproton Magnetic Moment
Authors:   ATRAP Collaboration; DiSciacca, J.; Marshall, M.; Marable, K.; Gabrielse, G.; Ettenauer, S.; Tardiff, E.; Kalra, R.; Fitzakerley, D. W.; George, M. C.; Hessels, E. A.; Storry, C. H.; Weel, M.; Grzonka, D.; Oelert, W.; Sefzick, T.
Publication:   eprint arXiv:1301.6310
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   Physics - Atomic Physics
Comment:   4 pages, 4 figures. arXiv admin note: substantial text overlap with arXiv:1201.3038
Bibliographic Code:   2013arXiv1301.6310A

Abstract

For the first time a single trapped p is used to measure the p magnetic moment μp . The moment μp = μpS/(~/2) is given in terms of its spin S and the nuclear magneton (μN) by μp/μN = −2.792 845 ± 0.000 012. The 4.4 parts per million (ppm) uncertainty is 680 times smaller than previously realized. Comparing to the proton moment measured using the same method and trap electrodes gives μp/μp = −1.000 000 ± 0.000 005 to 5 ppm, for a proton moment μp = μpS/(~/2), consistent with the prediction of the CPT theorem.
 

Title:   Increased Network Interdependency Leads to Aging
Authors:   Vural, Dervis Can; Morrison, Greg; Mahadevan, L.
Publication:   eprint arXiv:1301.6375
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   Quantitative Biology - Populations and Evolution, Physics - Biological Physics, Quantitative Biology - Molecular Networks
Comment:   11 pages, 10 figures, Preprint
Bibliographic Code:   2013arXiv1301.6375V

Abstract

Although species longevity is subject to a diverse range of selective forces, the mortality curves of a wide variety of organisms are rather similar. We argue that aging and its universal characteristics may have evolved by means of a gradual increase in the systemic interdependence between a large collection of biochemical or mechanical components. Modeling the organism as a dependency network which we create using a constructive evolutionary process, we age it by allowing nodes to be broken or repaired according to a probabilistic algorithm that accounts for random failures/repairs and dependencies. Our simulations show that the network slowly accumulates damage and then catastrophically collapses. We use our simulations to fit experimental data for the time dependent mortality rates of a variety of multicellular organisms and even complex machines such as automobiles. Our study suggests that aging is an emergent finite-size effect in networks with dynamical dependencies and that the qualitative and quantitative features of aging are not sensitively dependent on the details of system structure.
 

Title:   Collective thermoregulation in bee clusters
Authors:   Ocko, Samuel A.; Mahadevan, L.
Publication:   eprint arXiv:1301.7277
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   Quantitative Biology - Populations and Evolution, Quantitative Biology - Quantitative Methods
Comment:   18 pages, 8 figures
Bibliographic Code:   2013arXiv1301.7277O

Abstract

Swarming is an essential part of honeybee behaviour, wherein thousands of bees cling onto each other to form a dense cluster that may be exposed to the environment for several days. This cluster has the ability to maintain its core temperature actively without a central controller, and raises the question of how this is achieved. We suggest that the swarm cluster is akin to an active porous structure whose functional requirement is to adjust to outside conditions by varying its porosity to control its core temperature. Using a continuum model that takes the form of a set of advection-diffusion equations for heat transfer in a mobile porous medium, we show that the equalization of an effective "behavioural pressure", which propagates information about the ambient temperature through variations in density, leads to effective thermoregulation. Our model extends and generalizes previous models by focusing the question of mechanism on the form and role of the behavioural pressure, and allows us to explain the vertical asymmetry of the cluster (as a consequence of buoyancy driven flows), the ability of the cluster to overpack at low ambient temperatures without breaking up at high ambient temperatures, and the relative insensitivity to large variations in the ambient temperature. Finally, our theory makes testable hypotheses for how the cluster bee density should respond to externally imposed temperature inhomogeneities, and suggests strategies for biomimetic thermoregulation.
 

Title:   Optimal control of quantum revival
Authors:   Räsänen, Esa; Heller, Eric J.
Publication:   The European Physical Journal B, Volume 86, Issue 1, 2013, id.17, 5 pp. (EPJB Homepage)
Publication Date:   01/2013
Origin:   EDP Sciences; SPRINGER
Keywords:   Computational Methods
Abstract Copyright:   (c) 2013: EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg
DOI:   10.1140/epjb/e2012-30921-4
Bibliographic Code:   2013EPJB...86...17R

Abstract

Increasing fidelity is the ultimate challenge of quantum information technology. In addition to decoherence and dissipation, fidelity is affected by internal imperfections such as impurities in the system. Here we show that the quality of quantum revival, i.e., periodic recurrence in the time evolution, can be restored almost completely by coupling the distorted system to an external field obtained from quantum optimal control theory. We demonstrate the procedure with wave-packet calculations in both one- and two-dimensional quantum wells, and analyze the required physical characteristics of the control field. Our results generally show that the inherent dynamics of a quantum system can be idealized at an extremely low cost.
 

Title:   Measurements of top quark pair relative differential cross-sections with ATLAS in pp collisions at sqrt{s} = 7 TeV
Authors:   Aad, G.; Abajyan, T.; Abbott, B.;...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2869 coauthors.
Publication:   The European Physical Journal C, Volume 73, article id. #2261 (EPJC Homepage)
Publication Date:   01/2013
Origin:   SPRINGER
Abstract Copyright:   (c) 2013: CERN for the benefit of the ATLAS collaboration
DOI:   10.1140/epjc/s10052-012-2261-1
Bibliographic Code:   2013EPJC...73.2261A

Abstract

Measurements are presented of differential cross-sections for top quark pair production in pp collisions at sqrt{s} = 7 TeV relative to the total inclusive top quark pair production cross-section. A data sample of 2.05 fb-1 recorded by the ATLAS detector at the Large Hadron Collider is used. Relative differential cross-sections are derived as a function of the invariant mass, the transverse momentum and the rapidity of the top quark pair system. Events are selected in the lepton (electron or muon) + jets channel. The background-subtracted differential distributions are corrected for detector effects, normalized to the total inclusive top quark pair production cross-section and compared to theoretical predictions. The measurement uncertainties range typically between 10 % and 20 % and are generally dominated by systematic effects. No significant deviations from the Standard Model expectations are observed.
 

Title:   Search for pair-produced massive coloured scalars in four-jet final states with the ATLAS detector in proton-proton collisions at sqrt{s} = 7 TeV
Authors:   Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.;...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2905 coauthors.
Publication:   The European Physical Journal C, Volume 73, article id. #2263 (EPJC Homepage)
Publication Date:   01/2013
Origin:   SPRINGER
Abstract Copyright:   (c) 2013: CERN for the benefit of the ATLAS collaboration
DOI:   10.1140/epjc/s10052-012-2263-z
Bibliographic Code:   2013EPJC...73.2263A

Abstract

A search for pair-produced massive coloured scalar particles decaying to a four-jet final state is performed by the ATLAS experiment at the LHC in proton-proton collisions at sqrt{s} = 7 TeV. The analysed data sample corresponds to an integrated luminosity of 4.6 fb-1. No deviation from the Standard Model is observed in the invariant mass spectrum of the two-jet pairs. A limit on the scalar gluon pair production cross section of 70 pb (10 pb) is obtained at the 95 % confidence level for a scalar gluon mass of 150 GeV (350 GeV). Interpreting these results as mass limits on scalar gluons, masses ranging from 150 GeV to 287 GeV are excluded at the 95 % confidence level.
 

Title:   Charming CP violation and dipole operators from RS flavor anarchy
Authors:   Delaunay, Cédric; Kamenik, Jernej F.; Perez, Gilad; Randall, Lisa
Publication:   Journal of High Energy Physics, Volume 2013, article id. #27
Publication Date:   01/2013
Origin:   SPRINGER
Keywords:   Phenomenology of Field Theories in Higher Dimensions
Abstract Copyright:   (c) 2013: SISSA
DOI:   10.1007/JHEP01(2013)027
Bibliographic Code:   2013JHEP...01..027D

Abstract

Recently the LHCb collaboration reported evidence for direct CP violation in charm decays. The value is sufficiently large that either substantially enhanced Standard Model contributions or non-Standard Model physics is required to explain it. In the latter case only a limited number of possibilities would be consistent with other existing flavor-changing constraints. We show that warped extra dimensional models that explain the quark spectrum through flavor anarchy can naturally give rise to contributions of the size required to explain the the LHCb result. The D meson asymmetry arises through a sizable CP-violating contribution to a chromomagnetic dipole operator. This happens naturally without introducing inconsistencies with existing constraints in the up quark sector. We discuss some subtleties in the loop calculation that are similar to those in Higgs to γγ. Loop-induced dipole operators in warped scenarios and their composite analogs exhibit non-trivial dependence on the Higgs profile, with the contributions monotonically decreasing when the Higgs is pushed away from the IR brane. We show that the size of the dipole operator quickly saturates as the Higgs profile approaches the IR brane, implying small dependence on the precise details of the Higgs profile when it is quasi IR localized. We also explain why the calculation of the coefficient of the lowest dimension 5D operator is guaranteed to be finite. This is true not only in the charm sector but also with other radiative processes such as electric dipole moments, b → sγ, ɛ '/ ɛ K and μ → eγ. We furthermore discuss the interpretation of this contribution within the framework of partial compositeness in four dimensions and highlight some qualitative differences between the generic result of composite models and that obtained for dynamics that reproduces the warped scenario.
 

Title:   ATLAS search for new phenomena in dijet mass and angular distributions using pp collisions at sqrt{s}=7 TeV
Authors:   Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.;...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2896 coauthors.
Publication:   Journal of High Energy Physics, Volume 2013, article id. #29
Publication Date:   01/2013
Origin:   SPRINGER
Keywords:   Hadron-Hadron Scattering
Abstract Copyright:   (c) 2013: CERN for the benefit of the ATLAS collaboration
DOI:   10.1007/JHEP01(2013)029
Bibliographic Code:   2013JHEP...01..029A

Abstract

Mass and angular distributions of dijets produced in LHC proton-proton collisions at a centre-of-mass energy sqrt{s}=7 TeV have been studied with the ATLAS detector using the full 2011 data set with an integrated luminosity of 4.8 fb-1. Dijet masses up to 4.0 TeV have been probed. No resonance-like features have been observed in the dijet mass spectrum, and all angular distributions are consistent with the predictions of QCD. Exclusion limits on six hypotheses of new phenomena have been set at 95% CL in terms of mass or energy scale, as appropriate. These hypotheses include excited quarks below 2.83 TeV, colour octet scalars below 1.86 TeV, heavy W bosons below 1.68 TeV, string resonances below 3.61 TeV, quantum black holes with six extra space-time dimensions for quantum gravity scales below 4.11 TeV, and quark contact interactions below a compositeness scale of 7.6 TeV in a destructive interference scenario.[Figure not available: see fulltext.]
 

Title:   Measurement of isolated-photon pair production in pp collisions at sqrt{s}=7TeV with the ATLAS detector
Authors:   Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.;...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2893 coauthors.
Publication:   Journal of High Energy Physics, Volume 2013, article id. #86
Publication Date:   01/2013
Origin:   SPRINGER
Keywords:   Hadron-Hadron Scattering
Abstract Copyright:   (c) 2013: CERN for the benefit of the ATLAS collaboration
DOI:   10.1007/JHEP01(2013)086
Bibliographic Code:   2013JHEP...01..086A

Abstract

The ATLAS experiment at the LHC has measured the production cross section of events with two isolated photons in the final state, in proton-proton collisions at sqrt{s}=7TeV . The full data set collected in 2011, corresponding to an integrated luminosity of 4 .9 fb-1, is used. The amount of background, from hadronic jets and isolated electrons, is estimated with data-driven techniques and subtracted. The total cross section, for two isolated photons with transverse energies above 25 GeV and 22 GeV respectively, in the acceptance of the electromagnetic calorimeter (| η| < 1 .37 and 1 .52 < | η| < 2 .37) and with an angular separation Δ R > 0 .4, is 44.0_{-4.2}^{+3.2 } pb. The differential cross sections as a function of the di-photon invariant mass, transverse momentum, azimuthal separation, and cosine of the polar angle of the largest transverse energy photon in the Collins-Soper di-photon rest frame are also measured. The results are compared to the prediction of leading-order parton-shower and next-to-leading-order and next-to-next-to-leading-order parton-level generators.[Figure not available: see fulltext.]
 

Title:   Search for resonances decaying into top-quark pairs using fully hadronic decays in pp collisions with ATLAS at sqrt{s}=7 TeV
Authors:   Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.;...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2903 coauthors.
Publication:   Journal of High Energy Physics, Volume 2013, article id. #116
Publication Date:   01/2013
Origin:   SPRINGER
Keywords:   Hadron-Hadron Scattering
Abstract Copyright:   (c) 2013: Cern for the benefit of the ATLAS collaboration
DOI:   10.1007/JHEP01(2013)116
Bibliographic Code:   2013JHEP...01..116A

Abstract

A search for resonances produced in 7 TeV proton-proton collisions and decaying into top-quark pairs is described. In this Letter events where the top-quark decay produces two massive jets with large transverse momenta recorded with the ATLAS detector at the Large Hadron Collider are considered. Two techniques that rely on jet substructure are used to separate top-quark jets from those arising from light quarks and gluons. In addition, each massive jet is required to have evidence of an associated bottom-quark decay. The data are consistent with the Standard Model, and limits can be set on the production cross section times branching fraction of a Z' boson and a Kaluza-Klein gluon resonance. These limits exclude, at the 95% credibility level, Z' bosons with masses 0.70-1.00 TeV as well as 1.28-1.32 TeV and Kaluza-Klein gluons with masses 0.70-1.62 TeV.
 

Title:   Search for direct chargino production in anomaly-mediated supersymmetry breaking models based on a disappearing-track signature in pp collisions at sqrt{s}=7TeV with the ATLAS detector
Authors:   Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.;...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2905 coauthors.
Publication:   Journal of High Energy Physics, Volume 2013, article id. #131
Publication Date:   01/2013
Origin:   SPRINGER
Keywords:   Hadron-Hadron Scattering
Abstract Copyright:   (c) 2013: CERN for the benefit of the ATLAS collaboration
DOI:   10.1007/JHEP01(2013)131
Bibliographic Code:   2013JHEP...01..131A

Abstract

A search for direct chargino production in anomaly-mediated supersymmetry breaking scenarios is performed in pp collisions at sqrt{s}=7TeV using 4.7 fb-1 of data collected with the ATLAS experiment at the LHC. In these models, the lightest chargino is predicted to have a lifetime long enough to be detected in the tracking detectors of collider experiments. This analysis explores such models by searching for chargino decays that result in tracks with few associated hits in the outer region of the tracking system. The transverse-momentum spectrum of candidate tracks is found to be consistent with the expectation from the Standard Model background processes and constraints on chargino properties are obtained.

 

Title:   Search for pair production of heavy top-like quarks decaying to a high-pTW boson and a b quark in the lepton plus jets final state at s=7 TeV with the ATLAS detector
Authors:   Atlas Collaboration; Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.;... Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2898 coauthors.
Publication:   Physics Letters B, Volume 718, Issue 4, p. 1284-1302.
Publication Date:   01/2013
Origin:   ELSEVIER
Abstract Copyright:   CERN
DOI:   10.1016/j.physletb.2012.11.071
Bibliographic Code:   2013PhLB..718.1284A

Abstract

A search is presented for production of a heavy up-type quark (t) together with its antiparticle, assuming a significant branching ratio for subsequent decay into a W boson and a b quark. The search is based on 4.7 fb-1 of pp collisions at s=7 TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. Data are analyzed in the lepton + jets final state, characterized by a high-transverse-momentum isolated electron or muon, large missing transverse momentum and at least three jets. The analysis strategy relies on the substantial boost of the W bosons in the tt signal when m≳400 GeV. No significant excess of events above the Standard Model expectation is observed and the result of the search is interpreted in the context of fourth-generation and vector-like quark models. Under the assumption of a branching ratio BR(t→Wb)=1, a fourth-generation t quark with mass lower than 656 GeV is excluded at 95% confidence level. In addition, in light of the recent discovery of a new boson of mass ˜126 GeV at the LHC, upper limits are derived in the two-dimensional plane of BR(t→Wb) versus BR(t→Ht), where H is the Standard Model Higgs boson, for vector-like quarks of various masses.
 

Title:   Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using 4.7fb-1 of s=7TeV proton-proton collision data
Authors:   Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.;...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2883 coauthors.
Publication:   Physical Review D, vol. 87, Issue 1, id. 012008 (PhRvD Homepage)
Publication Date:   01/2013
Origin:   APS
PACS Keywords:   Supersymmetric models, Limits on production of particles, Supersymmetric partners of known particles
DOI:   10.1103/PhysRevD.87.012008
Bibliographic Code:   2013PhRvD..87a2008A

Abstract

A search for squarks and gluinos in final states containing jets, missing transverse momentum and no high-pT electrons or muons is presented. The data represent the complete sample recorded in 2011 by the ATLAS experiment in 7 TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 4.7fb-1. No excess above the Standard Model background expectation is observed. Gluino masses below 860 GeV and squark masses below 1320 GeV are excluded at the 95% confidence level in simplified models containing only squarks of the first two generations, a gluino octet and a massless neutralino, for squark or gluino masses below 2 TeV, respectively. Squarks and gluinos with equal masses below 1410 GeV are excluded. In minimal supergravity/constrained minimal supersymmetric Standard Model models with tan⁡β=10, A0=0 and μ>0, squarks and gluinos of equal mass are excluded for masses below 1360 GeV. Constraints are also placed on the parameter space of supersymmetric models with compressed spectra. These limits considerably extend the region of supersymmetric parameter space excluded by previous measurements with the ATLAS detector.
 

Title:   3D Maps of the Galaxy's Dust using PanSTARRS-1
Authors:   Schlafly, Eddie; Green, G.; Finkbeiner, D. P.
Affiliation:   AA(MPIA, Germany), AB(Harvard), AC(Harvard)
Publication:   American Astronomical Society, AAS Meeting #221, #145.06
Publication Date:   01/2013
Origin:   AAS
Abstract Copyright:   (c) 2013: American Astronomical Society
Bibliographic Code:   2013AAS...22114506S

Abstract

We present preliminary maps of the three-dimensional distribution of the dust in the Galaxy using photometry from Pan-STARRS1. We photometrically infer the distance and reddening to over half a billion stars well-observed at this stage of the Pan-STARRS1 survey (see related poster by G. Green). We then find, along each 6 arcminute line of sight, the reddening as a function of distance most consistent with the observations, taking into consideration the full shape of the posterior of the reddening and distance to each star. We are able to reproduce the known distances to nearby dust clouds, and expect to be able to measure the distances to most clouds within about 4 kpc. Our maps of the reddening at 4 kpc agree closely with the maps of Schlegel, Finkbeiner, and Davis (1998) outside of the plane of the Galaxy, and are able to reveal some known limitations of those maps.
 

Title:   Towards a Full-sky Map of Galactic 12 Micron Dust Emission with WISE
Authors:   Meisner, Aaron; Finkbeiner, D. P.
Publication:   American Astronomical Society, AAS Meeting #221, #223.06
Publication Date:   01/2013
Origin:   AAS
Abstract Copyright:   (c) 2013: American Astronomical Society
Bibliographic Code:   2013AAS...22122306M

Abstract

We describe our custom processing of the entire Wide-field Infrared Survey Explorer (WISE) 12 micron imaging data set, aimed at creating a high-resolution, full-sky map of diffuse emission from Galactic dust that is free of compact sources and all other contaminating artifacts. The principal distinctions between our resulting co-added images and the WISE Atlas stacks are our removal of compact sources, including their associated electronic and optical artifacts, and our preservation of spatial modes larger than ~1.5 degrees. We present sample mosaics which illustrate our progress and the imperfections that remain to be addressed. When combined appropriately with other mid and far-infrared data sets, we expect our WISE 12 micron map to form the basis for a full-sky dust extinction map with angular resolution approximately 10 times better than that of SFD (1998).
 

Title:   Non-equilibrium Fractional Quantum Hall state of light
Authors:   Hafezi, Mohammad; Lukin, Mikhail D.; Taylor, Jacob M.
Publication:   eprint arXiv:1301.1344
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   Quantum Physics, Condensed Matter - Quantum Gases, Condensed Matter - Strongly Correlated Electrons
Bibliographic Code:   2013arXiv1301.1344H

Abstract

We investigate the quantum dynamics of systems involving small numbers of strongly interacting photons. Specifically, we develop an efficient method to investigate such systems when they are externally driven with a coherent field. Furthermore, we show how to quantify the many-body quantum state of light via correlation functions. Finally, we apply this method to two strongly interacting cases: the Bose-Hubbard and fractional quantum Hall models, and discuss an implementation of these ideas in atom-photon system.
 

Title:   Probing Charged Matter Through Higgs Diphoton Decay, Gamma Ray Lines, and EDMs
Authors:   Fan, JiJi; Reece, Matthew
Publication:   eprint arXiv:1301.2597
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   High Energy Physics - Phenomenology
Bibliographic Code:   2013arXiv1301.2597F

Abstract

Numerous experiments currently underway offer the potential to indirectly probe new charged particles with masses at the weak scale. For example, the tentative excess in Higgs diphoton decay and the tentative gamma-ray line in Fermi-LAT data have recently attracted attention as possible one-loop signatures of new charged particles. We explore the interplay between such signals, dark matter direct detection through Higgs exchange, and measurements of the electron EDM, by studying the size of these effects in several models. We compute one-loop effects to explore the relationship among couplings probed by different experiments. In particular, models in which dark matter and the Higgs both interact with charged particles at a detectable level typically induce, at loop level, couplings between dark matter and the Higgs that are around the level of current direct detection sensitivity. Intriguingly, one-loop Higgs diphoton decay and DM annihilation into two photons, two-loop EDMs, and loop-induced direct detection rates are all coming within range of existing experiments for approximately the same range of charged particle masses, offering the prospect of an exciting coincidence of signals at collider, astrophysical, underground and atomic physics measurements.
 

Title:   Phonon-induced spin-spin interactions in diamond nanostructures: application to spin squeezing
Authors:   Bennett, S. D.; Yao, N. Y.; Otterbach, J.; Zoller, P.; Rabl, P.; Lukin, M. D.
Publication:   eprint arXiv:1301.2968
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   Condensed Matter - Mesoscale and Nanoscale Physics, Quantum Physics
Comment:   10 pages, 4 figures
Bibliographic Code:   2013arXiv1301.2968B

Abstract

We propose and analyze a novel mechanism for long-range spin-spin interactions in diamond nanostructures. The interactions between electronic spins, associated with nitrogen-vacancy centers in diamond, are mediated by their coupling via strain to the vibrational mode of a diamond mechanical nanoresonator. This coupling results in phonon-mediated effective spin-spin interactions that can be used to generate squeezed states of a spin ensemble. We show that spin dephasing and relaxation can be largely suppressed, allowing for substantial spin squeezing under realistic experimental conditions. Our approach has implications for spin-ensemble magnetometry, as well as phonon-mediated quantum information processing with spin qubits.
 

Title:   Proposal for coherent coupling of Majorana and fluxonium qubits
Authors:   Pekker, David; Hou, Chang-Yu; Manucharyan, Vladimir; Demler, Eugene
Publication:   eprint arXiv:1301.3161
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Superconductivity
Comment:   4 pages + references + supplemental materials
Bibliographic Code:   2013arXiv1301.3161P

Abstract

We propose to use an ancilla fluxonium qubit to interact with a Majorana qubit hosted by a topological 1D wire. The coupling is obtained using the Majorana qubit controlled $4\pi$ Josephson effect to flux bias the fluxonium qubit. We demonstrate how this coupling can be used to sensitively identify topological superconductivity, to measure the state of the Majorana qubit, to construct 2-qubit operations, and to implement quantum memories with topological protection.

 

Title:   Theory of interacting dislocations on cylinders
Authors:   Amir, Ariel; Paulose, Jayson; Nelson, David R.
Publication:   eprint arXiv:1301.4226
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   Condensed Matter - Soft Condensed Matter, Condensed Matter - Materials Science, Condensed Matter - Statistical Mechanics
Bibliographic Code:   2013arXiv1301.4226A

Abstract

We study the mechanics and statistical physics of dislocations interacting on cylinders, motivated by the elongation of rod-shaped bacterial cell walls and cylindrical assemblies of colloidal particles subject to external stresses. The interaction energy and forces between dislocations are solved analytically, and analyzed asymptotically. The results of continuum elastic theory agree well with numerical simulations on finite lattices even for relatively small systems. Isolated dislocations on a cylinder act like grain boundaries. With colloidal crystals in mind, we show that saddle points are created by a Peach-Koehler force on the dislocations in the circumferential direction, causing dislocation pairs to unbind. The thermal nucleation rate of dislocation unbinding is calculated, for an arbitrary mobility tensor and external stress, including the case of a twist-induced Peach-Koehler force along the cylinder axis. Surprisingly rich phenomena arise for dislocations on cylinders, despite their vanishing Gaussian curvature.
 

Title:   Updated search for the standard model Higgs boson in events with jets and missing transverse energy using the full CDF data set
Authors:   CDF Collaboration; Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... Guimaraes da Costa, J.;...; and 405 coauthors.
Publication:   eprint arXiv:1301.4440
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   High Energy Physics - Experiment, High Energy Physics - Phenomenology
Comment:   Submitted to Phys. Rev. D
Bibliographic Code:   2013arXiv1301.4440C

Abstract

We present an updated search for the Higgs boson produced in association with a vector boson in the final state with missing transverse energy and two jets. We use the full CDF data set corresponding to an integrated luminosity of 9.45 fb${}^{-1}$ at a proton-antiproton center-of-mass energy of $\sqrt{s}=1.96$ TeV. New to this analysis is the inclusion of a $b$-jet identification algorithm specifically optimized for $H\to b\bar{b}$ searches. Across the Higgs boson mass range $90 \le m_H \le 150$ GeV$/c^2$, the expected 95% credibility level upper limits on the $V H$ production cross section times the $H\to b\bar{b}$ branching fraction are improved by an average of 14% relative to the previous analysis. At a Higgs boson mass of 125 GeV$/c^2$, the observed (expected) limit is 3.06 (3.33) times the standard model prediction, corresponding to one of the most sensitive searches to date in this final state.
 

Title:   Single atom trapping and control inside a nanosize photonic crystal cavity
Authors:   Kuznetsova, Elena; Feist, Johannes; Quan, Qimin; Thompson, Jeff D.; Tiecke, Tobias; Yelin, Susanne F.; Lukin, Mikhail D.
Publication:   eprint arXiv:1301.4559
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   Quantum Physics, Physics - Atomic Physics
Comment:   This paper has been withdrawn to include some critical changes
Bibliographic Code:   2013arXiv1301.4559K

Abstract

We analyze a possibility to trap, control and load a single atom inside a nanosize cavity formed in a photonic crystal. We consider a 1D nanobeam crystal having two nearly degenerate localized modes with mode maxima at the central air gap, forming a cavity with a mode volume <\lambda^{3}. For this system we found that an atom can be trapped by a mode detuned from an atomic transition and controled by the second resonant mode. We show that atomic motion can be cooled using cavity-enhanced rf Sisyphus cooling. We also discuss how an atom can be loaded inside the nanosize crystal air gap from short-wavelength optical tweezers.
 

Title:   Electron neutrino and antineutrino appearance in the full MINOS data sample
Authors:   Adamson, P.; Anghel, I.; Backhouse, C.;... Feldman, G. J.; ; and 105 coauthors
Publication:   eprint arXiv:1301.4581
Publication Date:   01/2013
Origin:   ARXIV
Keywords:   High Energy Physics - Experiment
Bibliographic Code:   2013arXiv1301.4581A

Abstract

We report the results of a search for $\nu_e$ and $\bar{\nu}_e$ appearance in $\nu_\mu$ and $\bar{\nu}_\mu$ beams using the full MINOS data sample. This analysis uses an exposure of $10.6\times10^{20}$ ($3.3\times10^{20}$) protons-on-target taken with a $\nu$ ($\bar{\nu}$) beam mode and is the first accelerator long-baseline search for $\bar{\nu}_\mu\rightarrow\bar{\nu}_e$. With the $\nu_e$ and $\bar{\nu}_e$ data, we probe $\theta_{13}$, $\delta$, and the mass hierarchy. Assuming a normal (inverted) mass hierarchy, $\delta$ = 0, and $\theta_{23}$ $<$ $\frac{\pi}{4}$, we set a constraint of 0.01 (0.03) $<$ 2sin$^2(2\theta_{13})$sin$^2(\theta_{23})$ $<$ 0.12 (0.18) at 90% C.L. with the best-fit value of 2sin$^2(2\theta_{13})$sin$^2(\theta_{23})$ $=$ $0.051^{+0.038}_{-0.030}$ ($0.093^{+0.054}_{-0.049}$).


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