Faculty Publications: May, 2013

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Title:   Technical results from the surface run of the LUX dark matter experiment
Authors:   Akerib, D. S.; Bai, X.; Bernard, E.; Bernstein, A.;... Morii, M.; ...; and 62 coauthors.
Publication:   Astroparticle Physics, Volume 45, p. 34-43. (APh Homepage)
Publication Date:   05/2013
Origin:   ELSEVIER
Abstract Copyright:   Elsevier B.V.
DOI:   10.1016/j.astropartphys.2013.02.001
Bibliographic Code:   2013APh....45...34A

Abstract

We present the results of the three-month above-ground commissioning run of the Large Underground Xenon (LUX) experiment at the Sanford Underground Research Facility located in Lead, South Dakota, USA. LUX is a 370 kg liquid xenon detector that will search for cold dark matter in the form of Weakly Interacting Massive Particles (WIMPs). The commissioning run, conducted with the detector immersed in a water tank, validated the integration of the various sub-systems in preparation for the underground deployment. Using the data collected, we report excellent light collection properties, achieving 8.4 photoelectrons per keV for 662 keV electron recoils without an applied electric field, measured in the center of the WIMP target. We also find good energy and position resolution in relatively high-energy interactions from a variety of internal and external sources. Finally, we have used the commissioning data to tune the optical properties of our simulation and report updated sensitivity projections for spin-independent WIMP-nucleon scattering.
 

Title:   New boundary conditions for AdS3
Authors:   Compère, Geoffrey; Song, Wei; Strominger, Andrew
Publication:   Journal of High Energy Physics, Volume 2013, article id. #152
Publication Date:   05/2013
Origin:   SPRINGER
Keywords:   AdS-CFT Correspondence, Space-Time Symmetries, Black Holes in String Theory, Conformal Field Models in String Theory
Abstract Copyright:   (c) 2013: SISSA, Trieste, Italy
DOI:   10.1007/JHEP05(2013)152
Bibliographic Code:   2013JHEP...05..152C

Abstract

New chiral boundary conditions are found for quantum gravity with matter on AdS3. The associated asymptotic symmetry group is generated by a single right-moving U(1) Kac-Moody-Virasoro algebra with {c_R}={3ℓ}/2G . The Kac-Moody zero mode generates global left-moving translations and equals, for a BTZ black hole, the sum of the total mass and spin. The level is positive about the global vacuum and negative in the black hole sector, corresponding to ergosphere formation. Realizations arising in Chern-Simons gravity and string theory are analyzed. The new boundary conditions are shown to naturally arise for warped AdS3 in the limit that the warp parameter is taken to zero.
 

Title:   Chiral Liouville gravity
Authors:   Compère, Geoffrey; Song, Wei; Strominger, Andrew
Publication:   Journal of High Energy Physics, Volume 2013, article id. #154
Publication Date:   05/2013
Origin:   SPRINGER
Keywords:   Models of Quantum Gravity, Conformal Field Models in String Theory, Black Holes in String Theory, AdS-CFT Correspondence
Abstract Copyright:   (c) 2013: SISSA, Trieste, Italy
DOI:   10.1007/JHEP05(2013)154
Bibliographic Code:   2013JHEP...05..154C

Abstract

Classical two-dimensional Liouville gravity is often considered in conformal gauge which has a residual left and right Virasoro symmetry algebra. We consider an alternate, chiral, gauge which has a residual right Virasoro Kac-Moody algebra, and no left Virasoro algebra. The Kac-Moody zero mode is the left-moving energy. Dirac brackets of the constrained Hamiltonian theory are derived, and the residual symmetries are shown to be generated by integrals of the conserved chiral currents. The central charge and Kac-Moody level are computed. The possible existence of a corresponding quantum theory is discussed.
 

Title:   Microwave dielectric heating of non-aqueous droplets in a microfluidic device for nanoparticle synthesis
Authors:   Koziej, Dorota; Floryan, Caspar; Sperling, Ralph A.; Ehrlicher, Allen J.; Issadore, David; Westervelt, Robert; Weitz, David A.
Publication:   Nanoscale, Volume 5, Issue 12, pp. 5468-5475 (2013).
Publication Date:   05/2013
Origin:   RSC
Abstract Copyright:   (c) 2013: The Royal Society of Chemistry
DOI:   10.1039/c3nr00500c
Bibliographic Code:   2013Nanos...5.5468K

Abstract

We describe a microfluidic device with an integrated microwave heater specifically designed to dielectrically heat non-aqueous droplets using time-varying electrical fields with the frequency range between 700 and 900 MHz. The precise control of frequency, power, temperature and duration of the applied field opens up new vistas for experiments not attainable by conventional microwave heating. We use a non-contact temperature measurement system based on fluorescence to directly determine the temperature inside a single droplet. The maximum temperature achieved of the droplets is 50 °C in 15 ms which represents an increase of about 25 °C above the base temperature of the continuous phase. In addition we use an infrared camera to monitor the thermal characteristics of the device allowing us to ensure that heating is exclusively due to the dielectric heating and not due to other effects like non-dielectric losses due to electrode or contact imperfection. This is crucial for illustrating the potential of dielectric heating of benzyl alcohol droplets for the synthesis of metal oxides. We demonstrate the utility of this technology for metal oxide nanoparticle synthesis, achieving crystallization of tungsten oxide nanoparticles and remarkable microstructure, with a reaction time of 64 ms, a substantial improvement over conventional heating methods.We describe a microfluidic device with an integrated microwave heater specifically designed to dielectrically heat non-aqueous droplets using time-varying electrical fields with the frequency range between 700 and 900 MHz. The precise control of frequency, power, temperature and duration of the applied field opens up new vistas for experiments not attainable by conventional microwave heating. We use a non-contact temperature measurement system based on fluorescence to directly determine the temperature inside a single droplet. The maximum temperature achieved of the droplets is 50 °C in 15 ms which represents an increase of about 25 °C above the base temperature of the continuous phase. In addition we use an infrared camera to monitor the thermal characteristics of the device allowing us to ensure that heating is exclusively due to the dielectric heating and not due to other effects like non-dielectric losses due to electrode or contact imperfection. This is crucial for illustrating the potential of dielectric heating of benzyl alcohol droplets for the synthesis of metal oxides. We demonstrate the utility of this technology for metal oxide nanoparticle synthesis, achieving crystallization of tungsten oxide nanoparticles and remarkable microstructure, with a reaction time of 64 ms, a substantial improvement over conventional heating methods.

Electronic supplementary information (ESI) available: Optical images of the microfluidic device; measurements of dependence of the microwave frequency on the temperature of benzyl alcohol droplets; a summary of dielectric properties of common solvents; a quasi-static electrical field simulation; TEM, HRTEM and SEAD of nanoparticles washed with ethanol. See DOI: 10.1039/c3nr00500c
 

Title:   The ATLAS Collaboration
Authors:   Aad, G.; Abajyan, T.; Abbott, B..; Franklin, M....; Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2692 coauthors.
Publication:   Nuclear Physics A, Volume 904, p. 1041-1058c.
Publication Date:   05/2013
Origin:   ELSEVIER
Abstract Copyright:   (c) 2013 Elsevier Science B.V. All rights reserved.
DOI:   10.1016/j.nuclphysa.2013.02.192
Bibliographic Code:   2013NuPhA.904.1041A

Abstract

Not Available
 

Title:   Geometric Mechanics of Periodic Pleated Origami
Authors:   Wei, Z. Y.; Guo, Z. V.; Dudte, L.; Liang, H. Y.; Mahadevan, L.
Publication:   Physical Review Letters, vol. 110, Issue 21, id. 215501 (PhRvL Homepage)
Publication Date:   05/2013
Origin:   APS
PACS Keywords:   Beams, plates, and shells
DOI:   10.1103/PhysRevLett.110.215501
Bibliographic Code:   2013PhRvL.110u5501W

Abstract

Origami structures are mechanical metamaterials with properties that arise almost exclusively from the geometry of the constituent folds and the constraint of piecewise isometric deformations. Here we characterize the geometry and planar and nonplanar effective elastic response of a simple periodically folded Miura-ori structure, which is composed of identical unit cells of mountain and valley folds with four-coordinated ridges, defined completely by two angles and two lengths. We show that the in-plane and out-of-plane Poisson’s ratios are equal in magnitude, but opposite in sign, independent of material properties. Furthermore, we show that effective bending stiffness of the unit cell is singular, allowing us to characterize the two-dimensional deformation of a plate in terms of a one-dimensional theory. Finally, we solve the inverse design problem of determining the geometric parameters for the optimal geometric and mechanical response of these extreme structures.
 

Title:   Shot-noise-limited spin measurements in a pulsed molecular beam
Authors:   Kirilov, E.; Campbell, W. C.; Doyle, J. M.; Gabrielse, G.; Gurevich, Y. V.; Hess, P. W.; Hutzler, N. R.; O'Leary, B. R.; Petrik, E.; Spaun, B.; Vutha, A. C.; DeMille, D.
Publication:   eprint arXiv:1305.2179
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   Physics - Atomic Physics, Quantum Physics
Comment:   12 pages, 6 figures
Bibliographic Code:   2013arXiv1305.2179K

Abstract

Heavy diatomic molecules have been identified as good candidates for use in electron electric dipole moment (eEDM) searches. Suitable molecular species can be produced in pulsed beams, but with a total flux and/or temporal evolution that varies significantly from pulse to pulse. These variations can degrade the experimental sensitivity to changes in spin precession phase of an electri- cally polarized state, which is the observable of interest for an eEDM measurement. We present two methods for measurement of the phase that provide immunity to beam temporal variations, and make it possible to reach shot-noise-limited sensitivity. Each method employs rapid projection of the spin state onto both components of an orthonormal basis. We demonstrate both methods using the eEDM-sensitive H state of thorium monoxide (ThO), and use one of them to measure the magnetic moment of this state with increased accuracy relative to previous determinations.
 

Title:   Fermi Surface Pairing & Coherence in a High Tc Superconductor
Authors:   He, Yang; Yin, Yi; Zech, M.; Soumyanarayanan, Anjan; Zeljkovic, Ilija; Yee, Michael M.; Boyer, M. C.; Chatterjee, Kamalesh; Wise, W. D.; Kondo, Takeshi; Takeuchi, T.; Ikuta, H.; Mistark, Peter; Markiewicz, Robert S.; Bansil, Arun; Sachdev, Subir; Hudson, E. W.; Hoffman, Jennifer. E.
Publication:   eprint arXiv:1305.2778
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Bibliographic Code:   2013arXiv1305.2778H

Abstract

Superconductivity arises from the pairing of electrons on the Fermi surface. In high temperature cuprate superconductors, evidence compiled from several materials suggests that the Fermi surface expands at a critical doping. However, the nature of the altered Fermi surface, its availability for pairing, and its relationship to the long-mysterious pseudogap phase are unknown. Here we use scanning tunneling microscopy to reveal a quantum phase transition in Fermi surface topology within a single material (PbxBi2-x)LaySr2-yCuO6+z (Bi2201). In lightly doped samples, the Fermi surface terminates at the antiferromagnetic Brillouin zone boundary, but upon increased doping we detect a new Fermi surface component extending to the antinode. We use phase-sensitive quasiparticle interference mapping to prove that d-wave Bogoliubov quasiparticles exist on this recovered antinodal Fermi surface despite the coexisting pseudogap. By magnetic-field-dependent imaging, we finally identify the competitive role of the pseudogap: it inhomogeneously suppresses superconducting phase coherence, while leaving a robust superconducting gap intact. The discovery of these three phenomena within a single cuprate material provides a new basis for understanding the phenomenology of high-Tc superconductivity.
 

Title:   Singularity of the London penetration depth at quantum critical points in superconductors
Authors:   Chowdhury, Debanjan; Swingle, Brian; Berg, Erez; Sachdev, Subir
Publication:   eprint arXiv:1305.2918
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Statistical Mechanics, Condensed Matter - Superconductivity, High Energy Physics - Theory
Comment:   4 pages, 4 figures
Bibliographic Code:   2013arXiv1305.2918C

Abstract

We present a general theory of the singularity in the London penetration depth at symmetry-breaking and topological quantum critical points within a superconducting phase. While the critical exponents, and ratios of amplitudes on the two sides of the transition are universal, an overall sign depends upon the interplay between the critical theory and the underlying Fermi surface. We determine these features for critical points to spin density wave and nematic ordering, and for a topological transition between a superconductor with $\mathbb{Z}_2$ fractionalization and a conventional superconductor. We note implications for recent measurements of the London penetration depth in BaFe$_2$(As$_{1-x}$P$_x$)$_2$ (Hashimoto et al., Science 336, 1554 (2012)).
 

Title:   Closing in on the Fermi Line with a New Observation Strategy
Authors:   Weniger, Christoph; Su, Meng; Finkbeiner, Douglas P.; Bringmann, Torsten; Mirabal, Nestor
Publication:   eprint arXiv:1305.4710
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Phenomenology
Comment:   21 pages, 10 figures, 2 tables. White paper for alternative Fermi observing strategy, as submitted to the Fermi mission
Bibliographic Code:   2013arXiv1305.4710W

Abstract

Evidence for a spectral line in the inner Galaxy has caused a great deal of excitement over the last year, mainly because of its interpretation as a possible dark matter signal. The observation has raised important questions about statistics and suspicions about systematics, especially in photons from the Earth limb. With enough additional data, we can address these concerns. In this white paper, we summarize the current observational situation and project future sensitivities, finding that the status quo is dangerously close to leaving the issue unresolved until 2015. We advocate a change in survey strategy that more than doubles the data rate in the inner Galaxy, and is relatively non-disruptive to other survey science. This strategy will clearly separate the null hypothesis from the line signal hypothesis and provide ample limb data for systematics checks by the end of 2014. The standard survey mode may not.
 

Title:   Sensitive Chiral Analysis via Microwave Three-wave Mixing
Authors:   Patterson, David; Doyle, John M.
Publication:   eprint arXiv:1305.5223
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   Physics - Chemical Physics, Physics - Atomic Physics
Comment:   Submitted Physical Review Letters 9 April 2013
Bibliographic Code:   2013arXiv1305.5223P

Abstract

We demonstrate chirality-induced three-wave mixing in the microwave regime, using rotational transitions in cold gas-phase samples of 1,2-propanediol and 1,3-butanediol. We show that bulk three-wave mixing, which can only be realized in a chiral environment, provides a sensitive, species selective probe of enantiomeric excess and is applicable to a broad class of molecules. The doubly resonant condition provides simultaneous identification of species and of handedness, which should allow sensitive chiral analysis even within a complex mixture.
 

Title:   Lacerta I and Cassiopeia III: Two luminous and distant Andromeda satellite dwarf galaxies found in the 3{\pi} Pan-STARRS1 survey
Authors:   Martin, Nicolas F.; Slater, Colin T.; Schlafly, Edward F.; Morganson, Eric; Rix, Hans-Walter; Bell, Eric F.; Laevens, Benjamin P. M.; Bernard, Edouard J.; Ferguson, Annette M. N.; Finkbeiner, Douglas P.; Burgett, William S.; Chambers, Kenneth C.; Hodapp, Klaus W.; Kaiser, Nicholas; Kudritzki, Rolf-Peter; Magnier, Eugene A.; Morgan, Jeffrey S.; Price, Paul A.; Tonry, John L.; Wainscoat, Richard J.
Publication:   eprint arXiv:1305.5301
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:   7 pages, 5 figures. Accepted for publication in ApJ
Bibliographic Code:   2013arXiv1305.5301M

Abstract

We report the discovery of two new dwarf galaxies, Lacerta I/Andromeda XXXI (Lac I/And XXXI) and Cassiopeia III/Andromeda XXXII (Cas III/And XXXII), in stacked Pan-STARRS1 r_P1- and i_P1-band imaging data. Both are luminous systems (M_V ~ -12) located at projected distances of 20.3{\deg} and 10.5{\deg} from M31. Lac I and Cas III are likely satellites of the Andromeda galaxy with heliocentric distances of 756^{+44}_{-28} kpc and 772^{+61}_{-56} kpc, respectively, and corresponding M31-centric distances of 275+/-7 kpc and 144^{+6}_{-4} kpc . The brightest of recent Local Group member discoveries, these two new dwarf galaxies owe their late discovery to their large sizes (r_h = 4.2^{+0.4}_{-0.5} arcmin or 912^{+124}_{-93} pc for Lac I; r_h = 6.5^{+1.2}_{-1.0} arcmin or 1456+/-267 pc for Cas III), and consequently low surface brightness (\mu_0 ~ 26.0 mag/arcsec^2), as well as to the lack of a systematic survey of regions at large radii from M31, close to the Galactic plane. This latter limitation is now alleviated by the 3{\pi} Pan-STARRS1 survey, which could lead to the discovery of other distant Andromeda satellite dwarf galaxies.
 

Title:   Quasinormal Quantization in deSitter Spacetime
Authors:   Jafferis, Daniel L.; Lupsasca, Alexandru; Lysov, Vyacheslav; Ng, Gim Seng; Strominger, Andrew
Publication:   eprint arXiv:1305.5523
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   High Energy Physics - Theory, General Relativity and Quantum Cosmology
Comment:   23 pages
Bibliographic Code:   2013arXiv1305.5523J

Abstract

A scalar field in four-dimensional deSitter spacetime (dS_4) has quasinormal modes which are singular on the past horizon of the south pole and decay exponentially towards the future. These are found to lie in two complex highest-weight representations of the dS_4 isometry group SO(4,1). The Klein-Gordon norm cannot be used for quantization of these modes because it diverges. However a modified `R-norm', which involves reflection across the equator of a spatial S^3 slice, is nonsingular. The quasinormal modes are shown to provide a complete orthogonal basis with respect to the R-norm. Adopting the associated R-adjoint effectively transforms SO(4,1) to the symmetry group SO(3,2) of a 2+1-dimensional CFT. It is further shown that the conventional Euclidean vacuum may be defined as the state annihilated by half of the quasinormal modes, and the Euclidean Green function obtained from a simple mode sum. Quasinormal quantization contrasts with some conventional approaches in that it maintains manifest dS-invariance throughout. The results are expected to generalize to other dimensions and spins.
 

Title:   Elastic and Plastic Deformations of Bacterial Cell Walls
Authors:   Amir, Ariel; Babaeipour, Farinaz; Nelson, David R.; Jun, Suckjoon
Publication:   eprint arXiv:1305.5843
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   Condensed Matter - Soft Condensed Matter, Physics - Biological Physics, Quantitative Biology - Cell Behavior
Bibliographic Code:   2013arXiv1305.5843A

Abstract

Cell walls define a cell shape in bacteria. They are rigid enough to resist large internal pressures, but also surprisingly plastic to grow under a wide range of external forces and geometric constraints. Understanding the mechanics of bacterial cell walls and the interaction between their growth and mechanical cues is a long standing problem. Here, we show that bacterial cell wall growth is affected by mechanical stress, leading to remarkable materials properties unique to living cells. By applying a precisely controllable hydrodynamic force to growing rod-shaped Escherichia coli cells, we show that they can significantly deflect either elastically or plastically depending on the duration of the applied force. Our experimental results are in a good quantitative agreement with the predictions of dislocation-mediated cell-wall growth. These findings provide insight into how bacteria use the material properties of cell walls to robustly maintain their shape under varying physical environments.
 

Title:   1/16 BPS States in N=4 SYM
Authors:   Chang, Chi-Ming; Yin, Xi
Publication:   eprint arXiv:1305.6314
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   High Energy Physics - Theory
Comment:   13 pages
Bibliographic Code:   2013arXiv1305.6314C

Abstract

We investigate the problem of counting 1/16 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 multi-graviton states in the gravity dual AdS5xS5. Further, we conjecture that all 1/16 BPS operators in N=4 SYM are of the multi-graviton form, and give numerical evidences 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:   M-Strings
Authors:   Haghighat, Babak; Iqbal, Amer; Kozcaz, Can; Lockhart, Guglielmo; Vafa, Cumrun
Publication:   eprint arXiv:1305.6322
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   High Energy Physics - Theory
Comment:   75 pages, 16 figures
Bibliographic Code:   2013arXiv1305.6322H

Abstract

M2 branes suspended between adjacent parallel M5 branes lead to light strings, the `M-strings'. In this paper we compute the elliptic genus of M-strings, twisted by maximally allowed symmetries that preserve 2d (2,0) supersymmetry. In a codimension one subspace of parameters this reduces to the elliptic genus of the (4,4) supersymmetric A_{n-1} quiver theory in 2d. We contrast the elliptic genus of N M-strings with the (4,4) sigma model on the N-fold symmetric product of R^4. For N=1 they are the same, but for N>1 they are close, but not identical. Instead the elliptic genus of (4,4) N M-strings is the same as the elliptic genus of (4,0) sigma models on the N-fold symmetric product of R^4, but where the right-moving fermions couple to a modification of the tangent bundle. This construction arises from a dual A_{n-1} quiver 6d gauge theory with U(1) gauge groups. Moreover we compute the elliptic genus of domain walls which separate different numbers of M2 branes on the two sides of the wall.
 

Title:   Elastic Platonic Shells
Authors:   Hou Yong, Ee; Nelson, David R.; Mahadevan, L.
Publication:   eprint arXiv:1305.6618
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   Condensed Matter - Soft Condensed Matter, Condensed Matter - Materials Science
Bibliographic Code:   2013arXiv1305.6618H

Abstract

On microscopic scales, the crystallinity of flexible tethered or cross linked membranes determines their mechanical response. We show that by controlling the type, number and distribution of defects on a spherical elastic shell, it is possible to direct the morphology of these structures. Our numerical simulations show that by deflating a crystalline shell with defects, we can create elastic shell analogs of the classical Platonic solids. These morphologies arise via a sharp buckling transition from the sphere which is strongly hysteretic in loading-unloading. We construct a minimal Landau theory for the transition using quadratic and cubic invariants of the spherical harmonic modes. Our approach suggests methods to engineer shape into soft spherical shells using a frozen defect topology.
 

Title:   The Dynamics of Genetic Draft in Rapidly Adapting Populations
Authors:   Kosheleva, Katya; Desai, Michael
Publication:   eprint arXiv:1305.7194
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   Quantitative Biology - Populations and Evolution
Bibliographic Code:   2013arXiv1305.7194K

Abstract

The accumulation of beneficial mutations on many competing genetic backgrounds in rapidly adapting populations has a striking impact on evolutionary dynamics. This effect, known as clonal interference, causes erratic fluctuations in the frequencies of observed mutations, randomizes the fixation times of successful mutations, and leaves distinct signatures on patterns of genetic variation. Here, we show how this form of `genetic draft' affects the forward-time dynamics of site frequencies in rapidly adapting asexual populations. We calculate the probability that mutations at individual sites shift in frequency over a characteristic timescale, extending Gillespie's original model of draft to the case where many strongly selected beneficial mutations segregate simultaneously. We then derive the sojourn time of mutant alleles, the expected fixation time of successful mutants, and the site frequency spectrum of beneficial and neutral mutations. We show how this form of draft affects inferences in the McDonald-Kreitman test, and how it relates to recent observations that some aspects of genetic diversity are described by the Bolthausen-Sznitman coalescent in the limit of very rapid adaptation. Finally, we describe how our method can be extended to model evolution on fitness landscapes that include some forms of epistasis, such as landscapes that are partitioned into two or more incompatible evolutionary trajectories.
 

Title:   Searches for the Higgs boson decaying to W^{+} W^{-} -> l^{+}nu l^{-}nubar with the CDF II detector
Authors:   CDF Collaboration; Aaltonen, T.; Amerio, S.; Amidei, D.;...Franklin, M.;...Guimaraes da Costa, J.;...; and 416 coauthors.
Publication:   eprint arXiv:1306.0023
Publication Date:   05/2013
Origin:   ARXIV
Keywords:   High Energy Physics - Experiment
Comment:   Submitted to Phys. Rev. D
Bibliographic Code:   2013arXiv1306.0023C

Abstract

We present a search for a standard model Higgs boson decaying to two $W$ bosons that decay to leptons using the full data set collected with the CDF II detector in $\sqrt{s}=1.96$ TeV $p\bar{p}$ collisions at the Fermilab Tevatron, corresponding to an integrated luminosity of 9.7 fb${}^{-1}$. We obtain no evidence for production of a standard model Higgs boson with mass between 110 and 200 GeV/$c^2$, and place upper limits on the production cross section within this range. We exclude standard model Higgs boson production at the 95% confidence level in the mass range between 149 and 172 GeV/$c^2$, while expecting to exclude, in the absence of signal, the range between 155 and 175 GeV/$c^2$. We also interpret the search in terms of standard model Higgs boson production in the presence of a fourth generation of fermions and within the context of a fermiophobic Higgs boson model. For the specific case of a standard model-like Higgs boson in the presence of fourth-generation fermions, we exclude at the 95% confidence level Higgs boson production in the mass range between 124 and 200 GeV/$c^2$, while expecting to exclude, in the absence of signal, the range between 124 and 221 GeV/$c^2$.
 

Title:   State/operator correspondence in higher-spin dS/CFT
Authors:   Ng, Gim Seng; Strominger, Andrew
Publication:   Classical and Quantum Gravity, Volume 30, Issue 10, article id. 104002 (2013). (CQGra Homepage)
Publication Date:   05/2013
Origin:   IOP
DOI:   10.1088/0264-9381/30/10/104002
Bibliographic Code:   2013CQGra..30j4002N

Abstract

A recently conjectured microscopic realization of the dS4/CFT3 correspondence relating Vasiliev's higher-spin gravity on dS4 to a Euclidean Sp(N) CFT3 is used to illuminate some previously inaccessible aspects of the dS/CFT dictionary. In particular it is argued that states of the boundary CFT3 on S2 are holographically dual to bulk states on geodesically complete, spacelike R3 slices which terminate on an S2 at future infinity. The dictionary is described in detail for the case of free scalar excitations. The ground states of the free or critical Sp(N) model are dual to dS-invariant plane-wave type vacua, while the bulk Euclidean vacuum is dual to a certain mixed state in the CFT3. CFT3 states created by operator insertions are found to be dual to (anti) quasinormal modes in the bulk. A norm is defined on the R3 bulk Hilbert space and shown for the scalar case to be equivalent to both the Zamolodchikov and pseudounitary C-norm of the Sp(N) CFT3.
 

Title:   Whole Spectrum of Cytochrome P450 Genes and Molecular Responses to Water-Accommodated Fractions Exposure in the Marine Medaka
Authors:   Rhee, Jae-Sung; Kim, Bo-Mi; Choi, Beom-Soon; Choi, Ik-Young; Wu, Rudolf S. S.; Nelson, David R.; Lee, Jae-Seong
Publication:   Environmental Science & Technology, vol. 47, issue 9, pp. 4804-4812
Publication Date:   05/2013
Origin:   CROSSREF
DOI:   10.1021/es400186r
Bibliographic Code:   2013EnST...47.4804R

Abstract

Not Available
 

Title:   Measurement of k T splitting scales in W→ ℓν events at sqrt{s} = 7 TeV with the ATLAS detector
Authors:   Aad, G.; Abajyan, T.; Abbott, B.;...; Franklin, M....; Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2925 coauthors.
Publication:   The European Physical Journal C, Volume 73, article id. #2432 (EPJC Homepage)
Publication Date:   05/2013
Origin:   SPRINGER
Abstract Copyright:   (c) 2013: CERN for the benefit of the ATLAS collaboration
DOI:   10.1140/epjc/s10052-013-2432-8
Bibliographic Code:   2013EPJC...73.2432A

Abstract

A measurement of splitting scales, as defined by the k T clustering algorithm, is presented for final states containing a W boson produced in proton-proton collisions at a centre-of-mass energy of 7 TeV. The measurement is based on the full 2010 data sample corresponding to an integrated luminosity of 36 pb-1 which was collected using the ATLAS detector at the CERN Large Hadron Collider. Cluster splitting scales are measured in events containing W bosons decaying to electrons or muons. The measurement comprises the four hardest splitting scales in a k T cluster sequence of the hadronic activity accompanying the W boson, and ratios of these splitting scales. Backgrounds such as multi-jet and top-quark-pair production are subtracted and the results are corrected for detector effects. Predictions from various Monte Carlo event generators at particle level are compared to the data. Overall, reasonable agreement is found with all generators, but larger deviations between the predictions and the data are evident in the soft regions of the splitting scales.
 

Title:   String theory origin of bipartite SCFTs
Authors:   Heckman, Jonathan J.; Vafa, Cumrun; Xie, Dan; Yamazaki, Masahito
Affiliation:   AA(Jefferson Physical Laboratory, Harvard University), AB(Jefferson Physical Laboratory, Harvard University), AC(School of Natural Sciences, Institute for Advanced Study), AD(Department of Physics, Princeton University)
Publication:   Journal of High Energy Physics, Volume 2013, article id. #148
Publication Date:   05/2013
Origin:   SPRINGER
Keywords:   Supersymmetric gauge theory, Brane Dynamics in Gauge Theories
Abstract Copyright:   (c) 2013: SISSA, Trieste, Italy
DOI:   10.1007/JHEP05(2013)148
Bibliographic Code:   2013JHEP...05..148H

Abstract

We provide a string theory embedding for {N} = 1 superconformal field theories defined by bipartite graphs inscribed on a disk. We realize these theories by exploiting the close connection with related {N} = 2 generalized ( A k-1 , A n-1) Argyres-Douglas theories. The {N} = 1 theory is obtained from spacetime filling D5-branes wrapped on an algebraic curve and NS5-branes wrapped on special Lagrangians of {{{C}}^2} which intersect along the BPS flow lines of the corresponding {N} = 2 Argyres-Douglas theory. Dualities of the {N} = 1 field theory follow from geometric deformations of the brane configuration which leave the UV boundary conditions fixed. In particular we show how to recover the classification of IR fixed points from cells of the totally non-negative Grassmannian Gr_{k,n+k}^{tnn} . Additionally, we present evidence that in the 3D theory obtained from dimensional reduction on a circle, VEVs of line operators given by D3-branes wrapped over faces of the bipartite graph specify a coordinate system for Gr_{k,n+k}^{tnn}.
 

Title:   The higher spin/vector model duality
Authors:   Giombi, Simone; Yin, Xi
Affiliation:   AA(Perimeter Institute for Theoretical Physics, Waterloo, Ontario, N2 L 2Y5, Canada), AB(Center for the Fundamental Laws of Nature, Jefferson Physical Laboratory, Harvard University, Cambridge, MA 02138, USA)
Publication:   Journal of Physics A: Mathematical and Theoretical, Volume 46, Issue 21, article id. 214003 (2013).
Publication Date:   05/2013
Origin:   IOP
DOI:   10.1088/1751-8113/46/21/214003
Bibliographic Code:   2013JPhA...46u4003G

Abstract

This paper is mainly a review of the dualities between Vasiliev’s higher spin gauge theories in AdS4 and three dimensional large N vector models, with focus on the holographic calculation of correlation functions of higher spin currents. We also present some new results in the computation of parity odd structures in the three point functions in parity violating Vasiliev theories.

This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Higher spin theories and holography’.
 

Title:   ABJ triality: from higher spin fields to strings
Authors:   Chang, Chi-Ming; Minwalla, Shiraz; Sharma, Tarun; Yin, Xi
Publication:   Journal of Physics A: Mathematical and Theoretical, Volume 46, Issue 21, article id. 214009 (2013).
Publication Date:   05/2013
Origin:   IOP
DOI:   10.1088/1751-8113/46/21/214009
Bibliographic Code:   2013JPhA...46u4009C

Abstract

We demonstrate that a supersymmetric and parity violating version of Vasiliev’s higher spin gauge theory in AdS4 admits boundary conditions that preserve N=0,1,2,3,4 or 6 supersymmetries. In particular, we argue that the Vasiliev theory with U(M) Chan–Paton and N=6 boundary condition is holographically dual to the 2+1 dimensional U(N)k × U(M)‑k ABJ theory in the limit of large N, k and finite M. In this system all bulk higher spin fields transform in the adjoint of the U(M) gauge group, whose bulk t’Hooft coupling is M/N. Analysis of boundary conditions in Vasiliev theory allows us to determine exact relations between the parity breaking phase of Vasiliev theory and the coefficients of two and three point functions in Chern–Simons vector models at large N. Our picture suggests that the supersymmetric Vasiliev theory can be obtained as a limit of type IIA string theory in AdS_4\times {CP}^3, and that the non-Abelian Vasiliev theory at strong bulk ’t Hooft coupling smoothly turn into a string field theory. The fundamental string is a singlet bound state of Vasiliev’s higher spin particles held together by U(M) gauge interactions. This is illustrated by the thermal partition function of free ABJ theory on a two sphere at large M and N even in the analytically tractable free limit. In this system the traces or strings of the low temperature phase break up into their Vasiliev particulate constituents at a U(M) deconfinement phase transition of order unity. At a higher temperature of order T=\sqrt{\frac{N}{M}} Vasiliev’s higher spin fields themselves break up into more elementary constituents at a U(N) deconfinement temperature, in a process described in the bulk as black hole nucleation.

This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Higher spin theories and holography’.
 

Title:   Morphological Evolution of Si Nanowires upon Lithiation: A First-Principles Multiscale Model
Authors:   Cubuk, Ekin D.; Wang, Wei L.; Zhao, Kejie; Vlassak, Joost J.; Suo, Zhigang; Kaxiras, Efthimios
Publication:   Nano Letters, vol. 13, issue 5, pp. 2011-2015
Publication Date:   05/2013
Origin:   CROSSREF
DOI:   10.1021/nl400132q
Bibliographic Code:   2013NanoL..13.2011C

Abstract

Not Available
 

Title:   Morphological Evolution of Si Nanowires upon Lithiation: A First-Principles Multiscale Model
Authors:   Cubuk, Ekin D.; Wang, Wei L.; Zhao, Kejie; Vlassak, Joost J.; Suo, Zhigang; Kaxiras, Efthimios
Publication:   Nano Letters, vol. 13, issue 5, pp. 2011-2015
Publication Date:   05/2013
Origin:   CROSSREF
DOI:   10.1021/nl400132q
Bibliographic Code:   2013NanoL..13.2011C

Abstract

Not Available
 

Title:   Search for extra dimensions in diphoton events from proton–proton collisions at \sqrt {s} = 7\,  TeV in the ATLAS detector at the LHC
Authors:   Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.;... Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2692 coauthors.
Publication:   Nuclear Physics A, Volume 904, p. 1041-1058c.
Publication Date:   05/2013
Origin:   ELSEVIER
Abstract Copyright:   (c) 2013 Elsevier Science B.V. All rights reserved.
DOI:   10.1016/j.nuclphysa.2013.02.192
Bibliographic Code:   2013NuPhA.904.1041A

Abstract

Not Available
 

Title:   Searc
Authors:   Aaltonen, T.; Álvarez González, B.; Amerio, S.;... Franklin, M.;... Guimaraes da Costa, J.;...; and 469 coauthors.
Publication:   Physics Letters B, Volume 722, Issue 1-3, p. 48-54.
Publication Date:   05/2013
Origin:   ELSEVIER
Abstract Copyright:   Elsevier B.V.
DOI:   10.1016/j.physletb.2013.03.032
Bibliographic Code:   2013PhLB..722...48A

Abstract

We present a measurement of the W-boson polarization in top-quark decays in tt¯ events with decays to dilepton final states using data corresponding to 5.1 fb of integrated luminosity in pp¯ collisions collected by the CDF II detector at the Tevatron. Assuming a top-quark mass of 172.5 GeV/c2, a simultaneous measurement of the fractions of longitudinal (f0) and right-handed (f+) W-bosons yields the results f0=0.70-0.17+0.18(stat)±0.06(syst) and f+=-0.09±0.09(stat)±0.03(syst). Combining this measurement with our previous measurement based on single-lepton final states, we obtain f0=0.84±0.09(stat)±0.05(syst) and f+=-0.16±0.05(stat)±0.04(syst). The results are consistent with the standard model expectation.
 

Title:   Search for long-lived, multi-charged particles in pp collisions at s=7 TeV using the ATLAS detector
Authors:   Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.;... Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2692 coauthors.
Publication:   Physics Letters B, Volume 722, Issue 4-5, p. 305-323.
Publication Date:   05/2013
Origin:   ELSEVIER
Abstract Copyright:   CERN
DOI:   10.1016/j.physletb.2013.04.036
Bibliographic Code:   2013PhLB..722..305A

Abstract

A search for highly ionising, penetrating particles with electric charges from |q|=2e to 6e is performed using the ATLAS detector at the CERN Large Hadron Collider. Proton–proton collision data taken at s=7 TeV during the 2011 running period, corresponding to an integrated luminosity of 4.4 fb, are analysed. No signal candidates are observed, and 95% confidence level cross-section upper limits are interpreted as mass-exclusion lower limits for a simplified Drell–Yan production model. In this model, masses are excluded from 50 GeV up to 430, 480, 490, 470 and 420 GeV for charges 2e, 3e, 4e, 5e and 6e, respectively.
 

Title:   Nanoscale surface element identification and dopant homogeneity in the high-Tc superconductor PrxCa1‑xFe2As2
Authors:   Zeljkovic, Ilija; Huang, Dennis; Song, Can-Li; Lv, Bing; Chu, Ching-Wu; Hoffman, Jennifer E.
Publication:   Physical Review B, vol. 87, Issue 20, id. 201108 (PhRvB Homepage)
Publication Date:   05/2013
Origin:   APS
PACS Keywords:   Scanning tunneling microscopy, Effects of crystal defects, doping and substitution
DOI:   10.1103/PhysRevB.87.201108
Bibliographic Code:   2013PhRvB..87t1108Z

Abstract

We use scanning tunneling microscopy to determine the surface structure and dopant distribution in PrxCa1‑xFe2As2, the highest-Tc 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-Tc superconducting phase is unlikely to originate from Pr inhomogeneity.
 

Title:   Local compressibility measurement of the νtot=1 quantum Hall state in a bilayer electron system
Authors:   Zhang, Ding; Schmult, Stefan; Venkatachalam, Vivek; Dietsche, Werner; Yacoby, Amir; von Klitzing, Klaus; Smet, Jurgen
Publication:   Physical Review B, vol. 87, Issue 20, id. 205304 (PhRvB Homepage)
Publication Date:   05/2013
Origin:   APS
PACS Keywords:   Quantum phase transitions, Strongly correlated electron systems; heavy fermions, Magnetoresistance
DOI:   10.1103/PhysRevB.87.205304
Bibliographic Code:   2013PhRvB..87t5304Z

Abstract

The filling νtot=1 quantum Hall state under charge imbalance is investigated through both transport and thermodynamic measurements on a high-mobility low-density GaAs bilayer sample with negligible single particle tunneling. The νtot=1 state demonstrates its robustness against imbalance by evolving continuously from the single layer regime (νupper=1, νlower=0) to the bilayer regime with fillings νupper=1/3 and νlower=2/3 for the separate layers. The energy gap of the νtot=1 state obtained from compressibility measurements using single electron transistors depends on position, i.e., the local disorder potential. Nevertheless, compressibility and thermal activation measurements yield comparable values for the energy gap under imbalance.
 

Title:   Measurement of the top quark forward-backward production asymmetry and its dependence on event kinematic properties
Authors:   Aaltonen, T.; Amerio, S.; Amerio, S.;... Franklin, M.;... Guimaraes da Costa, J.;...; and 406 coauthors.
Publication:   Physical Review D, vol. 87, Issue 9, id. 092002 (PhRvD Homepage)
Publication Date:   05/2013
Origin:   APS
PACS Keywords:   Charge conjugation, parity, time reversal, and other discrete symmetries, Experimental tests, Top quarks
DOI:   10.1103/PhysRevD.87.092002
Bibliographic Code:   2013PhRvD..87i2002A

Abstract

We present new measurements of the inclusive forward-backward tt¯ production asymmetry, AFB, and its dependence on several properties of the tt¯ system. The measurements are performed with the full Tevatron data set recorded with the CDF II detector during pp¯ collisions at s=1.96TeV, corresponding to an integrated luminosity of 9.4fb-1. We measure the asymmetry using the rapidity difference Δy=yt-y. Parton-level results are derived, yielding an inclusive asymmetry of 0.164±0.047(stat+syst). We establish an approximately linear dependence of AFB on the top-quark pair mass Mtt¯ and the rapidity difference |Δy| at detector and parton levels. Assuming the standard model, the probabilities to observe the measured values or larger for the detector-level dependencies are 7.4×10-3 and 2.2×10-3 for Mtt¯ and |Δy| respectively. Lastly, we study the dependence of the asymmetry on the transverse momentum of the tt¯ system at the detector level. These results are consistent with previous lower-precision measurements and provide additional quantification of the functional dependencies of the asymmetry.
 

Title:   Study of the decay B¯0→Λc+p¯π+π- and its intermediate states
Authors:   Lees, J. P.; Poireau, V.; Tisserand, V.;... Morii, M.;...; and 350 coauthors.
Publication:   Physical Review D, vol. 87, Issue 9, id. 092004 (PhRvD Homepage)
Publication Date:   05/2013
Origin:   APS
PACS Keywords:   Decays of bottom mesons, Baryon production, Charmed baryons
DOI:   10.1103/PhysRevD.87.092004
Bibliographic Code:   2013PhRvD..87i2004L

Abstract

We study the decay B¯0→Λc+p¯π+π-, reconstructing the Λc+ baryon in the pK-π+ mode, using a data sample of 467×106 BB¯ pairs collected with the BABAR detector at the PEP-II storage rings at SLAC. We measure branching fractions for decays with intermediate Σc baryons to be B[B¯0→Σc(2455)++p¯π-]=(21.3±1.0±1.0±5.5)×10-5, B[B¯0→Σc(2520)++p¯π-]=(11.5±1.0±0.5±3.0)×10-5, B[B¯0→Σc(2455)0p¯π+]=(9.1±0.7±0.4±2.4)×10-5, and B[B¯0→Σc(2520)0p¯π+]=(2.2±0.7±0.1±0.6)×10-5, where the uncertainties are statistical, systematic, and due to the uncertainty on the Λc+→pK-π+ branching fraction, respectively. For decays without Σc(2455) or Σc(2520) resonances, we measure B[B¯0→Λc+p¯π+π-]non-Σc=(79±4±4±20)×10-5. The total branching fraction is determined to be B[B¯0→Λc+p¯π+π-]total=(123±5±7±32)×10-5. We examine multibody mass combinations in the resonant three-particle Σcp¯π final states and in the four-particle Λc+p¯π+π- final state, and observe different characteristics for the p¯π combination in neutral versus doubly charged Σc decays.
 

Title:   Observation of Associated Near-Side and Away-Side Long-Range Correlations in sNN=5.02TeV Proton-Lead Collisions with the ATLAS Detector
Authors:   Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.;... Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;...; and 2917 coauthors.
Publication:   Physical Review Letters, vol. 110, Issue 18, id. 182302 (PhRvL Homepage)
Publication Date:   05/2013
Origin:   APS
PACS Keywords:   Relativistic heavy-ion collisions
DOI:   10.1103/PhysRevLett.110.182302
Bibliographic Code:   2013PhRvL.110r2302A

Abstract

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in sNN=5.02TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ˜0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ˜π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT.
 

Title:   Search for Supersymmetry with Like-Sign Lepton-Tau Events at CDF
Authors:   Aaltonen, T.; Amerio, S.; Amerio, S.;... Franklin, M.;... Guimaraes da Costa, J.;...; and 406 coauthors.
Publication:   Physical Review Letters, vol. 110, Issue 20, id. 201802 (PhRvL Homepage)
Publication Date:   05/2013
Origin:   APS
PACS Keywords:   Supersymmetric models, Inclusive production with identified leptons, photons, or other nonhadronic particles, Limits on production of particles, Supersymmetric partners of known particles
DOI:   10.1103/PhysRevLett.110.201802
Bibliographic Code:   2013PhRvL.110t1802A

Abstract

We present a search for chargino-neutralino associated production using like electric charge dilepton events collected by the CDF II detector at the Fermilab Tevatron in proton-antiproton collisions at s=1.96TeV. One lepton is identified as the hadronic decay of a tau lepton, while the other is an electron or muon. In data corresponding to 6.0fb-1 of integrated luminosity, we obtain good agreement with standard model predictions and set limits on the chargino-neutralino production cross section for simplified gravity- and gauge-mediated models. As an example, assuming that the chargino and neutralino decays to taus dominate, in the simplified gauge-mediated model we exclude cross sections greater than 300 fb at 95% credibility level for chargino and neutralino masses of 225GeV/c2. This analysis is the first to extend the LHC searches for electroweak supersymmetric production of gauginos to high tan⁡β and slepton next-to-lightest supersymmetric particle scenarios.
 

Title:   Dark-Disk Universe
Authors:   Fan, JiJi; Katz, Andrey; Randall, Lisa; Reece, Matthew
Publication:   Physical Review Letters, vol. 110, Issue 21, id. 211302 (PhRvL Homepage)
Publication Date:   05/2013
Origin:   APS
PACS Keywords:   Dark matter
DOI:   10.1103/PhysRevLett.110.211302
Bibliographic Code:   2013PhRvL.110u1302F

Abstract

We point out that current constraints on dark matter imply only that the majority of dark matter is cold and collisionless. A subdominant fraction of dark matter could have much stronger interactions. In particular, it could interact in a manner that dissipates energy, thereby cooling into a rotationally supported disk, much as baryons do. We call this proposed new dark matter component double-disk dark matter (DDDM). We argue that DDDM could constitute a fraction of all matter roughly as large as the fraction in baryons, and that it could be detected through its gravitational effects on the motion of stars in galaxies, for example. Furthermore, if DDDM can annihilate to gamma rays, it would give rise to an indirect detection signal distributed across the sky that differs dramatically from that predicted for ordinary dark matter. DDDM and more general partially interacting dark matter scenarios provide a large unexplored space of testable new physics ideas.
 

Title:   Jet Charge at the LHC
Authors:   Krohn, David; Schwartz, Matthew D.; Lin, Tongyan; Waalewijn, Wouter J.
Publication:   Physical Review Letters, vol. 110, Issue 21, id. 212001 (PhRvL Homepage)
Publication Date:   05/2013
Origin:   APS
PACS Keywords:   Fragmentation into hadrons, Perturbative calculations, Factorization
DOI:   10.1103/PhysRevLett.110.212001
Bibliographic Code:   2013PhRvL.110u2001K

Abstract

Knowing the charge of the parton initiating a light-quark jet could be extremely useful both for testing aspects of the standard model and for characterizing potential beyond-the-standard-model signals. We show that despite the complications of hadronization and out-of-jet radiation such as pileup, a weighted sum of the charges of a jet’s constituents can be used at the LHC to distinguish among jets with different charges. Potential applications include measuring electroweak quantum numbers of hadronically decaying resonances or supersymmetric particles, as well as standard model tests, such as jet charge in dijet events or in hadronically decaying W bosons in tt¯ events. We develop a systematically improvable method to calculate moments of these charge distributions by combining multihadron fragmentation functions with perturbative jet functions and pertubative evolution equations. We show that the dependence on energy and jet size for the average and width of the jet charge can be calculated despite the large experimental uncertainty on fragmentation functions. These calculations can provide a validation tool for data independent of Monte Carlo fragmentation models.


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