Faculty Publications: October, 2013

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Title:
On orbifolds of M-Strings
Authors:
Haghighat, Babak; Kozcaz, Can; Lockhart, Guglielmo; Vafa, Cumrun
Publication:
eprint arXiv:1310.1185
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
High Energy Physics - Theory
Comment:
40 pages, 14 figures
Bibliographic Code:
2013arXiv1310.1185H

Abstract

We consider M-theory in the presence of M parallel M5-branes probing a transverse A_{N-1} singularity. This leads to a superconformal theory with (1,0) supersymmetry in six dimensions. We compute the supersymmetric partition function of this theory on a two-torus, with arbitrary supersymmetry preserving twists, using the topological vertex formalism. Alternatively, we show that this can also be obtained by computing the elliptic genus of an orbifold of recently studied M-strings. The resulting 2d theory is a (4,0) supersymmetric quiver gauge theory whose Higgs branch corresponds to strings propagating on the moduli space of SU(N)^{M-1} instantons on R^4 where the right-moving fermions are coupled to a particular bundle.

 

Title:
In wino veritas? Indirect searches shed light on neutralino dark matter
Authors:
Fan, JiJi; Reece, Matthew
Affiliation:
AA(Department of Physics, Harvard University), AB(Department of Physics, Harvard University)
Publication:
Journal of High Energy Physics, Volume 2013, article id. #124
Publication Date:
10/2013
Origin:
SPRINGER
Keywords:
Supersymmetry Phenomenology
Abstract Copyright:
(c) 2013: SISSA, Trieste, Italy
DOI:
10.1007/JHEP10(2013)124
Bibliographic Code:
2013JHEP...10..124F

Abstract

Indirect detection constraints on gamma rays (both continuum and lines) have set strong constraints on wino dark matter. By combining results from Fermi-LAT and HESS, we show that: dark matter made entirely of light nonthermal winos is strongly excluded; dark matter consisting entirely of thermal winos is allowed only if the Milky Way dark matter distribution has a significant (≳ 0.4 kpc) core; and for plausible NFW and Einasto distributions the possibility that winos are all the dark matter can be excluded over the entire range of wino masses from 100 GeV up to 3 TeV. The case of light, nonthermal wino dark matter is particularly interesting in scenarios with decaying moduli that reheat the universe to a low temperature. Typically such models have been discussed for low reheating temperatures, not far above the BBN bound of a few MeV. We show that constraints on the allowed wino relic density push such models to higher reheating temperatures and hence heavier moduli. Even for a flattened halo model consisting of an NFW profile with constant-density core inside 1 kpc and a density near the sun of 0.3 GeV/cm3, for 150 GeV winos current data constrains the reheat temperature to be above 1.4 GeV. As a result, for models in which the wino mass is a loop factor below m 3/2, the data favor moduli that are more than an order of magnitude heavier than m 3/2. We discuss some of the sobering implications of this result for the status of supersymmetry. We also comment on other neutralino dark matter scenarios, in particular the case of mixed bino/higgsino dark matter. We show that in this case, direct and indirect searches are complementary to each other and could potentially cover most of the parameter space.

 

Title:
Search for new phenomena in final states with large jet multiplicities and missing transverse momentum at TeV proton-proton collisions using the ATLAS experiment
Authors:
Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.; ...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;... and 2912 coauthors.
Publication:
Journal of High Energy Physics, Volume 2013, article id. #130
Publication Date:
10/2013
Origin:
SPRINGER
Keywords:
Hadron-Hadron Scattering, Jet physics, Supersymmetry, Exotics
Abstract Copyright:
(c) 2013: CERN for the benefit of the ATLAS collaboration
DOI:
10.1007/JHEP10(2013)130
Bibliographic Code:
2013JHEP...10..130A

Abstract

A search is presented for new particles decaying to large numbers (7 or more) of jets, with missing transverse momentum and no isolated electrons or muons. This analysis uses 20.3 fb-1 of pp collision data at TeV collected by the ATLAS experiment at the Large Hadron Collider. The sensitivity of the search is enhanced by considering the number of b-tagged jets and the scalar sum of masses of large-radius jets in an event. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of various simplified supersymmetry-inspired models where gluinos are pair produced, as well as an mSUGRA/CMSSM model. [Figure not available: see fulltext.]

 

Title:
Semiclassical deconstruction of quantum states in graphene
Authors:
Mason, Douglas J.; Borunda, Mario F.; Heller, Eric J.
Publication:
Physical Review B, vol. 88, Issue 16, id. 165421 (PhRvB Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Semiclassical theories and applications
DOI:
10.1103/PhysRevB.88.165421
Bibliographic Code:
2013PhRvB..88p5421M

Abstract

We present a method for bridging the gap between the Dirac effective field theory and atomistic simulations in graphene based on the Husimi projection, allowing us to depict phenomena in graphene at arbitrary scales. This technique takes the atomistic wave function as an input, and produces semiclassical pictures of quasiparticles in the two Dirac valleys. We use the Husimi technique to produce maps of the scattering behavior of boundaries, giving insight into the properties of wave functions at energies both close to and far from the Dirac point. Boundary conditions play a significant role to the rise of Fano resonances, which we examine using the processed Husimi map to deepen our understanding of bond currents near resonance.

 

Title:
Measurement of the mass of the D0 meson
Authors:
Lees, J. P.; Poireau, V.; Tisserand, V.;... Morii, M.;... and 331 coauthors
Publication:
Physical Review D, vol. 88, Issue 7, id. 071104 (PhRvD Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Decays of charmed mesons, Charmed mesons
DOI:
10.1103/PhysRevD.88.071104
Bibliographic Code:
2013PhRvD..88g1104L

Abstract

We report a measurement of the D0 meson mass using the decay chain D*(2010)+→D0π+ with D0→K-K-K+π+. The data were recorded with the BABAR detector at center-of-mass energies at and near the Υ(4S) resonance, and correspond to an integrated luminosity of approximately 477fb-1. We obtain m(D0)=(1864.841±0.048±0.063)MeV, where the quoted errors are statistical and systematic, respectively. The uncertainty of this measurement is half that of the best previous measurement.

 

Title:
Measurement of the e+e-→pp¯ cross section in the energy range from 3.0 to 6.5 GeV
Authors:
Lees, J. P.; Poireau, V.; Tisserand, V.; ... Morii, M.;... and 336 coauthors
Publication:
Physical Review D, vol. 88, Issue 7, id. 072009 (PhRvD Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Hadron production in e-e+ interactions, Protons and neutrons, Electromagnetic form factors, Decays of J/psi Upsilon and other quarkonia
DOI:
10.1103/PhysRevD.88.072009
Bibliographic Code:
2013PhRvD..88g2009L

Abstract

The e+e-→pp¯ cross section and the proton magnetic form factor have been measured in the center-of-mass energy range from 3.0 to 6.5 GeV using the initial-state radiation technique with an undetected photon. This is the first measurement of the form factor at energies higher than 4.5 GeV. The analysis is based on 469fb-1 of integrated luminosity collected with the BABAR detector at the PEP-II collider at e+e- center-of-mass energies near 10.6 GeV. The branching fractions for the decays J/ψ→pp¯ and ψ(2S)→pp¯ have also been measured.

 

Title:
Search for flavor-changing non-standard neutrino interactions by MINOS
Authors:
Adamson, P.; Barr, G.; Bishai, M.;... Feldman, G. J.;... and 98 coauthors
Publication:
Physical Review D, vol. 88, Issue 7, id. 072011 (PhRvD Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Neutrino interactions, Ordinary neutrinos (nuW bosons, Neutrino mass and mixing, Non-standard-model neutrinos right-handed neutrinos etc.
DOI:
10.1103/PhysRevD.88.072011
Bibliographic Code:
2013PhRvD..88g2011A

Abstract

We report new constraints on flavor-changing non-standard neutrino interactions from the MINOS experiment, in which neutrino versus antineutrino interactions can be distinguished on an event-by-event basis. We analyzed a combined set of beam neutrino and antineutrino data from the well-understood NuMI beam, and found no evidence for deviations from standard neutrino mixing. The observed energy spectra constrain the non-standard neutrino interactions parameter to the range -0.20<ɛμτ<0.07(90%C.L.).

 

Title:
Preparation of Nuclear Spin Singlet States Using Spin-Lock Induced Crossing
Authors:
DeVience, Stephen J.; Walsworth, Ronald L.; Rosen, Matthew S.
Publication:
Physical Review Letters, vol. 111, Issue 17, id. 173002 (PhRvL Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Nuclear resonance and relaxation
DOI:
10.1103/PhysRevLett.111.173002
Bibliographic Code:
2013PhRvL.111q3002D

Abstract

We introduce a broadly applicable technique to create nuclear spin singlet states in organic molecules and other many-atom systems. We employ a novel pulse sequence to produce a spin-lock induced crossing (SLIC) of the spin singlet and triplet energy levels, which enables triplet-singlet polarization transfer and singlet-state preparation. We demonstrate the utility of the SLIC method by producing a long-lived nuclear spin singlet state on two strongly coupled proton pairs in the tripeptide molecule phenylalanine-glycine-glycine dissolved in D2O and by using SLIC to measure the J couplings, chemical shift differences, and singlet lifetimes of the proton pairs. We show that SLIC is more efficient at creating nearly equivalent nuclear spin singlet states than previous pulse sequence techniques, especially when triplet-singlet polarization transfer occurs on the same time scale as spin-lattice relaxation.

 

Title:
Elastic Platonic Shells
Authors:
Yong, Ee Hou; Nelson, David R.; Mahadevan, L.
Publication:
Physical Review Letters, vol. 111, Issue 17, id. 177801 (PhRvL Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
General theory of phase transitions, Viscoelasticity plasticity viscoplasticity, Beams plates and shells
DOI:
10.1103/PhysRevLett.111.177801
Bibliographic Code:
2013PhRvL.111q7801Y

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 or 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:
Measurement of an excess of B¯→D(*)τ-ν¯τ decays and implications for charged Higgs bosons
Authors:
Lees, J. P.; Poireau, V.; Tisserand, V.; ... Morii, M.;... and 338 coauthors
Publication:
Physical Review D, vol. 88, Issue 7, id. 072012 (PhRvD Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Decays of bottom mesons, Bottom mesons
DOI:
10.1103/PhysRevD.88.072012
Bibliographic Code:
2013PhRvD..88g2012L

Abstract

Based on the full BABAR data sample, we report improved measurements of the ratios R(D)=B(B¯→Dτ-ν¯τ)/B(B¯→Dℓ-ν¯) and R(D*)=B(B¯→D*τ-ν¯τ)/B(B¯→D*-ν¯), where ℓ refers to either an electron or muon. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D)=0.440±0.058±0.042 and R(D*)=0.332±0.024±0.018, which exceed the standard model expectations by 2.0σ and 2.7σ, respectively. Taken together, the results disagree with these expectations at the 3.4σ level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. Kinematic distributions presented here exclude large portions of the more general type III two-Higgs-doublet model, but there are solutions within this model compatible with the results.

 

Title:
Degree-Scale CMB Polarization Measurements from Three Years of BICEP1 Data
Authors:
BICEP1 Collaboration; Aikin, R.; Bischoff, C.; Buder, I.; Kovac, J. M.; Su, M.; Ade, P. A. R.; Battle, J. O.; Bierman, E. M.; Bock, J. J.; Chiang, H. C.; Dowell, C. D.; Duband, L.; Filippini, J.; Hivon, E. F.; Holzapfel, W. L.; Hristov, V. V.; Jones, W. C.; Kaufman, J. P.; Keating, B. G.; Kuo, C. L.; Leitch, E. M.; Mason, P. V.; Matsumura, T.; Nguyen, H. T.; Ponthieu, N.; Pryke, C.; Richter, S.; Sheehy, C.; Kernasovskiy, S. S.; Takahashi, Y. D.; Tolan, J. E.; Yoon, K. W.
Publication:
eprint arXiv:1310.1422
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Astrophysics - Cosmology and Extragalactic Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Comment:
19 pages, 13 figures. Submitted to ApJ. Data release for this publication: http://bicep.rc.fas.harvard.edu/bicep1_3yr/
Bibliographic Code:
2013arXiv1310.1422B

Abstract

BICEP1 is a millimeter-wavelength telescope designed specifically to measure the inflationary B-mode polarization of the Cosmic Microwave Background (CMB) at degree angular scales. We present results from an analysis of the data acquired during three seasons of observations at the South Pole (2006 to 2008). This work extends the two-year result published in Chiang et al. (2010), with additional data from the third season and relaxed detector-selection criteria. This analysis also introduces a more comprehensive estimation of band-power window functions, improved likelihood estimation methods and a new technique for deprojecting monopole temperature-to-polarization leakage which reduces this class of systematic uncertainty to a negligible level. We present maps of temperature, E- and B-mode polarization, and their associated angular power spectra. The improvement in the map noise level and polarization spectra error bars are consistent with the 52% increase in integration time relative to Chiang et al. (2010). We confirm both self-consistency of the polarization data and consistency with the two-year results. We measure the angular power spectra at 21 <= l <= 335 and find that the EE spectrum is consistent with Lambda Cold Dark Matter (LCDM) cosmology, with the first acoustic peak of the EE spectrum now detected at 15sigma. The BB spectrum remains consistent with zero. From B-modes only, we constrain the tensor-to-scalar ratio to r = 0.03+0.27-0.23, or r < 0.70 at 95% confidence level.

 

Title:
Magnetic Trapping of Molecules via Optical Loading and Magnetic Slowing
Authors:
Lu, Hsin-I; Kozyryev, Ivan; Hemmerling, Boerge; Piskorski, Julia; Doyle, John M.
Publication:
eprint arXiv:1310.2669
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Physics - Atomic Physics
Bibliographic Code:
2013arXiv1310.2669L

Abstract

Calcium monofluoride (CaF) is magnetically slowed and trapped using optical pumping. Starting from a collisionally cooled slow beam, CaF with an initial velocity of ~ 30 m/s is slowed via magnetic forces as it enters a 800 mK deep magnetic trap. Employing two-stage optical pumping, CaF is irreversibly loaded into the trap via two scattered photons. We observe a trap lifetime exceeding 500 ms, limited by background collisions. This method paves the way for cooling and magnetic trapping of chemically diverse molecules without closed cycling transitions.

 

Title:
Buffer-gas loaded magneto-optical traps for Yb, Tm, Er and Ho
Authors:
Hemmerling, Boerge; Drayna, Garrett K.; Chae, Eunmi; Ravi, Aakash; Doyle, John M.
Publication:
eprint arXiv:1310.3239
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Physics - Atomic Physics
Bibliographic Code:
2013arXiv1310.3239H

Abstract

Direct loading of magneto-optical traps from a very slow cryogenic buffer-gas beam of lanthanides is achieved and studied, without the need for laser slowing. A collisionally cooled cryogenic atomic source with average forward velocity of 60-70 m/s and a width of ~70 m/s allows for loading without additional dissipation, unlike oven or supersonic sources. The lanthanides Yb, Tm, Er, and Ho are trapped. Despite the He buffer-gas background, we observe a maximum lifetime of about 80 ms (with Yb). We further show that the addition of a single-frequency slowing laser increases the number of trapped Yb atoms by an order of magnitude, yielding a total of 4.0(2) x 10^8. We study decay to metastable states in all species and report decay rates. Extension of this approach to MOTs of molecules is discussed.

 

Title:
Quantum Error Correction for Metrology
Authors:
Kessler, Eric M.; Lovchinsky, Igor; Sushkov, Alexander O.; Lukin, Mikhail D.
Publication:
eprint arXiv:1310.3260
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Quantum Physics
Comment:
6 pages, 1 figure
Bibliographic Code:
2013arXiv1310.3260K

Abstract

We propose an error-correction-based approach to improve quantum metrology protocols in the presence of noise. We derive a set of conditions under which it is possible to correct for errors arising from the coupling to the environment without perturbing the signal of the quantum measurement. The scheme is complementary to current dynamical decoupling techniques, and can improve sensing under realistic experimental conditions. We discuss specific applications to nanoscale sensing using nitrogen-vacancy centers in diamond, e.g., for the imaging of neural activity.

 

Title:
Perseus I: A distant satellite dwarf galaxy of Andromeda
Authors:
Martin, Nicolas F.; Schlafly, Edward F.; Slater, Colin T.; Bernard, Edouard J.; Rix, Hans-Walter; Bell, Eric F.; Ferguson, Annette M. N.; Finkbeiner, Douglas P.; Laevens, Benjamin P. M.; Burgett, William S.; Chambers, Kenneth C.; Draper, Peter W.; Hodapp, Klaus W.; Kaiser, Nicholas; Kudritzki, Rolf-Peter; Magnier, Eugene A.; Metcalfe, Nigel; Morgan, Jeffrey S.; Price, Paul A.; Tonry, John L.; Wainscoat, Richard J.; Waters, Christopher
Publication:
eprint arXiv:1310.4170
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:
6 pages, 4 figures. Accepted for publication in ApJL
Bibliographic Code:
2013arXiv1310.4170M

Abstract

We present the discovery of a new dwarf galaxy, Perseus I/Andromeda XXXIII, found in the vicinity of Andromeda (M31) in stacked imaging data from the Pan-STARRS1 3{\pi} survey. Located 27.9{\deg} away from M31, Perseus I has a heliocentric distance of 785 +/- 65 kpc, compatible with it being a satellite of M31 at 374 +14/-10 kpc from its host. The properties of Perseus I are typical for a reasonably bright dwarf galaxy (M_V = -10.3 +/- 0.7), with an exponential half-light radius of r_h = 1.7 +/- 0.4 arcminutes or r_h = 400 +105/-85 pc at this distance, and a moderate ellipticity (\epsilon = 0.43 +0.15/-0.17). The late discovery of Perseus I is due to its fairly low surface brightness (\mu_0=25.7 +1.0/-0.9 mag/arcsec^2), and to the previous lack of deep, high quality photometric data in this region. If confirmed to be a companion of M31, the location of Perseus I, far east from its host, could place interesting constraints on the bulk motion of the satellite system of M31.

 

Title:
Using the Discrete Dipole Approximation and Holographic Microscopy to Measure Rotational Dynamics of Non-spherical Colloids
Authors:
Wang, Anna; Dimiduk, Thomas G.; Fung, Jerome; Razavi, Sepideh; Kretzschmar, Ilona; Chaudhary, Kundan; Lewis, Jennifer A.; Manoharan, Vinothan N.
Publication:
eprint arXiv:1310.4517
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Physics - Optics, Condensed Matter - Soft Condensed Matter
Comment:
29 pages, 8 figures, 2 tables
Bibliographic Code:
2013arXiv1310.4517W

Abstract

We present a new, high-speed technique to track the three-dimensional translation and rotation of non-spherical colloidal particles. We capture digital holograms of micrometer-scale silica rods and sub-micrometer-scale Janus particles freely diffusing in water, and then fit numerical scattering models based on the discrete dipole approximation to the measured holograms. This inverse-scattering approach allows us to extract the the position and orientation of the particles as a function of time, along with static parameters including the size, shape, and refractive index. The best-fit sizes and refractive indices of both particles agree well with expected values. The technique is able to track the center of mass of the rod to a precision of 35 nm and its orientation to a precision of 1.5$^\circ$, comparable to or better than the precision of other 3D diffusion measurements on non-spherical particles. Furthermore, the measured translational and rotational diffusion coefficients for the silica rods agree with hydrodynamic predictions for a spherocylinder to within 0.3%. We also show that although the Janus particles have only weak optical asymmetry, the technique can track their 2D translation and azimuthal rotation over a depth of field of several micrometers, yielding independent measurements of the effective hydrodynamic radius that agree to within 0.2%. The internal and external consistency of these measurements validate the technique. Because the discrete dipole approximation can model scattering from arbitrarily shaped particles, our technique could be used in a range of applications, including particle tracking, microrheology, and fundamental studies of colloidal self-assembly or microbial motion.

 

Title:
Disk entanglement entropy for a Maxwell field
Authors:
Agon, Cesar A.; Headrick, Matthew; Jafferis, Daniel L.; Kasko, Skyler
Publication:
eprint arXiv:1310.4886
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
High Energy Physics - Theory, Condensed Matter - Statistical Mechanics
Comment:
34 pages
Bibliographic Code:
2013arXiv1310.4886A

Abstract

In three dimensions, the pure Maxwell theory with compact U(1) gauge group is dual to a free compact scalar, and flows from the Maxwell theory with non-compact gauge group in the ultraviolet to a non-compact free massless scalar theory in the infrared. We compute the vacuum disk entanglement entropy all along this flow, and show that the renormalized entropy F(r) decreases monotonically with the radius r as predicted by the F-theorem, interpolating between a logarithmic growth for small r (matching the behavior of the S^3 free energy) and a constant at large r (equal to the free energy of the conformal scalar). The calculation is carried out by the replica trick, employing the scalar formulation of the theory. The Renyi entropies for n>1 are given by a sum over winding sectors, leading to a Riemann-Siegel theta function. The extrapolation to n=1, to obtain the von Neumann entropy, is done by analytic continuation in the large- and small-r limits and by a numerical extrapolation method at intermediate values. We also compute the leading contribution to the renormalized entanglement entropy of the compact free scalar in higher dimensions. Finally, we point out some interesting features of the reduced density matrix for the compact scalar, and its relation to that for the non-compact theory.

 

Title:
A mathematical theory of D-string world-sheet instantons, II: Moduli stack of $Z$-(semi)stable morphisms from Azumaya nodal curves with a fundamental module to a projective Calabi-Yau 3-fold
Authors:
Liu, Chien-Hao; Yau, Shing-Tung
Publication:
eprint arXiv:1310.5195
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Mathematics - Algebraic Geometry, High Energy Physics - Theory, Mathematics - Symplectic Geometry, 14D20, 81T30, 14F05, 14N35, 14A22
Comment:
47 + 2 pages, 3 figures
Bibliographic Code:
2013arXiv1310.5195L

Abstract

In this Part II, D(10.2), of D(10), we take D(10.1) (arXiv:1302.2054 [math.AG]) as the foundation to define the notion of $Z$-semistable morphisms from general Azumaya nodal curves, of genus $\ge 2$, with a fundamental module to a projective Calabi-Yau 3-fold and show that the moduli stack of such $Z$-semistable morphisms of a fixed type is compact. This gives us a counter moduli stack to D-strings as the moduli stack of stable maps in Gromov-Witten theory to the fundamental string. It serves and prepares for us the basis toward a new invariant of Calabi-Yau 3-fold that captures soft-D-string world-sheet instanton numbers in superstring theory. This note is written hand-in-hand with D(10.1) and is to be read side-by-side with ibidem.

 

Title:
Ultrafast and Fault-Tolerant Quantum Communication across Long Distances
Authors:
Muralidharan, Sreraman; Kim, Jungsang; Lütkenhaus, Norbert; Lukin, Mikhail D.; Jiang, Liang
Publication:
eprint arXiv:1310.5291
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Quantum Physics
Comment:
5 pages + supplemental material
Bibliographic Code:
2013arXiv1310.5291M

Abstract

Quantum repeaters (QRs) provide a way of enabling long distance quantum communication by establishing entangled qubits between remote locations. We investigate a new approach to QRs in which quantum information can be faithfully transmitted via a noisy channel without the use of long distance teleportation, thus eliminating the need to establish remote entangled links. Our approach makes use of small encoding blocks to fault-tolerantly correct both operational and photon loss errors. We describe a way to optimize the resource requirement for these QRs with the aim of the generation of a secure key. Numerical calculations indicate that the number of quantum memory bits required for our scheme has favorable poly-logarithmic scaling with the distance across which the communication is desired.

 

Title:
Heisenberg-limited atom clocks based on entangled qubits
Authors:
Kessler, Eric M.; Kómár, Peter; Bishof, Michael; Jiang, Liang; Sørensen, Anders S.; Ye, Jun; Lukin, Mikhail D.
Publication:
eprint arXiv:1310.6043
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Quantum Physics
Comment:
13 pages, 2 figures
Bibliographic Code:
2013arXiv1310.6043K

Abstract

We present a quantum-enhanced atomic clock protocol based on groups of sequentially larger Greenberger-Horne-Zeilinger (GHZ) states, that achieves the best clock stability allowed by quantum theory up to a logarithmic correction. The simultaneous interrogation of the laser phase with such a cascade of GHZ states realizes an incoherent version of the phase estimation algorithm that enables Heisenberg-limited operation while extending the Ramsey interrogation time beyond the laser noise limit. We compare the new protocol with state of the art interrogation schemes, and show that entanglement allow a significant quantum gain in the stability for short averaging time.

 

Title:
A quantum network of clocks
Authors:
Kómár, Peter; Kessler, Eric M.; Bishof, Michael; Jiang, Liang; Sørensen, Anders S.; Ye, Jun; Lukin, Mikhail D.
Publication:
eprint arXiv:1310.6045
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Quantum Physics
Comment:
13 pages, 5 figures
Bibliographic Code:
2013arXiv1310.6045K

Abstract

The development of precise atomic clocks has led to many scientific and technological advances that play an increasingly important role in modern society. Shared timing information constitutes a key resource for positioning and navigation with a direct correspondence between timing accuracy and precision in applications such as the Global Positioning System (GPS). By combining precision metrology and quantum networks, we propose here a quantum, cooperative protocol for the operation of a network consisting of geographically remote optical atomic clocks. Using non-local entangled states, we demonstrate an optimal utilization of the global network resources, and show that such a network can be operated near the fundamental limit set by quantum theory yielding an ultra-precise clock signal. Furthermore, the internal structure of the network, combined with basic techniques from quantum communication, guarantees security both from internal and external threats. Realization of such a global quantum network of clocks may allow construction of a real-time single international time scale (world clock) with unprecedented stability and accuracy.

 

Title:
Chromium tip etching and spin-polarized imaging of antiferromagnetic terraces in the bilayer manganite La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ ($x$ = 0.30)
Authors:
Liu, Stephen; Huang, Dennis; Zeljkovic, Ilija; Mitchell, J. F.; Hoffman, Jennifer E.
Publication:
eprint arXiv:1310.6733
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons
Bibliographic Code:
2013arXiv1310.6733L

Abstract

We report the preparation of bulk Cr tips for scanning tunneling microscopy by direct current drop-off etching, and we detail the role of $ex$-$situ$ fabrication parameters on the tip apex geometry. We present a new strategy to evaluate the tunneling characteristics of the Cr tips using cleaved crystal planes, circumventing the need for ultra-high vacuum preparation of clean surfaces or films. Using constant current spin-polarized tunneling, we image layered antiferromagnetism over nanoscale terraces in the bilayer manganite La$_{1.4}$Sr$_{1.6}$Mn$_2$O$_7$. Atomic-resolution imaging is also obtained on Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$.

 

Title:
Intermodal Energy Transfer in a Tapered Optical Fiber: Optimizing Transmission
Authors:
Ravets, S.; Hoffman, J. E.; Kordell, P. R.; Wong-Campos, J. D.; Rolston, S. L.; Orozco, L. A.
Publication:
eprint arXiv:1310.7228
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Physics - Optics, Physics - Atomic Physics
Comment:
29 pages, 17 figures; JOSA A, Vol. 30, Issue 11, pp. 2361-2371 (2013); doi:10.1364/JOSAA.30.002361
Bibliographic Code:
2013arXiv1310.7228R

Abstract

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

 

Title:
Properties of the ground $^3$F$_2$ state and the excited $^3$P$_0$ state of atomic thorium in cold collisions with $^3$He
Authors:
Au, Yat Shan; Connolly, Colin B.; Ketterle, Wolfgang; Doyle, John M.
Publication:
eprint arXiv:1310.7264
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Physics - Atomic Physics
Bibliographic Code:
2013arXiv1310.7264A

Abstract

We measure inelastic collisional cross sections for the ground $^3$F$_2$ state and the excited $^3$P$_0$ state of atomic thorium in cold collisions with $^3$He. We determine for Th ($^3$F$_2$) at 800 mK the ratio $\gamma \approx 500$ of the momentum-transfer to Zeeman relaxation cross sections for collisions with $^3$He. For Th ($^3$P$_0$), we study electronic inelastic processes and find no quenching even after $10^6$ collisions. We also determine the radiative lifetime of Th ($^3$P$_0$) to be $\tau > 130$ ms. This great stability of the metastable state opens up the possibility for further study, including trapping.

 

Title:
Vibrational quenching of the electronic ground state in ThO in cold collisions with $^3$He
Authors:
Au, Yat Shan; Connolly, Colin B.; Ketterle, Wolfgang; Doyle, John M.
Publication:
eprint arXiv:1310.7279
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Physics - Atomic Physics, Physics - Atomic and Molecular Clusters
Bibliographic Code:
2013arXiv1310.7279A

Abstract

We measure the ratio $\gamma$ of the momentum-transfer to the vibrational quenching cross section for the X ($^1\Sigma^+$), $\nu=1$, $\mathrm{J=0}$ state of molecular thorium monoxide (ThO) in collisions with atomic $^3$He between 800 mK and 2.4 K. We observe indirect evidence for ThO--He van der Waals' complex formation, which has been predicted by theory. We determine the 3-body recombination rate constant $\Gamma_3$ at 2.4 K, and establish that the binding energy E$_b >$ 4 K.

 

Title:
Order of Magnitude Smaller Limit on the Electric Dipole Moment of the Electron
Authors:
ACME Collaboration; Baron, Jacob; Campbell, Wesley C.; DeMille, David; Doyle, John M.; Gabrielse, Gerald; Gurevich, Yulia V.; Hess, Paul W.; Hutzler, Nicholas R.; Kirilov, Emil; Kozyryev, Ivan; O'Leary, Brendon R.; Panda, Cristian D.; Parsons, Maxwell F.; Petrik, Elizabeth S.; Spaun, Ben; Vutha, Amar C.; West, Adam D.
Publication:
eprint arXiv:1310.7534
Publication Date:
10/2013
Origin:
ARXIV
Keywords:
Physics - Atomic Physics, High Energy Physics - Experiment
Bibliographic Code:
2013arXiv1310.7534A

Abstract

The Standard Model (SM) of particle physics fails to explain dark matter and why matter survived annihilation with antimatter following the Big Bang. Extensions to the SM, such as weak-scale Supersymmetry, may explain one or both of these phenomena by positing the existence of new particles and interactions that are asymmetric under time-reversal (T). These theories nearly always predict a small, yet potentially measurable ($10^{-27}$-$10^{-30}$ $e$ cm) electron electric dipole moment (EDM, $d_e$), which is an asymmetric charge distribution along the spin ($\vec{S}$). The EDM is also asymmetric under T. Using the polar molecule thorium monoxide (ThO), we measure $d_e = (-2.1 \pm 3.7_\mathrm{stat} \pm 2.5_\mathrm{syst})\times 10^{-29}$ $e$ cm. This corresponds to an upper limit of $|d_e| < 8.7\times 10^{-29}$ $e$ cm with 90 percent confidence, an order of magnitude improvement in sensitivity compared to the previous best limits. Our result constrains T-violating physics at the TeV energy scale.

 

Title:
The Role of Vimentin Intermediate Filaments in Cortical and Cytoplasmic Mechanics
Authors:
Guo, Ming; Ehrlicher, Allen J.; Mahammad, Saleemulla; Fabich, Hilary; Jensen, Mikkel H.; Moore, Jeffrey R.; Fredberg, Jeffrey J.; Goldman, Robert D.; Weitz, David A.
Publication:
Biophysical Journal, vol. 105, issue 7, pp. 1562-1568
Publication Date:
10/2013
Origin:
CROSSREF
DOI:
10.1016/j.bpj.2013.08.037
Bibliographic Code:
2013BpJ...105.1562G

Abstract

Not Available

 

Title:
Extended X-ray absorption fine structure spectroscopy of selenium-hyperdoped silicon
Authors:
Newman, Bonna K.; Ertekin, Elif; Sullivan, Joseph T.; Winkler, Mark T.; Marcus, Matthew A.; Fakra, Sirine C.; Sher, Meng-Ju; Mazur, Eric; Grossman, Jeffrey C.; Buonassisi, Tonio
Publication:
Journal of Applied Physics, Volume 114, Issue 13, pp. 133507-133507-8 (2013). (JAP Homepage)
Publication Date:
10/2013
Origin:
AIP
Keywords:
annealing, bonds (chemical), density functional theory, diffusion, elemental semiconductors, EXAFS, optical constants, point defects, precipitation, selenium, silicon
PACS Keywords:
X-ray absorption spectra, Solid-phase precipitation, Kinetics of defect formation and annealing, Diffusion of other defects, Optical constants
Abstract Copyright:
(c) 2013: American Institute of Physics
DOI:
10.1063/1.4824279
Bibliographic Code:
2013JAP...114m3507N

Abstract

Silicon doped with an atomic percent of chalcogens exhibits strong, uniform sub-bandgap optical absorptance and is of interest for photovoltaic and infrared detector applications. This sub-bandgap absorptance is reduced with subsequent thermal annealing indicative of a diffusion mediated chemical change. However, the precise atomistic origin of absorptance and its deactivation is unclear. Herein, we apply Se K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy to probe the chemical states of selenium dopants in selenium-hyperdoped silicon annealed to varying degrees. We observe a smooth and continuous selenium chemical state change with increased annealing temperature, highly correlated to the decrease in sub-bandgap optical absorptance. In samples exhibiting strong sub-bandgap absorptance, EXAFS analysis reveals that the atoms nearest to the Se atom are Si at distances consistent with length scales in energetically favorable Se substitutional-type point defect complexes as calculated by density functional theory. As the sub-bandgap absorptance increases, EXAFS data indicate an increase in the Se-Si bond distance. In specimens annealed at 1225 K exhibiting minimal sub-bandgap absorptance, fitting of the EXAFS spectra indicates that Se is predominantly in a silicon diselenide (SiSe2) precipitate state. The EXAFS study supports a model of highly optically absorbing point defects that precipitate during annealing into structures with no sub-bandgap absorptance.

 

Title:
Exothermic double-disk dark matter
Authors:
McCullough, Matthew; Randall, Lisa
Publication:
Journal of Cosmology and Astroparticle Physics, Issue 10, article id. 058, pp. (2013). (JCAP Homepage)
Publication Date:
10/2013
Origin:
IOP
DOI:
10.1088/1475-7516/2013/10/058
Bibliographic Code:
2013JCAP...10..058M

Abstract

If a subdominant component of dark matter (DM) interacts via long-range dark force carriers it may cool and collapse to form complex structures within the Milky Way galaxy, such as a rotating dark disk. This scenario was proposed recently and termed ``Double-Disk Dark Matter'' (DDDM). In this paper we consider the possibility that DDDM remains in a cosmologically long-lived excited state and can scatter exothermically on nuclei (ExoDDDM). We investigate the current status of ExoDDDM direct detection and find that ExoDDDM can readily explain the recently announced ~ 3σ excess observed at CDMS-Si, with almost all of the 90% best-fit parameter space in complete consistency with limits from other experiments, including XENON10 and XENON100. In the absence of isospin-dependent couplings, this consistency requires light DM with mass typically in the 5-15 GeV range. The hypothesis of ExoDDDM can be tested in direct detection experiments through its peaked recoil spectra, reduced annual modulation amplitude, and, in some cases, its novel time-dependence. We also discuss future direct detection prospects and additional indirect constraints from colliders and solar capture of ExoDDDM. As theoretical proof-of-principle, we combine the features of exothermic DM models and DDDM models to construct a complete model of ExoDDDM, exhibiting all the required properties.

 

Title:
Measurement of the differential cross-section of B + meson production in pp collisions at TeV at ATLAS
Authors:
Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.; ...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;... and 2910 coauthors.
Publication:
Journal of High Energy Physics, Volume 2013, article id. #42
Publication Date:
10/2013
Origin:
SPRINGER
Keywords:
Hadron-Hadron Scattering
Abstract Copyright:
(c) 2013: CERN for the benefit of the ATLAS collaboration
DOI:
10.1007/JHEP10(2013)042
Bibliographic Code:
2013JHEP...10..042A

Abstract

The production cross-section of B + mesons is measured as a function of transverse momentum p T and rapidity y in proton-proton collisions at centre-of-mass energy TeV, using 2.4 fb-1 of data recorded with the ATLAS detector at the Large Hadron Collider. The differential production cross-sections, determined in the range 9 GeV < p T < 120 GeV and | y| < 2 .25, are compared to next-to-leading-order theoretical predictions. [Figure not available: see fulltext.]

 

Title:
Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC
Authors:
Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.; ...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;... and 2916 coauthors.
Publication:
Physics Letters B, Volume 726, Issue 1, p. 88-119.
Publication Date:
10/2013
Origin:
ELSEVIER
Abstract Copyright:
CERN
DOI:
10.1016/j.physletb.2013.08.010
Bibliographic Code:
2013PhLB..726...88A

Abstract

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H→γγ, H→ZZ*→4ℓ and H→WW*→ℓνℓν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of s=7 TeV and s=8 TeV, corresponding to an integrated luminosity of about 25 fb-1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson.

 

Title:
Evidence for the spin-0 nature of the Higgs boson using ATLAS data
Authors:
Aad, G.; Abajyan, T.; Abbott, B.; ... Franklin, M.; ...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;... and 2916 coauthors.
Publication:
Physics Letters B, Volume 726, Issue 1, p. 120-144.
Publication Date:
10/2013
Origin:
ELSEVIER
Abstract Copyright:
CERN
DOI:
10.1016/j.physletb.2013.08.026
Bibliographic Code:
2013PhLB..726..120A

Abstract

Studies of the spin and parity quantum numbers of the Higgs boson are presented, based on proton-proton collision data collected by the ATLAS experiment at the LHC. The Standard Model spin-parity JP=0+ hypothesis is compared with alternative hypotheses using the Higgs boson decays H→γγ, H→ZZ*→4ℓ and H→WW*→ℓνℓν, as well as the combination of these channels. The analysed dataset corresponds to an integrated luminosity of 20.7 fb-1 collected at a centre-of-mass energy of s=8TeV. For the H→ZZ*→4ℓ decay mode the dataset corresponding to an integrated luminosity of 4.6 fb-1 collected at s=7TeV is included. The data are compatible with the Standard Model JP=0+ quantum numbers for the Higgs boson, whereas all alternative hypotheses studied in this Letter, namely some specific JP=0-,1+,1-,2+ models, are excluded at confidence levels above 97.8%. This exclusion holds independently of the assumptions on the coupling strengths to the Standard Model particles and in the case of the JP=2+ model, of the relative fractions of gluon-fusion and quark-antiquark production of the spin-2 particle. The data thus provide evidence for the spin-0 nature of the Higgs boson, with positive parity being strongly preferred.

 

Title:
Conserved current correlators of conformal field theories in 2+1 dimensions
Authors:
Huh, Yejin; Strack, Philipp; Sachdev, Subir
Publication:
Physical Review B, vol. 88, Issue 15, id. 155109 (PhRvB Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Strongly correlated electron systems, heavy fermions, Critical-point effects specific heats short-range order, Gauge field theories
DOI:
10.1103/PhysRevB.88.155109
Bibliographic Code:
2013PhRvB..88o5109H

Abstract

We compute current correlators of the CPN-1 field theory in 2+1 dimensions, both at the critical point and in the phase with spontaneously broken SU(N) symmetry. Universal constants are obtained to next-to-leading order in the 1/N expansion. Implications are noted for quantum critical points of antiferromagnets and their vicinity.

 

Title:
Evidence for a bottom baryon resonance Λb*0 in CDF data
Authors:
Aaltonen, T.; Amerio, S.; Amidei, D.;... Guimaraes da Costa, J.; ... Franklin, M.;... and 402 coauthors.
Publication:
Physical Review D, vol. 88, Issue 7, id. 071101 (PhRvD Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Bottom baryons, Hadronic decays, Bottom quarks
DOI:
10.1103/PhysRevD.88.071101
Bibliographic Code:
2013PhRvD..88g1101A

Abstract

Using data from proton-antiproton collisions at s=1.96TeV recorded by the CDF II detector at the Fermilab Tevatron, evidence for the excited resonance state Λb*0 is presented in its Λb0π-π+ decay followed by the Λb0→Λc+π- and Λc+→pK-π+ decays. The analysis is based on a data sample corresponding to an integrated luminosity of 9.6fb-1 collected by an online event selection based on charged-particle tracks displaced from the proton-antiproton interaction point. The significance of the observed signal is 3.5σ. The mass of the observed state is found to be 5919.22±0.76MeV/c2 in agreement with similar findings in proton-proton collision experiments.

 

Title:
Search for a low-mass scalar Higgs boson decaying to a tau pair in single-photon decays of Υ(1S)
Authors:
Lees, J. P.; Poireau, V.; Tisserand, V.;... Morii, M.;... and 362 coauthors.
Publication:
Physical Review D, vol. 88, Issue 7, id. 071102 (PhRvD Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Extensions of electroweak Higgs sector, Supersymmetric models, Decays of J/psi Upsilon and other quarkonia
DOI:
10.1103/PhysRevD.88.071102
Bibliographic Code:
2013PhRvD..88g1102L

Abstract

We search for a low-mass scalar CP-odd Higgs boson, A0, produced in the radiative decay of the upsilon resonance and decaying into a τ+τ- pair: Υ(1S)→γA0. The production of Υ(1S) mesons is tagged by Υ(2S)→π+π-Υ(1S) transitions, using a sample of (98.3±0.9)×106 Υ(2S) mesons collected by the BABAR detector. We find no evidence for a Higgs boson in the mass range 3.5≤mA0≤9.2GeV, and combine these results with our previous search for the tau decays of the light Higgs in radiative Υ(3S) decays, setting limits on the coupling of A0 to the bb¯ quarks in the range 0.09–1.9. Our measurements improve the constraints on the parameters of the next-to-minimal-supersymmetric Standard Model and similar theories with low-mass scalar degrees of freedom.

 

Title:
Search for microscopic black holes in a like-sign dimuon final state using large track multiplicity with the ATLAS detector
Authors:
Aad, G.; Abajyan, T.; Abbott, B.;... Franklin, M.; ...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;... and 2934 coauthors.
Publication:
Physical Review D, vol. 88, Issue 7, id. 072001 (PhRvD Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Limits on production of particles, Higher-dimensional gravity and other theories of gravity, Higher-dimensional black holes black strings and related objects, Field theories in dimensions other than four
DOI:
10.1103/PhysRevD.88.072001
Bibliographic Code:
2013PhRvD..88g2001A

Abstract

A search is presented for microscopic black holes in a like-sign dimuon final state in proton-proton collisions at s=8TeV. The data were collected with the ATLAS detector at the Large Hadron Collider in 2012 and correspond to an integrated luminosity of 20.3fb-1. Using a high track multiplicity requirement, 0.6±0.2 background events from Standard Model processes are predicted and none observed. This result is interpreted in the context of low-scale gravity models and 95% C.L. lower limits on microscopic black hole masses are set for different model assumptions.

 

Title:
Indirect measurement of sin⁡2θW (MW) using e+e- pairs in the Z-boson region with pp¯ collisions at a center-of-momentum energy of 1.96 TeV
Authors:
Aaltonen, T.; Amerio, S.; Amidei, D.;... Guimaraes da Costa, J.; ... Franklin, M.;... and 406 coauthors.
Publication:
Physical Review D, vol. 88, Issue 7, id. 072002 (PhRvD Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Electroweak radiative corrections, Inclusive production with identified leptons photons or other nonhadronic particles, Z bosons
DOI:
10.1103/PhysRevD.88.072002
Bibliographic Code:
2013PhRvD..88g2002A

Abstract

Drell-Yan lepton pairs are produced in the process pp¯→e+e-+X through an intermediate γ*/Z boson. The lepton angular distributions are used to provide information on the electroweak-mixing parameter sin⁡2θW via its observable effective-leptonic sin⁡2θW, or sin⁡2θefflept. A new method to infer sin⁡2θW or, equivalently, the W-boson mass MW in the on-shell scheme, is developed and tested using a previous CDF Run II measurement of angular distributions from electron pairs in a sample corresponding to 2.1fb-1 of integrated luminosity from pp¯ collisions at a center-of-momentum energy of 1.96 TeV. The value of sin⁡2θefflept is found to be 0.2328±0.0011. Within a specified context of the standard model, this results in sin⁡2θW=0.2246±0.0011, which corresponds to a W-boson mass of 80.297±0.055GeV/c2, in agreement with previous determinations in electron-position collisions and at the Tevatron collider.

 

Title:
Measurement of the leptonic asymmetry in tt¯ events produced in pp¯ collisions at s=1.96TeV
Authors:
Aaltonen, T.; Amerio, S.; Amidei, D.;... Guimaraes da Costa, J.; ... Franklin, M.;... and 403 coauthors.
Publication:
Physical Review D, vol. 88, Issue 7, id. 072003 (PhRvD Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Top quarks, Charge conjugation parity time reversal and other discrete symmetries, Experimental tests, Inclusive production with identified leptons photons or other nonhadronic particles
DOI:
10.1103/PhysRevD.88.072003
Bibliographic Code:
2013PhRvD..88g2003A

Abstract

We measure the asymmetry in the charge-weighted rapidity qy of the lepton in semileptonic tt¯ decays recorded with the CDF II detector using the full Tevatron Run II sample, corresponding to an integrated luminosity of 9.4fb-1. A parametrization of the asymmetry as a function of qy is used to correct for the finite acceptance of the detector and recover the production-level asymmetry. The result of AFB=0.094-0.029+0.032 is to be compared to the standard model next-to-leading-order prediction of AFB=0.038±0.003.

 

Title:
Measurement of the B+→ωℓ+ν branching fraction with semileptonically tagged B mesons
Authors:
Lees, J. P.; Poireau, V.; Tisserand, V.;... Morii, M.;... and 340 coauthors.
Publication:
Physical Review D, vol. 88, Issue 7, id. 072006 (PhRvD Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Decays of bottom mesons, Determination of Kobayashi-Maskawa matrix elements, Experimental tests, Bottom mesons
DOI:
10.1103/PhysRevD.88.072006
Bibliographic Code:
2013PhRvD..88g2006L

Abstract

We report a measurement of the branching fraction of the exclusive charmless semileptonic decay B+→ωℓ+ν, where ℓ is either an electron or a muon. We use samples of B+ mesons tagged by a reconstructed charmed semileptonic decay of the other B meson in the event. The measurement is based on a data set of 426.1fb-1 of e+e- collisions at a center-of-mass energy of 10.58 GeV recorded with the BABAR detector at the PEP-II asymmetric-energy e+e- storage rings. We measure a branching fraction of B(B+→ωℓ+ν)=(1.35±0.21±0.11)×10-4, where the uncertainties are statistical and systematic, respectively. We also present measurements of the partial branching fractions in three bins of q2, the invariant-mass squared of the lepton-neutrino system, and we compare them to theoretical predictions of the form factors.

 

Title:
Probing Real-Space and Time-Resolved Correlation Functions with Many-Body Ramsey Interferometry
Authors:
Knap, Michael; Kantian, Adrian; Giamarchi, Thierry; Bloch, Immanuel; Lukin, Mikhail D.; Demler, Eugene
Publication:
Physical Review Letters, vol. 111, Issue 14, id. 147205 (PhRvL Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Quantized spin models, Ion trapping, Nonequilibrium gas dynamics, Ultracold gases trapped gases
DOI:
10.1103/PhysRevLett.111.147205
Bibliographic Code:
2013PhRvL.111n7205K

Abstract

We propose to use Ramsey interferometry and single-site addressability, available in synthetic matter such as cold atoms or trapped ions, to measure real-space and time-resolved spin correlation functions. These correlation functions directly probe the excitations of the system, which makes it possible to characterize the underlying many-body states. Moreover, they contain valuable information about phase transitions where they exhibit scale invariance. We also discuss experimental imperfections and show that a spin-echo protocol can be used to cancel slow fluctuations in the magnetic field. We explicitly consider examples of the two-dimensional, antiferromagnetic Heisenberg model and the one-dimensional, long-range transverse field Ising model to illustrate the technique.

 

Title:
Measurement of the Azimuthal Angle Dependence of Inclusive Jet Yields in Pb+Pb Collisions at sNN=2.76TeV with the ATLAS Detector
Authors:
Aad, G.; Abajyan, T.; Abbott, B.; ... Franklin, M.; ...Guimaraes da Costa, J.;... Huth, J.;... Morii, M.;... and 2911 coauthors.
Publication:
Physical Review Letters, vol. 111, Issue 15, id. 152301 (PhRvL Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Relativistic heavy-ion collisions
DOI:
10.1103/PhysRevLett.111.152301
Bibliographic Code:
2013PhRvL.111o2301A

Abstract

Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, Δϕ, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has measured the Δϕ dependence of jet yields in 0.14nb-1 of sNN=2.76TeV Pb+Pb collisions at the LHC for jet transverse momenta pT>45GeV in different collision centrality bins using an underlying event subtraction procedure that accounts for elliptic flow. The variation of the jet yield with Δϕ was characterized by the parameter, v2jet, and the ratio of out-of-plane (Δϕ˜π/2) to in-plane (Δϕ˜0) yields. Nonzero v2jet values were measured in all centrality bins for pT<160GeV. The jet yields are observed to vary by as much as 20% between in-plane and out-of-plane directions.

 

Title:
Singularity of the London Penetration Depth at Quantum Critical Points in Superconductors
Authors:
Chowdhury, Debanjan; Swingle, Brian; Berg, Erez; Sachdev, Subir
Publication:
Physical Review Letters, vol. 111, Issue 15, id. 157004 (PhRvL Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Strongly correlated electron systems, heavy fermions, Heavy-fermion superconductors
DOI:
10.1103/PhysRevLett.111.157004
Bibliographic Code:
2013PhRvL.111o7004C

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 Z2 fractionalization and a conventional superconductor. We note implications for recent measurements of the London penetration depth in BaFe2(As1-xPx)2 [K. Hashimoto , Science 336, 1554 (2012)SCIEAS0036-807510.1126/science.1219821].

 

Title:
Vector Boson Excitations Near Deconfined Quantum Critical Points
Authors:
Huh, Yejin; Strack, Philipp; Sachdev, Subir
Publication:
Physical Review Letters, vol. 111, Issue 16, id. 166401 (PhRvL Homepage)
Publication Date:
10/2013
Origin:
APS
PACS Keywords:
Strongly correlated electron systems, heavy fermions, Gauge field theories, Critical-point effects specific heats short-range order
DOI:
10.1103/PhysRevLett.111.166401
Bibliographic Code:
2013PhRvL.111p6401H

Abstract

We show that the Néel states of two-dimensional antiferromagnets have low energy vector boson excitations in the vicinity of deconfined quantum critical points. We compute the universal damping of these excitations arising from spin-wave emission. Detection of such a vector boson will demonstrate the existence of emergent topological gauge excitations in a quantum spin system.


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