41,652 research outputs found
Flavor-twisted boundary condition for simulations of quantum many-body systems
We present an approximative simulation method for quantum many-body systems
based on coarse graining the space of the momentum transferred between
interacting particles, which leads to effective Hamiltonians of reduced size
with the flavor-twisted boundary condition. A rapid, accurate, and fast
convergent computation of the ground-state energy is demonstrated on the
spin-1/2 quantum antiferromagnet of any dimension by employing only two sites.
The method is expected to be useful for future simulations and quick estimates
on other strongly correlated systems.Comment: 6 pages, 2 figure
Momentum Kick Model Description of the Ridge in (Delta-phi)-(Delta eta) Correlation in pp Collisions at 7 TeV
The near-side ridge structure in the (Delta phi)-(Delta eta) correlation
observed by the CMS Collaboration for pp collisions at 7 TeV at LHC can be
explained by the momentum kick model in which the ridge particles are medium
partons that suffer a collision with the jet and acquire a momentum kick along
the jet direction. Similar to the early medium parton momentum distribution
obtained in previous analysis for nucleus-nucleus collisions at 0.2 TeV, the
early medium parton momentum distribution in pp collisions at 7 TeV exhibits a
rapidity plateau as arising from particle production in a flux tube.Comment: Talk presented at Workshop on High-pT Probes of High-Density QCD at
the LHC, Palaiseau, May 30-June2, 201
The correlations between the twin kHz QPO frequencies of LMXBs
We analyzed the recently published kHz QPO data in the neutron star low-mass
X-ray binaries (LMXBs), in order to investigate the different correlations of
the twin peak kilohertz quasi-eriodic oscillations (kHz QPOs) in bright Z
sources and in the less luminous Atoll sources. We find that a power-law
relation \no\sim\nt^{b} between the upper and the lower kHz QPOs with
different indices: 1.5 for the Atoll source 4U 1728-34 and
1.9 for the Z source Sco X-1. The implications of our results for
the theoretical models for kHz QPOs are discussed.Comment: 6 pages, accepted by MNRA
Ground States for Exponential Random Graphs
We propose a perturbative method to estimate the normalization constant in
exponential random graph models as the weighting parameters approach infinity.
As an application, we give evidence of discontinuity in natural parametrization
along the critical directions of the edge-triangle model.Comment: 12 pages, 3 figures, 1 tabl
NMR Investigation of the Low Temperature Dynamics of solid 4He doped with 3He impurities
The lattice dynamics of solid 4He has been explored using pulsed NMR methods
to study the motion of 3He impurities in the temperature range where
experiments have revealed anomalies attributed to superflow or unexpected
viscoelastic properties of the solid 4He lattice. We report the results of
measurements of the nuclear spin-lattice and spin-spin relaxation times that
measure the fluctuation spectrum at high and low frequencies, respectively, of
the 3He motion that results from quantum tunneling in the 4He matrix. The
measurements were made for 3He concentrations 16<x_3<2000 ppm. For 3He
concentrations x_3 = 16 ppm and 24 ppm, large changes are observed for both the
spin-lattice relaxation time T_1 and the spin-spin relaxation time T_2 at
temperatures close to those for which the anomalies are observed in
measurements of torsional oscillator responses and the shear modulus. These
changes in the NMR relaxation rates were not observed for higher 3He
concentrations.Comment: 23 pages, 10 figure
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