2,530 research outputs found
Flavor distributions in the nucleons: SU(2) sea asymmetry or isospin symmetry breaking?
The Gottfried sum-rule violation reported by the New Muon Collaboration was interpreted as an indication for a flavor asymmetry of the sea quark in the nucleon. We investigate the alternative possibility that isospin symmetry between the proton and the neutron is breaking. We examine systematically the consequences of this possibility for several processes, namely, neutrino deep inelastic scattering, the charged pion Drell-Yan process, the proton Drell-Yan process, and semi-inclusive deep inelastic scattering, and conclude that a decision between the two alternative explanations is possible
Mott Insulator - Superfluid Transitions in a Two Band Model at Finite Temperature and Possible Application to Supersolid 4He
We study Mott insulator - superfluid transition in a two-band boson Hubbard
model, which can be mapped onto a spin-1/2 XY model with spins coupled to an
additional Ising degree of freedom. By using a modified mean field theory that
include the effects of phase fluctuations, we show that the transition is first
order at both zero and finite temperatures. On the Mott insulator side, there
may be reentrance in phase transition. These features are consequences of the
underlying transition between competing defect poor and defect rich phases. The
relevance of the model and our results to supersolid 4He and cold bosonic atoms
in optical lattices are discussed
Measuring entanglement entropy through the interference of quantum many-body twins
Entanglement is one of the most intriguing features of quantum mechanics. It
describes non-local correlations between quantum objects, and is at the heart
of quantum information sciences. Entanglement is rapidly gaining prominence in
diverse fields ranging from condensed matter to quantum gravity. Despite this
generality, measuring entanglement remains challenging. This is especially true
in systems of interacting delocalized particles, for which a direct
experimental measurement of spatial entanglement has been elusive. Here, we
measure entanglement in such a system of itinerant particles using quantum
interference of many-body twins. Leveraging our single-site resolved control of
ultra-cold bosonic atoms in optical lattices, we prepare and interfere two
identical copies of a many-body state. This enables us to directly measure
quantum purity, Renyi entanglement entropy, and mutual information. These
experiments pave the way for using entanglement to characterize quantum phases
and dynamics of strongly-correlated many-body systems.Comment: 14 pages, 12 figures (6 in the main text, 6 in supplementary
material
Probing the Superfluid to Mott Insulator Transition at the Single Atom Level
Quantum gases in optical lattices offer an opportunity to experimentally
realize and explore condensed matter models in a clean, tunable system. We
investigate the Bose-Hubbard model on a microscopic level using single
atom-single lattice site imaging; our technique enables space- and
time-resolved characterization of the number statistics across the
superfluid-Mott insulator quantum phase transition. Site-resolved probing of
fluctuations provides us with a sensitive local thermometer, allows us to
identify microscopic heterostructures of low entropy Mott domains, and enables
us to measure local quantum dynamics, revealing surprisingly fast transition
timescales. Our results may serve as a benchmark for theoretical studies of
quantum dynamics, and may guide the engineering of low entropy phases in a
lattice
State-Relevant Maxwell's Equation from Kaluza-Klein Theory
We study a five-dimensional perfect fluid coupled with Kaluza-Klein (KK)
gravity. By dimensional reduction, a modified form of Maxwell's equation is
obtained, which is relevant to the equation of state of the source. Since the
relativistic magnetohydrodynamics (MHD) and the 3-dimensional formulation are
widely used to study space matter, we derive the modified Maxwell's equations
and relativistic MHD in 3+1 form. We then take an ideal Fermi gas as an example
to study the modified effect, which can be visible under high density or high
energy condition, while the traditional Maxwell's equation can be regarded as a
result in the low density and low temperature limit. We also indicate the
possibility to test the state-relevant effect of KK theory in a telluric
laboratory.Comment: 11 pages, 3 figures; version published in PR
Finite Volume Effect of Nucleons and the Formation of the Quark-Gluon Plasma
We study a thermodynamically consistent implementation of the nucleon volume
in the mean field theory, and find that this volume has large consequences on
the properties of hadronic matter under extreme conditions such as in
astrophysical objects and high energy heavy-ion collisions. It is shown that we
can reproduce the critical temperature MeV predicted by
lattice QCD calculations for the phase transition from hadronic matter to
quark-gluon plasma, by using parameters which are adjusted to fit all empirical
data for normal nuclear matter.Comment: 11 Latex pages, 4 figures upon reques
Fritzsch Texture in SUSY-SO(10) with Large Neutrino Mixing
Fritzsch's texture is imposed on {\em all} mass matrices in a SUSY-SO(10) via
a family symmetry. The observed charged fermion parameters fix the
-masses and mixing, while the later are evolved from the GUT scale to low
energies using the RG. Large results. As in a SUSY-GUT
no intermediate scale is allowed, the RH-neutrino scale is the unification one
and this gives in our model , in
accordance with the vacuum oscillation solution to the solar- puzzle.Comment: 10 pages (standard LaTeX, 3 figures included as postscript files), WU
B 93-1
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Photon-Assisted Tunneling in a Biased Strongly Correlated Bose Gas
We study the impact of coherently generated lattice photons on an atomic Mott insulator subjected to a uniform force. Analogous to an array of tunnel-coupled and biased quantum dots, we observe sharp, interaction-shifted photon-assisted tunneling resonances corresponding to tunneling one and two lattice sites either with or against the force and resolve multiorbital shifts of these resonances. By driving a Landau-Zener sweep across such a resonance, we realize a quantum phase transition between a paramagnet and an antiferromagnet and observe quench dynamics when the system is tuned to the critical point. Direct extensions will produce gauge fields and site-resolved spin flips, for topological physics and quantum computing.Physic
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