28,261 research outputs found
Phase diagram of Kondo-Heisenberg model on honeycomb lattice with geometrical frustration
We calculated the phase diagram of the Kondo-Heisenberg model on
two-dimensional honeycomb lattice with both nearest-neighbor and
next-nearest-neighbor antiferromagnetic spin exchanges, to investigate the
interplay between RKKY and Kondo interactions at presence of magnetic
frustration. Within a mean-field decoupling technology in slave-fermion
representation, we derived the zero-temperature phase diagram as a function of
Kondo coupling and frustration strength . The geometrical frustration
can destroy the magnetic order, driving the original antiferromagnetic (AF)
phase to non-magnetic valence bond state (VBS). In addition, we found two
distinct VBS. As is increased, a phase transition from AF to Kondo
paramagnetic (KP) phase occurs, without the intermediate phase coexisting AF
order with Kondo screening found in square lattice systems. In the KP phase,
the enhancement of frustration weakens the Kondo screening effect, resulting in
a phase transition from KP to VBS. We also found a process to recover the AF
order from VBS by increasing in a wide range of frustration strength. Our
work may provide deeper understanding for the phase transitions in
heavy-fermion materials, particularly for those exhibiting triangular
frustration
New feature of low charm quark hadronization in collisions at TeV
Treating the light-flavor constituent quarks and antiquarks that can well
describe the data of light-flavor hadrons in collisions at
TeV as the underlying source of chromatically neutralizing the charm quarks of
low transverse momenta (), we show that the experimental data of
spectra of single-charm hadrons , ,
and at mid-rapidity in the low range
( GeV/) in collisions at TeV can
be well understood by the equal-velocity combination of perturbatively-created
charm quarks and those light-flavor constituent quarks and antiquarks. This
suggests a possible new scenario of low charm quark hadronization, in
contrast to the traditional fragmentation mechanism, in collisions at LHC
energies. This is also another support for the exhibition of the effective
constituent quark degrees of freedom for the small parton system created in
collisions at LHC energies.Comment: 7 pages, 5 figure
Subsystem eigenstate thermalization hypothesis for entanglement entropy in CFT
We investigate a weak version of subsystem eigenstate thermalization
hypothesis (ETH) for a two-dimensional large central charge conformal field
theory by comparing the local equivalence of high energy state and thermal
state of canonical ensemble. We evaluate the single-interval R\'enyi entropy
and entanglement entropy for a heavy primary state in short interval expansion.
We verify the results of R\'enyi entropy by two different replica methods. We
find nontrivial results at the eighth order of short interval expansion, which
include an infinite number of higher order terms in the large central charge
expansion. We then evaluate the relative entropy of the reduced density
matrices to measure the difference between the heavy primary state and thermal
state of canonical ensemble, and find that the aforementioned nontrivial eighth
order results make the relative entropy unsuppressed in the large central
charge limit. By using Pinsker's and Fannes-Audenaert inequalities, we can
exploit the results of relative entropy to yield the lower and upper bounds on
trace distance of the excited-state and thermal-state reduced density matrices.
Our results are consistent with subsystem weak ETH, which requires the above
trace distance is of power-law suppression by the large central charge.
However, we are unable to pin down the exponent of power-law suppression. As a
byproduct we also calculate the relative entropy to measure the difference
between the reduced density matrices of two different heavy primary states.Comment: 28 pages, 4 figures;v2 change author list;v3 related subtleties about
weak ETH clarified; v4 minor correction to match JHEP versio
Dissimilarities of reduced density matrices and eigenstate thermalization hypothesis
We calculate various quantities that characterize the dissimilarity of
reduced density matrices for a short interval of length in a
two-dimensional (2D) large central charge conformal field theory (CFT). These
quantities include the R\'enyi entropy, entanglement entropy, relative entropy,
Jensen-Shannon divergence, as well as the Schatten 2-norm and 4-norm. We adopt
the method of operator product expansion of twist operators, and calculate the
short interval expansion of these quantities up to order of for the
contributions from the vacuum conformal family. The formal forms of these
dissimilarity measures and the derived Fisher information metric from
contributions of general operators are also given. As an application of the
results, we use these dissimilarity measures to compare the excited and thermal
states, and examine the eigenstate thermalization hypothesis (ETH) by showing
how they behave in high temperature limit. This would help to understand how
ETH in 2D CFT can be defined more precisely. We discuss the possibility that
all the dissimilarity measures considered here vanish when comparing the
reduced density matrices of an excited state and a generalized Gibbs ensemble
thermal state. We also discuss ETH for a microcanonical ensemble thermal state
in a 2D large central charge CFT, and find that it is approximately satisfied
for a small subsystem and violated for a large subsystem.Comment: V1, 34 pages, 5 figures, see collection of complete results in the
attached Mathematica notebook; V2, 38 pages, 5 figures, published versio
Elliptic flow splitting as a probe of the QCD phase structure at finite baryon chemical potential
Using a partonic transport model based on the 3-flavor Nambu-Jona-Lasinio
model and a relativistic hadronic transport model to describe, respectively,
the evolution of the initial partonic and the final hadronic phase of heavy-ion
collisions at energies carried out in the Beam-Energy Scan program of the
Relativistic Heavy Ion Collider, we have studied the effects of both the
partonic and hadronic mean-field potentials on the elliptic flow of particles
relative to that of their antiparticles. We find that to reproduce the measured
relative elliptic flow differences between nucleons and antinucleons as well as
between kaons and antikaons requires a vector coupling constant as large as 0.5
to 1.1 times the scalar coupling constant in the Nambu-Jona-Lasinio model.
Implications of our results in understanding the QCD phase structure at finite
baryon chemical potential are discussed.Comment: 5 pages, 4 figures, discussions added, version accepted by Phys. Rev.
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