6,461 research outputs found
Holographic R\'enyi entropy in AdS/LCFT correspondence
The recent study in AdS/CFT correspondence shows that the tree level
contribution and 1-loop correction of holographic R\'enyi entanglement entropy
(HRE) exactly match the direct CFT computation in the large central charge
limit. This allows the R\'enyi entanglement entropy to be a new window to study
the AdS/CFT correspondence. In this paper we generalize the study of R\'enyi
entanglement entropy in pure AdS gravity to the massive gravity theories at
the critical points. For the cosmological topological massive gravity (CTMG),
the dual conformal field theory (CFT) could be a chiral conformal field theory
or a logarithmic conformal field theory (LCFT), depending on the asymptotic
boundary conditions imposed. In both cases, by studying the short interval
expansion of the R\'enyi entanglement entropy of two disjoint intervals with
small cross ratio , we find that the classical and 1-loop HRE are in exact
match with the CFT results, up to order . To this order, the difference
between the massless graviton and logarithmic mode can be seen clearly.
Moreover, for the cosmological new massive gravity (CNMG) at critical point,
which could be dual to a logarithmic CFT as well, we find the similar agreement
in the CNMG/LCFT correspondence. Furthermore we read the 2-loop correction of
graviton and logarithmic mode to HRE from CFT computation. It has distinct
feature from the one in pure AdS gravity.Comment: 28 pages. Typos corrected, published versio
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
Boundary-induced singularity in strongly-correlated quantum systems at finite temperature
Exploring the bulk-boundary correspondences and the boundary-induced
phenomena in the strongly-correlated quantum systems belongs to the most
fundamental topics of condensed matter physics. In this work, we show that the
entanglement-bath Hamiltonian (EBH) can induce exotic thermodynamic properties
in the bulk of a quantum spin chain from the boundaries, analogous to heat
bath. The EBH is defined as the local Hamiltonian located on the boundary of a
finite-size system, which approximately generates the bulk entanglement
Hamiltonian of the translational-invariant system in the thermodynamic limit
(i.e., the infinite boundary condition). The ``boundary quench point'' (BQP) is
identified by the discontinuity in the coefficients of the EBH and in the bulk
entropy versus the effective boundary temperature. The physical implication of
BQP is to distinguish the point, below which the thermal effects become
insignificant and the bulk properties are dominated by the ground state. It
singularity differs from those in the conventional thermodynamic phase
transition points that normally fall into the Landau-Ginzburg paradigm. The
relations between the symmetry of Hamiltonian and BQP, and the impacts from the
entanglement-bath dimension are also explored. Our work shows the opportunities
on exploring the exotic phenomena induced by the competition between the bulk
and boundaries.Comment: 10 pages, 8 figure
1,3-Bis(4-methoxybenzyl)-6-methylpyrimidine-2,4(1H,3H)-dione
The title compound, C21H22N2O4, was prepared by reaction of 6-methylpyrimidine-2,4(1H,3H)-dione and 1-chloromethyl-4-methoxybenzene. In the title molecule, the central pyrimidine ring forms dihedral angles of 62.16 (4) and 69.77 (3)° with the two benzene rings. In the crystal, weak intermolecular C—H⋯O hydrogen bonds link the molecules into chains
Robust Dancer: Long-term 3D Dance Synthesis Using Unpaired Data
How to automatically synthesize natural-looking dance movements based on a
piece of music is an incrementally popular yet challenging task. Most existing
data-driven approaches require hard-to-get paired training data and fail to
generate long sequences of motion due to error accumulation of autoregressive
structure. We present a novel 3D dance synthesis system that only needs
unpaired data for training and could generate realistic long-term motions at
the same time. For the unpaired data training, we explore the disentanglement
of beat and style, and propose a Transformer-based model free of reliance upon
paired data. For the synthesis of long-term motions, we devise a new
long-history attention strategy. It first queries the long-history embedding
through an attention computation and then explicitly fuses this embedding into
the generation pipeline via multimodal adaptation gate (MAG). Objective and
subjective evaluations show that our results are comparable to strong baseline
methods, despite not requiring paired training data, and are robust when
inferring long-term music. To our best knowledge, we are the first to achieve
unpaired data training - an ability that enables to alleviate data limitations
effectively. Our code is released on https://github.com/BFeng14/RobustDancerComment: Preliminary video demo: https://youtu.be/gJbxG9QlcU
Human herpesvirus 6A induces apoptosis of primary human fetal astrocytes via both caspase-dependent and -independent pathways
<p>Abstract</p> <p>Background</p> <p>Human herpesvirus 6 (HHV-6) is a T-lymphtropic and neurotropic virus that can infect various types of cells. Sequential studies reported that apoptosis of glia and neurons induced by HHV-6 might act a potential trigger for some central nervous system (CNS) diseases. HHV-6 is involved in the pathogenesis of encephalitis, multiple sclerosis (MS) and fatigue syndrome. However, the mechanisms responsible for the apoptosis of infected CNS cells induced by HHV-6 are poorly understood. In this study, we investigated the cell death processes of primary human fetal astrocytes (PHFAs) during productive HHV-6A infection and the underlying mechanisms.</p> <p>Results</p> <p>HHV-6A can cause productive infection in primary human fetal astrocytes. Annexin V-PI staining and electron microscopic analysis indicated that HHV-6A was an inducer of apoptosis. The cell death was associated with activation of caspase-3 and cleavage of poly (ADP-ribose) polymerase (PARP), which is known to be an important substrate for activated caspase-3. Caspase-8 and -9 were also significantly activated in HHV-6A-infected cells. Moreover, HHV-6A infection led to Bax up-regulation and Bcl-2 down-regulation. HHV-6A infection increased the release of Smac/Diablo, AIF and cytochrome c from mitochondria to cytosol, which induced apoptosis via the caspase-dependent and -independent pathways. In addition, we also found that anti-apoptotic factors such as IAPs and NF-κB decreased in HHV-6A infected PHFAs.</p> <p>Conclusion</p> <p>This is the first demonstration of caspase-dependent and -independent apoptosis in HHV-6A-infected glial cells. These findings would be helpful in understanding the mechanisms of CNS diseases caused by HHV-6.</p
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