9,248 research outputs found
Triangular singularity and a possible resonance in the decay
We study the decay by considering a triangle
singularity mechanism. In this mechanism, the decays into the
, the decays into the (or
), and then the (or ) interact to produce the
in the final state. This mechanism produces a peak structure around
MeV. In addition, the possibility that there is a hidden-strange
pentaquark-like state is also considered by taking into account the final state
interactions of , , and . We conclude that it
is difficult to search for the hidden-strange analogue of the states in
this decay. However, we do expect nontrivial behavior in the invariant
mass distribution. The predictions can be tested by experiments such as BESIII,
LHCb and Belle-II.Comment: 7 pages, 3 figure
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
Two-Body Strong Decay of Z(3930) as the State
The new particle Z(3930) found by the Belle and BaBar Collaborations through
the process is identified to be the
state. Since the mass of this particle is above the threshold, the OZI-allowed two-body strong decays are the main
decay modes. In this paper, these strong decay modes are studied with two
methods. One is the instantaneous Bethe-Salpeter method within Mandelstam
formalism. The other is the combination of the model and the former
formalism. The total decay widths are 26.3 and 27.3 MeV for the methods with or
without the vertex, respectively. The ratio of over
which changes along with the mass of the initial meson
is also presented.Comment: 11 pages, 3 figure
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