52,029 research outputs found
Exotic , and states
After constructing the possible and
tetraquark interpolating currents in a systematic way, we
investigate the two-point correlation functions and extract the corresponding
masses with the QCD sum rule approach. We study the ,
and systems with various isospins . Our numerical analysis indicates that the masses of doubly-bottomed
tetraquark states are below the threshold of the two bottom mesons, two bottom
baryons and one doubly bottomed baryon plus one anti-nucleon. Very probably
these doubly-bottomed tetraquark states are stable.Comment: 37 pages, 2 figure
Spin-1 charmonium-like states in QCD sum rule
We study the possible spin-1 charmonium-like states by using QCD sum rule
approach. We calculate the two-point correlation functions for all the local
form tetraquark interpolating currents with and
and extract the masses of the tetraquark charmonium-like states. The
mass of the state is GeV, which implies
a possible tetraquark interpretation for Y(4660) meson. The masses for both the
and states are GeV,
which is slightly above the mass of X(3872). For the and
states, the extracted masses are GeV and GeV respectively.Comment: 7 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:1010.339
Possible Charmonium-like State
We study the possible charmonium-like states with
using the tetraquark interpolating currents with the QCD sum rules approach.
The extracted masses are around 4.5 GeV for the charmonium-like states
and 4.6 GeV for the charmonium-like states while their
bottomonium-like analogues lie around 10.6 GeV. We also discuss the possible
decay, production and the experiment search of the charmonium-like
state.Comment: 12 pages, 10 figures, 3 table
Possible Exotic State
We study the possible exotic states with using the
tetraquark interpolating currents with the QCD sum rule approach. The extracted
masses are around 4.85 GeV for the charmonium-like states and 11.25 GeV for the
bottomomium-like states. There is no working region for the light tetraquark
currents, which implies the light state may not exist below 2 GeV.Comment: 13 pages, 11 figures, 2 table
Assessing Percolation Threshold Based on High-Order Non-Backtracking Matrices
Percolation threshold of a network is the critical value such that when nodes
or edges are randomly selected with probability below the value, the network is
fragmented but when the probability is above the value, a giant component
connecting large portion of the network would emerge. Assessing the percolation
threshold of networks has wide applications in network reliability, information
spread, epidemic control, etc. The theoretical approach so far to assess the
percolation threshold is mainly based on spectral radius of adjacency matrix or
non-backtracking matrix, which is limited to dense graphs or locally treelike
graphs, and is less effective for sparse networks with non-negligible amount of
triangles and loops. In this paper, we study high-order non-backtracking
matrices and their application to assessing percolation threshold. We first
define high-order non-backtracking matrices and study the properties of their
spectral radii. Then we focus on 2nd-order non-backtracking matrix and
demonstrate analytically that the reciprocal of its spectral radius gives a
tighter lower bound than those of adjacency and standard non-backtracking
matrices. We further build a smaller size matrix with the same largest
eigenvalue as the 2nd-order non-backtracking matrix to improve computation
efficiency. Finally, we use both synthetic networks and 42 real networks to
illustrate that the use of 2nd-order non-backtracking matrix does give better
lower bound for assessing percolation threshold than adjacency and standard
non-backtracking matrices.Comment: to appear in proceedings of the 26th International World Wide Web
Conference(WWW2017
A Numerical Analysis to the {} and {K} Coupled--Channel Scalar Form-factor
A numerical analysis to the scalar form-factor in the and KK
coupled--channel system is made by solving the coupled-channel dispersive
integral equations, using the iteration method. The solutions are found not
unique. Physical application to the central production in the process is discussed based upon the numerical solutions we found.Comment: 8 pages, Latex, 3 figures. Minor changes and one reference adde
- …