37,624 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
The electromagnetic decays of the charmed and bottom baryons in chiral perturbation theory
We have investigated the electromagnetic decays of the antitriplet and sextet
charmed baryon systems with in the
framework of the heavy baryon chiral perturbation theory. We first construct
the chiral Lagrangians at and . Then we calculate the
electromagnetic (EM) decay amplitudes of the charmed baryon systems up to
. With the help of the quark model, we estimate the low energy
constants. The numerical results of the EM decay widths show good convergence
of the chiral expansion. We notice that the two neutral EM decay processes
and
are strongly suppressed by the SU(3) U-spin flavor symmetry. With the same
formalism, we also estimate the EM decay widths of the bottomed baryons. The EM
decay widths of the heavy baryons may be measured at facilities such as LHCb
and JPARC. The explicit chiral structures of the heavy baryon decay amplitudes
derived in this work may be useful to the possible chiral extrapolations of the
future lattice simulations of these EM decay amplitudes
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
The hidden-charm pentaquark and tetraquark states
In the past decade many charmonium-like states were observed experimentally.
Especially those charged charmonium-like states and bottomonium-like
states can not be accommodated within the naive quark model. These
charged states are good candidates of either the hidden-charm tetraquark
states or molecules composed of a pair of charmed mesons. Recently, the LHCb
Collaboration discovered two hidden-charm pentaquark states, which are also
beyond the quark model. In this work, we review the current experimental
progress and investigate various theoretical interpretations of these
candidates of the multiquark states. We list the puzzles and theoretical
challenges of these models when confronted with the experimental data. We also
discuss possible future measurements which may distinguish the theoretical
schemes on the underlying structures of the hidden-charm multiquark states.Comment: Review accepted by Physics Reports, 152 pages, 66 figures, and 29
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