52 research outputs found
Light Four-quark States and New Observations by BES
Four-quark states are discussed within the constituent quark model.
Incompleteness of existed studies of four-quark state with QCD sum rule is
analyzed. The masses of diquark cluster were determined by QCD sum rules, and
light four-quark states masses were obtained in terms of the diquark. The
four-quark state possibility of the newly observed near-threshold p\bar p
enhancement, X(1835), X(1812) and X(1576) by BES is discussed.Comment: 4pages, no figure, PTPTEX, talk at the Yukawa International Seminar
(YKIS2006), "New frontiers in QCD", Kyoto, Japa
The and mass of light-quark hybrid in QCD sum rules
We calculate masses of the light-quark hybrid mesons with the quantum number
and by using the QCD sum rules. Two kinds of the interpolated
currents with the same quantum number are employed. We find that the
approximately equal mass is predicted for the hybrid state from the
different current and the different mass is obtained for the hybrid
state from the different current. The prediction depends on the interaction
between the gluon and quarks in the low-lying hybrid mesons. The mixing effect
on the mass of the light-quark hybrid meson through Low-energy theorem has been
examined too, and it is found that this mixing shifts the mass of hybrid meson
and glueball a little.Comment: 11 pages, Latex, 5 ps figure
Diquark and light four-quark states
Four-quark states with different internal clusters are discussed within the
constituent quark model. It is pointed out that the diquark concept is not
meaningful in the construction of a tetraquark interpolating current in the QCD
sum rule approach, and hence existing sum-rule studies of four-quark states are
incomplete. An updated QCD sum-rule determination of the properties of diquark
clusters is then used as input for the constituent quark model to obtain the
masses of light tetraquark states ({\it i.e.\} a bound state of two
diquark clusters). The results support the identification of ,
and as the light tetraquark states, and seem to
be inconsistent with the tetraquark state interpretation of the new BES
observations of the near-threshold enhancements, X(1835) and X(1812),
with the possible exception that X(1576) may be an "exotic" first orbital
excitation of or .Comment: 7 pages, 4 eps figures, RevTex, two figures and some references
added, published version in PR
Construction, expression, and characterization of rSEA-EGF and in vitro evaluation of its antitumor activity against nasopharyngeal cancer
Distinct roles of NMB and GRP in itch transmission
A key question in our understanding of itch coding mechanisms is whether itch is relayed by dedicated molecular and neuronal pathways. Previous studies suggested that gastrin-releasing peptide (GRP) is an itch-specific neurotransmitter. Neuromedin B (NMB) is a mammalian member of the bombesin family of peptides closely related to GRP, but its role in itch is unclear. Here, we show that itch deficits in mice lacking NMB or GRP are non-redundant and Nmb/Grp double KO (DKO) mice displayed additive deficits. Furthermore, both Nmb/Grp and Nmbr/Grpr DKO mice responded normally to a wide array of noxious stimuli. Ablation of NMBR neurons partially attenuated peripherally induced itch without compromising nociceptive processing. Importantly, electrophysiological studies suggested that GRPR neurons receive glutamatergic input from NMBR neurons. Thus, we propose that NMB and GRP may transmit discrete itch information and NMBR neurons are an integral part of neural circuits for itch in the spinal cord
Four-quark state in QCD
The spectra of some 0++ four-quark states, which are composed of \bar qq
pairs, are calculated in QCD. The light four-quark states are calculated using
the traditional sum rules while four-quark states containing one heavy quark
are computed in HQET. For constructing the interpolating currents, different
couplings of the color and spin inside the \bar qq pair are taken into account.
It is found that the spin and color combination has little effect on the mass
of the four-quark states.Comment: 10 pages, 4 ps figures, Late
Exploration of sensory and spinal neurons expressing gastrin-releasing peptide in itch and pain related behaviors
- …