515 research outputs found
Spin-3/2 pentaquark in the QCD sum rule
We study and pentaquark states with in
the QCD sum rule approach. The QCD sum rule for positive parity states and that
for negative parity are independently derived. The sum rule suggests that there
exist the and the states. These states may be observed as
extremely narrow peaks since they can be much below the -wave threshold and
since the only allowed decay channels are in -wave, whose centrifugal
barriers are so large that the widths are strongly suppressed. The
state may be assigned to the observed and the state
can be a candidate for .Comment: 27 pages, 14 figure
Increase Rate of fCO2 in the Eastern Equatorial Pacific Ocean
In the Eastern Equatorial Pacific Ocean, increase rates of fCO2 in the air and the ocean were evaluated using the CDIAC data set. The fCO2 in the air was increasing about 1.28μatm/year during 1957-1995. This result is almost same as the rate at the Mauna Loa, Hawaii in Tropical Pacific Ocean. The increase rate of fCO2 in the seawater was estimated as 1.64μatm/year. In this study it is found that the increase rate of fCO2 in the seawater is the almost same as that of fCO2 in the air. This reault supports the result on the snapshot analysis of Takahashi et al. (1983) in thr North Atlantic Ocean during 1958-1982. It is smaller than the result including seasonal variation in the Eastern Subtropical Pacific Ocean. These reault indicated that the anthropogenic CO2 in the air has affected fCO2 in seawater through CO2 gas exchange between the atmosphere and the ocean. It is found that fCO2 in the seawater has increased in the Eastern Equatiorial Pacific Ocean in spite of the large CO2 source region. It suggested that CO2 source potential has not changed in this ocean durung 1957-1995
THE FUNCTIONAL MORPHOLOGICAL STUDIES ON THE FUNDIC GLANDS II. THE OUANTITATIVE DISTRIBUTION OF THE THREE MAIN CELL TYPES
Model-independent study of the QCD sum rule for the pi NN coupling constant
We reinvestigate the QCD sum rule for the pi NN coupling constant, g,
starting from the vacuum-to-pion matrix element of the correlation function of
the interpolating fields of two nucleons. We study in detail the physical
content of the correlation function without referring to the effective theory.
We consider the invariant correlation functions by splitting the correlation
function into different Dirac structures. We show that the coefficients of the
double-pole terms are proportional to g but that the coefficients of the
single-pole terms are not determined by g. In the chiral limit the single-pole
terms as well as the continuum terms are ill defined in the dispersion
integral. Therefore, the use of naive QCD sum rules obtained from the invariant
correlation functions is not justified. A possible procedure to avoid this
difficulty is discussed.Comment: 20 pages, 2 figure
Tyrosine kinase, phosphatidylinositol 3-kinase, and protein kinase C regulate insulin-stimulated NaCl absorption in the thick ascending limb
Tyrosine kinase, phosphatidylinositol 3-kinase, and protein kinase C regulate insulin-stimulated NaCl absorption in the thick ascending limb. We have previously shown a direct stimulatory effect of insulin on NaCl absorption in the medullary thick ascending limb of Henle's loop (mTAL). To further investigate the signal transduction involved, we determined whether tyrosine kinase, phosphatidylinositol 3-kinase (PI3-kinase), and/or protein kinase C (PKC) regulate insulin-stimulated NaCl absorption in the mTAL by in vitro microperfusion methods. In control experiments, insulin increased transepithelial voltage (Vte) and net lumen-to-bath Cl− flux (JCl). Genistein and methyl 2,5-dihydroxycinnamate, two specific tyrosine kinase inhibitors, abolished the effects of insulin. Wort-mannin, a specific PI3-kinase inhibitor, inhibited the action of insulin. The effects of insulin also were inhibited by staurosporin and calphostin C, which are dissimilar inhibitors of PKC. These results indicate that insulin stimulates NaCl absorption in the mTAL through tyrosine kinase, PI3-kinase, and PKC-mediated mechanisms. Moreover, because we have reported previously that insulin causes no detectable change in cytosolic free Ca2+ in the mTAL cells, the present results also suggest that insulin-induced PKC activation is not related to inositol 1,4,5-triphosphate (IP3) production
Coupled QCD sum rules for positive and negative-parity nucleons
A new approach of the QCD sum rule is proposed in which positive and
negative-parity baryons couple with each other. With positive and
negative-parity states explicitly taken into account, sum rules are derived by
means of the dispersion relation in energy. The method is applied to the
nucleon channel and the parity splitting of the nucleon resonance states is
studied. It is found that the obtained sum rules have a very good Borel
stability. This suggests that the ansatz for the spectral function in the
present sum rule approximates the physical spectrum better than the usual
lowest pole plus continuum ansatz. The predicted masses of the positive and
negative nucleons reproduce the experimental ones fairly well. Especially, the
mass difference is extremely close to the experimental value.Comment: 14pages, 2figure
Theta++ from QCD sum rule
We study the pentaquark with and I=1 () in
the QCD sum rule approach. We derive the QCD sum rules for positive and
negative parity states of the pentaquark. The QCD sum rule predicts that there
exists with negative parity and its mass is GeV. The
negative parity can be extremely narrow, since it lies much below
the threshold and the decay into state is strongly suppressed
due to the -wave centrifugal barrier. Also, the possibility of the existence
of the with positive parity is not excluded. Although it nearly
degenerates with the negative parity state, it may be broader than the negative
parity state.Comment: 5 pages, 4 figure
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