Predicative Ability of QCD Sum Rules for Decuplet Baryons

QCD sum rules for decuplet baryon two-point functions are investigated using a comprehensive Monte-Carlo based procedure. In this procedure, all uncertainties in the QCD input parameters are incorporated simultaneously, resulting in realistic estimates of the uncertainties in the extracted phenomenological parameters. Correlations between the QCD input parameters and the phenomenological parameters are studied by way of scatter plots. The predicted couplings are useful in evaluating matrix elements of decuplet baryons in the QCD sum rule approach. They are also used to check a cubic scaling law between baryon couplings and masses, as recently found by Dey and coworkers. The results show a significant reduction in the scaling constant and some possible deviations from the cubic law.Comment: 13 pages, RevTeX, 5 PS figures embedded with psfig.st

Three-loop non-diagonal current correlators in QCD and NLO corrections to single-top-quark production

The non-diagonal correlators of vector and scalar currents are considered at three-loop order in QCD. The full mass dependence is computed in the case where one of the quarks is massless and the other one carries the mass $M$. As applications we consider the single-top-quark production via the process $q\bar{q}\to t\bar{b}$ and the decay rate of a charged Higgs into hadrons. In both cases the computed NLO corrections are shown to be numerically much less important than the leading ones.Comment: 13 page

Positive and negative-parity flavor-octet baryons in coupled QCD sum rules

We apply the method of the QCD sum rule, in which positive- and negative-parity baryons couple with each other, to the flavor-octet hyperons and investigate the parity splittings. We also reexamine the nucleon in the method, which was studied in our previous paper, by carefully choosing the Borel weight. Both in the nucleon and hyperon channels the obtained sum rules turn out to have a very good Borel stability and also have a Borel window, an energy region in which the OPE converges and the pole contribution dominates over the continuum contribution. The predicted masses of the positive- and negative-parity baryons reproduce the experimental ones fairly well in the $\Lambda$ and $\Sigma$ channels, if we assign the $\Lambda(1670)$ and the $\Sigma(1620)$ to the parity partners of the $\Lambda$ and the $\Sigma$, respectively. This implies that the $\Lambda(1405)$ is not the party partner of the $\Lambda$ and may be a flavor-singlet or exotic state. In the $\Xi$ channel, the sum rule predicts the mass of the negative-parity state to be about 1.8 GeV, which leads to two possibilities; one is that the observed state with the closest mass, $\Xi(1690)$, is the parity partner and the other is that the parity partner is not yet found but exists around 1.8 GeV.Comment: 15 pages, 4 figure

Transport Activity of Rice Sucrose Transporters OsSUT1 and OsSUT5

Expression in Xenopus oocytes and electrophysiology was used to test for transport activity of the five sucrose transporter (SUT) homologs from rice. Expression of OsSUT1 and OsSUT5 resulted in sucrose-dependent currents that were analyzed by two-electrode voltage clamping. We examined the transport kinetics, substrate specificity and pH dependence of sucrose transport and K0.5 for sucrose. OsSUT1 showed similar features to those of other type II SUTs from monocots examined previously, with a K0.5 value of 7.50 mM at pH 5.6. In contrast, OsSUT5 had a higher substrate affinity (K0.5 = 2.32 mM at pH 5.6), less substrate specificity and less pH dependence compared with all type II SUTs tested to date. Regulation of the rice SUTs, as well as ZmSUT1 from maize and HvSUT1 from barley, by reduced (GSH) and oxidized (GSSG) forms of glutathione was tested. GSSG and GSH were found to have no significant effect on the activity of sucrose transporters when expressed in Xenopus oocytes. In conclusion, differences in transport activity between OsSUT1 and OsSUT5 indicate that type II SUTs have a range of transport activities that are tuned to their function in the plant

QCD determination of the axial-vector coupling of the nucleon at finite temperature

A thermal QCD Finite Energy Sum Rule (FESR) is used to obtain the temperature dependence of the axial-vector coupling of the nucleon, $g_{A}(T)$. We find that $g_{A}(T)$ is essentially independent of $T$, in the very wide range $0 \leq T \leq 0.9 T_{c}$, where $T_{c}$ is the critical temperature. While $g_{A}$ at T=0 is $q^{2}$-independent, it develops a $q^{2}$ dependence at finite temperature. We then obtain the mean square radius associated with $g_{A}$ and find that it diverges at $T=T_{c}$, thus signalling quark deconfinement. As a byproduct, we study the temperature dependence of the Goldberger-Treiman relation.Comment: 8 pages and 3 figure

More about on the short distance contribution to the "B_c -> B_u^* gamma" decay

We calculate the transition form factor for the 'B_c -> B_u^* gamma' decay taking into account only the short distance contribution, in framework of QCD sum rules method. We observe that the transition form factor predicted by the QCD sum rules method is approximately two times larger compared to the result predicted by the Isgur, Scora, Grinstein and Wise model.Comment: 12 pages, 2 figures, LaTeX formatte

Negative Parity Baryons in the QCD Sum Rule

Masses and couplings of the negative parity excited baryons are studied in the QCD sum rule. Separation of the negative-parity spectrum is proposed and is applied to the flavor octet and singlet baryons. We find that the quark condensate is responsible for the mass splitting of the ground and the negative-parity excited states. This is expected from the chiral symmetry and supports the idea that the negative-parity baryon forms a parity doublet with the ground state. The meson-baryon coupling constants are also computed for the excited states in the QCD sum rule. It is found that the \pi NN^* coupling vanishes in the chiral limit.Comment: 13pp, LaTeX, 1 EPS figure, uses epsf.sty, Talk given by M.O. at CEBAF/INT workshop "N* physics", Seattle, September (1996), to appear in the proceeding

In silico predictions of variant deleteriousness in the genomes of pig species

Predicting the deleteriousness of observed genomic variants has taken a step forward with the development of the Combined Annotation Dependent Depletion (CADD) [1] methodology, as it allows for comparable evaluations of variants on a genome-wide scale for coding and non-coding variants respectively. ..

Learning Analytics and Online Language learning

This chapter addresses the challenges and future potential of learning analytics. It examines some of the key questions raised by the research literature that will influence language education over the next decade, and investigates what kind of data can be used to inform effective decision-making in online language-learning contexts and how it can be visualized. The chapter turns to consider preliminary data arising from the needs analysis phase of the VITAL Project (Visualization Tools and Analytics to Monitor Online Language Learning and Teaching), a two-year EU-funded project that specifically addresses the gap in the research literature on analytics in language learning and teaching. Turning to the first large-scale project on learning analytics and online language learning, Link & Li's theoretical framework provides a useful starting point to consider the role of dashboards for language learners and instructors

Critical Behavior of J/psi across the Phase Transition from QCD sum rules

We study behavior of J/psi in hot gluonic matter using QCD sum rules. Taking into account temperature dependences of the gluon condensates extracted from lattice thermodynamics for the pure SU(3) system, we find that the mass and width of J/psi exhibit rapid change across the critical temperature.Comment: 5 pages, 3 figures. Poster contribution for Quark Matter 2008. To be published in the proceeding