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

The catalytic oxidation of organic contaminants in a packed bed reactor

The catalytic oxidation of several hydrocarbons was studied over noble metal and metal oxide catalysts. A fast empirical method was developed to determine the minimum operating temperature required to guarantee complete conversion of the hydrocarbon.\ud \ud The influence of the operating parameters such as the inlet concentration and residence time, as well as the chemical character of the component to be oxidized, have been investigated. The results can be described satisfactorily by a simple isothermal, plug flow reactor model and first-order reaction kinetics. In the case of simultaneous oxidation of different components a significant mixture effect was not observed. The presence of water in the feed did significantly inhibit the oxidation of alkanes.\ud \ud Of the applied catalysts, Pt was the most effective for the combustion of the alkenes, whereas Pd showed a higher activity for the oxidation of alkanes

Eta-nucleon coupling constant in QCD with SU(3) symmetry breaking

We study the $\eta$NN coupling constant using the method of QCD sum rules starting from the vacuum-to-eta correlation function of the interpolating fields of two nucleons. The matrix element of this correlation has been taken with respect to nucleon spinors to avoid unwanted pole contribution. The SU(3)-flavor symmetry breaking effects have been accounted for via the $\eta$-mass, s-quark mass and eta decay constant to leading order. Out of the four sum rules obtained by taking the ratios of the two sum rules in conjunction with the two sum rules in nucleon mass, three are found to give mutually consistent results. We find the SU(3) breaking effects significant, as large as 50% of the SU(3) symmetric part.Comment: 13 pages, 12 figure

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

Citizen science against the plastic soup: background, motivation and expectations of volunteers studying plastic pollution on Dutch riverbanks

In the field of investigating and addressing plastic pollution, the public is increasingly involved in research as citizen scientists. Long-term monitoring for this topic is needed, and recruiting and retaining volunteers is challenging. Therefore, it is important to learn more about the demographic background, motivations and expectations of involved citizen scientists, and if these change during participation. Our research studied these aspects of the citizen scientists in the Dutch Clean Rivers project, who monitor plastic pollution on riverbanks. Participants (n = 122) completed pre- and post-survey after one year of the project. While there was no gender bias, the participants were mostly middle-aged and highly educated, and almost half had previous experience with scientific research. Their motivation to participate was mostly activistic, as they wanted to tackle the source of plastic pollution and contribute to solutions. More personal motivations, such as wanting to learn more and because it is fun to do scientific research, decreased significantly after one year of participation. Their expectations were in line with the main motivations. Understanding the background, motivations and expectations of volunteers helps this project, and the field of citizen science in plastic pollution research

Management of hyperuricemia in gout: focus on febuxostat

Gout is the most common inflammatory arthritis in an elderly population, and can be diagnosed with absolute certainty by polarization microscopy. However, diagnosis may be challenging because atypical presentations are more common in the elderly. Management of hyperuricemia in the elderly with gout requires special consideration because of co-medication, contra-indications, and risk of adverse reactions. Urate-lowering agents include allopurinol and uricosuric agents. These also must be used sensibly in the elderly, especially when renal function impairment is present. However, if used at the lowest dose that maintains the serum urate level below 5.0 to 6.0 mg/dL (0.30 to 0.36 mmol/L), the excess urate in the body will eventually be eliminated, acute flares will no longer occur, and tophi will resolve. Febuxostat, a new xanthine oxidase inhibitor, is welcomed, as few alternatives for allopurinol are available. Its pharmacokinetics and pharmacodynamics are not significantly altered in patients with moderate renal function or hepatic impairment. Its antihyperuricemic efficacy at 80 to 120 mg/day is better than “standard dosage” allopurinol (300 mg/day). Long-term safety data and efficacy data on tophus diminishment and reduction of gout flares have recently become available. Febuxostat may provide an important option in patients unable to use allopurinol, or refractory to allopurinol

QCD sum rules for the pseudoscalar decay constants - To constrain the strange quark mass

We study the higher order corrections of quark masses to the Gell-Mann$-$Oakes$-$Renner (GOR) relation by constructing QCD sum rules exclusively for pseudoscalar mesons from the axial-vector correlation function, $i \int d^4x~ e^{ip\cdot x}$. To project out the pseudoscalar meson contributions, we apply $-p^\mu p^\nu/p^2$ to this correlation function and construct sum rules for the decay constants of pseudoscalar mesons, $f_\pi, f_k$ and $f_{\eta_8}$. The OPE is proportional to quark masses due to PCAC. To leading order in quark mass, each sum rule reproduces the corresponding GOR relation. For kaon and $\eta_8$, the deviation from the GOR relation due to higher orders in quark mass is found to be substantial. But the deviation gives better agreements with the phenomenology. Our sum rule provides a sensitive relation between $f_K$ and $m_s$, which stringently constrain the value for $m_s$. To reproduce the experimental value for $f_K$, $m_s$ is found to be 186 MeV at 1 GeV scale. The $f_{\eta_8}$ sum rule also supports this finding.Comment: 14 pages including 3 figures. slightly revised. Accepted for publication in Physical Review

Calculation of coupling constant g_phi-pi-gamma in QCD sum rules

The coupling constant of g_phi-pi-gamma decay is calculated in the method of QCD sum rules. A comparison of our prediction on the coupling constant with the result obtained from analysis of the experimental data is performed.Comment: 6 pages, 3 figure

The electromagnetic effects in isospin symmetry breakings of q{\bar q} systems

The isospin symmetry breakings of q{\bar q} are investigated in the QCD sum rule method. The electromagnetic effects are evaluated following the procedure requiring that the electromagnetic effects for charged meson be gauge invariant. We find that the electromagnetic effects are also dominant in the isospin violations of rho meson, which have been shown to be the case in the mass splittings of pions. The numerical results for the difference of pion decay constants and the masses of rho mesons are presented, which are consistent with the data.Comment: To appear in Phys. Rev. D (1997

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