K. Kubodera

Study of meson properties and quark condensates in the Nambu-Jona-Lasinio model with instanton effects

Abstract We study the properties of scalar, pseudoscalar, vector and axial-vector mesons and the quark condensates using an extended three-flavor Nambu-Jona-Lasinio model that includes instantoninduced interactions. The t Hooft six-quark determinantal interaction and its correction due to instanton-density effects are taken into account. The results are in reasonable agreement with the experimental data and with the consequences of the QCD sum rule. The instanton-induced interactions give rise to flavor mixing, and, within the assumed validity of the extended Nambu-Jona-Lasinio model, we can make predictions on the mixing angles of pseudoscalar and vector mesons. The predicted mixing angles are −13.6° for the ηη′ mixing and 37.4° for the ωφ mixing, which are consistent with the experimental values.

Weak interaction form factors and magnetic moments of octet baryons: Chiral bag model with gluonic effects

Abstract The weak interaction form factors and the magnetic moments of the octet baryons are calculated in the volume-type cloudy bag model including clouds of all the octet mesons. In addition, one-gluon exchange effects are also evaluated. The theoretical predictions including both the mesonic and gluonic effects are compared, wherever possible, with experimental data.

13C as a solar neutrino detector

Abstract We argue a variety of advantages using 13 C as a target for solar neutrino detection in scintillation counters. This makes the detector drastically more sensitive to charged-current solar neutrino reactions and enables the determination of neutrino energy, and, more importantly, it makes a very efficient detector for neutral-current induced reactions. We also point out that even 13 C with a natural abundance may allow neutral-current detection in a massive CH 2 -scintillator.

semi-leptonic beta-decay form factors and magnetic moments of octet baryons: Recoil effects and center-of-mass corrections in the cloudy bag model including gluonic effects

Abstract In a previous article we made a detailed study of the weak interaction form factors and the magnetic moments of the octet baryons. The volume-type cloudy bag model was used as a possible framework for incorporating mesonic contributions in a systematic manner, and, furthermore, gluonic effects were included through evaluating one-gluon exchange diagrams. Despite the rather detailed treatment of these dynamical effects, the previous work was based on the static bag picture and fell short of including such kinematical effects as: (i) recoil corrections and (ii) center-of-mass corrections. One of the purposes of the present work is to investigate these kinematical effects and examine their influences on the results of the previous calculations based on the static bag picture. A second purpose of the present paper is to provide an extensive comparison of the calculated results with the existing experimental data. Regarding the weak interaction form factors of the hyperon beta-decays, it is customary to compare the theoretical values with the “semi-empirical” values obtained through Cabibbo-type fitting to the data, rather than directly dealing with the experimental observables. We make here a direct comparison of the theoretical prediction for various observables with the measured values. In particular, an attempt is made to determine the best-fit values of the Kobayashi-Maskawa matrix elements V ud and V us .

The 0+-0− transitions in the A=16 system and meson-exchange currents

Abstract In connection with the exchange-current in the time component of the axial current, we make a further study of the 0+-0− transitions in the A=16 system, examining the existing calculations

Weak Current Form-factors of Octet Baryons in the Volume Type Cloudy Bag Model

Abstract A systematic calculation is made of the weak-current form factors of the octet baryons; all form factors for every possible beta-decay between the octet baryons are evaluated. We use the volume-type cloudy bag model which includes the clouds of all the octet mesons.

Chiral-bag model study of weak-interaction form factors and magnetic moments of octet baryons

Abstract The weak-current form factors and the magnetic moments of the octet baryons are calculated using the volume-type cloudy bag model that includes the clouds of all the octet mesons. The effects of one-gluon exchange are also examined.

Exchange currents in the neutrino-deuteron reactions and the solar neutrino problem

In spite of intensive studies on the solar neutrino flux over fifteen years, there still exists a significant discrepancy between the observed capture rate and the expected value from the standard solar model. Recently, there is augmenting interest in the direct observation of the solar neutrinos with large water Cerenkov counters, such as developed at KAMIOKANDE[1–4]. The interest is enhanced even more by the project[5] to construct a KAMIOKANDE-type detector which uses D2O instead of H2O. These combined experimental data are expected to provide us a more fruitful information on the properties of the solar neutrinos. Motivated by this situation, we have made a detailed evaluation of the cross section for the following two reactions[2] n n

Study of Meson Flavor Mixing in the Nambu-Jona-Lasinio Model Including Instanton Effects

{nu_e} + d to {e^{ - }} + p + p