Takamitsu Oka

Parity Nonconserving Nuclear Interactions and Weak Neutral Currents

This is a review article on recent developments, of researches on the parity nonconserving nuclear interactions in connection with the weak neutral currents. Properties of the weak neutral currents clarified by high energy neutrino reactions are presented. Problems of the parity violating nueleon-meson vertices and of the parity nonconserving nuclear potentials are discussed. Dependences on inner parts of strong interaction potentials are argued. Parity nonconserving quantities are explicitly given in terms of the parjty nonconserving weak interactions and discussed in details.

Determination of the Electronic Neutral-Current Couplings from e-d and e-p Scattering in Connection with the Effects of Sea Components

We make analyses of the parity-violating asymmetries of electron-deuteron and electronxad proton deep inelastic scatterings including sea quark contribution am! adopting three different kinds of parton distribution functions. Both results from electron-deuteron and from electronxad proton scatterings coincide with the prediction of the Weinberg-Salam model. Our results are found to be insensitive to the difference among the three kinds of parton distribution functions. Ve also study the x-, y- and sin21lw-dependences of AIQ in the Weinbcrg-Salam model. Experiments at higher y values will be useful for more precise determination of the Weinberg angle llw. § I. Introduction For these years enormous progress has been made in the determination of the weak neutral-current couplings of quarks and of leptons. In addition to the exxad periments on neutrino-induced neutral-current reactions, measurements of the parity violating asymmetries A./Q in the inelastic scattering of longitudinally polarized electrons from deuterium targetll allow a more discriminating study of neutralxad current couplings. So far many analyses of neutral-current data have been prexad sented, and are divided into two classes. One is to test the validity of the models of unified gauge theories of weak and electromagnetic interactions. The other is to determine, in a phenomenological and model-independent way, the space-time and isospin structures of the hadronic neutral-currents and the space-time structure of the leptonic ones. Model-independent analyses of neutrino-nucleon reactions have been made by Abbott-Barnett,) Hung-Sakurai, 3l Langacker-Sidhu,J Claudsonxad Paschos-Sulak5) and others. They made a unique or almost unique determination of the weak neutral-current couplings of u and d quarks. Furthermore, Konuma and the present author 6J and Abbott-Barnettn have determined the couplings of the electronic weak neutral-current, using the above mentioned solutions of u and d quarks, experimental value of 1/ Q in electron-deuteron (c-d) scattering and elasxad tic neutrino-electron data. Our result has indicated that there exists a umque solution of the electronic weak coupling constants which is consistent with the

Generalization of the Weak Charged V-A Current

In view of possible existence of the nucleonic sccond·class current, the weak charged urbaryonic and leptonic V-A currents are generalized so as to contain derivative currents by assuming two-component neutrino theory and baryon-lepton correspondence. Values of parameters associated with the derivative currents of lepton are determined from p-, i:- ·and K-decays. The generalized currents can explain ~ parameter of the p-decay. §I. Introduction Recently some experiments have been performed to study the possible existence of second-class currents. Measurements 11 of decay asymmetries in polarized nuclei showed that the coupling constants associated with the second-class current 1 seem to be larger than the corresponding theoretical values expected from the SU (2) symmetry breaking. On the other hand, the latest experimental results in aligned nuclei are consistent with absence of the second-class current. 1 Although the experimental situation about the second-class current is in an unsettled state, it will be interesting to examine some consequences front the assumption of the existence of the second-class currents both in urbaryonic and leptonic levels. We generalize the weak charged V-A currents so as to involve derivative terms such as tensor (6 a,l (f§ +a) S), pseudo-tensor (u aS75 (fJ + 8) S), scalar (i (fJ +a) a) and pseudo-scalar (ir5 cf§ +a) a) as well as vector Cr a) and axial-vector Cr ar5) terms. We assume the following which gives further limitations on the form of the currents: i) The current is hermitian as well as T-in variant. ii) Neutrinos (v~, Ve) are massless with two components and the neutrinos and anti-neutrinos are leftxad handed and right-handed, respectively. iii) Baryon-lepton (B-L) correspondence 41~61 is adopted. These assumptions imply that a P-type urbaryon appears as left-handed in the urbaryon current and that the coupling constant of the tensor term becomes equal to that of the pseudo-tensor one. Ve show that the leptonic current involving derivative terms well reproduces the experimental value of e) parameter in the ,11-decay, while the com-entional V-A current theory with two-component neutrinos 81 shows some departure from experimental results. This conventional V-A current well reproduces experimental results except for the c; parameter. The theoretical value is c;v-A = 1, whereas the experimental value is slightly smaller; c;exp = 0.972 ± 0.013. 71 In a weak-intermedi