International Journal of Modern Physics A

We review the subject of the energy levels of light and heavy quark-antiquark bound states in potential models, with emphasis on potentials which are motivated from quantum chromodynamics. In addition to pointing out the successes of potential models, we discuss problems with the potential approach, including uncertainties in the form of the potential, its spin dependence, its transformation properties, and its nondiagonal terms. We consider two-body wave equations with both nonrelativistic and relativistic kinematics, pointing out that in the latter case, a wide variety of different wave equations have been used in the literature.

BEPC, which is the first high energy particle accelerator to be built in the People’s Republic of China, is being constructed in Beijing. It consists of four main subsystems: a 1.4 GeV electron-positron linac, a 2.2–2.8 GeV storage ring, a magnetic spectrometer for high energy physics experiments, and synchrotron radiation facilities. All its components are described here in detail, and the current status of the construction is reported.

A unified physical picture for multiparticle emission in hadron-hadron and e⁺e⁻ collisions is presented. It is based on the wide range of values of the total angular momentum in hadron-hadron collisions. Experimental support is reviewed. An extension of the considerations to give a theory of the momentum distribution of the outgoing particles is compared with experiments.

It is shown that quantization of gravitation consistent with the presence of Weyl fermions is possible, in spite of the existence of Lorentz anomalies: the group of local Lorentz transformations is quantized becoming a physical field and the anomaly is absorbed.

Geometrical aspects of several classes of σ models are studied. The geometrical meaning of perturbative quantum field theory is discussed in the content of nonlinear σ models. Results on the one-loop effective action are recovered and generalized.

The supermoduli space and the measure on this space arising from fermionic string theory are studied. Analytic properties of this measure are analyzed. Our considerations, combined with previous results by Voronov, give an expression of string measure through analytic superfields and their zeros. The behavior of measure in the vicinity of the boundary of moduli space is studied on the base of this expression.

We show how a meson effective action, in which all of the meson parameters are finite, arises from a “global color symmetry” model involving a nonlocal current-current (four-quark) interaction. As an application of this general approach we present a covariant analysis of the ρ-π system and thus obtain estimates for the ρ meson mass and the coupling constant g_ρππ.

Baryogenesis in the inflationary universe is investigated, assuming that the universe is reheated instantaneously. Boltzmann equations are numerically integrated to trace time evolution of asymmetries in quarks and leptons in the Friedmann stage after the reheating, starting from the thermal equilibrium state. It is shown that the sign of the final baryon asymmetry may change depending on the reheating temperature as a result of interplay of superheavy gauge and Higgs bosons, and its mechanism is clarified. Furthermore we suggest a mechanism of generating isocurvature fluctuations which could be the origin of the large scale structure of the universe. It is also found in the instantaneous reheating model that the reheating temperature T_i must satisfy T_i>M_H/10 (M_H: Higgs boson mass) for the observed baryon/entropy ratio to be explained.

We have investigated the form factors of the π and K mesons within the framework of the statistical model. Our results reveal several well-spaced minima and maxima for different values of Q², the square of the momentum transfer. The characteristic features of the elastic differential cross section, dσ/dt, for π^±P and K^±P scattering data are well reproduced, as a consequence.

We explore general properties of matter coupled supergravities with antisymmetric tensor fields embedded in linear multiplets. The four-dimensional supersymmetric version of the Green-Schwarz mechanism leads to the introduction of super Chern-Simons form multiplets whose general component expressions are derived. The use of superconformal techniques allows us to discuss several topics relevant to superstring effective actions and in particular to give simple forms for the string-loop corrections to the Kahler potential and the U(1) anomaly cancelling term present in certain superstring compactifications.

By considering 14 different pion and proton form-factor combinations it is shown that the Chou-Yang model is not successful in describing πp elastic data at 200 GeV/c. It is further shown that a modified version in which the proton matter distribution is different from its electromagnetic form factors is able to describe the data well. Aspects of amplitude structure are also discussed.

We study the one-loop radiative correction to the mass operator of an S-wave fermion in the background monopole field and investigate whether it produces an efficient repulsive barrier outside the monopole core. It is shown that the ultraviolet divergency of this mass operator is eliminated by the usual renormalization of the fermion mass and electromagnetic charge in QED. The main result is that the radiative correction due to the interactions of the S-wave fermions with fluctuations of fields gives rise to finite and small, i.e. proportional to α≡e²/4π amplitude of the reflection of the incoming S-wave and therefore does not lead to any qualitative alterations of the standard mechanism of the monopole catalysis of proton decay.