Modern Physics Letters A

We provide a brief review of the current situation concerning gamma ray bursts, with emphasis on the role that particle physics may play in the interesting phenomena. The current understanding of GRB origins allows for a large range of physical processes from primordial black hole evaporation to neutron star and black hole collisions. There does not seem to be a simple standard luminosity function and the burst times range from ms to 1000 s of seconds five orders of magnitude. It is likely that some type of fireball model is needed to explain the GRBs. No counterparts of GRB have been detected. We indicate some ways in which progress can be made in either the study of the fine time structure (~μs) or the detection of very high energy photons (>100 GeV to >100 TeV). We also indicate how a small but unique class of the GRB could come from primordial black hole evaporation.

The differential cross-sections for elastic scattering of deuterons on ¹²C and ¹⁶O nuclei at 700 MeV are calculated on the basis of multiple diffraction scattering theory and the α-cluster model with dispersion. For d−¹²C scattering it was shown that the results of the calculations by the model, when the effects related with the deuteron structure included via deuteron-α amplitude are in better agreement with the experimental data than those by the model, in which incident deuteron is considered as composed of neutron and proton.

We study the inflation due to the D-flat direction of an extra U(1). This scenario is a hybrid of a right-handed sneutrino inflaton scenario and a gauge nonsinglet inflaton scenario. The inflaton is a gauge nonsinglet field which induces a right-handed neutrino mass spontaneously through an extra U(1) D-flat direction. This right-handed neutrino mass can be used to explain the solar neutrino problem. The reheating temperature resulting from the decay of the coherent oscillation of the right-handed sneutrino is sufficiently high so that the baryogenesis based on the lepton number asymmetry can be applicable. We also discuss the realistic model building.

The Zamolodchikov and Fateev transformation used in the elaboration of Z_N×Z_N parafermionic models is re-examined. It is shown that this transformation is in fact a projection of general Z_2N×Z_N models down to the standard Z_N×Z_N ones.

There is an open question as to whether or not the recently-proposed tanh method can be modified in order to proceed beyond the traveling or solitary wave solutions for nonlinear evolution equations. On the other hand, the class of the breaking soliton equations, which the self-dual Yang-Mills equation is found to belong to, is of current interest. In this letter, we propose a generalized tanh method, with symbolic computation, to construct a family of soliton-like solutions for a (2+1)-dimensional breaking soliton equation.

The Higgs boson mass problem is considered in the next-to-minimal supersymmetric standard model. The Higgs potential and the renormalization group equations for the gauge, Yukawa and scalar coupling constants are analyzed. The restrictions on the Higgs boson masses are found for the cases of presence and absence of spontaneous CP-violation.

A lattice regularized Lax operator for the non-ultralocal modified Korteweg de Vries (mKdV) equation is proposed at the quantum level with the basic operators satisfying a q-deformed braided algebra. From the associated quantum R and Z-matrices the exact integrability of the model is proved through the braided quantum Yang-Baxter equation which is a suitably generalized equation for the non-ultralocal models. Using the algebraic Bethe ansatz the eigenvalue problem of the quantum mKdV model is exactly solved and its connection with the spin-1/2 XXZ chain is established, facilitating the investigation of the corresponding conformal properties.

An extended free fermionic construction of the internal N=1 worldsheet supercurrent for four-dimensional superstring theory is given. We show how it can describe theories with massless fermions, and we discuss the corresponding N=2 superconformal algebra. As an intermediate step, we show that an internal N=2 global superconformal invariance occurs in any superstring theory with massless fermions at tree level. To demonstrate this fact, we give the N=2 supercurrents for a model with N=1 spacetime supersymmetry and a model without spacetime supersymmetry.