Modern Physics Letters A

Consideration of particle creation on a topologically nontrivial instanton leads to the possibility of a “topological Hawking effect”, whereby virtual pairs are converted to real particles because of a “change in topology”. This effect, calculable in a coherent state representation, is illustrated here for a manifold with two boundaries and one handle. It is also argued that this effect could provide a natural explanation of the Hot Big Bang scenario whereby the Universe “tunnels into being”.

This paper reports a study on the coherent production of pions in central ²⁴Mg-AgBr collisions at 4.5 GeV/c per nucleon. The analysis is based on a comparison of experimental multiplicity distribution in different pseudo rapidity bins with Poissonic distributions. It has been observed that pion multiplicity is Poissonian in some specific zone. The physical implication is also discussed.

Experimental data obtained recently have confirmed the predicted possibility for the appearance of a minimum in the behavior of the e⁺e⁻-annihilation into six pions near the threshold. From the theoretical analysis of the observed irregularity in the framework of a coupled channels model, the existence of a narrow vector state corresponding to 2³³S₁-state in the system with a mass of about 1800 MeV and a width of 15 MeV follows.

We determine a parasupersymmetric annihilation operator for the (l-dimensional) harmonic oscillator and construct its eigenstates leading to a basis of parasupersymmetric coherent states with expected degeneracies according to the work of Rubakov and Spiridonov.

The degenerate minima in a recently proposed N=1 supersymmetric SO(10) GUT model are investigated. It is found that the natural missing-partner mechanism and a flipped SU(5)×U(1) phase cannot be simultaneously implemented in the SO(10) model. The splitting of supersymmetry degeneracy is analyzed. It is shown that the SU(3)_C × SU(2)_L × SU(2)_R × U(1) _B−L × D symmetry is favored as an intermediate phase in a restricted region of parameter space.

We treat the open p-adic string world sheet as a coset space F=T/Γ, where T is the Bruhat-Tits tree for the p-adic linear group GL(2, ℚ_p) and Γ⊂PGL(2, ℚ_p) is some Schottky group. The boundary of this world sheet corresponds to p-adic Mumford curve of finite genus. The string dynamics is governed by the local gaussian action on the tree T. We find the amplitudes for emission processes of the tachyon states from the boundary.

A gauge-invariant theory of a massive spin-3/2 particle interacting with external electromagnetic and gravitational fields, obtained earlier by Kaluza-Klein reduction of a massless Rarita-Schwinger theory, is quantized using Dirac’s procedure. The field anticommutators are found to be positive definite. The theory, which was earlier shown to be free from the classical Velo-Zwanziger problem of noncausal propagation modes, is thus also free from the problem of negative-norm states, a longstanding problem associated with massive spin-3/2 theories with external interaction.

A new form of curvature on a 2-dimensional Regge manifold is proposed and the higher derivative quantum gravity is studied numerically by use of both a fixed and a random coordination number lattice. Results previously reported by Hamber and Williams are followed. Also checked are the stability and the absence of phase transition of the theory whose action has a cosmological term and an R² term.

The asymptotics of the evolution kernels P_ab(z) of parton distributions is investigated as z→1. It is proven that to all orders of perturbative QCD, where is the cusp anomalous dimension of the contour functionals in the fundamental (α=“quark”) and adjoint (α=“gluon”) representations of gauge group and, to the lowest orders, C_α are related to the anomalous dimension of a quark field in the axial gauge and the beta function of QCD by a simple equation.

The adequacy of using the Breit-Fermi type of interactions for describing the fine hyperfine splittings of heavy quarkonia has been examined critically. A potential model which just about accommodates the trend of the recent data on ¹P₁ states has been studied. The possibility of including the spin-dependent contributions of a pseudoscalar exchange potential is also considered. It is shown that the choice of the Breit-Fermi form for the spin-dependent interactions severely constrains the generally accepted non-relativistic potential and do not allow enough freedom to fit the recent data on ¹P₁ levels.

An appropriate subsidiary condition is introduced in the classical actions of the p-branes (p arbitrary). A general class of exact solutions of the resulting nonlinear equations of motion are obtained which yield a broad class of characteristics for the original covariant equations of the p-branes.