Modern Physics Letters A

In this review we present the calculation of the splitting rate in flat space of a macroscopic fundamental string either intersecting at a generic angle a Dp-brane or lying on it. The result is then applied, in the context of the string/gauge theory correspondence, to the study of exclusive decay rates of large spin mesons into mesons. As examples, we discuss the cases of SYM with a small number of flavors, and of QCD-like theories in the quenched approximation. In the latter context, explicit analytic formulas are given for decay rates of mesons formed either by heavy quarks or by massless quarks.

In the study of pseudo(quasi)-hermitian operators, the key role is played by the positive-definite metric operator. It enables physical interpretation of the considered systems. In this paper, we study the pseudo-hermitian systems with constant number of particles in equilibrium. We show that the explicit knowledge of the metric operator is not essential for the study of thermodynamic properties of the system. We introduce a simple example where the physically relevant quantities are derived without explicit calculation of either metric operator or spectrum of the Hamiltonian.

We show explicitly in D = 2 that N = 2 nonlinear supersymmetric (SUSY) Volkov–Akulov model is equivalent to a spontaneously broken N = 2 linear SUSY interacting theory containing the ordinary Yukawa interactions and mass terms, which is renormalizable, by using SUSY invariant relations.

The studies of influence of spin on a photon motion in a Schwarzschild spacetime is continued. In the previous paper² the first-order correction to the geodesic motion is reduced to a non-uniform linear ordinary differential equation and the equation obtained has been solved by the standard method of integration of the Green function. If each photon draws a world line specified by this solution, then light rays from infinitely distant source form a caustic which does not appear without the spin-gravity interaction. The goal of this work is to obtain explicit form of caustic.

We show that the stochastic background of gravitational waves, produced in the early cosmological epochs, depends strictly on the assumed theory of gravity. In particular, the specific form of the function f(R), where R is the Ricci scalar, is related to the evolution and the production mechanism of gravitational waves. On the other hand, detecting the stochastic background by the forthcoming interferometric experiments (VIRGO, LIGO, LISA) could be a further tool to select the effective theory of gravity.

The transverse momentum distribution of charged particles is investigated for gold–gold collisions at . A simple parametrization is suggested for the particle distribution based on the nuclear stopping effect. The model can fit very well in both the transverse momentum distributions at different pseudo-rapidities and the pseudo-rapidity distributions at different centralities. The ratio of rapidity distributions for peripheral and central collisions is calculated and compared with the data.

The Maxwell–Chern–Simons model with scalar matter in the adjoint representation is analyzed from an alternative approach which is regular in the θ→0 limit. This method is complementary to the usual operator formalism applied to explore the nonperturbative solutions which give singular results in the θ→0 limit. The absence of any regular non-trivial lumpy solutions satisfying B–P–S bound has been conclusively demonstrated.