Modern Physics Letters A

We review some recent results obtained in the analysis of two-dimensional quantum field theories by means of semiclassical techniques, which generalize methods introduced during the '70s by Dashen, Hasllacher and Neveu and by Goldstone and Jackiw. The approach is best suited to deal with quantum field theories characterized by a nonlinear interaction potential with different degenerate minima, that generates kink excitations of large mass in the small coupling regime. Under these circumstances, although the results obtained are based on a small coupling assumption, they are nevertheless nonperturbative, since the kink backgrounds around which the semiclassical expansion is performed are nonperturbative too. We will discuss the efficacy of the semiclassical method as a tool to control analytically spectrum and finite-size effects in these theories.

Lorentz invariant supersymmetric deformations of superspaces based on Moyal star product parametrized by Majorana spinor λ_a and Ramond Grassmannian vector in the spinor realization⁴² are proposed. The map of supergravity background into composite supercoordinates: valid up to the second order corrections in deformation parameter h and transforming the background dependent Lorentz noninvariant (anti)commutators of supercoordinates into their invariant Moyal brackets is revealed. We found one of the deformations to depend on the axial vector and to vanish for the θ components with the same chiralities. The deformations in the (super)twistor picture are discussed.

General relativity supersedes Newtonian dynamics in the analysis of galactic rotation and eliminates the need for vast halos of exotic dark matter. We present new results to complete the global picture of galactic models which indicate that we can model relatively modest mass accumulations surrounding galaxies with mass concentrations roughly contained within the contours of the extended disk. An observational test of the extent of any external matter distribution is shown to derive from the velocity dispersion of rotation curves in planes parallel to the galactic symmetry plane. We reply to recent critics of our work.

In the past, Hawking radiation was viewed as a tunneling process and the barrier was just created by the outgoing particle itself. In this paper, Parikh's recent work is extended to the case of massive particles' tunneling. We investigate the behavior of the tunneling massive particles from a particular black hole solution — G.H. Dilaton black hole which is obtained from the string theory, and calculate the emission rate at which massive particles tunnel across the event horizon. We obtain that the result is also consistent with an underlying unitary theory. Furthermore, the result takes the same functional form as that of massless particles.

We study quantum mechanics on the noncommutative cylinder via Moyal deformed geodesic flows on the group of area preserving diffeomorphism. This equation coincides exactly with the von Neumann equation. Using discretization techniques of Kemmoku and Saito we obtain the discrete Schrödinger equation on noncommutative cylinder. Thus we reproduce the result of Balachandran et al.¹

Four-dimensional N=1 supersymmetric Yang–Mills theory action is written in terms of the spinor superfields in transverse gauge. This action is seemingly first order in spacetime derivatives. Thus, it suggests that the generalized fields approach of obtaining Batalin–Vilkovisky quantization can be applicable. In fact, generalized fields which collect spinor superfields possessing different ghost numbers are introduced to obtain the minimal solution of its Batalin–Vilkovisky master equation in a compact form.