International Journal of Modern Physics A

The axial anomaly is a quantum term that violates the classical conservation of the the axial current.

In this paper we investigate the perturbations by a massless Dirac spinor of a Born–Infeld black hole. The decay rates of the spinor field which is given by the quasinormal mode frequencies are computed using the sixth-order WKB approximation. The behavior of the quasinormal modes with the nonlinear parameter, temperature and charge of the black hole are analyzed in detail. We also compare the decay rates of the Born–Infeld black hole with its linear counterpart Reissner–Nordstrom black hole.

Within the framework of a semiclassical approximation the general theory of calculation of effective currents and sources generating bremsstrahlung of an arbitrary number of soft quarks and soft gluons at collision of a high-energy color-charged particle with thermal partons in a hot quark–gluon plasma is developed. For the case of one- and two-scattering thermal partons with radiation of one or two soft excitations, the effective currents and sources are calculated in an explicit form. In the model case of "frozen" medium, approximate expressions for energy losses induced by the most simple processes of bremsstrahlung of soft quark and soft gluon are derived. On the basis of a conception of the mutual cancellation of singularities in the sum of so-called "diagonal" and "off-diagonal" contributions to the energy losses, an effective method of determining color factors in scattering probabilities containing the initial values of Grassmann color charges is suggested. The dynamical equations for Grassmann color charges of hard particle used by us earlier on are proved to be insufficient for investigation of the higher radiative processes. It is shown that for correct description of these processes the given equations should be supplemented successively with the higher-order terms in powers of the soft fermionic field.

This document describes the physics potential of a new fixed-target program based on a ~1 TeV proton source. Two proton sources are potentially available in the future: the existing Tevatron at Fermilab, which can provide 800 GeV protons for fixed-target physics, and a possible upgrade to the SPS at CERN, called SPS+, which would produce 1 TeV protons on target. In this paper we use an example Tevatron fixed-target program to illustrate the high discovery potential possible in the charm and neutrino sectors. We highlight examples which are either unique to the program or difficult to accomplish at other venues.

It is rigorously shown how the extended relativity theory in Clifford spaces (C-spaces) can explain the variable radial dependence a_p(r) of the Pioneer anomaly; its sign (pointing towards the Sun); why planets do not experience the anomalous acceleration and why the present day value of the Hubble scale R_H appears. It is the curvature–spin coupling of the planetary motions that hold the key. The difference in the rate at which clocks tick in C-space translates into the C-space analog of Doppler shifts which may explain the anomalous redshifts in cosmology, where objects which are not that far apart from each other exhibit very different redshifts. We conclude by showing how the empirical formula for the flybys anomalies obtained by Anderson et al.¹⁷ can be derived within the framework of Clifford geometry.

We present our derivations for Kerr–de Sitter metric in a proper comoving coordinate system. It asymptotically approaches to the de Sitter metric in Robertson–Walker form. This has been done by considering the stationary axially-symmetric space–time in which motion of particle is integrable. That is the Hamilton–Jacobi and Klein–Gordon equations are separable. In this form it is asymptotically consistent with comoving frame.

We reexamine the supersymmetric gauge theories with product gauge groups by adding the mass terms and the quartic terms for the flavors: two-gauge group theory with fundamentals, bifundamentals and adjoints, three-gauge group theory with fundamentals and bifundamentals, and their orientifold 4-plane generalizations. By moving the branes appropriately, we obtain the corresponding dual gauge theories. By analyzing the dual superpotentials, we present the type IIA nonsupersymmetric meta-stable brane configurations.