International Journal of Modern Physics A

Predictions on central rapidity densities of charged particles at energies of the relativistic heavy ion collider and the large hadron collider, for central collisions between the largest nuclei that will be available at these accelerators, are reviewed. Differences among the results of the existing models are discussed in relation with their underlying physical basis and with the possibilities to discriminate them.

The Fermi momentum P_f for the B_c meson has been estimated in the framework of the statistical model. The matrix element |V_cb| has been extracted from the lepton energy spectrum using the estimated value of the Fermi momentum, in the framework of the ACCMM model. The value of P_f for B_c meson has been estimated as P_f=1.14 GeV which is somewhat large compared to the existing estimates.

We study the canonical quantum theory of the spherically symmetric geometry with the cosmological constant and the electromagnetic field. We obtain a solution of the Wheeler–DeWitt equation for the geometrical variables and investigate the wave function from a viewpoint of the de Broglie–Bohm interpretation of the ordinary quantum mechanics. The de Broglie–Bohm interpretation introduces deterministic rigid trajectories on the minisuperspace without any outside observers nor the collapse of the wave function. It is shown that the wave function does not only correspond to the classical Reissner–Nordström–de Sitter black hole in the semiclassical region, but it also represents quantum geometrical fluctuations near the black hole horizon and the cosmological one. The result suggests that the semiclassical gravity on which the Hawking radiation is based is broken near the horizons.

Previously we have shown that open groups whose generators are in arbitrary involutions may be quantized within a ghost extended framework in terms of the nilpotent BFV–BRST charge operator. Here we show that they may also be quantized within an Sp(2)-frame in which there are two odd anticommuting operators called Sp(2)-charges. Previous results for finite open group transformations are generalized to the Sp(2)-formalism. We show that in order to define open group transformations on the whole ghost extended space we need Sp(2)-charges in the nonminimal sector which contains dynamical Lagrange multipliers. We give an Sp(2)-version of the quantum master equation with extended Sp(2)-charges and a master charge of a more involved form, which is proposed to represent the integrability conditions of defining operators of connection operators and which therefore should encode the generalized quantum Maurer–Cartan equations for arbitrary open groups. General solutions of this master equation are given in explicit form. A further extended Sp(2)-formalism is proposed in which the group parameters are quadrupled to a supersymmetric set and from which all results may be derived.

We generalize a previous work on Dirac eigenvalues as dynamical variables of Euclidean supergravity. The most general set of constraints on the curvatures of the tangent bundle and on the spinor bundle of the space–time manifold, under which space–time admits Dirac eigenvalues as observables, are derived.

Recent observations of atmospheric and solar neutrinos strongly support the phenomenon of neutrino oscillations — a manifestation of a nonzero and nondegenerate mass spectrum. Neutrinos emitted during stellar core collapse leading to a supernova are of the electron neutrino type at source — as for solar and reactor (anti-)neutrinos — and provide another useful tool in the search for flavor oscillations. Their propagation to an earth-bound detector involves length scales that can uniquely probe very small neutrino mass differences hitherto unobservable. Although the number of neutrinos emitted during the collapse phase is much smaller than that emitted in the post-bounce epoch (in which all flavors of neutrinos are emitted), a nearby supernova event may nevertheless register a substantial number of detections from the collapse phase at SuperKamiokande (SK) and the Sudbury Neutrino Observatory (SNO). The measurement of the fluence of these neutrinos at SNO and the distortion of the spectrum detected at SK can yield valuable information about neutrino mass difference and mixing which are illustrated here in terms of two- and three-flavor oscillation models. In particular, we find that R_SNO, the ratio of the calorimetric detection of the neutrino fluence via the neutral current channel to the total energy integrated fluence observed via the charged current channel at SNO, is a sensitive probe for oscillations. We also find that α_n, the ratio of the nth central moments of the distributions seen at SK and SNO (charged current), can be a useful tool (especially for n=3) to look for neutrino oscillations.

A version of the Exact Renormalization Group Equation consistent with gauge symmetry is presented. A discussion of its regularization and renormalization is given. The relation with the Callan–Symanzik equation is clarified.

We give a Wilsonian formulation of non-Abelian gauge theories explicitly consistent with axial gauge Ward identities. The issues of unitarity and dependence on the quantization direction are carefully investigated. A Wilsonian computation of the one-loop QCD beta function is performed.