International Journal of Modern Physics A

A survey of our current understanding of the strange particle signature of quark gluon plasma is presented. Emphasis is placed on the theory of strangeness production in the plasma and recent pertinent experimental results. Useful results on spectra of thermal particles are given.

The oscillator-type realization is proposed for the continuous set of infinite-dimensional algebras of quantum operators on the two-dimensional sphere and hyperboloid. This realization is typical for infinite-dimensional higher spin algebras related to higher spin gauge theories. It involves the Klein-type operator that emerges nontrivially in the Heisenberg-type commutation relations for the oscillators. The invariant trace and bilinear form are constructed. The latter is shown to degenerate for all odd-integer values of the continuous parameter ν, which parametrizes the class of algebras under investigation. The degeneration points are shown to correspond to ordinary finite-dimensional matrix algebras and superalgebras. Possible applications of these results to higher spin gauge theories are discussed. In particular, it is noted that the deformation parameter ν can be interpreted as a vacuum value of some auxiliary scalar field in an appropriate higher spin gauge theory.

We investigate the general conditions for a Wess-Zumino-Witten model with a super-group as a gauge group to be quantum-mechanically consistent. A specific model with extended space-time supersymmetry is briefly discussed.

In this paper we classify the (2, 2) superstring vacua corresponding to non-linear σ-models on SU(2)³ groupfolds fermionized by 18 + 18 Majorana fermions. For the subclass of the completely bosonizable vacua, the generation number ½X is a multiple of 12 and the number of tangent-bundle deformations End(T) is a multiple of 4. The dimensions of the moduli spaces h^1,1, h^{2, 1} are small odd numbers in the range 1 ÷ ~50. Very few of these vacua have the same Dolbeault cohomology as those described by minimal model tensor products, CICY, or Calabi-Yau threefolds in weighted P₄. The vacua we classify are characterized by a rank 8 enhancement group and some of them can be viewed as N=2 truncations. We also discuss examples of vacua that are only partially bosonizable, showing that the class of vacua obtained by free fermion constructions is not fully contained in the class of vacua obtained by lattice constructions.

The theory of a closed bosonic string interacting with background fields, namely, with metric, antisymmetric tensor of second rank and dilaton, is considered. The classical formulation of the constrained theory is developed and the canonical quantization is carried out. The combined symbols of the Virasoro operators corresponding to the Weyl ordering of zero string modes and to the Wick ordering of oscillating ones are constructed. The quantum Virasoro algebra is formulated by means of star-commutators corresponding to these symbols and the nonlocal first quantum correction in the algebra is calculated. The local part of the correction linear in curvature is derived and effective equations of motion for background fields are obtained in the lowest order.

Two-dimensional supergravity coupled to the supersymmetric minimal models is quantized by the BRST method. We analysed the physical state condition and found that a state allowed in the physical spectrum must be a direct product of primary states in the matter and gravity sectors. The decoupling mechanism of the unphysical modes is quite similar to the first quantized string theory in the RNS formalism. The formula of KPZ for gravitational scaling dimensions is rederived from the physical state condition. This analysis is done in the conformal gauge.