Canonical quantization of the relativistic particle in static spacetimes

We perform the canonical quantization of a relativistic spinless particle moving in a curved and static spacetime. We show that the classical theory already describes at the same time both particle and antiparticle. The analyses involves time-depending constraints and we are able to construct the two-particle Hilbert space. The requirement of a static spacetime is necessary in order to have a well defined Schr\"odinger equation and to avoid problems with vacuum instabilities. The severe ordering ambiguities we found are in essence the same ones of the well known non-relativistic case.Comment: Revtex, 9 page

Phase Transition and Hybrid Star in a Nonlinear σ−ω\sigma - \omega model

The phase transition between the nuclear matter and the quark matter is examined. The relativistic mean field theory(RMF) is consider with interacting nucleons and mesons using TM1 parameter set for the nuclear matter equations of state. It is found that the trasition point depends on coupling constant $\alpha_s$ and bag pressure. From the study of the structure of a hybrid neutron star, it is observed that the star contains quark matter in the interior and neutron matter on the outer perifery.Comment: 8 pages, 7 figures, to appear in Int. J. Mod. Phy.

Monodromy Matrix in the PP-Wave Limit

We construct the monodromy matrix for a class of gauged WZWN models in the plane wave limit and discuss various properties of such systems.Comment: 16 page

U(1,1)--Invariant Generation of Charges for Einstein--Maxwell--Dilaton--Axion Theory

The action of the isometry subgroup which preserves the trivial values of the fields is studied for the stationary D=4 Einstein--Maxwell--Dilaton--Axion theory. The technique for generation of charges and the corresponding procedure for construction of new solutions is formulated. A solution describing the double rotating dyon with independent values of all physical charges is presented.Comment: 14 pages, RevTex, no figurie

Kaluza-Klein Black Holes in String Theory

Exact solutions of heterotic string theory corresponding to four-dimensional magnetic black holes in $N=4$ supergravity are described. The solutions describe the black holes in the throat limit, and consist of a tensor product of an $SU(2)$ WZW orbifold with the linear dilaton vacuum, supersymmetrized to $(1,0)$ world sheet SUSY. One dimension of the $SU(2)$ model is interpreted as a compactified fifth dimension, leading to a four dimensional solution with a Kaluza-Klein gauge field having a magnetic monopole background; this corresponds to a solution in $N=4$ supergravity, since that theory is obtained by dimensional reduction of string theory.Comment: 13p. uses Harvma

An Infinite Dimensional Symmetry Algebra in String Theory

Symmetry transformations of the space-time fields of string theory are generated by certain similarity transformations of the stress-tensor of the associated conformal field theories. This observation is complicated by the fact that, as we explain, many of the operators we habitually use in string theory (such as vertices and currents) have ill-defined commutators. However, we identify an infinite-dimensional subalgebra whose commutators are not singular, and explicitly calculate its structure constants. This constitutes a subalgebra of the gauge symmetry of string theory, although it may act on auxiliary as well as propagating fields. We term this object a {\it weighted tensor algebra}, and, while it appears to be a distant cousin of the $W$-algebras, it has not, to our knowledge, appeared in the literature before.Comment: 14 pages, Plain TeX, report RU93-8, CTP-TAMU-2/94, CERN-TH.7022/9

Soliton solution in dilaton-Maxwell gravity

The inverse scattering problem method application to construction of exact solution for Maxwell dilaton gravity system ia considered. By use of Belinsky and Zakharov L - A pair the solution of the theory is constructed. The rotating Kerr - like configuration with NUT - parameter is obtained.Comment: 8 pages in LaTex; published in Gen. Rel. Grav. pp. 32 (2000) 2219-222

Warped Spectroscopy: Localization of Frozen Bulk Modes

We study the 10D equation of motion of dilaton-axion fluctuations in type IIB string compactifications with three-form flux, taking warping into account. Using simplified models with physics comparable to actual compactifications, we argue that the lightest mode localizes in long warped throats and takes a mass of order the warped string scale. Also, Gukov-Vafa-Witten superpotential is valid for the lightest mass mode; however, the mass is similar to the Kaluza-Klein scale, so the dilaton-axion should be integrated out of the effective theory in this long throat regime (leaving a constant superpotential). On the other hand, there is a large hierarchy between flux-induced and KK mass scales for moderate or weak warping. This hierarchy agrees with arguments given for trivial warping. Along the way, we also estimate the effect of the other 10D supergravity equations of motion on the dilaton-axion fluctuation, since these equations act as constraints. We argue that they give negligible corrections to the simplest approximation.Comment: 24pp + appendices, 6 figs, JHEP3 class; v2. corrected reference; v3. added clarifications; v4. corrected typo

Propagating modes of non-Abelian tensor gauge field of second rank

In the recently proposed extension of the YM theory, non-Abelian tensor gauge field of the second rank is represented by a general tensor whose symmetric part describes the propagation of charged gauge boson of helicity two and its antisymmetric part - the helicity zero charged gauge boson. On the non-interacting level these polarizations are similar to the polarizations of the graviton and of the Abelian antisymmetric B field, but the interaction of these gauge bosons carrying non-commutative internal charges cannot be directly identified with the interaction of gravitons or B field. Our intention here is to illustrate this result from different perspectives which would include Bianchi identity for the corresponding field strength tensor and the analysis of the second-order partial differential equation which describes in this theory the propagation of non-Abelian tensor gauge field of the second rank.Comment: 22 pages, Latex fil

Exact solutions in two-dimensional string cosmology with back reaction

We present analytic cosmological solutions in a model of two-dimensional dilaton gravity with back reaction. One of these solutions exhibits a graceful exit from the inflationary to the FRW phase and is nonsingular everywhere. A duality related second solution is found to exist only in the ``pre-big-bang'' epoch and is singular at $\tau = 0$. In either case back reaction is shown to play a crucial role in determining the specific nature of these geometries.Comment: Shortened slightly, references added, to appear in Physical Review D (Rapid Communications). 16 pages, RevTex, 3 PostScript figure