27 research outputs found
Laurent Series Representation for the Open Superstring Free Energy
Open superstrings at non-zero temperature are considered. A novel
representation for the free energy (Laurent series representation) is
constructed. It is shown that the Hagedorn temperature arises in this formalism
as the convergence condition (specifically, the radius of convergence) of the
Laurent series.Comment: Latex, 10 Page
A Novel Representation for the Free Energy in String Theory at Non-Zero Temperature
A novel representation ---in terms of a Laurent series--- for the free energy
of string theory at non-zero temperature is constructed. The examples of open
bosonic, open supersymmetric and closed bosonic strings are studied in detail.
In all these cases the Laurent series representation for the free energy is
obtained explicitly.
It is shown that the Hagedorn temperature arises in this formalism as the
convergence condition (specifically, the radius of convergence) of the
corresponding Laurent series. Some prospects for further applications are also
discussed. In particular, an attempt to describe string theory above the
Hagedorn temperature ---via Borel analytical continuation of the Laurent series
representation--- is provided.Comment: 21 pages, LaTeX file, HUPD-92-12, UB-ECM-PF 92/25, UFT 273-9
One Loop Counterterms in 2D Dilaton-Maxwell Quantum Gravity
The renormalization structure of two-dimensional quantum gravity is
investigated, in a covariant gauge. One-loop divergences of the effective
action are calculated. All the surface divergent terms are taken into account,
thus completing previous one-loop calculations of the theory. It is shown that
the on-shell effective action contains only surface divergences. The off-shell
renormalizability of the theory is discussed and classes of renormalizable
dilaton and Maxwell potentials are found.Comment: 9 pages, LaTeX file, HUPD-92-1
Poincar\'e Gauge Theories for Lineal Garvity
We have shown that two of the most studied models of lineal gravities -
Liouville gravity and a ``string-inspired'' model exhibiting the main
characteristic features of a black-hole solution - can be formulated as gauge
invariant theories of the Poincar\'e group. The gauge invariant couplings to
matter (particles, scalar and spinor fields) and explicit solutions for some
matter field configurations, are provided. It is shown that both the models, as
well as the couplings to matter, can be obtained as suitable dimensional
reductions of a 2+1-dimensional ISO(2,1) gauge invariant theory.Comment: TeX Manuscript, 30 page
Quantum Gravity in Two Dimensions
Two-dimensional quantum gravity with an term is investigated in the
continuum framework. It is shown that the partition function for small area
is highly suppressed by an exponential factor ,
where is the coefficient (times ) of and is the genus
of the surface. Although positivity is violated, at a short distance scale (
) surfaces are smooth and the problem of the branched polymer is
avoided.Comment: 12 pages, latex KEK-TH-355, KEK preprint 92-212, UT-63
Quantization of Two-Dimensional Gravity with Dynamical Torsion
We consider two-dimensional gravity with dynamical torsion in the Batalin -
Vilkovisky and Batalin - Lavrov - Tyutin formalisms of gauge theories
quantization as well as in the background field method.Comment: 12 pages, LaTe
THE HIGGS-YUKAWA MODEL IN CURVED SPACETIME
The Higgs-Yukawa model in curved spacetime (renormalizable in the usual
sense) is considered near the critical point, employing the --expansion
and renormalization group techniques. By making use of the equivalence of this
model with the standard NJL model, the effective potential in the linear
curvature approach is calculated and the dynamically generated fermionic mass
is found. A numerical study of chiral symmetry breaking by curvature effects is
presented.Comment: LaTeX, 9 pages, 1 uu-figur
Factorization and Topological States in Matter Coupled to 2-D Gravity
Factorization of the -point amplitudes in two-dimensional quantum
gravity is understood in terms of short-distance singularities arising from the
operator product expansion of vertex operators after the Liouville zero mode
integration. Apart from the tachyon states, there are infinitely many
topological states contributing to the intermediate states.Comment: 16 page
One-loop Vilkovisky-DeWitt Counterterms for 2D Gravity plus Scalar Field Theory
The divergent part of the one-loop off-shell effective action is computed for
a single scalar field coupled to the Ricci curvature of 2D gravity (), and self interacting by an arbitrary potential term . The
Vilkovisky-DeWitt effective action is used to compute gauge-fixing independent
results. In our background field/covariant gauge we find that the Liouville
theory is finite on shell. Off-shell, we find a large class of renormalizable
potentials which include the Liouville potential. We also find that for
backgrounds satisfying , the Liouville theory is finite off shell, as
well.Comment: 19 pages, OKHEP 92-00
Quantum Black Holes in Two Dimensions
We show that a whole class of quantum actions for dilaton-gravity, which
reduce to the CGHS theory in the classical limit, can be written as a
Liouville-like theory. In a sub-class of this, the field space singularity
observed by several authors is absent, regardless of the number of matter
fields, and in addition it is such that the dilaton-gravity functional
integration range (the real line) transforms into itself for the Liouville
theory fields. We also discuss some problems associated with the usual
calculation of Hawking radiation, which stem from the neglect of back reaction.
We give an alternative argument incorporating back reaction but find that the
rate is still asymptotically constant. The latter is due to the fact that the
quantum theory does not seem to have a lower bound in energy and Hawking
radiation takes positive Bondi (or ADM) mass solutions to arbitrarily large
negative mass.Comment: 28 pages, phyzzx, revised discussion of Hawking radiatio