615 research outputs found
On the Initial Singularity Problem in Two Dimensional Quantum Cosmology
The problem of how to put interactions in two-dimensional quantum gravity in
the strong coupling regime is studied. It shows that the most general
interaction consistent with this symmetry is a Liouville term that contain two
parameters satisfying the algebraic relation in order to assure the closure of the diffeomorphism algebra. The model is
classically soluble and it contains as general solution the temporal
singularity. The theory is quantized and we show that the propagation amplitude
fall tozero in . This result shows that the classical singularities
are smoothed by quantum effects and the bing-bang concept could be considered
as a classical extrapolation instead of a physical concept.Comment: 9pp, Revtex 3.0. New references added. To appear in Phys. Rev.
On the N=1 super Liouville four-point functions
We construct the four-point correlation functions containing the top
component of the supermultiplet in the Neveu-Schwarz sector of the N=1 SUSY
Liouville field theory. The construction is based on the recursive
representation for the NS conformal blocks. We test our results in the case
where one of the fields is degenerate with a singular vector on the level 3/2.
In this case, the correlation function satisfies a third-order ordinary
differential equation, which we derive. We numerically verify the crossing
symmetry relations for the constructed correlation functions in the
nondegenerate case.Comment: 23 page
Muon simulation codes MUSIC and MUSUN for underground physics
The paper describes two Monte Carlo codes dedicated to muon simulations:
MUSIC (MUon SImulation Code) and MUSUN (MUon Simulations UNderground). MUSIC is
a package for muon transport through matter. It is particularly useful for
propagating muons through large thickness of rock or water, for instance from
the surface down to underground/underwater laboratory. MUSUN is designed to use
the results of muon transport through rock/water to generate muons in or around
underground laboratory taking into account their energy spectrum and angular
distribution.Comment: 22 pages, 9 figures, 1 table, to be published in Computer Physics
Communication
On Paragrassmann Differential Calculus
Explicit general constructions of paragrassmann calculus with one and many
variables are given. Relations of the paragrassmann calculus to quantum groups
are outlined and possible physics applications are briefly discussed. This
paper is the same as the original 9210075 except added Appendix and minor
changes in Acknowledgements and References. IMPORTANT NOTE: This paper bears
the same title as the Dubna preprint E5-92-392 but is NOT identical to it,
containing new results, extended discussions, and references.Comment: 19p
On Adler-Bell-Jackiw Anomaly in 3-brane Scenario
We investigate the ABJ anomaly in the framework of an effective field theory
for a 3-brane scenario and show that the contribution from induced gravity on
the brane depends on both the topological structure of the bulk space-time and
the embedding of the brane in the bulk. This fact implies the existence of a
non-trivial vacuum structure of bulk quantum gravity. Furthermore, we argue
that this axial gravitational anomaly may not necessarily be cancelled by
choosing the matter content on the brane since it could be considered as a
possible effect from bulk quantum gravity.Comment: 17 pages, RevTex, no figures. Some further misprints are correcte
Anomalies, Anomalous U(1)'s and generalized Chern-Simons terms
A detailed analysis of anomalous U(1)'s and their effective couplings is
performed both in field theory and string theory. It is motivated by the
possible relevance of such couplings in particle physics, as well as a
potential signal distinguishing string theory from other UV options. The most
general anomaly related effective action is analyzed and parameterized. It
contains Stuckelberg, axionic and Chern-Simons-like couplings. It is shown that
such couplings are generically non-trivial in orientifold string vacua and are
not in general fixed by anomalies. A similar analysis in quantum field theories
provides similar couplings. The trilinear gauge boson couplings are also
calculated and their phenomenological relevance is advocated. We do not find
qualitative differences between string and field theory in this sector.Comment: 52 pages, 2 eps figures, LaTeX, feynmf & youngtab packages (v2 -
Minor corrections, references added
Polarization phenomena in open charm photoproduction processes
We analyze polarization effects in associative photoproduction of
pseudoscalar () charmed mesons in exclusive processes , , . Circularly polarized photons
induce nonzero polarization of the -hyperon with - and -components
(in the reaction plane) and non vanishing asymmetries and for polarized nucleon target. These polarization observables can be
predicted in model-independent way for exclusive -production processes
in collinear kinematics. The T-even -polarization and asymmetries for
non-collinear kinematics can be calculated in framework of an effective
Lagrangian approach. The depolarization coefficients , characterizing
the dependence of the -polarization on the nucleon polarization are also
calculated.Comment: 36 pages 13 figure
Cosmic Neutrinos and the Energy Budget of Galactic and Extragalactic Cosmic Rays
Although kilometer-scale neutrino detectors such as IceCube are discovery
instruments, their conceptual design is very much anchored to the observational
fact that Nature produces protons and photons with energies in excess of
10^{20} eV and 10^{13} eV, respectively. The puzzle of where and how Nature
accelerates the highest energy cosmic particles is unresolved almost a century
after their discovery. We will discuss how the cosmic ray connection sets the
scale of the anticipated cosmic neutrino fluxes. In this context, we discuss
the first results of the completed AMANDA detector and the science reach of its
extension, IceCube.Comment: 13 pages, Latex2e, 3 postscript figures included. Talk presented at
the International Workshop on Energy Budget in the High Energy Universe,
Kashiwa, Japan, February 200
The structure of radiatively induced Lorentz and CPT violation in QED at finite temperature
We obtain the induced Lorentz- and CPT-violating term in QED at finite
temperature using imaginary-time formalism and dimensional regularization. Its
form resembles a Chern-Simons-like structure, but, unexpectedly, it does not
depend on the temporal component of the fixed constant vector that is
coupled to the axial current. Nevertheless Ward identities are respected and
its coefficient vanishes at T=0, consistently with previous computations with
the same regularization procedure, and it is a non-trivial function of
temperature. We argue that at finite a Chern-Simons-like Lorentz- and
CPT-violating term is generically present, the value of its coefficient being
unambiguously determined up to a independent constant, related to the
zero-temperature renormalization conditions.Comment: 15 pages, Latex, 1 figure in eps-format (included
Field Theoretical Quantum Effects on the Kerr Geometry
We study quantum aspects of the Einstein gravity with one time-like and one
space-like Killing vector commuting with each other. The theory is formulated
as a \coset nonlinear -model coupled to gravity. The quantum analysis
of the nonlinear -model part, which includes all the dynamical degrees
of freedom, can be carried out in a parallel way to ordinary nonlinear
-models in spite of the existence of an unusual coupling. This means
that we can investigate consistently the quantum properties of the Einstein
gravity, though we are limited to the fluctuations depending only on two
coordinates. We find the forms of the beta functions to all orders up to
numerical coefficients. Finally we consider the quantum effects of the
renormalization on the Kerr black hole as an example. It turns out that the
asymptotically flat region remains intact and stable, while, in a certain
approximation, it is shown that the inner geometry changes considerably however
small the quantum effects may be.Comment: 16 pages, LaTeX. The hep-th number added on the cover, and minor
typos correcte
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