558 research outputs found
Quantum States of String-Inspired Lineal Gravity
We construct quantum states for a (1+1) dimensional gravity-matter model that
is also a gauge theory based on the centrally extended Poincar\'e group.
Explicit formulas are found, which exhibit interesting structures. For example
wave functionals are gauge invariant except for a gauge non-invariant phase
factor that is the Kirillov-Kostant 1-form on the (co-) adjoint orbit of the
group. However no evidence for gravity-matter forces is found.Comment: 23 pages in REVTEX, MIT-CTP-227
Extended de Sitter Theory of Two Dimensional Gravitational Forces
We present a simple unifying gauge theoretical formulation of gravitational
theories in two dimensional spacetime. This formulation includes the effects of
a novel matter-gravity coupling which leads to an extended de Sitter symmetry
algebra on which the gauge theory is based. Contractions of this theory
encompass previously studied cases.Comment: 19pp, no figs., CTP 2228, UCONN-93-
String-Inspired Gravity Coupled to Yang-Mills Fields
String-inspired 1+1-dimensional gravity is coupled to Yang-Mills fields in
the Cangemi-Jackiw gauge-theoretical formulation, based on the extended
Poincar\'e group. A family of couplings, which involves metrics obtainable from
the physical metric with a conformal rescaling, is considered, and the
resulting family of models is investigated both at the classical and the
quantum level. In particular, also using a series of Kirillov-Kostant phases,
the wave functionals that solve the constraints are identified.Comment: 15 pages, LaTex
Non Abelian BF theories with sources and 2-D gravity
We study the interaction of non-Abelian topological theories defined on
two dimensional manifolds with point sources carrying non-Abelian charges. We
identify the most general solution for the field equations on simply and
multiply connected two-manifolds. Taking the particular choice of the so-called
extended Poincar\'e group as the gauge group we discuss how recent discussions
of two dimensional gravity models do fit in this formalism.Comment: 20 pages, Latex, To appear in Phys Rev D5
A WZW model based on a non-semi-simple group
We present a conformal field theory which desribes a homogeneous four
dimensional Lorentz-signature space-time. The model is an ungauged WZW model
based on a central extension of the Poincar\'e algebra. The central charge of
this theory is exactly four, just like four dimensional Minkowski space. The
model can be interpreted as a four dimensional monochromatic plane wave. As
there are three commuting isometries, other interesting geometries are expected
to emerge via duality.Comment: 8 pages, phyzzx, IASSNS-HEP-93/61 Texable versio
Dirac Quantization of Two-Dimensional Dilaton Gravity Minimally Coupled to N Massless Scalar Fields
It is shown that the Callan-Giddings-Harvey-Strominger theory on the cylinder
can be consistently quantized (using Dirac's approach) without imposing any
constraints on the sign of the gravitational coupling constant or the sign (or
value) of the cosmological constant. The quantum constraints in terms of the
original geometrical variables are also derived
Exact Quantum States for all Two-Dimensional Dilaton Gravity Theories
It is shown that the recently obtained quantum wave functionals in terms of
the CJZ variables for generic 2d dilaton gravity are equivalent to the
previously reported exact quantum wave functionals in geometrical variables. A
third representation of these exact quantum states is also presented
Geomorphological and geochemical characterization of the 11 August 2008 mud volcano eruption at S. Barbara village (Sicily, Italy) and its possible relationship with seismic activity
On 11 August 2008 a paroxysmal eruption occurred at Santa Barbara mud volcano (MV), located close to Caltanissetta, one of the most densely populated cities of Sicily (Italy). An associated minor event took place on August 2009. Both the events caused severe damage to civil infrastructures located within a range of about 2 km from the eruptive vent. Geomorphological, geochemical, and seismological investigations were carried out for framing the events in the appropriate geodynamic context. Geomorphological surveys recognized, in the immediate surrounding of the main emission point, two different families of processes and landforms: (i) ground deformations and (ii) changes in morphology and number of the fluid emitting vents. These processes were associated to a wider network of fractures, seemingly generated by the shock wave produced by the gas blast that occurred at the main paroxysm. Geochemical characterization allowed an estimation of the source of the fluids, or at least their last standing, at about 3 km depth. Finally, the close time relationships observed between anomalous increments of seismic activity and the two main paroxysmal events accounted for a possible common trigger for both the phenomena, even with different timing due to the very different initial conditions and characteristics of the two processes, i.e. seismogenesis and gas overloading
Unitary Theory of Evaporating 2D Black Holes
We study a manifestly unitary formulation of 2d dilaton quantum gravity based
on the reduced phase space quantization. The spacetime metric can be expanded
in a formal power series of the matter energy-momentum tensor operator. This
expansion can be used for calculating the quantum corrections to the classical
black hole metric by evaluating the expectation value of the metric operator in
an appropriate class of the physical states. When the normal ordering in the
metric operator is chosen to be with respect to Kruskal vacuum, the lowest
order semiclassical metric is exactly the one-loop effective action metric
discovered by Bose, Parker and Peleg. The corresponding semiclassical geometry
describes an evaporating black hole which ends up as a remnant. The calculation
of higher order corrections and implications for the black hole fate are
discussed.Comment: LaTex fil
Gauge Invariant Formulations of Lineal Gravity
It is shown that the currently studied ``string-inspired'' model for gravity
on a line can be formulated as a gauge invariant theory based on the Poincar\'e
group with central extension -- a formulation that complements and simplifies
H.~Verlinde's construction based on the unextended Poincar\'e group.Comment: 11 p
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