3,148 research outputs found
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
Spinning Relativistic Particle in an External Electromagnetic Field
The Hamiltonian formulation of the motion of a spinning relativistic particle
in an external electromagnetic field is considered. The approach is based on
the introduction of new coordinates and their conjugated momenta to describe
the spin degrees of freedom together with an appropriate set of constraints in
the Dirac formulation. For particles with gyromagnetic ratio , the
equations of motion do not predict any deviation from the standard Lorentz
force, while for an additional force, which corresponds to the
magnetic dipole force, is obtained.Comment: Latex file, 11 page
Kruskal coordinates as canonical variables for Schwarzschild black holes
We derive a transformation from the usual ADM metric-extrinsic curvature
variables on the phase space of Schwarzschild black holes, to new canonical
variables which have the interpretation of Kruskal coordinates. We explicitly
show that this transformation is non-singular, even at the horizon. The
constraints of the theory simplify in terms of the new canonical variables and
are equivalent to the vanishing of the canonical momenta. Our work is based on
earlier seminal work by Kuchar in which he reconstructed curvature coordinates
and a mass function from spherically symmetric canonical data. The key feature
in our construction of a nonsingular canonical transformation to Kruskal
variables, is the scaling of the curvature coordinate variables by the mass
function rather than by the mass at left spatial infinity.Comment: 18 pages, no figure
Geometrodynamical Formulation of Two-Dimensional Dilaton Gravity
Two-dimensional matterless dilaton gravity with arbitrary dilatonic potential
can be discussed in a unitary way, both in the Lagrangian and canonical
frameworks, by introducing suitable field redefinitions. The new fields are
directly related to the original spacetime geometry and in the canonical
picture they generalize the well-known geometrodynamical variables used in the
discussion of the Schwarzschild black hole. So the model can be quantized using
the techniques developed for the latter case. The resulting quantum theory
exhibits the Birkhoff theorem at the quantum level.Comment: 15 pages, LATE
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
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
The 2D analogue of the Reissner-Nordstrom solution
A two-dimensional (2D) dilaton gravity model, whose static solutions have the
same features of the Reissner-Nordstrom solutions, is obtained from the
dimensional reduction of a four-dimensional (4D) string effective action
invariant under S-duality transformations. The black hole solutions of the 2D
model and their relationship with those of the 4D theory are discussed.Comment: 5 pages, Plain-Tex, no figure
A note on Weyl transformations in two-dimensional dilaton gravity
We discuss Weyl (conformal) transformations in two-dimensional matterless
dilaton gravity. We argue that both classical and quantum dilaton gravity
theories are invariant under Weyl transformations.Comment: 8 pages, accepted for publication in Mod. Phys. Lett.
TWO DIMENSIONAL DILATON GRAVITY COUPLED TO AN ABELIAN GAUGE FIELD
The most general two-dimensional dilaton gravity theory coupled to an Abelian
gauge field is considered. It is shown that, up to spacetime diffeomorphisms
and gauge transformations, the field equations admit a two-parameter
family of distinct, static solutions.
For theories with black hole solutions, coordinate invariant expressions are
found for the energy, charge, surface gravity, Hawking temperature and entropy
of the black holes. The Hawking temperature is proportional to the surface
gravity as expected, and both vanish in the case of extremal black holes in the
generic theory. A Hamiltonian analysis of the general theory is performed, and
a complete set of (global) Dirac physical observables is obtained. The theory
is then quantized using the Dirac method in the WKB approximation. A connection
between the black hole entropy and the imaginary part of the WKB phase of the
Dirac quantum wave functional is found for arbitrary values of the mass and
charge. The imaginary part of the phase vanishes for extremal black
holes and for eternal, non-extremal Reissner-Nordstrom black holes.Comment: Minor revisions only. Some references have been added, and some
typographical errors correcte
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