508 research outputs found
Interactions for Winding Strings in Misner Space
We compute correlation functions of closed strings in Misner space, a big
crunch big bang universe. We develop a general method for correlators with
twist fields, which are relevant for the investigation on the condensation of
winding tachyon. We propose to compute the correlation functions by performing
an analytic continuation of the results in C/Z_N Euclidean orbifold. In
particular, we obtain a finite result for a general four point function of
twist fields, which might be important for the interpretation as the quartic
term of the tachyon potential. Three point functions are read off through the
factorization, which are consistent with the known results.Comment: 29 pages, no figure; typos corrected, references adde
Topological String on OSP(1|2)/U(1)
We propose an equivalence between topological string on OSP(1|2)/U(1) and
\hat{c} \leq 1 superstring with N=1 world-sheet supersymmetry. We examine this
by employing a free field representation of OSP(1|2) WZNW model and find an
agreement on the spectrum. We also analyze this proposal at the level of
scattering amplitudes by applying a map between correlation functions of
OSP(1|2) WZNW model and those of N=1 Liouville theory.Comment: 25 pages, refereces adde
The adiabatic evolution of orbital parameters in the Kerr spacetime
We investigate the adiabatic orbital evolution of a point particle in the
Kerr spacetime due to the emission of gravitational waves. In the case that the
timescale of the orbital evolution is enough smaller than the typical timescale
of orbits, the evolution of orbits is characterized by the change rates of
three constants of motion, the energy , the azimuthal angular momentum ,
and the Carter constant . For and , we can evaluate their change
rates from the fluxes of the energy and the angular momentum at infinity and on
the event horizon according to the balance argument. On the other hand, for the
Carter constant, we cannot use the balance argument because we do not know the
conserved current associated with it. %and the corresponding conservation law.
Recently, Mino proposed a new method of evaluating the averaged change rate of
the Carter constant by using the radiative field. In our previous paper we
developed a simplified scheme for practical evaluation of the evolution of the
Carter constant based on the Mino's proposal. In this paper we describe our
scheme in more detail, and derive explicit analytic formulae for the change
rates of the energy, the angular momentum and the Carter constant.Comment: 34 pages, no figur
Self-force Regularization in the Schwarzschild Spacetime
We discuss the gravitational self-force on a particle in a black hole
space-time. For a point particle, the full (bare) self-force diverges. The
metric perturbation induced by a particle can be divided into two parts, the
direct part (or the S part) and the tail part (or the R part), in the harmonic
gauge, and the regularized self-force is derived from the R part which is
regular and satisfies the source-free perturbed Einstein equations. But this
formulation is abstract, so when we apply to black hole-particle systems, there
are many problems to be overcome in order to derive a concrete self-force.
These problems are roughly divided into two parts. They are the problem of
regularizing the divergent self-force, i.e., ``subtraction problem'' and the
problem of the singularity in gauge transformation, i.e., ``gauge problem''. In
this paper, we discuss these problems in the Schwarzschild background and
report some recent progress.Comment: 34 pages, 2 figures, submitted to CQG, special volume for Radiation
Reaction (CAPRA7
Liouville Field Theory on an Unoriented Surface
Liouville field theory on an unoriented surface is investigated, in
particular, the one point function on a RP^2 is calculated. The constraint of
the one point function is obtained by using the crossing symmetry of the two
point function. There are many solutions of the constraint and we can choose
one of them by considering the modular bootstrap.Comment: 13 pages, no figures, LaTeX, minor changes, equations in section 4
are correcte
Crosscap States for Orientifolds of Euclidean AdS_3
Crosscap states for orientifolds of Euclidean AdS_3 are constructed. We show
that our crosscap states describe the same orientifolds which were obtained by
the classical analysis. The spectral density of open strings in the system with
orientifold can be read from the M"obius strip amplitudes and it is compared to
that of the open strings stretched between branes and their mirrors. We also
compute the Klein bottle amplitudes.Comment: 17 pages, LaTeX2e, v2: clarification and discussion added, v3: minor
changes, to appear in JHE
Orbital evolution of a test particle around a black hole: Indirect determination of the self force in the post Newtonian approximation
Comparing the corrections to Kepler's law with orbital evolution under a self
force, we extract the finite, already regularized part of the latter in a
specific gauge. We apply this method to a quasi-circular orbit around a
Schwarzschild black hole of an extreme mass ratio binary, and determine the
first- and second-order conservative gravitational self force in a post
Newtonian expansion. We use these results in the construction of the
gravitational waveform, and revisit the question of the relative contribution
of the self force and spin-orbit coupling.Comment: 5 pages, 2 figure
DDF and Pohlmeyer invariants of (super)string
We show how the Pohlmeyer invariants of the bosonic string are expressible in
terms of DDF invariants. Quantization of the DDF observables in the usual way
yields a consistent quantization of the algebra of Pohlmeyer invariants.
Furthermore it becomes straightforward to generalize the Pohlmeyer invariants
to the superstring as well as to all backgrounds which allow a free field
realization of the worldsheet theory.Comment: 17 pp, minor typos corrected, references to papers by Isaev and
Borodulin added, which contain essentially the same results as reported her
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