169 research outputs found
An Exact Solution to O(26) Sigma Model coupled to 2-D Gravity
By a mapping to the bosonic string theory, we present an exact solution to
the O(26) sigma model coupled to 2-D quantum gravity. In particular, we obtain
the exact gravitational dressing to the various matter operators classified by
the irreducible representations of O(26). We also derive the exact form of the
gravitationally modified beta function for the original coupling constant
. The relation between our exact solution and the asymptotic solution
given in ref[3] is discussed in various aspects.Comment: 10 pages, pupt-144
A note on positive energy of topologically massive gravity
I review how "classical SUGRA" embeddability establishes positive energy E
for D=3 topologically massive gravity (TMG), with or without a cosmological
term, a procedure familiar from D=4 Einstein gravity (GR). It also provides
explicit expressions for E. In contrast to GR, E is not manifestly positive,
due to the peculiar two-term nature of TMG.Comment: 7 page
The Effect of Filteret Sugarcane Juice in Egg Yolk Citrate on Viability and Spermatozoa Abnormality, and pH of Bali Catle Semen
This study aims to determine the effect of the sugarcane juice diluent in egg yolk citrate on viability, spermatozoa abnormality, and pH of Bali bull semen. This study has been carried out in Poultry Housing of Animal Science Study Program, and the Laboratory of the Faculty of Agriculture, University of Timor. Semen is collected from a a bull, ± 4.5 years old, in healthy condition. The method used in this study was a completely randomized design method with 5 treatments and 4 replications. The treatment giving are: T0 (diluent citrate-egg yolk without sugarcane juice); T1 (diluent citrate-egg yolk + 5ml sugarcane juice); T2 (diluent citrate-egg yolk + 10 ml sugarcane juice); T3 (diluent citrate-egg yolk + 15 ml sugarcane juice) and T4 (diluent citrate-yolk + sugar cane juice 20 ml). The variables measured were viability, abnormal spermatozoa, and semen pH of Bali bull. The results showed that T4 treatment with a 20 ml sugarcane juice level showed the best value for spermatozoa viability (92.875%), spermatozoa abnormality (6.375%), and semen pH (6.6). Conclusion: that the level of 20 ml of sugarcane juice in semen diluent can maintain the life of Bali bull spermatozoa
(2,0) Chern-Simons Supergravity Plus Matter Near the Boundary of AdS_3
We examine the boundary behaviour of the gauged N=(2,0) supergravity in D=3
coupled to an arbitrary number of scalar supermultiplets which parametrize a
Kahler manifold. In addition to the gravitational coupling constant, the model
depends on two parameters, namely the cosmological constant and the size of the
Kahler manifold. It is shown that regular and irregular boundary conditions can
be imposed on the matter fields depending on the size of the sigma model
manifold. It is also shown that the super AdS transformations in the bulk
produce the transformations of the N=(2,0) conformal supergravity and scalar
multiplets on the boundary, containing fields with nonvanishing Weyl weights
determined by the ratio of the sigma model and the gravitational coupling
constants. Various types of (2,0) superconformal multiplets are found on the
boundary and in one case the superconformal symmetry is shown to be realized in
an unconventional way.Comment: 28 pages, latex, references adde
Renormalization Group Flows in Sigma--Models Coupled to Two--Dimensional Dynamical Gravity
We consider a bosonic \s--model coupled to two--dimensional gravity. In the
semiclassical limit, , we compute the gravity dressing of
the \b--functions at two--loop order in the matter fields. We find that the
corrections due to the presence of dynamical gravity are {\em not} expressible
simply in terms of a multiplicative factor as previously obtained at the
one--loop level. Our result indicates that the critical points of the theory
are nontrivially influenced and modified by the induced gravity.Comment: Latex file, 18 pages plus 7 figure
Decay widths of lowest massive Regge excitations of open strings
With the advent of the LHC there is widespread interest in the discovery
potential for physics beyond the standard model. In TeV-scale open string
theory, the new physics can be manifest in the excitation and decay of new
resonant structures, corresponding to Regge recurrences of standard model
particles. An essential input for the prediction of invariant mass spectra of
the decay products (which could serve to identify the resonance as a string
excitation) are the partial and total widths of the decay products. We present
a parameter-free calculation of these widths for the first Regge recurrence of
the SU(3) gluon octet, of the U(1) gauge boson which accompanies gluons in
D-brane constructions, and of the quark triplet.Comment: 12 pages revtex, 1 eps figur
CP^{N-1} models and the Quantized 2D Black Holes
We have examined the coupled system of the dilaton gravity and the
theory known as a model of the confinement of massive scalar quarks. After the
quantization of the system, we could see the quantum effect of the gravitation
on the coupling constant of model and how the coupling constant of
dynamically induced gauge field changes near the black hole configuration.Comment: 12 pages, Late
Kundt spacetimes as solutions of topologically massive gravity
We obtain new solutions of topologically massive gravity. We find the general
Kundt solutions, which in three dimensions are spacetimes admitting an
expansion-free null geodesic congruence. The solutions are generically of
algebraic type II, but special cases are types III, N or D. Those of type D are
the known spacelike-squashed AdS_3 solutions, and of type N are the known AdS
pp-waves or new solutions. Those of types II and III are the first known
solutions of these algebraic types. We present explicitly the Kundt solutions
that are CSI spacetimes, for which all scalar polynomial curvature invariants
are constant, whereas for the general case we reduce the field equations to a
series of ordinary differential equations. The CSI solutions of types II and
III are deformations of spacelike-squashed AdS_3 and the round AdS_3,
respectively.Comment: 30 pages. This material has come from splitting v1 of arXiv:0906.3559
into 2 separate papers. v2: minor changes
Gravitational Dressing of N=2 Sigma-Models Beyond Leading Order
We study the beta-function of the N=2 sigma-model coupled to N=2 induced
supergravity. We compute corrections to first order in the semiclassical limit,
, beyond one-loop in the matter fields. As compared to the
corresponding bosonic, metric sigma-model calculation, we find new types of
contributions arising from the dilaton coupling automatically accounted for,
once the K\"ahler potential is coupled to N=2 supergravity.Comment: latex, 16 pages, 8 figure
Timelike Boundary Liouville Theory
The timelike boundary Liouville (TBL) conformal field theory consisting of a
negative norm boson with an exponential boundary interaction is considered. TBL
and its close cousin, a positive norm boson with a non-hermitian boundary
interaction, arise in the description of the accumulation point of
minimal models, as the worldsheet description of open string tachyon
condensation in string theory and in scaling limits of superconductors with
line defects. Bulk correlators are shown to be exactly soluble. In contrast,
due to OPE singularities near the boundary interaction, the computation of
boundary correlators is a challenging problem which we address but do not fully
solve. Analytic continuation from the known correlators of spatial boundary
Liouville to TBL encounters an infinite accumulation of poles and zeros. A
particular contour prescription is proposed which cancels the poles against the
zeros in the boundary correlator d(\o) of two operators of weight \o^2 and
yields a finite result. A general relation is proposed between two-point CFT
correlators and stringy Bogolubov coefficients, according to which the
magnitude of d(\o) determines the rate of open string pair creation during
tachyon condensation. The rate so obtained agrees at large \o with a
minisuperspace analysis of previous work. It is suggested that the mathematical
ambiguity arising in the prescription for analytic continuation of the
correlators corresponds to the physical ambiguity in the choice of open string
modes and vacua in a time dependent background.Comment: 28 pages, 1 figure, v2 reference and acknowledgement adde
- âŠ