6,878 research outputs found
The excitation of a charged string passing through a shock wave in a charged Aichelburg-Sexl spacetime
We investigate how much a first-quantized charged bosonic test string gets
excited after crossing a shock wave generated by a charged particle with mass
and charge . On the basis of Kaluza-Klein theory, we pay
attention to a closed string model where charge is given by a momentum along a
compactified extra-dimension. The shock wave is given by a charged
Aichelburg-Sexl (CAS) spacetime where corresponds to the ordinary
Aichelburg-Sexl one. We first show that the CAS spacetime is a solution to the
equations of motion for the metric, the gauge field, and the axion field in the
low-energy limit. Secondly, we compute the mass expectation value of the
charged test string after passing through the shock wave in the CAS spacetime.
In the case of small , gravitational and Coulomb forces are
canceled out each other and hence the excitation of the string remains very
small. This is independent of the particle mass or the strength of
the shock wave. In the case of large , however, every charged string
gets highly excited by quantum fluctuation in the extra-dimension caused by
both the gauge and the axion fields. This is quite different from classical
"molecule", which consists of two electrically charged particles connected by a
classical spring.Comment: Latex, 20 pages, no figures, accepted for Nucl. Phys.
Fundamental vs. Solitonic Description of D3 branes
Type IIB string theory expanded around D3 brane backgrounds describes the
dynamics of D3 branes as solitonic objects. On the other hand, there is a
fundamental description of them via Polchinski's open strings with Dirichlet
boundary conditions. Since these two descriptions describe the dynamics of the
same objects, D3 branes, it is natural to believe that they are dual. Therefore
at this level, we have a string-string duality as opposed to a string-field
theory duality. Once we take the same limits in both descriptions, Maldacena
Conjecture in its weaker form follows. We try to make this viewpoint precise
and study the implication of it for the stronger form of Maldacena Conjecture.Comment: 11 pages, 3 figures, typos correcte
A Polynomial Hybrid Monte Carlo Algorithm
We present a simulation algorithm for dynamical fermions that combines the
multiboson technique with the Hybrid Monte Carlo algorithm. We find that the
algorithm gives a substantial gain over the standard methods in practical
simulations. We point out the ability of the algorithm to treat fermion
zeromodes in a clean and controllable manner.Comment: Latex, 1 figure, 12 page
Strings in the pp-wave Background from Membrane
In this paper we study strings with quantized masses in the pp-wave
background. We obtain these strings from the membrane theory. For achieving to
this, one of the membrane and one of the spacetime directions will be
identified and wrapped. From the action of strings in the pp-wave background,
we obtain its mass dual action. Some properties of the closed and open strings
in this background will be studied.Comment: 15 pages, Latex, no figure, major changes have been introduce
Ordering monomial factors of polynomials in the product representation
The numerical construction of polynomials in the product representation (as
used for instance in variants of the multiboson technique) can become
problematic if rounding errors induce an imprecise or even unstable evaluation
of the polynomial. We give criteria to quantify the effects of these rounding
errors on the computation of polynomials approximating the function . We
consider polynomials both in a real variable and in a Hermitian matrix. By
investigating several ordering schemes for the monomials of these polynomials,
we finally demonstrate that there exist orderings of the monomials that keep
rounding errors at a tolerable level.Comment: Latex2e file, 7 figures, 32 page
Phase Structure of Black Holes and Strings on Cylinders
We use the (M,n) phase diagram recently introduced in hep-th/0309116 to
investigate the phase structure of black holes and strings on cylinders. We
first prove that any static neutral black object on a cylinder can be put into
an ansatz for the metric originally proposed in hep-th/0204047, generalizing a
result of Wiseman. Using the ansatz, we then show that all branches of
solutions obey the first law of thermodynamics and that any solution has an
infinite number of copies. The consequences of these two results are analyzed.
Based on the new insights and the known branches of solutions, we finally
present an extensive discussion of the possible scenarios for the
Gregory-Laflamme instability and the black hole/string transition.Comment: 26 pages, 10 figures, v2: refs. added, minor corrections and
addition
Recent Developments in Fermion Simulation Algorithms
A summary of recent developments in the field of simulation algorithms for
dynamical fermions is given.Comment: Plenary talk given at the International Symposium on Lattice Field
Theory, 4-8 June 1996, St. Louis, Mo, USA, Latex, 3 Figures, 7 page
Performance Tests of the Kramers Equation and Boson Algorithms for Simulations of QCD
We present a performance comparison of the Kramers equation and the boson
algorithms for simulations of QCD with two flavors of dynamical Wilson fermions
and gauge group . Results are obtained on , and
lattices. In both algorithms a number of optimizations are installed.Comment: uuencoded postscript file, no figures, 10 page
Strings in Plane Wave Backgrounds Revisited
String theory in an exact plane wave background is explored. A new example of
singularity in the sense of string theory for nonsingular spacetime metric is
presented. The 4-tachyon scattering amplitude is constructed. The spectrum of
states found from the poles in the factorization turns out to be equivalent to
that of the theory in flat space-time. The massless vertex operator is obtained
from the residue of the first order pole.Comment: 15 pages, GTCRG-8, RevTe
Entropy of Non-Extreme Rotating Black Holes in String Theories
We formulate the Rindler space description of rotating black holes in string
theories. We argue that the comoving frame is the natural frame for studying
thermodynamics of rotating black holes and statistical analysis of rotating
black holes gets simplified in this frame. We also calculate statistical
entropies of general class of rotating black holes in heterotic strings on tori
by applying D-brane description and the correspondence principle. We find at
least qualitative agreement between the Bekenstein-Hawking entropies and the
statistical entropies of these black hole solutions.Comment: 29 pages, uses RevTe
- …