15969913
Perturbed Electroweak Strings and Fermion Zero Modes
Abstract The effect of perturbations of electroweak strings on quark zero modes is studied in 2+1 and 3+1 dimensions. As first discovered by Naculich, it is found that the bosonic perturbations that destabilize the string give a mass to the zero modes and also lift their degeneracy. The effect of the zero modes on the stability of the string is discussed qualitatively and, based on general arguments, we conjecture that the fermionic vacuum instability found by Naculich should lead to a distortion of the bosonic string but not be responsible for decay.
119533356
SU(5) monopoles and the dual standard model
We find the spectrum of magnetic monopoles produced in the symmetry breaking SU(5){r_arrow}[SU(3){times}SU(2){times}U(1){prime}]/Z{sub 6} by constructing classical bound states of the fundamental monopoles. The spectrum of monopoles is found to correspond to the spectrum of one family of standard model fermions and, hence, is a starting point for constructing the dual standard model. At this level, however, there is an extra monopole state {emdash} the {open_quotes}diquark{close_quotes} monopole {emdash} with no corresponding standard model fermion. If the SU(3) factor now breaks down to Z{sub 3}, the monopoles with nontrivial SU(3) charge get confined by strings in SU(3) singlets. Another outcome of this symmetry breaking is that the diquark monopole becomes unstable (metastable) to fragmentation into fundamental monopoles and the one-one correspondence with the standard model fermions is restored. We discuss the fate of the monopoles if the [SU(2){times}U(1){prime}]/Z{sub 2} factor breaks down to U(1){sub Q} by a Higgs mechanism as in the electroweak model. Here we find that monopoles that are misaligned with the vacuum get connected by strings even though the electroweak symmetry breaking does not admit topological strings. We discuss the lowest order quantum corrections to the mass spectrum of monopoles. {copyright} {ital 1997} {ital The American Physical Society}
1675226
Ramond–Ramond couplings of noncommutative D-branes
Abstract We propose the leading couplings, in an α ′ expansion, of D-branes to Ramond–Ramond (RR) potentials in a constant NS–NS B-field for an arbitrary choice of noncommutative parameter. The proposal is motivated by some string amplitude computations. The zero momentum couplings are topological in nature and include Elliott's formula involving the noncommutative Chern character. The finite momentum couplings are given by smearing the zero momentum operators along an open Wilson line. Comparisons between the RR couplings in different descriptions lead to a better understanding of the field redefinitions between gauge field variables (the Seiberg–Witten map) and help constrain α ′ corrections. In particular we recover the Seiberg–Witten map conjectured by one of the authors in hep-th/0011125. We also discuss the dynamics of the transverse scalar fields and find evidence for a new derivative-driven dielectric effect.
7373383
Supergravity couplings of noncommutative D-branes
Abstract We discuss the supergravity couplings of noncommutative D-branes by considering the disk amplitudes with one closed string insertion. The result confirms a recent proposal for the general form of the noncommutative Yang–Mills operators coupling to the massless closed string modes. The construction involves smearing Yang–Mills field variables along an open Wilson line. For multiple D-branes interacting with background supergravity fields, this prescription reduces, in the B =0 limit, to the “symmetrized trace” prescription, and the supergravity fields are seen to be functionals of the nonabelian scalar fields on the branes.
17322710
Quantum hair, instantons, and black hole thermodynamics: some new results
Abstract We present results obtained by a consideration of the non-classical energy-momentum tensor associated with Euclidean instantons outside the event horizon of black holes. We demonstrate here how this allows for an analytic estimate to be made of the effect of discrete quantum hair on the temperature of the black hole, in which the role of violations of the weak energy condition associated with instantons is made explicit, and in which the previous results of Coleman, Preskill, and Wilczek are extended. Last, we demonstrate how the existence of a non-classical electric field outside the event horizon of black holes, uncovered by these authors, can be identified with a well-known effect in the Abelian Higgs mode] in two dimensions. In this case, there is a one-to-one connection between the discrete charge of a black hole and a topological phase in two dimensions.
16866051
Dirty Black Holes and Hairy Black Holes.
An approach based on considerations of the nonclassical energy momentum tensor outside the event horizon of a black hole provides additional physical insight into the nature of discrete quantum hair on black holes and its effect on black hole temperature. Our analysis both extends previous work based on the Euclidean action techniques and corrects an omission in that work. We also raise several issues related to the effects of instantons on black hole thermodynamics and the relation between these effects and results in two dimensional quantum field theory. {copyright} {ital 1996 The American Physical Society.}
119247810
Killing spinors for the bosonic string and Kaluza–Klein theory with scalar potentials
The paper consists mainly of two parts. In the first part, we obtain well-defined Killing spinor equations for the low-energy effective action of the bosonic string with the conformal anomaly term. We show that the conformal anomaly term is the only scalar potential that one can add into the action that is consistent with the Killing spinor equations. In the second part, we demonstrate that Kaluza–Klein theory can be gauged so that the Killing spinors are charged under the Kaluza–Klein vector. This gauging process generates a scalar potential with a maximum that gives rise to an AdS spacetime. We also construct solutions of these theories.
5671648
Time-dependent solution for a star immersed in a background radiation
We study a time-dependent and spherically symmetric solution with a starlike source. We show that this solution can be interpreted as an exterior solution of a contracting star which has a decreasing temperature and is immersed in a homogenous and isotropic background radiation. Distribution of the temperature in the fields and close-to-Schwarzschild approximation of the solution are studied. By identifying the radiation with the cosmic background one, we find that the close-to-Schwarzschild approximate solution is valid in a wide range in our solar system. Possible experimental tests of the solution are discussed briefly.
118582285
The dynamic behavior of quantum statistical entropy in 5D Ricci-flat black string with thin-layer approach
Abstract In this Letter, the statistical–mechanical entropies of 5D Ricci-flat black string is calculated through the wave modes of the quantum field with improved thin-layer brick-wall method. The modes along the fifth dimension are semi-classically quantized by Randall–Sundrum mass relationship. We use the two-dimensional area to describe this black string's entropy which, in the small-mass approximation, is a linear sum of the area of the black hole horizon and the cosmological horizon. The proportionality coefficients of entropy are discretized with quantized extra dimensional modes. It should be noted that the small-mass approximation used in our calculation is naturally justified by the assumption that the two branes are located far apart.
20448840
Statefinder parameters for interacting phantom energy with dark matter
In this paper we apply the statefinder parameters to the interacting phantom energy with dark matter. There are two kinds of scaling solution in this model. It is found that the evolving trajectories of these two scaling solutions in the statefinder parameter plane are quite different, and that they are also different from the statefinder diagnostic of other dark energy models.
118482632
The Numerical Solution of Scalar Field for Nariai Case in 5D Ricci-flat SdS Black String Space with Polynomial Approximation
As one exact candidate of the higher dimensional black hole, the 5D Ricci-flat Schwarzschild-de Sitter black string space presents something interesting. In this paper, we give a numerical solution to the real scalar field around the Nariai black hole by the polynomial approximation. Unlike the previous tangent approximation, this fitting function makes a perfect match in the leading intermediate region and gives a good description near both the event and the cosmological horizons. We can read from our results that the wave is close to a harmonic one with the tortoise coordinate. Furthermore, with the actual radial coordinate the waves pile up almost equally near the both horizons.