Microscopic Entropy of Non-dilatonic Branes: a 2D approach

We investigate non-dilatonic p-branes in the near-extremal, near-horizon regime. A two-dimensional gravity model, obtained from dimensional reduction, gives an effective description of the brane. We show that the AdS_p+2/CFT_p+1 correspondence at finite temperature admits an effective description in terms of a AdS_2/CFT_1 duality endowed with a scalar field, which breaks the conformal symmetry and generates a non-vanishing central charge. The entropy of the CFT_1 is computed using Cardy formula. Fixing in a natural way a free, dimensionless, parameter introduced in the model by a renormalization procedure, we find exact agreement between the CFT_1 entropy and the Bekenstein-Hawking entropy of the brane.Comment: 10 pages, no figure

Electromagnetic Corrections in Partially Quenched Chiral Perturbation Theory

We introduce photons in Partially Quenched Chiral Perturbation Theory and calculate the resulting electromagnetic loop-corrections at NLO for the charged meson masses and decay constants. We also present a numerical analysis to indicate the size of the different corrections. We show that several phenomenologically relevant quantities can be calculated consistently with photons which couple only to the valence quarks, allowing the use of gluon configurations produced without dynamical photons.Comment: 11 page

The Moduli Space of the N=2N=2 Supersymmetric G2G_{2} Yang-Mills Theory

We present the hyper-elliptic curve describing the moduli space of the N=2 supersymmetric Yang-Mills theory with the $G_2$ gauge group. The exact monodromies and the dyon spectrum of the theory are determined. It is verified that the recently proposed solitonic equation is also satisfied by our solution.Comment: Complete set of monodromies are included. To be published in Phys.lett.

A not so brief commentary on cosmological entropy bounds

There has been, quite recently, a discussion on how holographic-inspired bounds might be used to encompass the present-day dark energy and early-universe inflation into a single paradigm. In the current treatment, we point out an inconsistency in the proposed framework and then provide a viable resolution. We also elaborate on some of the implications of this framework and further motivate the proposed holographic connection. The manuscript ends with a more speculative note on cosmic time as an emergent (holographically induced) construct.Comment: 12 pages and Revtex; (v2) reference added and a few cosmetic change

Space Noncommutativity Corrections to the Cardy-Verlinde Formula

In this letter we compute the corrections to the Cardy-Verlinde formula of Schwarzschild black holes. These corrections stem from the space noncommutativity. Because the Schwarzschild black holes are non rotating, to the first order of perturbative calculations, there is no any effect on the properties of black hole due to the noncommutativity of space.Comment: 7 pages, no figures, accepted for publication in Int. J. Mod. Phys.

A matrix model black hole: act II

In this paper we discuss the connection between the deformed matrix model and two dimensional black holes in the light of the new developements involving fermionic type 0A-string theory. We argue that many of the old results can be carried over to this new setting and that the original claims about the deformed matrix model are essentially correct. We show the agreement between correlation functions calculated using continuum and matrix model techniques. We also explain how detailed properties of the space time metric of the extremal black hole of type 0A are reflected in the deformed matrix model.Comment: 17 pages, version 2: minor typos correcte

Creation of Fundamental Strings by Crossing D-branes

We study the force balance between orthogonally positioned $p$-brane and $(8-p)$-brane. The force due to graviton and dilaton exchange is repulsive in this case. We identify the attractive force that balances this repulsion as due to one-half of a fundamental string stretched between the branes. As the $p$-brane passes through the $(8-p)$-brane, the connecting string changes direction, which may be interpreted as creation of one fundamental string. We show this directly from the structure of the Chern-Simons terms in the D-brane effective actions. We also discuss the effect of string creation on the 0-brane quantum mechanics in the type I' theory. The creation of a fundamental string is related by U-duality to the creation of a 3-brane discussed by Hanany and Witten. Both processes have a common origin in M-theory: as two M5-branes with one common direction cross, a M2-brane stretched between them is created.Comment: 6 pages, Late

The Moduli Space and Monodromies of the N=2N=2 Supersymmetric Yang-Mills Theory with any Lie Gauge Groups

We propose a unified scheme for finding the hyperelliptic curve of $N=2$ SUSY YM theory with any Lie gauge groups. Our general scheme gives the well known results for classical gauge groups and exceptional $G_2$ group. In particular, we present the curve for the exceptional gauge groups $F_4, E_{6,7,8}$ and check consistency condition for them. The exact monodromies and the dyon spectrum of these theories are determined. We note that for any Lie gauge groups, the exact monodromies could be obtained only from the Cartan matrix.Comment: 17 pages, LaTeX fil