N=1 super Yang-Mills on a (3+1) dimensional transverse lattice with one exact supersymmetry

We formulate ${\cal N}$=1 super Yang-Mills theory in 3+1 dimensions on a two dimensional transverse lattice using supersymmetric discrete light cone quantization in the large-$N_c$ limit. This formulation is free of fermion species doubling. We are able to preserve one supersymmetry. We find a rich, non-trivial behavior of the mass spectrum as a function of the coupling $g\sqrt{N_c}$, and see some sort of "transition" in the structure of a bound state as we go from the weak coupling to the strong coupling. Using a toy model we give an interpretation of the rich behavior of the mass spectrum. We present the mass spectrum as a function of the winding number for those states whose color flux winds all the way around in one of the transverse directions. We use two fits to the mass spectrum and the one that has a string theory justification appears preferable. For those states whose color flux is localized we present an extrapolated value for $m^2$ for some low energy bound states in the limit where the numerical resolution goes to infinity.Comment: 23(+2 for v3) pages, 19 figures; v2: a footnote added; v3: an appendix, comments, references added. The version to appear PR

Dissipation of mechanical energy in fused silica fibers

For thermal noise considerations of LIGO suspensions, the sources of dissipation in the suspending fibers must be analyzed. To determine the dissipation induced by the surface of fused silica fibers, we measured the quality factor of fibers having various diameters. We measured a maximum quality factor of 21 million and extrapolated to obtain an intrinsic quality factor for fused silica of 30 million. Dissipation in the surface dominated at diameters less than about 1 mm. We developed a method for characterizing surface-induced dissipation that is independent of sample geometry or mode shape.Comment: 20 pages, 6 figures, RevTeX. Minor Revisions. Accepted for publication by Review of Scientific Instruments (29 June 1999). Projected publication date: October 199

D1D5 microstate geometries from string amplitudes

We reproduce the asymptotic expansion of the D1D5 microstate geometries by computing the emission amplitudes of closed string states from disks with mixed D1D5 boundary conditions. Thus we provide a direct link between the supergravity and D-brane descriptions of the D1D5 microstates at non-zero string coupling. Microscopically, the profile functions characterizing the microstate solutions are encoded in the choice of a condensate for the twisted open string states connecting D1 and D5 branes.Comment: 21 pages; added reference

Radiation from the non-extremal fuzzball

The fuzzball proposal says that the information of the black hole state is distributed throughout the interior of the horizon in a `quantum fuzz'. There are special microstates where in the dual CFT we have `many excitations in the same state'; these are described by regular classical geometries without horizons. Jejjala et.al constructed non-extremal regular geometries of this type. Cardoso et. al then found that these geometries had a classical instability. In this paper we show that the energy radiated through the unstable modes is exactly the Hawking radiation for these microstates. We do this by (i) starting with the semiclassical Hawking radiation rate (ii) using it to find the emission vertex in the CFT (iii) replacing the Boltzman distributions of the generic CFT state with the ones describing the microstate of interest (iv) observing that the emission now reproduces the classical instability. Because the CFT has `many excitations in the same state' we get the physics of a Bose-Einstein condensate rather than a thermal gas, and the usually slow Hawking emission increases, by Bose enhancement, to a classically radiated field. This system therefore provides a complete gravity description of information-carrying radiation from a special microstate of the nonextremal hole.Comment: corrected typo

Pulsating Strings in Deformed Backgrounds

This is a brief summary on pulsating strings in beta deformed backgrounds found recently.Comment: 8 pages. Talk presented at Quantum Theory and Symmetries 7, Prague, August 7-13, 201

M-theory Supertubes with Three and Four Charges

Using the covariant M5-brane action, we construct configurations corresponding to supertubes with three and four charges. We derive the BPS equations and study the full structure of the solutions. In particular, we find new solutions involving arbitrariness in field strengths.Comment: 24 pages, references added and typos correcte

On the stability and spectrum of non-supersymmetric AdS(5) solutions of M-theory compactified on Kahler-Einstein spaces

Eleven-dimensional supergravity admits non-supersymmetric solutions of the form AdS(5)xM(6) where M(6) is a positive Kahler-Einstein space. We show that the necessary and sufficient condition for such solutions to be stable against linearized bosonic supergravity perturbations can be expressed as a condition on the spectrum of the Laplacian acting on (1,1)-forms on M(6). For M(6)=CP(3), this condition is satisfied, although there are scalars saturating the Breitenlohner-Freedman bound. If M(6) is a product S(2)xM(4) (where M(4) is Kahler-Einstein) then there is an instability if M(4) has a continuous isometry. We show that a potential non-perturbative instability due to 5-brane nucleation does not occur. The bosonic Kaluza-Klein spectrum is determined in terms of eigenvalues of operators on M(6).Comment: 21 pages. v2: Includes SU(4) quantum numbers for CP3 case, typos fixed, refs adde

N=(1,1) super Yang--Mills theory in 1+1 dimensions at finite temperature

We present a formulation of N=(1,1) super Yang-Mills theory in 1+1 dimensions at finite temperature. The partition function is constructed by finding a numerical approximation to the entire spectrum. We solve numerically for the spectrum using Supersymmetric Discrete Light-Cone Quantization (SDLCQ) in the large-N_c approximation and calculate the density of states. We find that the density of states grows exponentially and the theory has a Hagedorn temperature, which we extract. We find that the Hagedorn temperature at infinite resolution is slightly less than one in units of (g^(2) N_c/pi)^(1/2). We use the density of states to also calculate a standard set of thermodynamic functions below the Hagedorn temperature. In this temperature range, we find that the thermodynamics is dominated by the massless states of the theory.Comment: 16 pages, 8 eps figures, LaTe

Splitting hairs of the three charge black hole

We construct the large radius limit of the metric of three charge supertubes and three charge BPS black rings by using the fact that supertubes preserve the same supersymmetries as their component branes. Our solutions reproduce a few of the properties of three charge supertubes found recently using the Born Infeld description. Moreover, we find that these solutions pass a number of rather nontrivial tests which they should pass if they are to describe some of the hair of three charge black holes and three charge black rings.Comment: 15 pages, LaTeX, v2 minor correction

Very high quality factor measured in annealed fused silica

We present the results of quality factor measurements for rod samples made of fused silica. To decrease the dissipation we annealed our samples. The highest quality factor that we observed was $Q=(2.03\pm0.01)\times10^8$ for a mode at 384 Hz. This is the highest published value of $Q$ in fused silica measured to date.Comment: 8 pages, 2 figure