15602764
Two black hole holography, lensing, and intensity
We numerically verify the analysis of the 'expanding horizon' theory of Susskind in relation to the 't Hooft holographic conjecture. By using a numerical simulation to work out the holographic image formed by two black holes upon a screen very far away, it is seen that it is impossible for a horizon to hide behind another. We also compute the holographic intensity distribution of such an arrangement.
13946666
A Quantum Mechanical Model of Spherical Supermembranes
We present a quantum mechanical model of spherical supermembranes. Using superfields to represent the cartesian coordinates of the membrane, we are able to exactly determine its supersymmetric vacua. We find there are two classical vacua, one corresponding to an extended membrane and one corresponding to a point-like membrane. For the = 2 case, instanton effects then lift these vacua to massive states. For the = 4 case, there is no instanton tunneling, and the vacua remain massless. Similarities to spherical supermembranes as giant gravitons and in Matrix theory on pp-waves is discussed.
3247660
Spin-statistics violations in superstring theory
I describe how superstring theory may violate spin statistics in an experimentally observable manner. Reviewing the basics of superstring interactions and how to utilize these to produce a statistical phase, I then apply these ideas to two specific examples. The first is the case of heterotic world sheet linkings, whereby one small closed string momentarily enlarges sufficiently to pass over another, producing such a statistical phase. The second is the braneworld model with noncommutative geometry, whereby matter composed of open strings may couple to a background in which spacetime coordinates do not commute, modifying the field (anti)commutator algebra. I conclude with ways to sharpen and experimentally test these exciting avenues to possibly verify superstring theory.
276424
Gravitational Wave Bursts from Cosmic Superstring Reconnections
We compute the gravitational waveform produced by cosmic superstring reconnections. This is done by first constructing the superstring reconnection trajectory, which closely resembles that of classical, instantaneous reconnection but with the singularities smoothed out due to the string path integral. We then evaluate the graviton vertex operator in this background to obtain the burst amplitude. The result is compared to the detection threshold for current and future gravitational wave detectors, finding that neither bursts nor the stochastic background would be detectable by Advanced LIGO. This disappointing but anticipated conclusion holds even for the most optimistic values of the reconnection probability and loop sizes.
7559823
Interactions of cosmic superstrings
We develop methods by which cosmic superstring interactions can be studied in detail. These include the reconnection probability and emission of radiation such as gravitons or small string loops. Loop corrections to these are discussed, as well as relationships to (p; q)-strings. These tools should allow a phenomenological study of string models in anticipation of upcoming experiments sensitive to cosmic string radiation.
18221217
A REFINED EPHEMERIS AND PHASE-RESOLVED X-RAY SPECTROSCOPY OF THE GEMINGA PULSAR
We present a refined, phase-connected, postglitch ephemeris for the Geminga pulsar that is a good fit to all the postglitch data from EGRET, ASCA, and XMM-Newton. We also present the results of phase-resolved spectroscopy of two XMM-Newton X-ray observations of the Geminga pulsar obtained in 2002 and 2004. An investigation is made into a previously claimed existence of a small hot spot on the neutron star surface. We conclude that that interpretation was more likely an artifact of an overly restrictive assumption used to fit the phase-resolved spectra: namely, that the spectral index of the nonthermal component is constant. When we allow the spectral index to vary as a function of rotation phase, we find systematic variations in spectral index, and such fits do not require an additional hot blackbody component.