Konstantin Bobkov

Non-thermal dark matter and the moduli problem in string frameworks

We address the cosmological moduli/gravitino problems and the issue of too little thermal but excessive non-thermal dark matter from the decays of moduli. The main examples we study are the G2-MSSM models arising from M theory compactifications, which allow for a precise calculation of moduli decay rates and widths. We find that the late decaying moduli satisfy both BBN constraints and avoid the gravitino problem. The non-thermal production of Wino LSPs, which is a prediction of G2-MSSM models, gives a relic density of about the right order of magnitude.

Explaining the electroweak scale and stabilizing moduli in M theory

In a recent paper [1] it was shown that in M theory vacua without fluxes, all moduli are stabilized by the effective potential and a stable hierarchy is generated, consistent with standard gauge unification. This paper explains the results of [1] in more detail and generalizes them, finding an essentially unique de Sitter (dS) vacuum under reasonable conditions. One of the main phenomenological consequences is a prediction which emerges from this entire class of vacua: namely gaugino masses are significantly suppressed relative to the gravitino mass. We also present evidence that, for those vacua in which the vacuum energy is small, the gravitino mass, which sets all the superpartner masses, is automatically in the TeV - 100 TeV range.

The G(2)-MSSM: An M Theory motivated model of Particle Physics

We continue our study of the low energy implications of

M theory Solution to the Hierarchy Problem

M

Laser alignment system for helical pinhole SPECT

theory vacua on

Helical-Path, Half-Cone-Beam Acquisition for SPECT Brain Imaging

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The effects of lead shielding of background organ activity in pinhole Single Photon Emission Computed Tomography (SPECT) breast tumor imaging

-manifolds, undertaken in B. S. Acharya, K. Bobkov, G. L. Kane, P. Kumar, and J. Shao, Phys. Rev. D 76, 126010 (2007); B. Acharya, K. Bobkov, G. Kane, P. Kumar, and D. Vaman, Phys. Rev. Lett. 97, 191601 (2006), where it was shown that the moduli can be stabilized and a TeV scale generated, with the Planck scale as the only dimensionful input. A well-motivated phenomenological model, the

Reduced incomplete-sampling artifacts in pinhole SPECT breast imaging using body-contour and lung-boundary constraints

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Statistical analysis of incomplete circular orbits for breast pinhole SPECT imaging

-MSSM, can be naturally defined within the above framework. In this paper, we study some of the important phenomenological features of the

Phantom assessment of new acquisition geometries for breast pinhole SPECT imaging

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