arXiv subjects

Emmanuel Kohlprath

Publications and source records attributed to Emmanuel Kohlprath.

5 recordsLinked to original sources

arXiv2004

Localized gravity in non-compact superstring models

We discuss a string-theory-derived mechanism for localized gravity, which produces a deviation from Newton's law of gravitation at cosmological distances. This mechanism can be realized for general non-compact Calabi-Yau manifolds, orbifolds and orientifolds. After discussing the cross-over scale and the thickness in these models we show that the localized higher derivative terms can be safely neglected at observable distances. We conclude by some observations on the massless open string spectrum for the orientifold models.

hep-th↗

arXiv2004

Induced gravity in Z_N orientifold models

We consider non-compact Z_N orientifold models of type IIB superstring theory with four-dimensional gravity induced on a set of coincident D3-branes. For the models with odd N the contribution to the one-loop renormalization of the Planck mass is shown to come only from the torus and to be O(N) as the contributions from annulus, Moebius strip and Klein bottle cancel. One can therefore realize the Dvali-Gabadadze-Porrati idea that four-dimensional gravity is induced by quantum effects at the one-loop level by considering large N.

hep-th↗

arXiv2002

Renormalization of the Planck mass for type II superstrings on symmetric orbifolds

We compute the one-loop renormalization of the Planck mass for type II string theories compactified to four dimensions on symmetric orbifolds that preserve ${\cal N}=2$ supersymmetry. Depending on the orbifold, the effect can be as large as to compete with the standard tree-level value.

hep-th↗

arXiv2002

Black holes from high-energy beam--beam collisions

Using a recent technique, proposed by Eardley and Giddings, we extend their results to the high-energy collision of two beams of massless particles, i.e. of two finite-front shock waves. Closed (marginally) trapped surfaces can be determined analytically in several cases even for collisions at non-vanishing impact parameter in D\ge 4 space-time dimensions. We are able to confirm and extend earlier conjectures by Yurtsever, and to deal with arbitrary axisymmetric profiles, including an amusing case of ``fractal'' beams. We finally discuss some implications of our results in high-energy experiments and in cosmology.

gr-qc↗

arXiv2002

Schwinger terms in gravitation in two dimensions as a consequence of the gravitational anomaly

We compute the Schwinger term in the gravitational constraints in two dimensions, starting from the path integral in Hamiltonian form and the Einstein anomaly.

hep-th↗