Browsing by Author "Exirifard, Ghasem"

Now showing 1 - 3 of 3
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    The alpha-prime stretched horizon in Heterotic string
    (2006-05-11T11:24:55Z) Exirifard, Ghasem; Physics; Elementary Particle Theory
    The linear alpha-prime corrections and the field redefinition ambiguities are studied for half-BPS singular backgrounds representing a wrapped fundamental string. It is shown that there exist schemes in which the inclusion of all the linear alpha-prime corrections converts these singular solutions to black holes with regular horizon for which the modified Hawking-Bekenstein entropy is in agreement with the statistical entropy.
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    Quadratic alpha' corrections to T-duality
    (2005) Exirifard, Ghasem; Physics; Elementary Particle Theory
    The quadratic alpha' corrections to the two-dimensional black hole and to its T-dual are calculated. These backgrounds are used to write the covariant form of the alpha'2 corrections to the T-duality for general time-dependent backgrounds of dilaton and diagonal metric in the bosonic string theory.
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    The world-sheet corrections to dyons in the Heterotic theory
    (2006-07-21T10:11:06Z) Exirifard, Ghasem; Physics; Elementary Particle Theory
    All the linear alpha-prime corrections in the compactification of the critical Heterotic string theory on T^6 are computed for a BPS static spherical four dimensional dyonic black hole representing a wrapped fundamental string carrying arbitrary winding and momentum charges along one cycle in the presence of KK-monopole and H-monopole charges associated to another cycle. It is showed that the corrections to the modified Hawking-Bekenstein entropy can not be reproduced by the inclusion of only the Gauss-Bonnet Lagrangian to the supergravity approximation of the Lagrangian for dyons.