52 research outputs found
Understanding Gravity: Some Extra Dimensional Perspectives
Gravity is one of the most inexplicable forces of nature, controlling
everything, from the expansion of the Universe to the ebb and flow of ocean
tides. The search for the laws of motion and gravitation began more than two
thousand years ago but still we do not have the complete picture of it. In this
article, we have outlined how our understanding of gravity is changing
drastically with time and how the previous explanations have shaped the most
recent developments in the field like superstrings and braneworlds.Comment: 21 page
Aspects of Black Holes in Gravitational Theories with Broken Lorentz and Diffeomorphism Symmetries
Since Stephen Hawking discovered that black holes emit thermal radiation,
black holes have become the theoretical laboratories for testing our ideas on
quantum gravity. This dissertation is devoted to the study of singularities,
the formation of black holes by gravitational collapse and the global structure
of spacetime. All our investigations are in the context of a recently proposed
approach to quantum gravity, which breaks Lorentz and diffeomorphism symmetries
at very high energies.Comment: XIV+147 pages, 19 figures, PhD Thesis, Baylor Universit
Plasmon Annihilation into Kaluza-Klein Graviton: New Astrophysical Constraints on Large Extra Dimensions
In large extra dimensional Kaluza-Klein (KK) scenario, where the usual
Standard Model (SM) matter is confined to a 3+1-dimensional hypersurface called
the 3-brane and gravity can propagate to the bulk (D=4+d, d being the number of
extra spatial dimensions), the light graviton KK modes can be produced inside
the supernova core due to the usual nucleon-nucleon bremstrahlung,
electron-positron and photon-photon annihilations. This photon inside the
supernova becomes plasmon due to the plasma effect. In this paper, we study the
energy-loss rate of SN 1987A due to the KK gravitons produced from the
plasmon-plasmon annihilation. We find that the SN 1987A cooling rate leads to
the conservative bound > 22.9 TeV and 1.38 TeV for the case of two and
three space-like extra dimensions.Comment: 13 pages, 1 ps figure, text is modified a little bit, conclusion
unchanged, new references are added, version accepted for publication in PR
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