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Broken symmetries at high temperatures and the problem of baryon excess of the universe

Description: A class of gauge theories, where spontaneously broken symmetries, instead of being restored, persist as the temperature is increased is discussed. A renormalization group analysis of this phenomena suggests that there may be more than one phase transition in these models with at least one symmetric phase. Applying these ideas to the specific case of soft CP-violation in grand unified theories, a mechanism to generate the baryon to entropy ratio of the universe is discussed. 34 references.
Date: June 1, 1979
Creator: Mohapatra, R.N. & Senjanovic, G.
Partner: UNT Libraries Government Documents Department

Supernova constraints on a superlight gravitino

Description: In supergravity models with low supersymmetry breaking scale the gravitinos can be superlight, with mass in the 10{sup -6} eV to few keV range. In such a case, gravitino emission provides a new cooling mechanism for protoneutron stars and therefore can provide constraints on the mass of a superlight gravitino. This happens because the coupling to matter of superlight gravitinos is dominated by its goldstino component, whose coupling to matter of superlight gravitinos is dominated by its goldstino component, whose coupling to matter is inversely proportional to the scale of supersymmetry breaking and increases as the gravitino mass decreases. Present observations therefore provide lower limits on the gravitino mass. Using the recently revised goldstino couplings, we find that the two dominant processes in supernova cooling are e{sup +} e{sup -} {yields} GG and {gamma}+e{sup -} {yields} e{sup -} GG. They lead to a lower limit on the supersymmetry breaking scale {Lambda}{sub s} from 160 to 500 GeV for core temperatures 30 to 60 MeV and electron chemical potentials 200 to 300 MeV. The corresponding lower limits on the gravitino mass are .6 - 6 x 10{sup -6} eV.
Date: October 1, 1997
Creator: Dicus, D. A.; Mohapatra, R. N. & Teplitz, V. L.
Partner: UNT Libraries Government Documents Department

Muonium to antimuonium conversion and the decay. mu. sup + yields e sup +. nu. sub e. nu. sub. mu. in left-right symmetric models

Description: We investigate muonium to antimuonium conversion and the exotic muon decay {mu}{sup +} {r arrow} e{sup +}{bar {upsilon}}{sub e} {epsilon}{sub {mu}} in SU(2){sub L} {times} SU(2){sub R} {times} U(1){sub B-L} models. 7 refs.
Date: January 1, 1991
Creator: Herczeg, P. (Los Alamos National Lab., NM (United States)) & Mohapatra, R.N. (Maryland Univ., College Park, MD (United States). Dept. of Physics and Astronomy)
Partner: UNT Libraries Government Documents Department

Theory of neutrinos: A White paper

Description: During 2004, four divisions of the American Physical Society commissioned a study of neutrino physics to take stock of where the field is at the moment and where it is going in the near and far future. Several working groups looked at various aspects of this vast field. The summary was published as a main report entitled ''The Neutrino Matrix'' accompanied by short 50 page versions of the report of each working group. Theoretical research in this field has been quite extensive and touches many areas and the short 50 page report [1] provided only a brief summary and overview of few of the important points. The theory discussion group felt that it may be of value to the community to publish the entire study as a white paper and the result is the current article. After a brief overview of the present knowledge of neutrino masses and mixing and some popular ways to probe the new physics implied by recent data, the white paper summarizes what can be learned about physics beyond the Standard Model from the various proposed neutrino experiments. It also comments on the impact of the experiments on our understanding of the origin of the matter-antimatter asymmetry of the Universe and the basic nature of neutrino interactions as well as the existence of possible additional neutrinos. Extensive references to original literature are provided.
Date: October 1, 2005
Creator: Mohapatra, R.N.; Antusch, S.; Babu, K.S.; Barenboim, G.; Chen, Mu-Chun; Davidson, S. et al.
Partner: UNT Libraries Government Documents Department

Theory of Neutrinos: a White Paper

Description: During 2004, four divisions of the American Physical Society commissioned a study of neutrino physics to take stock of where the field is at the moment and where it is going in the near and far future. Several working groups looked at various aspects of this vast field. The summary was published as a main report entitled ''The Neutrino Matrix'' accompanied by short 50 page versions of the report of each working group. Theoretical research in this field has been quite extensive and touches many areas and the short 50 page report [1] provided only a brief summary and overview of few of the important points. The theory discussion group felt that it may be of value to the community to publish the entire study as a white paper and the result is the current article. After a brief overview of the present knowledge of neutrino masses and mixing and some popular ways to probe the new physics implied by recent data, the white paper summarizes what can be learned about physics beyond the Standard Model from the various proposed neutrino experiments. It also comments on the impact of the experiments on our understanding of the origin of the matter-antimatter asymmetry of the Universe and the basic nature of neutrino interactions as well as the existence of possible additional neutrinos. Extensive references to original literature are provided.
Date: January 11, 2006
Creator: Mohapatra, R.N.; Antusch, S.; Babu, K.S.; Barenboim, G.; Chen, Mu-Chun; Davidson, S. et al.
Partner: UNT Libraries Government Documents Department