16,658 research outputs found
Cogenesis in a universe with vanishing within a gauged extension
We consider a gauged extension of the standard model and of the
minimal supersymmetric standard model where the dark matter fields are charged
under and carry lepton number while the standard model fields and
fields of the minimal supersymmetric standard model are neutral under .
We consider leptogenesis in this class of models with all fundamental
interactions having no violation of lepton number, and the total in the
universe vanishes. Such leptogenesis leads to equal and opposite lepton numbers
in the visible sector and in the dark sector, and thus also produces asymmetric
dark matter. Part of the lepton numbers generated in the leptonic sector
subsequently transfer to the baryonic sector via sphaleron interactions. The
stability of the dark particles is protected by the gauge symmetry. A
kinetic mixing between the and the gauge bosons allows for
dissipation of the symmetric component of dark matter. The case when
is is also discussed for the supersymmetric case. This case is
particularly interesting in that we have a gauged which ensures
the conservation of with an initial condition of a vanishing in the
universe. Phenomenological implications of the proposed extensions are
discussed, which include implications for electroweak physics, neutrino masses
and mixings, and lepton flavor changing processes such as . We also briefly discuss the direct detection of the dark matter in the
model.Comment: 9 pages, 3 figure
Geodesic-Einstein metrics and nonlinear stabilities
In this paper, we introduce notions of nonlinear stabilities for a relative
ample line bundle over a holomorphic fibration and define the notion of a
geodesic-Einstein metric on this line bundle, which generalize the classical
stabilities and Hermitian-Einstein metrics of holomorphic vector bundles. We
introduce a Donaldson type functional and show that this functional attains its
absolute minimum at geodesic-Einstein metrics, and we also discuss the
relations between the existence of geodesic-Einstein metrics and the nonlinear
stabilities of the line bundle. As an application, we will prove that a
holomorphic vector bundle admits a Finsler-Einstein metric if and only if it
admits a Hermitian-Einstein metric, which answers a problem posed by S.
Kobayashi.Comment: 21 pages, the final version, to appear in Transactions of the
American Mathematical Societ
Stringy explanation of anomalies
We show that the recent anomalies in transitions
observed by the LHCb collaboration can be accommodated within string motivated
models with a low mass gauge boson. Such gauge boson
can be obtained in compactifications with a low string scale. We consider a
class of intersecting D-brane models, in which different families of quarks and
leptons are simultaneously realized at different D-brane intersections. The
explanation of anomalies via a stringy
sets important restrictions on these viable D-brane constructions.Comment: 18 pages, 13 figure
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