25,764 research outputs found
Electrophilic dark matter with dark photon: from DAMPE to direct detection
The electron-positron excess reported by the DAMPE collaboration recently may
be explained by an electrophilic dark matter (DM). A standard model singlet
fermion may play the role of such a DM when it is stablized by some symmetries,
such as a dark gauge symmetry, and dominantly annihilates into the
electron-positron pairs through the exchange of a scalar mediator. The model,
with appropriate Yukawa couplings, can well interpret the DAMPE excess. Naively
one expects that in this type of models the DM-nucleon cross section should be
small since there is no tree-level DM-quark interactions. We however find that
at one-loop level, a testable DM-nucleon cross section can be induced for
providing ways to test the electrophilic model. We also find that a
kinetic mixing can generate a sizable DM-nucleon cross section although the
dark photon only has a negligible contribution to the DM
annihilation. Depending on the signs of the mixing parameter, the dark photon
can enhance/reduce the one-loop induced DM-nucleon cross section.Comment: 4 pages, typos are corrected, references are added as well as more
discussions on direct detectio
Leptogenesis parametrized by lepton mass matrices
The conventional seesaw-leptogenesis can simultaneously explain the
suppression of neutrino masses and the generation of cosmic baryon asymmetry,
but usually cannot predict an unambiguous relation between these two sectors.
In this work we shall demonstrate a novel left-right symmetric scenario,
motivated to solve the strong CP problem by parity symmetry, where the present
baryon asymmetry is determined by three charged lepton masses and a
seesaw-suppressed hermitian Dirac neutrino mass matrix up to an overall scale
factor. To produce the observed baryon asymmetry, this scenario requires that
the neutrinos must have a normal hierarchical mass spectrum and their mixing
matrix must contain a sizable Dirac CP phase. Our model can be tested in
neutrino oscillation and neutrinoless double beta decay experiments.Comment: 5 pages, 2 figures. Typos are correcte
Neutrino Dark Energy and Baryon Asymmetry from Higgs Sector
We propose a new model to explain the neutrino masses, the dark energy and
the baryon asymmetry altogether. In this model, neutrinos naturally acquire
small Majorana masses via type-II seesaw mechanism, while the
pseudo-Nambu-Goldstone bosons associated with the neutrino mass-generation
mechanism provide attractive candidates for dark energy. The baryon asymmetry
of the universe is produced from the Higgs triplets decay with CP-violation.Comment: 5 pages, 2 figures. Version accepted by PL
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