208,914 research outputs found
Exotic Charges, Multicomponent Dark Matter and Light Sterile Neutrinos
Generating small sterile neutrino masses via the same seesaw mechanism that
suppresses active neutrino masses requires a specific structure in the neutral
fermion mass matrix. We present a model where this structure is enforced by a
new U(1)' gauge symmetry, spontaneously broken at the TeV scale. In order not
to spoil the neutrino structure, the additional fermions necessary for anomaly
cancellations need to carry exotic charges, and turn out to form multicomponent
cold dark matter. The active-sterile mixing then connects the new particles and
the Standard Model---opening a new portal in addition to the usual Higgs- and
kinetic-mixing portals---which leads to dark matter annihilation almost
exclusively into neutrinos.Comment: 11 pages, 3 figures. More references, longer discussions. Matches
JHEP versio
Reducing \theta_13 to 9 degrees
We propose to consider the possibility that the observed value of
is not the result of a correction from an initially vanishing
value, but rather the result of a correction from an initially larger value. As
an explicit example of this approach, we consider analytically and numerically
well-known CKM-like charged lepton corrections to a neutrino diagonalization
matrix that corresponds to a certain mixing scheme. Usually this results in
generating from zero. We note here, however, that 9 is
not only given by , but also by . Hence, the extreme case of an
initial value of 18 degrees, reduced by charged lepton corrections to 9
degrees, is possible. For some cases under study new sum rules for the mixing
parameters, and correlations with CP phases are found.Comment: 11 pages, 6 figure
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