28,026 research outputs found
Neutrino masses and superheavy dark matter in the 3-3-1-1 model
In this work, we interpret the 3-3-1-1 model when the B-L and 3-3-1 breaking
scales behave simultaneously as the inflation scale. This setup not only
realizes the previously-achieved consequences of inflation and leptogenesis,
but also provides new insights in superheavy dark matter and neutrino masses.
We argue that the 3-3-1-1 model can incorporate a scalar sextet, which induces
both small masses for the neutrinos via a combined type I and II seesaw and
large masses for the new neutral fermions. Additionally, all the new particles
have the large masses in the inflation scale. The lightest particle among the
W-particles that have abnormal (i.e., wrong) B-L number in comparison to those
of the standard model particles may be a superheavy dark matter as it is
stabilized by the W-parity. The dark matter candidate may be a Majorana
fermion, a neutral scalar, or a neutral gauge boson, which was properly created
in the early universe due to the gravitational effects on the vacuum or the
thermal production after cosmic inflation.Comment: 34 pages, improved with discussions on inflation and reheating as
well as presentation, matches published version in EPJ
Thermoelectric effects in correlated quantum dots and molecules
We investigate thermoelectric properties of correlated quantum dots and
molecules, described by a single level Anderson model coupled to conduction
electron leads, by using Wilson's numerical renormalization group method. In
the Kondo regime, the thermopower, , exhibits two sign changes, at
temperatures and . We find that is of order
the level width and , where is the
position of the Kondo induced peak in the thermopower and is the Kondo
scale. No sign change is found outside the Kondo regime, or, for weak
correlations, making a sign change in a particularly sensitive signature
of strong correlations and Kondo physics. For molecules, we investigate the
effect of screening by conduction electrons on the thermoelectric transport. We
find that a large screening interaction enhances the figure of merit in the
Kondo and mixed valence regimes.Comment: 4 pages, 3 figures; to appear in the Proceedings of the International
Conference on Strongly Correlated Electron Systems, Santa Fe 2010; revised
version: typos corrected and references update
The 3-3-1 model with A_4 flavor symmetry
We argue that the A_4 symmetry as required by three flavors of fermions may
well-embed in the SU(3)_C X SU(3)_L X U(1)_X gauge model. The new neutral
fermion singlets as introduced in a canonical seesaw mechanism can be combined
with the standard model lepton doublets to perform SU(3)_L triplets. Various
leptoscalar multiplets such as singlets, doublets, and triplets as played in
the models of A_4 are unified in single SU(3)_L antisextets. As a result,
naturally light neutrinos with various kinds of mass hierarchies are obtained
as a combination of type I and type II seesaw contributions. The observed
neutrino mixing pattern in terms of the Harrison-Perkins-Scott proposal is
obtained by enforcing of the A_4 group. The quark masses and
Cabibbo-Kobayashi-Maskawa mixing matrix are also discussed. By virtue of very
heavy antisextets the nature of the vacuum alignments of scalar fields can be
given.Comment: Version published by PR
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