7,029 research outputs found
Neutrino Mass, Dark Matter, and Leptogenesis
It is proposed that dark matter is the origin of neutrino mass, thereby
linking inexorably two undisputed (and seemingly unrelated) pieces of evidence
for physics beyond the Standard Model. Leptogenesis at the TeV scale may also
be possible, as well as a measurable contribution to the muon anomalous
magnetic moment.Comment: 7 pages, 2 figure
Quark Mass Matrices from a Softly Broken U(1) Symmetry
Assigning U(1) charges to the quarks of the standard model, and allowing one
extra scalar doublet with m^2 > 0, the correct pattern of the up and down quark
mass matrices is obtained, together with their charged-current mixing matrix.Comment: 10 pages, no figur
Gauged B-3L_\tau, low-energy unification and proton decay
We point out that if there is a gauged symmetry at low energy, it
can prevent fast proton decay. This may help building models with theories with
extra dimensions at the TeV scale. For purpose of illustration we present an
explicit model with large extra dimensions. The Higgs required for a realistic
fermion masses and mixing are included. The problem of neutrino masses are
solved with triplet Higgs scalars. The proton remains stable even after the
symmetry breaking.Comment: 8 pages, Late
Verifiable Origin of Neutrino Mass at TeV Scale
The physics responsible for neutrino mass may reside at or below the TeV
energy scale. The neutrino mass matrix in the
basis may then be deduced from future high-energy accelerator experiments. The
newly observed excess in the muon anomalous magnetic moment may also be
related.Comment: 9 pages, 1 figure, talk at TAUP 200
Splitting of Three Nearly Mass-Degenerate Neutrinos
Assuming the canonical seesaw mechanism together with an SO(3) family
symmetry for leptons, broken only by the charged-lepton masses, I show that the
three neutrinos of Majorana mass are split radiatively in two loops by a
maximum finite calculable amount of order . This is very suitable
for dark matter and vacuum solar neutrino oscillations. I also discuss how
atmospheric neutrino oscillations can be incorporated.Comment: 11 pages including 1 figure, slightly revised version to appear in
Physics Letters
Tripartite Neutrino Mass Matrix
The 3 X 3 Majorana neutrino mass matrix is written as a sum of 3 terms, i.e.
M_nu = M_A + M_B + M_C, where M_A is proportional to the identity matrix and
M_B and M_C are invariant under different Z_3 transformations. This M_nu is
very suitable for understanding atmospheric and solar neutrino oscillations,
with sin^2 (2 theta_atm) and tan^2 (theta_sol) fixed at 1 and 0.5 respectively,
in excellent agreement with present data. It has in fact been proposed before,
but only as an ansatz. This paper uncovers its underlying symmetry, thus
allowing a complete theory of leptons and quarks to be constructed.Comment: 9 pages, no figur
Nearly Mass-Degenerate Majorana Neutrinos: Double Beta Decay and Neutrino Oscillations
Assuming equal tree-level Majorana masses for the standard-model neutrinos,
either from the canonical seesaw mechanism or from a heavy scalar triplet, I
discuss how their radiative splitting may be relevant to neutrinoless double
beta decay and neutrino oscillations.Comment: 12 pages, including 4 figures, talk at NANP9
Neutrino Mass from Triplet and Doublet Scalars at the TeV Scale
If the minimal standard model of particle interactions is extended to include
a scalar triplet with lepton number and a scalar doublet with ,
neutrino masses eV is possible,
where GeV is the electroweak symmetry breaking scale,
TeV is the typical mass of the new scalars, and GeV is a soft
lepton-number-violating parameter.Comment: 6 pages, no figur
Schizophrenic active neutrinos and exotic sterile neutrinos
We implement a schizophrenic scenario for the active neutrinos in a model in
which there are also exotic right-handed neutrinos making a model with a local
U(1)_(B-L) anomaly free. Two of right-handed neutrinos carry B-L=-4 while the
third one carries B-L=5.Comment: I, A. C. B. Machado, apologize for having submitted the wrong file
before. This is in fact the version to be published in Physics Letters B 698
(2011) pp. 128-13
Anomalous quantum-critical scaling corrections in two-dimensional antiferromagnets
We study the N\'eel-paramagnetic quantum phase transition in two-dimensional
dimerized Heisenberg antiferromagnets using finite-size scaling of
quantum Monte Carlo data. We resolve the long standing issue of the role of
cubic interactions arising in the bond-operator representation when the dimer
pattern lacks a certain symmetry. We find non-monotonic (monotonic) size
dependence in the staggered (columnar) dimerized model, where cubic
interactions are (are not) present. We conclude that there is an irrelevant
field in the staggered model that is not present in the columnar case, but, at
variance with previous claims, it is not the leading irrelevant field. The new
exponent is and the prefactor of the correction
is large and comes with a different sign from that of the
formally leading conventional correction with exponent .
Our study highlights the possibility of competing scaling corrections at
quantum critical points.Comment: 6 pages, 6 figure
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