1,563 research outputs found
Renormalization Group Analysis of Neutrino Mass Parameters
Tools for calculating the Renormalization Group Equations for renormalizable
and non-renormalizable operators in various theories are reviewed, which are
essential for comparing experimental results with predictions from models
beyond the Standard Model. Numerical examples for the running of the lepton
mixing angles in models with non-degenerate see-saw scales are shown, in which
the best-fit values of the experimentally favored LMA solution are produced
from maximal or from vanishing solar neutrino mixing at the GUT scale.Comment: 6 pages, 17 figures; to appear in the proceedings of the 10th
International Conference on Supersymmetry and Unification of Fundamental
Interactions (SUSY02), June 17 - 23, DESY Hambur
Right unitarity triangles and tri-bimaximal mixing from discrete symmetries and unification
We propose new classes of models which predict both tri-bimaximal lepton
mixing and a right-angled Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle,
alpha approximately 90 degrees. The ingredients of the models include a
supersymmetric (SUSY) unified gauge group such as SU(5), a discrete family
symmetry such as A4 or S4, a shaping symmetry including products of Z2 and Z4
groups as well as spontaneous CP violation. We show how the vacuum alignment in
such models allows a simple explanation of alpha approximately 90 degrees by a
combination of purely real or purely imaginary vacuum expectation values (vevs)
of the flavons responsible for family symmetry breaking. This leads to quark
mass matrices with 1-3 texture zeros that satisfy the phase sum rule and lepton
mass matrices that satisfy the lepton mixing sum rule together with a new
prediction that the leptonic CP violating oscillation phase is close to either
0, 90, 180, or 270 degrees depending on the model, with neutrino masses being
purely real (no complex Majorana phases). This leads to the possibility of
having right-angled unitarity triangles in both the quark and lepton sectors.Comment: 29 pages, 4 figures, version to be published in NP
Neutrino Mass Matrix Running for Non-Degenerate See-Saw Scales
We consider the running of the neutrino mass matrix in the Standard Model and
the Minimal Supersymmetric Standard Model, extended by heavy singlet Majorana
neutrinos. Unlike previous studies, we do not assume that all of the heavy mass
eigenvalues are degenerate. This leads to various effective theories when the
heavy degrees of freedom are integrated out successively. We calculate the
Renormalization Group Equations that govern the evolution of the neutrino mass
matrix in these effective theories. We show that an appropriate treatment of
the singlet mass scales can yield a substantially different result compared to
integrating out the singlets at a common intermediate scale.Comment: 12 pages, 9 figure
Sneutrino Hybrid Inflation
We review the scenario of sneutrino hybrid inflation, where one of the
singlet sneutrinos, the superpartners of the right-handed neutrinos, plays the
role of the inflaton. In a minimal model of sneutrino hybrid inflation, the
spectral index is given by . With constrained by WMAP, a running spectral index and a tensor-to-scalar ratio are predicted. Small
neutrino masses arise from the seesaw mechanism, with heavy masses for the
singlet (s)neutrinos generated by the vacuum expectation value of the waterfall
field after inflation. The baryon asymmetry of the universe can be explained by
non-thermal leptogenesis via sneutrino inflaton decay, with low reheat
temperature GeV.Comment: 7 pages, 2 figures; talk presented at the International Workshop on
The Dark Side of the Universe (DSU2006), Madrid, Spain, June 20-24, 200
Implications of Running Neutrino Parameters for Leptogenesis and for Testing Model Predictions
The running of neutrino parameters in see-saw models and its implications for
leptogenesis and for testing predictions of mass models with future precision
experiments are discussed using analytical approximations as well as numerical
results.Comment: 5 pages, 2 figures; talk presented at 10th International Symposium on
Particles, Strings and Cosmology (Pascos04), Northeastern University, Boston,
August 16-22, 2004; references adde
Searches for Sterile Neutrinos at Future Electron-Proton Colliders
Sterile neutrinos are an attractive extension of the Standard Model of
elementary particles towards including a mechanism for generating the observed
light neutrino masses. We discuss that when an approximate protective "lepton
number"-like symmetry is present, the sterile neutrinos can have masses around
the electroweak scale and potentially large neutrino Yukawa couplings, which
makes them well testable at planned future particle colliders. We
systematically discuss the production and decay channels for sterile neutrinos
at electron-proton colliders and give a complete list of the leading order
signatures for sterile neutrino searches. We highlight several novel search
channels and present a first look at the possible sensitivities for the
active-sterile mixing parameters and the heavy neutrino masses. We also compare
the performance of electron-proton colliders with the ones of proton-proton and
electron-positron colliders, and discuss the complementarity of the different
collider types.Comment: Conference proceedings for the DIS 2017 in Birmingham, 13 pages, 8
figures, 2 table
K\"ahler-driven Tribrid Inflation
We discuss a new class of tribrid inflation models in supergravity, where the
shape of the inflaton potential is dominated by effects from the K\"ahler
potential. Tribrid inflation is a variant of hybrid inflation which is
particularly suited for connecting inflation with particle physics, since the
inflaton can be a D-flat combination of charged fields from the matter sector.
In models of tribrid inflation studied so far, the inflaton potential was
dominated by either loop corrections or by mixing effects with the waterfall
field (as in "pseudosmooth" tribrid inflation). Here we investigate the third
possibility, namely that tribrid inflation is dominantly driven by effects from
higher-dimensional operators of the K\"ahler potential. We specify for which
superpotential parameters the new regime is realized and show how it can be
experimentally distinguished from the other two (loop-driven and
"pseudosmooth") regimes.Comment: 28 pages, v2: added some references, this version matches the
publication in JCA
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