299 research outputs found
Sterile Neutrinos in a Grand Unified Model
The recent experimental results indicating the neutrino oscillations may
strongly suggest that at least one more light neutrino species is required in
order to reconcile the existing data. In the simple GUT frameworks, this fact
seems difficult to preserve the parallelism between quarks and leptons. In this
letter, we investigate an SO(10) grand unified model with a pair of extra
generations in addition to the known three ones. Using the GUT relations, the
obtained neutrino mass matrix naturally indicates that one of the SU(2) singlet
(sterile) neutrino is very light and has large mixing with muon neutrino, which
can explain the atmospheric neutrino anomaly, and the hot dark matter neutrino
is also provided. The solar neutrino problem can be solved by the mixing with
muon neutrino consistently with quark mixing, namely, the Cabibbo angle.Comment: 15 pages, 5 eps figure
Kaluza-Klein Mediated Supersymmetry Breaking
We discuss a framework for communicating supersymmetry breaking to the
visible sector where the radius modulus, which determines the size of extra
dimensions, has an auxiliary vacuum expectation value. The modulus couplings
generate mass splitting in Kaluza-Klein supermultiplets and they act as
messengers of supersymmetry breaking. The soft masses are expressed in terms of
renormalization-group functions and the sparticle spectrum is determined by
what kind of field propagates in the bulk. This framework also provides new
possibilities for solving the supersymmetric flavor problem.Comment: 10 page
Soft Supersymmetry Breaking at Heavy Chiral Threshold
We discuss the structure of threshold corrections to soft
supersymmetry-breaking parameters at the mass threshold of heavy chiral
superfields. Nontrivial dependence on soft parameters of heavy matter fields
originates from the `physical' definition of the threshold scale, at which the
general form of soft supersymmetry breaking is derived in the superfield
coupling formalism.Comment: 7 pages, no figur
Radiative CP Phases in Supergravity Theories
In this letter, we point out that possible sources of CP violation originate
from radiative corrections to soft terms which are ubiquitous in supergravity
theories and also in other high-energy frameworks of supersymmetry breaking.
With these radiative phases of gaugino masses and scalar couplings, a complex
phase of Higgs holomorphic mass parameter is generated via
renormalization-group running down to low energy. It is found that its phase
value is mainly controlled by wino as well as gluino, which generally receive
different radiative corrections to their complex phases, even if the leading
part of mass parameters follow from the universality hypothesis. The
radiatively generated phases are constrained by the existing experimental
bounds on electric dipole moments, and may be detectable in future
measurements. They are also found to be available for the cancellation
mechanism to be worked.Comment: 14 pages, 5 figures, references adde
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