2,450 research outputs found
Pure Gravity Mediation and Spontaneous B-L Breaking from Strong Dynamics
In pure gravity mediation (PGM), the most minimal scheme for the mediation of
supersymmetry (SUSY) breaking to the visible sector, soft masses for the
standard model gauginos are generated at one loop rather than via direct
couplings to the SUSY-breaking field. In any concrete implementation of PGM,
the SUSY-breaking field is therefore required to carry nonzero charge under
some global or local symmetry. As we point out in this note, a prime candidate
for such a symmetry might be B-L, the Abelian gauge symmetry associated with
the difference between baryon number B and lepton number L. The F-term of the
SUSY-breaking field then not only breaks SUSY, but also B-L, which relates the
respective spontaneous breaking of SUSY and B-L at a fundamental level. As a
particularly interesting consequence, we find that the heavy Majorana neutrino
mass scale ends up being tied to the gravitino mass, Lambda_N ~ m_3/2. Assuming
nonthermal leptogenesis to be responsible for the generation of the baryon
asymmetry of the universe, this connection may then explain why SUSY
necessarily needs to be broken at a rather high energy scale, so that m_3/2 >~
1000 TeV in accord with the concept of PGM. We illustrate our idea by means of
a minimal model of dynamical SUSY breaking, in which B-L is identified as a
weakly gauged flavor symmetry. We also discuss the effect of the B-L gauge
dynamics on the superparticle mass spectrum as well as the resulting
constraints on the parameter space of our model. In particular, we comment on
the role of the B-L D-term.Comment: 25 pages, 1 figur
Quark and lepton masses and mixing in SO(10) with a GUT-scale vector matter
We explore in detail the effective matter fermion mass sum-rules in a class
of renormalizable SUSY SO(10) grand unified models where the quark and lepton
mass and mixing patterns originate from non-decoupling effects of an extra
vector matter multiplet living around the unification scale. If the
renormalizable type-II contribution governed by the SU(2)_L-triplet in 54_H
dominates the seesaw formula, we obtain an interesting correlation between the
maximality of the atmospheric neutrino mixing and the proximity of y_s/y_b to
V_cb in the quark sector.Comment: 13 pages, 1 figure, 2 tables; v2: major update, references adde
nuMSM--Predictions for Neutrinoless Double Beta Decay
We give the prediction on the effective Majorana mass for neutrinoless double
decay in a simple extension of the Standard Model (nuMSM). The model
adds three right-handed neutrinos with masses smaller than the electroweak
scale, and explains dark matter of the Universe. This leads to constraints
1.3meV<m_{bb}^{NH}<3.4meV in normal neutrino mass hierarchy and
13meV<m_{bb}^{IH}<50meV in inverted hierarchy.Comment: 5 page
Minimal Seesaw as an Ultraviolet Insensitive Cure for the Problems of Anomaly Mediation
We show that an intermediate scale supersymmetric left-right seesaw scenario
with automatic R-parity conservation can cure the problem of tachyonic slepton
masses that arises when supersymmetry is broken by anomaly mediation, while
preserving ultraviolet insensitivity. The reason for this is the existence of
light B - L = 2 higgses with yukawa couplings to the charged leptons. We find
these theories to have distinct predictions compared to the usual mSUGRA and
gauge mediated models as well as the minimal AMSB models. Such predictions
include a condensed gaugino mass spectrum and possibly a correspondingly
condensed sfermion spectrum.Comment: 19 pages, 1 figur
Observing Signals of the Bulk Matter RS Model through Rare Decays of SUSY Particles
The bulk matter Randall-Sundrum (RS) model is a setup where Standard Model
(SM) matter and gauge fields reside in the bulk of 5D warped spacetime while
the Higgs field is confined on the IR brane. The wavefunctions of the 1st and
2nd generation matter particles are localized towards the UV brane and those of
the 3rd generation towards the IR brane, so that the hierarchical structure of
the Yukawa couplings arises geometrically without hierarchy in fundamental
parameters. This paper discusses an experimental test of this model in the case
where the Kaluza-Klein scale is far above the collider scale, but the model is
combined with 5D Minimal SUSY Standard Model (MSSM) and SUSY particles are in
the reach of collider experiments. A general SUSY breaking mass spectrum
consistent with the bulk matter RS model is considered: SUSY breaking sector
locates on the IR brane and its effects are mediated to 5D MSSM through a
hybrid of gravity mediation, gaugino mediation and gauge mediation. This paper
argues that it is possible to observe the signals of the bulk matter RS model
through rare decays of "almost SU(2) singlet mass eigenstates" that are induced
by flavor-violating gravity mediation contributions to matter soft SUSY
breaking terms
Contribution of Type Ia and Type II Supernovae for Intra-Cluster Medium Enrichment
The origin of the chemical composition of the intracluster medium (ICM) is
discussed in this paper. In particular, the contribution from Type Ia
supernovae (SNe Ia) to the ICM enrichment is shown to exist by adopting the
fitting formulas which have been used in the analysis of the solar system
abundances. Our analysis means that we can use the frequency of SNe Ia relative
to SNe II as the better measure than for
estimating the contribution of SNe Ia. Moreover, the chemical compositions of
ICMs are shown to be similar to that of the solar system abundances. We can
also reproduce the sulfur/iron abundance ratio within a factor of 2, which
means that the abundance problem of sulfur needs not to be emphasized too
strongly. We need more precise observations to conclude whether ICMs really
suffer the shortage problem of sulfur or not.Comment: 20 pages, LaTeX text and 15 postscript figures. Accepted for
publication in Astrophysical Journa
Renormalization Group Evolution in the type I + II seesaw model
We carefully analyze the renormalization group equations in the type I + II
seesaw scenario in the extended standard model (SM) and minimal supersymmetric
standard model (MSSM). Furthermore, we present analytic formulae of the mixing
angles and phases and discuss the RG effect on the different mixing parameters
in the type II seesaw scenario. The renormalization group equations of the
angles have a contribution which is proportional to the mass squared difference
for a hierarchical spectrum. This is in contrast to the inverse proportionality
to the mass squared difference in the effective field theory case.Comment: 13 pages, 4 figures; corrected error due to wrong superfield
normalization in RG equations (24-28,C1-4) as well as error in RG equations
of mixing parameters (38,43); RG equations of mixing angles depend on
Majorana phase
Minimally Allowed Neutrinoless Double Beta Decay Rates From Approximate Flavor Symmetries
Neutrinoless double beta decay () is among the only realistic
probes of Majorana neutrinos. In the standard scenario, dominated by light
neutrino exchange, the process amplitude is proportional to , the
element of the Majorana mass matrix. Naively, current data allows for vanishing
, but this should be protected by an appropriate flavor symmetry. All
such symmetries lead to mass matrices inconsistent with oscillation
phenomenology. I perform a spurion analysis to break all possible Abelian
symmetries that guarantee vanishing rates and search for
minimally allowed values. I survey 230 broken structures to yield
values and current phenomenological constraints under a variety of scenarios.
This analysis also extracts predictions for both neutrino oscillation
parameters and kinematic quantities. Assuming reasonable tuning levels, I find
that eV at 99% confidence. Bounds below this value
might indicate the Dirac neutrino nature or the existence of new light (eV-MeV
scale) degrees of freedom that can potentially be probed elsewhere.Comment: 19 Pages, 4 .eps Figures, 3 Table
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