2,975 research outputs found
Lepton Flavor Violating Processes and Muon g-2 in Minimal Supersymmetric SO(10) Model
In the recently proposed minimal supersymmetric SO(10) model, the neutrino
Dirac Yukawa coupling matrix, together with all the other fermion mass
matrices, is completely determined once free parameters in the model are
appropriately fixed so as to accommodate the recent neutrino oscillation data.
Using this unambiguous neutrino Dirac Yukawa couplings, we calculate the lepton
flavor violating (LFV) processes and the muon g-2 assuming the minimal
supergravity scenario. The resultant rates of the LFV processes are found to be
large enough to well exceed the proposed future experimental bound, while the
magnitude of the muon g-2 can be within the recent result by Brookhaven E821
experiment. Furthermore, we find that there exists a parameter region which can
simultaneously realize the neutralino cold dark matter abundance consistent
with the recent WMAP data.Comment: 18 pages, 10 figures. The version to be published in Phys. Rev.
Yukawa-unified natural supersymmetry
Previous work on t-b-\tau Yukawa-unified supersymmetry, as expected from SUSY
GUT theories based on the gauge group SO(10), tended to have exceedingly large
electroweak fine-tuning (EWFT). Here, we examine supersymmetric models where we
simultaneously require low EWFT ("natural SUSY") and a high degree of Yukawa
coupling unification, along with a light Higgs scalar with m_h\sim125 GeV. As
Yukawa unification requires large tan\beta\sim50, while EWFT requires rather
light third generation squarks and low \mu\sim100-250 GeV, B-physics
constraints from BR(B\to X_s\gamma) and BR(B_s\to \mu+\mu-) can be severe. We
are able to find models with EWFT \Delta\lesssim 50-100 (better than 1-2% EWFT)
and with Yukawa unification as low as R_yuk\sim1.3 (30% unification) if
B-physics constraints are imposed. This may be improved to R_yuk\sim1.2 if
additional small flavor violating terms conspire to improve accord with
B-constraints. We present several Yukawa-unified natural SUSY (YUNS) benchmark
points. LHC searches will be able to access gluinos in the lower 1-2 TeV
portion of their predicted mass range although much of YUNS parameter space may
lie beyond LHC14 reach. If heavy Higgs bosons can be accessed at a high rate,
then the rare H, A\to \mu+\mu- decay might allow a determination of
tan\beta\sim50 as predicted by YUNS models. Finally, the predicted light
higgsinos should be accessible to a linear e+e- collider with \sqrt{s}\sim0.5
TeV.Comment: 18 pages, 7 figures, pdflatex; 3 references adde
An Alternative Yukawa Unified SUSY Scenario
Supersymmetric SO(10) Grand Unified Theories with Yukawa unification
represent an appealing possibility for physics beyond the Standard Model.
However Yukawa unification is made difficult by large threshold corrections to
the bottom mass. Generally one is led to consider models where the sfermion
masses are large in order to suppress these corrections. Here we present
another possibility, in which the top and bottom GUT scale Yukawa couplings are
equal to a component of the charged lepton Yukawa matrix at the GUT scale in a
basis where this matrix is not diagonal. Physically, this weak eigenstate
Yukawa unification scenario corresponds to the case where the charged leptons
that are in the 16 of SO(10) containing the top and bottom quarks mix with
their counterparts in another SO(10) multiplet. Diagonalizing the resulting
Yukawa matrix introduces mixings in the neutrino sector. Specifically we find
that for a large region of parameter space with relatively light sparticles,
and which has not been ruled out by current LHC or other data, the mixing
induced in the neutrino sector is such that , in
agreement with data. The phenomenological implications are analyzed in some
detail.Comment: 32 pages, 22 Figure
The Duck Redux: An Improved Proper Motion Upper Limit for the Pulsar B1757-24 Near the Supernova Remnant G5.4-1.2
"The Duck" is a complicated non-thermal radio system, consisting of the
energetic radio pulsar B1757-24, its surrounding pulsar wind nebula G5.27-0.90
and the adjacent supernova remnant (SNR) G5.4-1.2. PSR B1757-24 was originally
claimed to be a young (~15 000 yr) and extreme velocity (>~1500 km/s) pulsar
which had penetrated and emerged from the shell of the associated SNR G5.4-1.2,
but recent upper limits on the pulsar's motion have raised serious difficulties
with this interpretation. We here present 8.5 GHz interferometric observations
of the nebula G5.27-0.90 over a 12-year baseline, doubling the time-span of
previous measurements. These data correspondingly allow us to halve the
previous upper limit on the nebula's westward motion to 14 milliarcseconds/yr
(5-sigma), allowing a substantive reevaluation of this puzzling object. We rule
out the possibility that the pulsar and SNR were formed from a common supernova
explosion ~15 000 yrs ago as implied by the pulsar's characteristic age, but
conclude that an old (>~70 000 yr) pulsar / SNR association, or a situation in
which the pulsar and SNR are physically unrelated, are both still viable
explanations.Comment: 9 pages, including 1 color and 1 B/W figure. Minor changes following
referee's report. ApJ, in pres
Viability of MSSM scenarios at very large tan(beta)
We investigate the MSSM with very large tan(beta) > 50, where the fermion
masses are strongly affected by loop-induced couplings to the "wrong" Higgs,
imposing perturbative Yukawa couplings and constraints from flavour physics.
Performing a low-energy scan of the MSSM with flavour-blind soft terms, we find
that the branching ratio of B->tau nu and the anomalous magnetic moment of the
muon are the strongest constraints at very large tan(beta) and identify the
viable regions in parameter space. Furthermore we determine the scale at which
the perturbativity of the Yukawa sector breaks down, depending on the
low-energy MSSM parameters. Next, we analyse the very large tan(beta) regime of
General Gauge Mediation (GGM) with a low mediation scale. We investigate the
requirements on the parameter space and discuss the implied flavour
phenomenology. We point out that the possibility of a vanishing Bmu term at a
mediation scale M = 100 TeV is challenged by the experimental data on B->tau nu
and the anomalous magnetic moment of the muon.Comment: 29 pages, 7 figures. v2: discussion in sections 1 and 4 expanded,
conclusions unchanged. Matches version published in JHE
Factorial Moments of Continuous Order
The normalized factorial moments are continued to noninteger values of
the order , satisfying the condition that the statistical fluctuations
remain filtered out. That is, for Poisson distribution for all .
The continuation procedure is designed with phenomenology and data analysis in
mind. Examples are given to show how can be obtained for positive and
negative values of . With being continuous, multifractal analysis is
made possible for multiplicity distributions that arise from self-similar
dynamics. A step-by-step procedure of the method is summarized in the
conclusion.Comment: 15 pages + 9 figures (figures available upon request), Late
Intermediate scale as a source of lepton flavor violation in SUSY SO(10)
In supersymmetric SO(10) grand unified models, we examine the lepton flavor
violation process from having the SU(2)U(1) gauge symmetry broken at an intermediate scale below the
SO(10) grand unification scale . Even in the case that supersymmetry is
broken by universal soft terms introduced at the scale , we find
significant rates for with GeV or
less. These rates are further enhanced if the universal soft terms appear at a
scale greater than .Comment: 12 pages (Latex), 3 PS Figures (uuencoded, epsf.tex), small addition
to discussion in the text, as to appear in Phys. Rev. D Rapid Communication
Supersymmetric Flavor Models and the B --> phi K_S Anomaly
We consider the flavor structure of supersymmetric theories that can account
for the deviation of the observed time-dependent CP asymmetry in B --> phi K_S
from the standard model prediction. Assuming simple flavor symmetries and
effective field theory, we investigate possible correlations between sizable
supersymmetric contributions to b --> s transitions and to flavor changing
processes that are more tightly constrained. With relatively few assumptions,
we determine the properties of minimal Yukawa and soft mass textures that are
compatible with the desired supersymmetric flavor-changing effect and
constraints. We then present explicit models that are designed (at least
approximately) to realize these textures. In particular, we present an Abelian
model based on a single U(1) factor and a non-trivial extra-dimensional
topography that can explain the CP asymmetry in B --> phi K_S, while
suppressing other supersymmetric flavor changing effects through a high degree
of squark-quark alignment.Comment: 18 pages LaTeX, 3 eps figure
Possible Gauge Theoretic Origin for Quark-Lepton Complementarity
Similarity between the weak interaction properties of quarks and leptons has
led to suggestions that the origin of lepton mixing angles may be related to
those of quarks. In this paper, we present a gauge model based on group that leads to a new form for the quark
lepton complementarity which predicts the solar neutrino mixing angle in terms
of the Cabibbo angle for the case of inverted mass hierarchy for neutrinos. We
also indicate how these ideas can be implemented in an inspired
trinification model, which is more
closely allied to string theory by the AdS/CFT correspondence.Comment: 9 pages, latex, no figures; presentation improved; results unchanged;
minor typos correcte
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