165 research outputs found
Implications of the Muon Anomalous Magnetic Moment for Supersymmetry
We re-examine the bounds on supersymmetric particle masses in light of the
E821 data on the muon anomalous magnetic moment. We confirm, extend and
supersede previous bounds. In particular we find (at one sigma) no lower limit
on tan(beta) or upper limit on the chargino mass implied by the data at
present, but at least 4 sparticles must be lighter than 700 to 820 GeV and at
least one sparticle must be lighter than 345 to 440 GeV. However, the E821
central value bounds tan(beta) > 4.7 and the lighter chargino mass by 690 GeV.
For tan(beta) < 10, the data indicates a high probability for direct discovery
of SUSY at Run II or III of the Tevatron.Comment: 20 pages LaTeX, 14 figures; references adde
Semi-simple group unification in the supersymmetric brane world
The conventional supersymmetric grand unified theories suffer from two
serious problems, the large mass splitting between doublet and triplet Higgs
multiplets, and the too long lifetime of the proton. A unification model based
on a semi-simple group SU(5)_{GUT} \times U(3)_H has been proposed to solve
both of the problems simultaneously. Although the proposed model is perfectly
consistent with observations, there are various mysteries. In this paper, we
show that such mysterious features in the original model are naturally
explained by embedding the model into the brane world in a higher dimensional
space-time. In particular, the relatively small gauge coupling constant of the
SU(5)_{GUT} at the unification energy scale is a consequence of relatively
large volume of extra dimensions. Here, we put the SU(5)_{GUT} gauge multiplet
in a 6-dimensional bulk and assume all fields in the U(3)_H sector to reside on
a 3-dimensional brane located in the bulk. On the other hand, all chiral
multiplets of quarks, leptons and Higgs are assumed to reside on a 3-brane at a
T^2/Z_4 orbifold fixed point. The quasi-N=2 supersymmetry in the hypercolor
U(3)_H sector is understood as a low-energy remnant of the N=4 supersymmetry in
a 6-dimensional space-time. We further extend the 6-dimensional model to a
10-dimensional theory. Possible frameworks of string theories are also
investigated to accommodate the present brane-world model. We find that the
type IIB string theory with D3-D7 brane structure is an interesting candidate.Comment: 45 pages, including 1 figure, minor correctio
Sfermion masses in Nelson-Strassler type of models: SUSY standard models coupled with SCFTs
We study soft SUSY breaking parameters in the Nelson-Strassler type of
models: SUSY standard models coupled with SCFTs. In this type of models, soft
SUSY breaking parameters including sfermion masses can be suppressed around the
decoupling scale of SCFTs. We clarify the condition to derive exponential
suppression of sfermion masses within the framework of pure SCFTs. Such
behavior is favorable for degeneracy of sfermion masses. However, the realistic
sfermion masses are not quite degenerate due to the gauge couplings and the
gaugino masses in the SM sector. We show the sfermion mass spectrum obtained in
such models. The aspect of suppression for the soft SUSY breaking parameters is
also demonstrated in an explicit model. We also give a mechanism generating the
-term of the Electro-Weak scale by a singlet field coupled with the SCFT.Comment: 28 pages, 8 figures, LaTeX file; corrected typos and references adde
Super-conservative interpretation of muon g-2 results applied to supersymmetry
The recent developments in theory and experiment related to the anomalous
magnetic moment of the muon are applied to supersymmetry. We follow a very
cautious course, demanding that the supersymmetric contributions fit within
five standard deviations of the difference between experiment and the standard
model prediction. Arbitrarily small supersymmetric contributions are then
allowed, so no upper bounds on superpartner masses result. Nevertheless,
non-trivial exclusions are found. We characterize the substantial region of
parameter space ruled out by this analysis that has not been probed by any
previous experiment. We also discuss some implications of the results for
forthcoming collider experiments.Comment: 10 pages, latex, 3 fig
Lepton Dipole Moments and Rare Decays in the CP-violating MSSM with Nonuniversal Soft-Supersymmetry Breaking
We investigate the muon anomalous magnetic dipole moment (MDM), the muon
electric dipole moment (EDM) and the lepton-flavour-violating decays of the
lepton, and , in the CP-violating
Minimal Supersymmetric Standard Model (MSSM) with nonuniversal
soft-supersymmetry breaking. We evaluate numerically the muon EDM and the
branching ratios and , after taking
into account the experimental constraints from the electron EDM and muon MDM.
Upon imposition of the experimental limits on our theoretical predictions for
the aforementioned branching ratios and the muon MDM, we obtain an upper bound
of about on the muon EDM which lies well within the
explorable reach of the proposed experiment at BNL.Comment: Latex, 26 pages, 8 figures, accepted for publication in Phys. Rev.
The Reach of the Fermilab Tevatron and CERN LHC for Gaugino Mediated SUSY Breaking Models
In supersymmetric models with gaugino mediated SUSY breaking (inoMSB), it is
assumed that SUSY breaking on a hidden brane is communicated to the visible
brane via gauge superfields which propagate in the bulk. This leads to GUT
models where the common gaugino mass is the only soft SUSY breaking
term to receive contributions at tree level. To obtain a viable phenomenology,
it is assumed that the gaugino mass is induced at some scale beyond the
GUT scale, and that additional renormalization group running takes place
between and as in a SUSY GUT. We assume an SU(5) SUSY GUT above
the GUT scale, and compute the SUSY particle spectrum expected in models with
inoMSB. We use the Monte Carlo program ISAJET to simulate signals within the
inoMSB model, and compute the SUSY reach including cuts and triggers approriate
to Fermilab Tevatron and CERN LHC experiments. We find no reach for SUSY by the
Tevatron collider in the trilepton channel. %either with or without %identified
tau leptons. At the CERN LHC, values of (1160) GeV can be probed
with 10 (100) fb of integrated luminosity, corresponding to a reach in
terms of of 2150 (2500) GeV. The inoMSB model and mSUGRA can likely
only be differentiated at a linear collider with sufficient energy to
produce sleptons and charginos.Comment: 17 page revtex file with 9 PS figure
Moderate and heavy metabolic stress interval training improve arterial stiffness and heart rate dynamics in humans
Traditional continuous aerobic exercise training attenuates age-related increases of arterial stiffness, however, training studies have not determined whether metabolic stress impacts these favourable effects. Twenty untrained healthy participants (n = 11 heavy metabolic stress interval training, n = 9 moderate metabolic stress interval training) completed 6 weeks of moderate or heavy intensity interval training matched for total work and exercise duration. Carotid artery stiffness, blood pressure contour analysis, and linear and non-linear heart rate variability were assessed before and following training. Overall, carotid arterial stiffness was reduced (p  0.05). This study demonstrates the effectiveness of interval training at improving arterial stiffness and autonomic function, however, the metabolic stress was not a mediator of this effect. In addition, these changes were also independent of improvements in aerobic capacity, which were only induced by training that involved a high metabolic stress
Muon anomalous magnetic moment in the standard model with two Higgs doublets
The muon anomalous magnetic moment is investigated in the standard model with
two Higgs doublets (S2HDM) motivated from spontaneous CP violation. Thus all
the effective Yukawa couplings become complex. As a consequence of the non-zero
phase in the couplings, the one loop contribution from the neutral scalar
bosons could be positive and negative relying on the CP phases. The
interference between one and two loop diagrams can be constructive in a large
parameter space of CP-phases. This will result in a significant contribution to
muon anomalous magnetic moment even in the flavor conserving process with a
heavy neutral scalar boson ( 200 GeV) once the effective muon Yukawa
coupling is large (). In general, the one loop contributions
from lepton flavor changing scalar interactions become more important. In
particular, when all contributions are positive in a reasonable parameter space
of CP phases, the recently reported 2.6 sigma experiment vs. theory deviation
can be easily explained even for a heavy scalar boson with a relative small
Yukawa coupling in the S2HDM.Comment: 8 pages, RevTex file, 5 figures, published version Phys. Rev. D 54
(2001) 11501
Non-thermal dark matter via Affleck-Dine baryogenesis and its detection possibility
The formation and late time decays of Q-balls are generic consequences of the
Affleck-Dine (AD) baryogenesis. A substantial amount of the lightest
supersymmetry (SUSY) particles (LSPs) are produced non-thermally as the decay
products of these Q-balls. This requires a significantly large annihilation
cross section of the LSP so as not to overclose the universe, which predicts a
higgsino- or wino-like LSP instead of the standard bino LSP. We have reexamined
the AD baryogenesis with special attention to the late-time decays of the
Q-balls, and then specified the parameter regions where the LSPs produced by
the Q-ball decays result in a cosmologically interesting mass density of dark
matter by adopting several SUSY breaking models. This reveals new
cosmologically interesting parameter regions, which have not attracted much
attention so far. We have also investigated the prospects of direct and
indirect detection of these dark matter candidates, and found that there is an
intriguing possibility to detect them in various next generation dark matter
searches.Comment: 51 pages, 18 figures, version accepted for publication in Physical
Review
Revisiting superparticle spectra in superconformal flavor models
We study superparticle spectra in the superconformal flavor scenario with
non-universal gaugino masses. The non-universality of gaugino masses can lead
to the wino-like or higgsino-like neutralino LSP. Furthermore, it is shown that
the parameter space for the higgsino-like LSP includes the region where the
fine-tuning problem can be improved. The degeneracy of soft scalar masses
squared does not drastically change by taking ratios of gaugino masses of order
one. The degeneracy of scalar masses for squarks and left-handed sleptons would
be good to avoid the FCNC problem but that of right-handed slepton masses is
weak. However, the overall size of right-handed slepton masses become larger
when the bino becomes heavier. It is also pointed out that such region can be
realized, and thus, that would be favorable to avoid the FCNC problem for soft
scalar masses as well as A-terms.Comment: 18 pages, 12 figures, reference added, minor correction
- âŠ