505 research outputs found
Higgs bosons near 125 GeV in the NMSSM with constraints at the GUT scale
We study the NMSSM with universal Susy breaking terms (besides the Higgs
sector) at the GUT scale. Within this constrained parameter space, it is not
difficult to find a Higgs boson with a mass of about 125 GeV and an enhanced
cross section in the diphoton channel. An additional lighter Higgs boson with
reduced couplings and a mass <123 GeV is potentially observable at the LHC. The
NMSSM-specific Yukawa couplings lambda and kappa are relatively large and
tan(beta) is small, such that lambda, kappa and the top Yukawa coupling are of
order 1 at the GUT scale. The lightest stop can be as light as 105 GeV, and the
fine-tuning is modest. WMAP constraints can be satisfied by a dominantly
higgsino-like LSP with substantial bino, wino and singlino admixtures and a
mass of ~60-90 GeV, which would potentially be detectable by XENON100.Comment: 20 pages, 14 figure
Defect Detection in Bonded Structures Using the Reverberant Wavefield
With the increasing use of adhesives in the automotive, aerospace, and manufacturing industries, there is a growing interest in developing nondestructive methods for locating defects in adhesive bonds. While conventional techniques which utilize ultrasonic waves and Lamb waves are likely candidates for obtaining high resolution images of defects, these methods may not be practical for assembly line applications where the time required to scan the bonds and the access to the bonds are often limited. The objective of this work is to develop an approach for detecting defects in bonds that requires only a limited number of measurements of the reverberant acoustic wavefield (i.e., waves that are multiply scattered off the boundaries of the structure) made over a band of frequencies
Gravitino Dark Matter in the CMSSM and Implications for Leptogenesis and the LHC
In the framework of the CMSSM we study the gravitino as the lightest
supersymmetric particle and the dominant component of cold dark matter in the
Universe. We include both a thermal contribution to its relic abundance from
scatterings in the plasma and a non--thermal one from neutralino or stau decays
after freeze--out. In general both contributions can be important, although in
different regions of the parameter space. We further include constraints from
BBN on electromagnetic and hadronic showers, from the CMB blackbody spectrum
and from collider and non--collider SUSY searches. The region where the
neutralino is the next--to--lightest superpartner is severely constrained by a
conservative bound from excessive electromagnetic showers and probably
basically excluded by the bound from hadronic showers, while the stau case
remains mostly allowed. In both regions the constraint from CMB is often
important or even dominant. In the stau case, for the assumed reasonable ranges
of soft SUSY breaking parameters, we find regions where the gravitino abundance
is in agreement with the range inferred from CMB studies, provided that, in
many cases, a reheating temperature \treh is large, \treh\sim10^{9}\gev. On
the other side, we find an upper bound \treh\lsim 5\times 10^{9}\gev. Less
conservative bounds from BBN or an improvement in measuring the CMB spectrum
would provide a dramatic squeeze on the whole scenario, in particular it would
strongly disfavor the largest values of \treh\sim 10^{9}\gev. The regions
favored by the gravitino dark matter scenario are very different from standard
regions corresponding to the neutralino dark matter, and will be partly probed
at the LHC.Comment: JHEP version, several improvements and update
Upper and Lower Limits on Neutralino WIMP Mass and Spin--Independent Scattering Cross Section, and Impact of New (g-2)_{mu} Measurement
We derive the allowed ranges of the spin--independent interaction cross
section \sigsip for the elastic scattering of neutralinos on proton for wide
ranges of parameters of the general Minimal Supersymmetric Standard Model. We
investigate the effects of the lower limits on Higgs and superpartner masses
from colliders, as well as the impact of constraints from \bsgamma and the
new measurement of \gmtwo on the upper and lower limits on \sigsip. We
further explore the impact of the neutralino relic density, including
coannihilation, and of theoretical assumptions about the largest allowed values
of the supersymmetric parameters. For , requiring the latter to lie
below 1\tev leads to \sigsip\gsim 10^{-11}\pb at \mchi\sim100\gev and
\sigsip\gsim 10^{-8}\pb at \mchi\sim1\tev. When the supersymmetric
parameters are allowed above 1\tev, for 440\gev \lsim \mchi\lsim 1020 \gev
we derive a {\em parameter--independent lower limit} of \sigsip \gsim 2\times
10^{-12}\pb. (No similar lower limits can be set for nor for
1020\gev\lsim\mchi\lsim2.6\tev.) Requiring \abundchi<0.3 implies a {\em
parameter--independent upper limit} \mchi\lsim2.6\tev. The new \epem--based
measurement of restricts \mchi\lsim 350\gev at CL
and \mchi\lsim515\gev at CL, and implies . The largest
allowed values of \sigsip have already become accessible to recent
experimental searches.Comment: LaTeX, 17 pages, 9 eps figures. Version to appear in JHE
Exact Cross Sections for the Neutralino WIMP Pair-Annihilation
We derive a full set of exact, analytic expressions for the annihilation of
the lightest neutralino pairs into all two-body tree-level final states in the
framework of minimal supersymmetry. We make no simplifying assumptions about
the neutralino nor about sfermion masses and mixings other than the absence of
explicit CP--violating terms. The expressions should be particularly useful in
computing the neutralino WIMP relic abundance without the usual approximation
of partial wave expansion.Comment: LaTeX, 46 pages, no figures. Several minor typographical errors
correcte
Continuum limit of proton decay matrix elements in quenched lattice QCD
We present a lattice QCD calculation of the parameters \alpha and \beta which
are necessary in the theoretical estimation of the proton lifetime in grand
unified theories (GUTs) using chiral lagrangian approach. The simulation is
carried out using the Wilson quark action at three gauge coupling constants in
the quenched approximation. We obtain
|\alpha(2GeV)|=0.0091(08)(^{+10}_{-19})GeV^3 and
|\beta(2GeV)|=0.0098(08)(^{+10}_{-20})GeV^3 in the continuum limit where the
first error is statistical and the second one is due to scale setting.Comment: 3 pages, 2 figures, talk presented at Lattice2003(matrix
Lattice QCD calculation of the proton decay matrix element in the continuum limit
We present a quenched lattice QCD calculation of the \alpha and \beta
parameters of the proton decay matrix element. The simulation is carried out
using the Wilson quark action at three values of the lattice spacing in the
range a\approx 0.1-0.064 fm to study the scaling violation effect. We find only
mild scaling violation when the lattice scale is determined by the nucleon
mass. We obtain in the continuum limit,
|\alpha(NDR,2GeV)|=0.0090(09)(^{+5}_{-19})GeV^3 and
|\beta(NDR,2GeV)|=0.0096(09)(^{+6}_{-20})GeV^3 with \alpha and \beta in a
relatively opposite sign, where the first error is statistical and the second
is due to the uncertainty in the determination of the physical scale.Comment: 4 pages, 3 figure
Inflation and Gauge Hierarchy in Randall-Sundrum Compactification
We obtain the general inflationary solutions for the slab of five-dimensional
AdS spacetime where the fifth dimension is an orbifold and two
three-branes reside at its boundaries, of which the Randall-Sundrum model
corresponds to the static limit. The investigation of the general solutions and
their static limit reveals that the RS model recasts both the cosmological
constant problem and the gauge hierarchy problem into the balancing problem of
the bulk and the brane cosmological constants.Comment: 9 pages, revtex, minor changes and more references adde
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