66 research outputs found
CP Violating Phases and the Dark Matter Problem
New CP violating phases in the MSSM can affect both the abundance and
detection of neutralino dark matter. We discuss the effect of including
cosmological constraints in the limits on new sources of CP violation in the
MSSM and the effects of new CP violating parameters on dark matter densities
and detection.Comment: 9 pages in LaTeX2e, including 8 encapsulated postscript figures; uses
ws-p8-50x6-00.cls (included); to appear in the proceedings of COSMO99: 3rd
International Conference on Particle Physics and the Early Universe, Trieste,
Ital
The Angular Dependence of the Three-Point Correlation Function of the Cosmic Microwave Background Radiation as Predicted by Inflationary Cosmologies
Inflationary models predict a definite, model independent, angular dependence
for the three-point correlation function of at large angles
(greater than ) which we calculate. The overall amplitude is
model dependent and generically unobservably small, but may be large in some
specific models. We compare our results with other models of nongaussian
fluctuations.Comment: 7 pages, 3 figures (described but not included, available on
request), in Plain Tex, UCSBTH-92-3
More on Electric Dipole Moment Constraints on Phases in the Constrained MSSM
We reconsider constraints on \cp-violating phases in the Constrained
Minimal Supersymmetric Standard Model. We include the recent calculations of
Ibrahim and Nath on the chromoelectric and purely gluonic contributions to the
quark electric dipole moment and combine cosmological limits on gaugino masses
with experimental bounds on the neutron (and electron) electric dipole moments.
The constraint on the phase of the Higgs mixing mass , |\thm|, is
dependent on the value of the trilinear mass parameter, , in the model and
on . For values of |A| < 300 \gev at the GUT scale, we find
|\thm|/\pi \la 0.05, while for |A| < 1500 \gev, |\thm|/\pi \la 0.3. Thus,
we find that in principle, large CP violating phases are compatible with the
bounds on the electric dipole moments of the neutron and electron, as well as
remaining compatible with the cosmological upper bound on the relic density of
neutralinos. The other \cp-violating phase \tha is essentially
unconstrained.Comment: 11 pages in LaTeX + 4 postscript figures, uses epsf.sty. Added two
references, clarified figures. Accepted to Physics Letter
Supersymmetric Dark Matter in the Light of LEP and the Tevatron Collider
We analyze the accelerator constraints on the parameter space of the Minimal
Supersymmetric extension of the Standard Model, comparing those now available
from LEP II and anticipating the likely sensitivity of Tevatron Run II. The
most important limits are those from searches for charginos, neutralinos and
Higgs bosons at LEP, and searches for stop squarks, charginos and neutralinos
at the Tevatron Collider. We also incorporate the constraints derived from b
--> s + gamma decay, and discuss the relevance of charge- and colour-breaking
minima in the effective potential. We combine and compare the different
constraints on the Higgs-mixing parameter mu, the gaugino-mass parameter
m_{1/2} and the scalar-mass parameter m0, incorporating radiative corrections
to the physical particle masses. We focus on the resulting limitations on
supersymmetric dark matter, assumed to be the lightest neutralino,
incorporating coannihilation effects in the calculation of the relic abundance.
We find that m_chi > 51 GeV and tan(beta) > 2.2 if all soft
supersymmetry-breaking scalar masses are universal, including those of the
Higgs bosons, and that these limits weaken to m_chi > 46 GeV and tan(beta) >
1.9 if non-universal scalar masses are allowed. Light neutralino dark matter
cannot be primarily Higgsino in composition.Comment: 39 pages in LaTeX, including 44 encapsulated postscript figure
Charginos and Neutralinos in the Light of Radiative Corrections: Sealing the Fate of Higgsino Dark Matter
We analyze the LEP constraints from searches for charginos and
neutralinos , taking into account radiative corrections to the
relations between their masses and the underlying Higgs-mixing and gaugino-mass
parameters and the trilinear mass parameter . Whilst
radiative corrections do not alter the excluded domain in as a
function of , its mapping into the
plane is altered. We update our previous lower limits on the mass of gaugino
dark matter and on tan, the ratio of Higgs vacuum expectation values, in
the light of the latest LEP data and these radiative corrections. We also
discuss the viability of Higgsino dark matter, incorporating co-annihilation
effects into the calculation of the Higgsino relic abundance. We find that
Higgsino dark matter is viable for only a very limited range of and
, which will be explored completely by upcoming LEP runs.Comment: Version to appear in Phys. Rev. D., 21 pages in LateX, including 10
encapsulated postscript figures; uses epsf.sty.; Figures modified (one
deleted), conclusions unchange
Calculations of Neutralino-Stau Coannihilation Channels and the Cosmologically Relevant Region of MSSM Parameter Space
Assuming that the lightest supersymmetric particle (LSP) is the lightest
neutralino, we present a detailed exploration of neutralino-stau coannihilation
channels, including analytical expressions and numerical results. We also
include neutralino coannihilations with the selectron and smuon. We evaluate
the implications of coannihilations for the cosmological relic density of the
LSP, which is assumed to be stable, in the constrained minimal supersymmetric
extension of the Standard Model (CMSSM), in which the soft
supersymmetry-breaking parameters are universal at the supergravity GUT scale.
We evaluate the changes due to coannihilations in the region of the MSSM
parameter space that is consistent with the cosmological upper limit on the
relic LSP density. In particular, we find that the upper limit on the mass of
the neutralino is increased from about 200 GeV to about 600 GeV in the CMSSM,
and estimate a qualitatively similar increase for gauginos in the general MSSM.Comment: 38 pages in LaTeX, including 25 encapsulated postscript figures.
Added small clarification in the text, corrected some typos in the appendix.
Figures and conclusions unchange
Electric Dipole Moment Constraints on Phases in the Constrained MSSM
We consider constraints on \cp-violating phases in the Constrained Minimal
Supersymmetric Standard Model. We find that by combining cosmological limits on
gaugino masses with experimental bounds on the neutron and electron electric
dipole moments, we can constrain the phase of the Higgs mixing mass to be
, independent of choices of the other mass parameters in
the model. The other \cp-violating phase is essentially
unconstrained.Comment: 10 pages in LaTeX + 3 postscript figures, uses epsf.st
Neutralino-Stau Coannihilation and the Cosmological Upper Limit on the Mass of the Lightest Supersymmetric Particle
We consider the effects of neutralino-stau coannihilations on the
cosmological relic density of the lightest supersymmetric particle (LSP)
in the minimal supersymmetric extension of the Standard Model (MSSM),
particularly in the constrained MSSM in which universal supergravity inputs at
the GUT scale are assumed. For much of the parameter space in these models,
is approximately a U(1) gaugino , and constraints on the
cosmological relic density yield an upper bound on the
bino mass. We show that in regions of parameter space for which the
cosmological bound is nearly saturated, coannihilations of the with
the stau, the next lightest sparticle, are important and may reduce
significantly the bino relic density. Including also bino coannihilations with
the selectrons and smuons, we find that the upper limit on is
increased from about 200 GeV to about 600 GeV in the constrained MSSM, with a
similar new upper limit expected in the MSSM.Comment: 10 pages in LaTeX, including 2 encapsulated postscript figures; uses
epsf.sty; typo correcte
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