608 research outputs found
Heavy Sneutrinos as Dark Matter
We calculate the relic density of very heavy, stable scalar neutrinos in the
minimal supersymmetric standard model. We include all two-body final states, as
well as the effects of co-annihilation with scalar electrons. We find that the
sneutrino relic density is in the cosmologically interesting region
0.1\ltwid\Omega_{\sn}h^2\ltwid 1.0 for 550\gev\ltwid\msn\ltwid 2300\gev.
For nominal values of the parameters of our galactic halo, recent results from
the Heidelberg--Moscow direct detection experiment set an upper limit on
\Omega_{\sn} which is lower by a factor ranging from two to ten, depending on
\msn.Comment: 7 pages in LaTeX, plus 1 uuencoded figure (uses epsf),
UCSBTH--94--29, UMN--TH--1306/9
Corrections to Bino Annihilation I: Sfermion Mixing
We consider corrections to bino annihilation due to sfermion mixing.Comment: 11 pages in LaTex plus 4 postscript figures (included),
CfPA--93--th--21, UMN--TH--1205/9
Berry's conjecture and information theory
It is shown that, by applying a principle of information theory, one obtains
Berry's conjecture regarding the high-lying quantal energy eigenstates of
classically chaotic systems.Comment: 8 pages, no figure
Corrections to Bino Annihilation II: One-Loop Contribution to
We calculate the one-loop contribution to the bino annihilation rate due to
the process , which vanishes at tree level.Comment: 8 pages in LaTex plus 5 postscript figures (included),
UCSBTH--94--02, UMN--TH--1233/9
Relic Abundances and the Boltzmann Equation
I discuss the validity of the quantum Boltzmann equation for the calculation
of WIMP relic densities.Comment: 5 pages, no figures; talk given at Dark Matter 2000; an important
reference is added in the revised versio
Thermal Abundances of Heavy Particles
Matsumoto and Yoshimura [hep-ph/9910393] have argued that there are loop
corrections to the number density of heavy particles (in thermal equilibrium
with a gas of light particles) that are not Boltzmann suppressed by a factor of
e^(-M/T) at temperatures T well below the mass M of the heavy particle. We
argue, however, that their definition of the number density does not correspond
to a quantity that could be measured in a realistic experiment. We consider a
model where the heavy particles carry a conserved U(1) charge, and the light
particles do not. The fluctuations of the net charge in a given volume then
provide a measure of the total number of heavy particles in that same volume.
We show that these charge fluctuations are Boltzmann suppressed (to all orders
in perturbation theory). Therefore, we argue, the number density of heavy
particles is also Boltzmann suppressed.Comment: 9 pages, 1 figure; minor improvements in revised versio
Numerical determination of entanglement entropy for a sphere
We apply Srednicki's regularization to extract the logarithmic term in the
entanglement entropy produced by tracing out a real, massless, scalar field
inside a three dimensional sphere in 3+1 flat spacetime. We find numerically
that the coefficient of the logarithm is -1/90 to 0.2 percent accuracy, in
agreement with an existing analytical result
A Search For Solar Hadronic Axions Using Kr-83
We introduce a new experimental method for solar hadronic axions search. It
is suggested that these axions are created in the Sun during M1 transition
between the first thermally excited level at 9.4 keV and the ground state in
. Our method is based on axion detection via resonant absorption
process by the same nucleus in the laboratory. We use proportional gas counter
filled with krypton to detect signals for axions. With this setup, target and
detector are the same which increases the efficiency of the experiment. At
present, an upper limit on hadronic axion mass of 5.5 keV at the 95% confidence
level is obtained.Comment: 3 pages, contribution to ISRP9 Conference in Cape Town 2003. Version
accepted by Radiat. Phys. Che
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