19,042 research outputs found
Theoretical Predictions for the Direct Detection of Supersymmetric Dark Matter
We compute the neutralino-nucleon cross section in several supersymmetric
scenarios, taking into account all kind of experimental and astrophysical
constraints. In addition, the constraints that the absence of dangerous charge
and colour breaking minima imposes on the parameter space are also considered.
This computation is relevant for the theoretical analysis of the direct
detection of dark matter in current experiments. We discuss interesting
supergravity and superstring scenarios.Comment: 13 pages, 7 figures, Proceedings of the International Workshop on
Astroparticle and High Energy Physics, AHEP-200
Extra matter at low energy
Assuming that the Standard Model arises from the Heterotic
Superstring, we try to solve the discrepancy between the unification scale
predicted by this theory ( GeV) and
the value deduced from LEP experiments ( GeV). This
will allow us to predict the presence at low energies of three generations of
supersymmetric Higgses and vector-like colour triplets.Comment: Talk given at 1st International Conference on String Phenomenology,
Oxford, 6-11 July 2002. 6 pages, 1 figur
Experimental Constraints on the Neutralino-Nucleon Cross Section
In the light of recent experimental results for the direct detection of dark
matter, we analyze in the framework of SUGRA the value of the
neutralino-nucleon cross section. We study how this value is modified when the
usual assumptions of universal soft terms and GUT scale are relaxed. In
particular we consider scenarios with non-universal scalar and gaugino masses
and scenarios with intermediate unification scale. We also study superstring
constructions with D-branes, where a combination of the above two scenarios
arises naturally. In the analysis we take into account the most recent
experimental constraints, such as the lower bound on the Higgs mass, the branching ratio, and the muon .Comment: References added, bsgamma upper bound improved, results unchanged,
Talk given at Corfu Summer Institute on Elementary Particle Physics, August
31-September 20, 200
Lepton masses and mixings in orbifold models with three Higgs families
We analyse the phenomenological viability of heterotic Z(3) orbifolds with
two Wilson lines, which naturally predict three supersymmetric families of
matter and Higgs fields. Given that these models can accommodate realistic
scenarios for the quark sector avoiding potentially dangerous flavour-changing
neutral currents, we now address the leptonic sector, finding that viable
orbifold configurations can in principle be obtained. In particular,it is
possible to accomodate present data on charged lepton masses, while avoiding
conflict with lepton flavour-violating decays. Concerning the generation of
neutrino masses and mixings, we find that Z(3) orbifolds offer several
interesting possibilities.Comment: 28 pages, 11 figures. References adde
Right-handed sneutrino as thermal dark matter
We study an extension of the MSSM with a singlet S with coupling SH1H2 in
order to solve the mu problem as in the NMSSM, and right-handed neutrinos N
with couplings SNN in order to generate dynamically electroweak-scale Majorana
masses. We show how in this model a purely right-handed sneutrino can be a
viable candidate for cold dark matter in the Universe. Through the direct
coupling to the singlet, the sneutrino can not only be thermal relic dark
matter but also have a large enough scattering cross section with nuclei to
detect it directly in near future, in contrast with most of other right-handed
sneutrino dark matter models.Comment: 5 pages, 2 figures. References added and minor changes. Final version
to appear in Phys. Rev.
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