326 research outputs found
Dilaton and off-shell (non-critical string) effects in Boltzmann equation for species abundances
In this work we derive the modifications to the Boltzmann equation governing
the cosmic evolution of relic abundances induced by dilaton dissipative-source
and non-critical-string terms in dilaton-driven non-equilibrium string
Cosmologies. We also discuss briefly the most important phenomenological
consequences, including modifications of the constraints on the available
parameter space of cosmologically appealing particle physics models, imposed by
recent precision data of astrophysical measurements.Comment: 12 pages revTex, no figure
On the Radiative Corrections to the Pseudo-scalar Higgs Boson Mass
We reexamine the one-loop corrections to the mass of the pseudo-scalar Higgs boson, using the effective potential. In the absence of the chargino and neutralino contributions its mass exhibits a large scale dependence in the large regime, especially for values of . Thus, although of electroweak origin, the heaviness of the , in conjunction with the largeness of , makes these corrections very important for establishing a scale independent result and an unambiguous determination of the pseudo-scalar mass in this region of the parameter space
Neutralino Dark Matter Elastic Scattering in a Flat and Accelerating Universe
In SUGRA inspired supersymmetric models with universal boundary conditions
for the soft masses, the scalar cross section for the elastic
neutralino--nucleon scattering is in general several orders of magnitude below
the sensitivity of current experiments. For large and low
values, the theoretically predicted can
approach the sensitivity of these experiments () being at
the same time in agreement with recent cosmological data, which impose severe
restrictions on the CDM relic density, and with accelerator experiments which
put lower bounds on sparticle and Higgs boson masses. Further improvement of
the sensitivity of DAMA and CDMS experiments will probe the large
region of the parameter space in the vicinity of the boundaries of the
parameter space allowed by chargino and Higgs searches.Comment: 15 pages, 9 figures. A note added; version to appear in MPL
Supergravity and Superstring Signatures of the One-Parameter Model at LHC
Many string constructions have a classical no-scale structure, resulting in a
one-parameter model (OPM) for the supersymmetry breaking soft terms. As a
highly constrained subset of mSUGRA, the OPM has the potential to be
predictive. Conversely, if the observed superpartner spectrum at LHC is a
subset of the OPM parameter space, then this may provide a clue to the
underlying theory at high energies. We investigate the allowed supersymmetry
parameter space for a generic one-parameter model taking into account the most
recent experimental constraints. We find that in the strict moduli scenario,
there are no regions of the parameter space which may satisfy all constraints.
However, for the dilaton scenario, there are small regions of the parameter
space where all constraints may be satisfied and for which the observed dark
matter density may be generated. We also survey the possible signatures which
may be observable at the Large Hadron Collider (LHC). Finally, we compare
collider signatures of OPM to those from a model with non-universal soft terms,
in particular those of an intersecting D6-brane model. We find that it may be
possible to distinguish between these diverse scenarios at LHC.Comment: 25 pages, 10 figures, accepted for publication in PR
Decoherent Scattering of Light Particles in a D-Brane Background
We discuss the scattering of two light particles in a D-brane background. It
is known that, if one light particle strikes the D brane at small impact
parameter, quantum recoil effects induce entanglement entropy in both the
excited D brane and the scattered particle. In this paper we compute the
asymptotic `out' state of a second light particle scattering off the D brane at
large impact parameter, showing that it also becomes mixed as a consequence of
quantum D-brane recoil effects. We interpret this as a non-factorizing
contribution to the superscattering operator S-dollar for the two light
particles in a Liouville D-brane background, that appears when quantum D-brane
excitations are taken into account.Comment: 18 pages LATEX, one figure (incorporated
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