44 research outputs found
Probing High Reheating Temperature Scenarios at the LHC with Long-Lived Staus
We investigate the possibility of probing high reheating temperature
scenarios at the LHC, in supersymmetric models where the gravitino is the
lightest supersymmetric particle, and the stau is the next-to-lightest
supersymmetric particle. In such scenarios, the big-bang nucleosynthesis and
the gravitino abundance give a severe upper bound on the gluino mass. We find
that, if the reheating temperature is \sim 10^8 GeV or higher, the scenarios
can be tested at the LHC with an integrated luminosity of O(1 fb^{-1}) at
\sqrt{s}=7 TeV in most of the parameter space.Comment: 17 pages, 5 figures, minor modification
Vacuum Stability Bound on Extended GMSB Models
Extensions of GMSB models were explored to explain the recent reports of the
Higgs boson mass around 124-126 GeV. Some models predict a large mu term, which
can spoil the vacuum stability of the universe. We study two GMSB extensions:
i) the model with a large trilinear coupling of the top squark, and ii) that
with extra vector-like matters. In both models, the vacuum stability condition
provides upper bounds on the gluino mass if combined with the muon g-2. The
whole parameter region is expected to be covered by LHC at sqrt{s} = 14 TeV.
The analysis is also applied to the mSUGRA models with the vector-like matters.Comment: 22 pages, 4 figure
Gravitino Dark Matter in Tree Level Gauge Mediation with and without R-parity
We investigate the cosmological aspects of Tree Level Gauge Mediation, a
recently proposed mechanism in which the breaking of supersymmetry is
communicated to the soft scalar masses by extra gauge interactions at the tree
level. Embedding the mechanism in a Grand Unified Theory and requiring the
observability of sfermion masses at the Large Hadron Collider, it follows that
the Lightest Supersymmetric Particle is a gravitino with a mass of the order of
10 GeV. The analysis in the presence of R-parity shows that a typical Tree
Level Gauge Mediation spectrum leads to an overabundance of the Dark Matter
relic density and a tension with the constraints from Big Bang Nucleosynthesis.
This suggests to relax the exact conservation of the R-parity. The underlying
SO(10) Grand Unified Theory together with the bounds from proton decay provide
a rationale for considering only bilinear R-parity violating operators. We
finally analyze the cosmological implications of this setup by identifying the
phenomenologically viable regions of the parameter space.Comment: 28 pages, 5 figures. References added. To appear in JHE
Direct stau production at hadron colliders in cosmologically motivated scenarios
We calculate dominant cross section contributions for stau pair production at
hadron colliders within the MSSM, taking into account left-right mixing of the
stau eigenstates. We find that b-quark annihilation and gluon fusion can
enhance the cross sections by more than one order of magnitude with respect to
the Drell-Yan predictions. These additional production channels are not yet
included in the common Monte Carlo analysis programs and have been neglected in
experimental analyses so far. For long-lived staus, we investigate differential
distributions and prospects for their stopping in the collider detectors. New
possible strategies are outlined to determine the mass and width of the heavy
CP-even Higgs boson H0. Scans of the relevant regions in the CMSSM are
performed and predictions are given for the current experiments at the LHC and
the Tevatron. The obtained insights allow us to propose collider tests of
cosmologically motivated scenarios with long-lived staus that have an
exceptionally small thermal relic abundance.Comment: 49 pages, 13 figures; v2: references added, typos corrected, text
streamlined, results unchange
Theory and Phenomenology of mu in M theory
We consider a solution to the mu-problem within M theory on a G2-manifold.
Our study is based upon the discrete symmetry proposed by Witten that forbids
the mu-term and solves the doublet-triplet splitting problem. We point out that
the symmetry must be broken by moduli stabilization, describing in detail how
this can occur. The mu-term is generated via Kahler interactions after strong
dynamics in the hidden sector generate a potential which stabilizes all moduli
and breaks supersymmetry with m_{3/2} ~ 20 - 30 TeV. We show that mu is
suppressed relative to the gravitino mass, by higher dimensional operators, mu
~ 0.1 m_{3/2} ~ 2-3 TeV. This necessarily gives a Higgsino component to the
(mostly Wino) LSP, and a small but non-negligible LSP-nucleon scattering
cross-section. The maximum, spin-independent cross-sections are not within
reach of the current XENON100 experiment, but are within reach of upcoming runs
and upgrades.Comment: 34 pages, 3 figure