11 research outputs found
The NMSSM at the Cosmic Frontier for Snowmass 2013
We examine the NMSSM at the cosmic frontier in the post Higgs discovery
world. For DM relic abundance consistent with measurement, we find the
neutralino can either be singlino or bino dominated. Wino and higgsino DM
generally yield a lower abundance, but offer opportunities of detection at
IceCube. For both cases, future SI direct detection experiments cover a
majority of the model, including nearly all of the bino and higgsino scenarios.Comment: 3 pages, 1 figure, Snowmass whitepaper submissio
MadDM v.1.0: Computation of Dark Matter Relic Abundance Using MadGraph5
We present MadDM v.1.0, a numerical tool to compute dark matter relic
abundance in a generic model. The code is based on the existing MadGraph 5
architecture and as such is easily integrable into any MadGraph collider study.
A simple Python interface offers a level of user-friendliness characteristic of
MadGraph 5 without sacrificing functionality. MadDM is able to calculate the
dark matter relic abundance in models which include a multi-component dark
sector, resonance annihilation channels and co-annihilations. We validate the
code in a wide range of dark matter models by comparing the relic density
results from MadDM to the existing tools and literature.Comment: 35 pages, 6 figure
A Supersymmetric Model with Dirac Neutrino Masses
New models have recently been proposed in which a second Higgs doublet
couples only to the lepton doublets and right-handed neutrinos, yielding Dirac
neutrino masses. The vacuum value of this second "nu-Higgs" doublet is made
very small by means of a very softly-broken or U(1) symmetry. The latter
is technically natural and avoids fine-tuning and very light scalars. We
consider a supersymmetric version of this model, in which two additional
doublets are added to the MSSM. If kinematically allowed, the decay of the
heavy MSSM scalar into charged nu-Higgs scalars will yield dilepton events
which can be separated from the W-pair background. In addition, the
nu-Higgsinos can lead to very dramatic tetralepton, pentalepton and hexalepton
events which have negligible background and can be detected at the LHC and the
Tevatron.Comment: 18 pages, 3 figures, 6 tables; PRD versio
LHC Phenomenology of an Extended Standard Model with a Real Scalar Singlet
Gauge singlet extensions of the Standard Model (SM) scalar sector may help
remedy its theoretical and phenomenological shortcomings while solving
outstanding problems in cosmology. Depending on the symmetries of the scalar
potential, such extensions may provide a viable candidate for the observed
relic density of cold dark matter or a strong first order electroweak phase
transition needed for electroweak baryogenesis. Using the simplest extension of
the SM scalar sector with one real singlet field, we analyze the generic
implications of a singlet-extended scalar sector for Higgs boson phenomenology
at the Large Hadron Collider (LHC). We consider two broad scenarios: one in
which the neutral SM Higgs and singlet mix and the other in which no mixing
occurs and the singlet can be a dark matter particle. For the first scenario,
we analyze constraints from electroweak precision observables and their
implications for LHC Higgs phenomenology. For models in which the singlet is
stable, we determine the conditions under which it can yield the observed relic
density, compute the cross sections for direct detection in recoil experiments,
and discuss the corresponding signatures at the LHC.Comment: 39 pages, 11 figures, 2 table
Complex Singlet Extension of the Standard Model
We analyze a simple extension of the Standard Model (SM) obtained by adding a
complex singlet to the scalar sector (cxSM). We show that the cxSM can contain
one or two viable cold dark matter candidates and analyze the conditions on the
parameters of the scalar potential that yield the observed relic density. When
the cxSM potential contains a global U(1) symmetry that is both softly and
spontaneously broken, it contains both a viable dark matter candidate and the
ingredients necessary for a strong first order electroweak phase transition as
needed for electroweak baryogenesis. We also study the implications of the
model for discovery of a Higgs boson at the Large Hadron Collider.Comment: 30 pages, 10 figures, 1 table, PRD versio
Multi-lepton signals from the top-prime quark at the LHC
We analyze the collider signatures of models with a vector-like top-prime
quark and a massive color-octet boson. The top-prime quark mixes with the top
quark in the Standard Model, leading to richer final states than ones that are
investigated by experimental collaborations. We discuss the multi-lepton final
states, and show that they can provide increased sensitivity to models with a
top-prime quark and gluon-prime. Searches for new physics in high multiplicity
events are an important component of the LHC program and complementary to
analyses that have been performed.Comment: 7 pages, 4 figures, 2 table