3,114 research outputs found
Unification and Dark Matter in a Minimal Scalar Extension of the Standard Model
The six Higgs doublet model is a minimal extension of the Standard Model that
addresses dark matter and gauge coupling unification. Another Higgs doublet in
a 5 representation of a discrete symmetry group, such as S_6, is added to the
SM. The lightest components of the 5-Higgs are neutral, stable and serve as
dark matter so long as the discrete symmetry is not broken. Direct and indirect
detection signals, as well as collider signatures are discussed. The five-fold
multiplicity of the dark matter decreases its mass and typically helps make the
dark matter more visible in upcoming experiments.Comment: 10 pages, 7 figures; added references; corrected typo
Here be Dragons: The Unexplored Continents of the CMSSM
The Higgs boson mass and the abundance of dark matter constrain the
CMSSM/mSUGRA supersymmetry breaking inputs. A complete map of the CMSSM that is
consistent with these two measured quantities is provided. Various
"continents," consisting of non-excluded models, can be organized by their dark
matter dynamics. The following mechanisms manifest: well-tempering, resonant
pseudo-scalar Higgs annihilation, neutralino/stau coannihilations and
neutralino/stop coannihilations. Benchmark models are chosen in order to
characterize the viable regions. The expected visible signals of each are
described, demonstrating a wide range of predictions for the 13 TeV LHC and a
high degree of complementarity between dark matter and collider experiments.
The parameter space spans a finite volume, which can be probed in its entirety
with experiments currently under consideration.Comment: 58 pages + references, 21 figures, data files included on arXiv; v2:
references added, minor changes; v3: journal version, minor change
Parity Violation in Composite Inelastic Dark Matter Models
Recent experimental results indicate that the dark matter sector may have a
non-minimal structure with a spectrum of states and interactions. Inelastic
scattering has received particular attention in light of DAMA's annual
modulation signal. Composite inelastic dark matter (CiDM) provides a dynamical
origin for the mass splittings in inelastic dark matter models. We show that
higher dimensional operators in the CiDM Lagrangian lead to an admixture of
inelastic and elastic scattering in the presence of parity violation. This
scenario is consistent with direct detection experiments, even when parity
violation is nearly maximal. We present an effective field theory description
of such models and discuss the constraints from direct detection experiments.
The CiDM model with parity violation has non-trivial phenomenology because of
the multiple scattering channels that are allowed.Comment: 10 pages, 3 figure
Positive Correlations in Tunneling through coupled Quantum Dots
Due to the Fermi-Dirac statistics of electrons the temporal correlations of
tunneling events in a double barrier setup are typically negative. Here, we
investigate the shot noise behavior of a system of two capacitively coupled
quantum dot states by means of a Master equation model. In an asymmetric setup
positive correlations in the tunneling current can arise due to the bunching of
tunneling events. The underlying mechanism will be discussed in detail in terms
of the current-current correlation function and the frequency-dependent Fano
factor.Comment: HCIS 13 in Moden
Microscopic modelling of perpendicular electronic transport in doped multiple quantum wells
We present a microscopic calculation of transport in strongly doped
superlattices where domain formation is likely to occur. Our theoretical method
is based on a current formula involving the spectral functions of the system,
and thus allows, in principle, a systematic investigation of various
interaction mechanisms. Taking into account impurity scattering and optical
phonons we obtain a good quantitative agreement with existing experimental data
from Helgesen and Finstad (J. Appl. Phys. 69, 2689, (1991)). Furthermore the
calculated spectral functions indicate a significant increase of the average
intersubband spacing compared to the bare level differences which might explain
the experimental trend.Comment: 10 pages 5 figure
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