22,291 research outputs found
An effective scanning method of the NMSSM parameter space
The next-to-minimal supersymmetric standard model (NMSSM) naturally provides
a 125 GeV Higgs boson without the need for large loop corrections from
multi-TeV stop quarks. Furthermore, the NMSSM provides an electroweak scale
dark matter candidate consistent with all experimental data, like relic density
and non-observation of direct dark matter signals with the present experimental
sensitivity. However, more free parameters are introduced in the NMSSM, which
are strongly correlated. A simple parameter scan without knowing the
correlation matrix is not efficient and can miss significant regions of the
parameter space. We introduce a new technique to sample the NMSSM parameter
space, which takes into account the correlations. For this we project the 7D
NMSSM parameter space onto the 3D Higgs boson mass parameter space. The reduced
dimensionality allows for a non-random sampling and therefore a complete
coverage of the allowed NMSSM parameters. In addition, the parameter
correlations and possible deviations of the signal strengths of the observed
125 Higgs boson from the SM values are easily predicted.Comment: 15 pages, 5 figure
A new Determination of the Extragalactic Background of Diffuse Gamma Rays taking into account Dark Matter Annihilation
The extragalactic background (EGB) of diffuse gamma rays can be determined by
subtracting the Galactic contribution from the data. This requires a Galactic
model (GM) and we include for the first time the contribution of dark matter
annihilation (DMA), which was previously proposed as an explanation for the
EGRET excess of diffuse Galactic gamma rays above 1 GeV.
In this paper it is shown that the newly determined EGB shows a
characteristic high energy bump on top of a steeply falling soft contribution.
The bump is shown to be compatible with a contribution from an extragalactic
DMA signal from weakly interacting massive particles (WIMPs) with a mass
between 50 and 100 GeV in agreement with the EGRET excess of the Galactic
diffuse gamma rays and in disagreement with earlier analysis. The remaining
soft contribution of the EGB is shown to resemble the spectra of the observed
point sources in our Galaxy.Comment: 7 pages, 4 figures. Accepted by A&A, made Fig. 4 and table 1
consisten
A gobal fit to the anomalous magnetic moment, b->s gamma and Higgs limits in the constrained MSSM
New data on the anomalous magnetic moment a_mu of the muon together with the
b->s gamma decay rate are considered within the supergravity inspired
constrained minimal supersymmetric model. We perform a global statistical chi^2
analysis of these data and show that the allowed region of parameter space is
bounded from below by the Higgs limit, which depends on the trilinear coupling
and from above by the anomalous magnetic moment a_mu. The newest b->s gamma
data deviate 1.7 sigma from recent SM calculations and prefer a similar
parameter region as the 2.6 sigma deviation from a_mu.Comment: 12 pages, 7 figs. Refs. update
The impact of a 126 GeV Higgs on the neutralino mass
We highlight the differences of the dark matter sector between the
constrained minimal supersymmetric SM (CMSSM) and the next-to-minimal
supersymmetric SM (NMSSM) including the 126 GeV Higgs boson using GUT scale
parameters. In the dark matter sector the two models are quite orthogonal: in
the CMSSM the WIMP is largely a bino and requires large masses from the LHC
constraints. In the NMSSM the WIMP has a large singlino component and is
therefore independent of the LHC SUSY mass limits. The light NMSSM neutralino
mass range is of interest for the hints concerning light WIMPs in the Fermi
data. Such low mass WIMPs cannot be explained in the CMSSM. Furthermore,
prospects for discovery of XENON1T and LHC at 14 TeV are given.Comment: 18 pages, 5 figures, this version is accepted by PLB after
modifications including additional figure
Can we discover a light singlet-like NMSSM Higgs boson at the LHC?
In the next-to minimal supersymmetric standard model (NMSSM) one additional
singlet-like Higgs boson with small couplings to standard model (SM) particles
is introduced. Although the mass can be well below the discovered 125 GeV Higgs
boson mass its small couplings may make a discovery at the LHC difficult. We
use a novel scanning technique to efficiently scan the whole parameter space
and determine the range of cross sections and branching ratios for the light
singlet-like Higgs boson below 125 GeV. This allows to determine the
perspectives for the future discovery potential at the LHC. Specific LHC
benchmark points are selected representing the salient NMSSM features.Comment: 22 pages, 5 figures, this version is accepted by PLB after minor
modification
Critical behavior at Mott-Anderson transition: a TMT-DMFT perspective
We present a detailed analysis of the critical behavior close to the
Mott-Anderson transition. Our findings are based on a combination of numerical
and analytical results obtained within the framework of Typical-Medium Theory
(TMT-DMFT) - the simplest extension of dynamical mean field theory (DMFT)
capable of incorporating Anderson localization effects. By making use of
previous scaling studies of Anderson impurity models close to the
metal-insulator transition, we solve this problem analytically and reveal the
dependence of the critical behavior on the particle-hole symmetry. Our main
result is that, for sufficiently strong disorder, the Mott-Anderson transition
is characterized by a precisely defined two-fluid behavior, in which only a
fraction of the electrons undergo a "site selective" Mott localization; the
rest become Anderson-localized quasiparticles.Comment: 4+ pages, 4 figures, v2: minor changes, accepted for publication in
Phys. Rev. Let
The supersymmetric interpretation of the EGRET excess of diffuse Galactic gamma rays
Recently it was shown that the excess of diffuse Galactic gamma rays above 1
GeV traces the Dark Matter halo, as proven by reconstructing the peculiar shape
of the rotation curve of our Galaxy from the gamma ray excess. This can be
interpreted as a Dark Matter annihilation signal. In this paper we investigate
if this interpretation is consistent with Supersymmetry. It is found that the
EGRET excess combined with all electroweak constraints is fully consistent with
the minimal mSUGRA model for scalars in the TeV range and gauginos below 500
GeV.Comment: 11 pages, 6 figures, extended version with more figures, as accepted
for publication in Phys. Letters
Effect of farming system changes on life cycle assessment indicators for dairy farms in the Italian Alps.
In some Alpine areas dairy farming is going through a process of intensification with significant changes in farming systems. The aim of this study was to investigate environmental performance of a sample of 31 dairy farms in an Alpine area of Lombardy with different levels of intensification. A cradle to farm gate life cycle assessment was performed including the following impact categories: land use, non-renewable energy use, climate change, acidification and eutrophication. From a cluster analysis it resulted that the group of farms with lowest environmental impacts were characterized by low stocking density and production intensity; farms that combined good environmental performances with medium gross margins were characterized also by high feed self-sufficiency and lowland availability. Environmental impacts of dairy farms in the mountain areas could be mitigated by the improvement of forage production and quality and by the practice of summer highland grazing, that significantly reduced eutrophication per kg of milk of the less self-sufficient farms
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