599 research outputs found
Neutralino Dark Matter in MSSM Models with Non-Universal Higgs Masses
We consider the Minimal Supersymmetric Standard Model (MSSM) with varying
amounts of non-universality in the soft supersymmetry-breaking contributions to
the Higgs scalar masses. In addition to the constrained MSSM (CMSSM) in which
these are universal with the soft supersymmetry-breaking contributions to the
squark and slepton masses at the input GUT scale, we consider scenarios in
which both the Higgs masses are non-universal by the same amount (NUHM1), and
scenarios in which they are independently non-universal (NUHM2). As the
lightest neutralino is a dark matter candidate, we demand that the relic
density of neutralinos not be in conflict with measurements by WMAP and others,
and examine the viable regions of parameter space. Prospects for direct
detection of neutralino dark matter via elastic scattering in these scenarios
are discussed.Comment: 8 pages, 6 figures, to be published in the proceedings of the
Invisible Universe International Conference, UNESCO, Paris, June 29 - July 3,
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Dark Matter and EWSB Naturalness in Unified SUSY Models
The relationship between the degree of fine-tuning in Electroweak Symmetry
Breaking (EWSB) and the discoverability of dark matter in current and next
generation direct detection experiments is investigated in the context of two
unified Supersymmetry scenarios: the constrained Minimal Supersymmetric
Standard Model (CMSSM) and models with non-universal Higgs masses (NUHM).
Attention is drawn to the mechanism(s) by which the relic abundance of
neutralino dark matter is suppressed to cosmologically viable values. After a
summary of Amsel, Freese, and Sandick (2011), results are updated to reflect
current constraints, including the discovery of a new particle consistent with
a Standard Model-like Higgs boson. We find that a Higgs mass of ~125 GeV
excludes the least fine-tuned CMSSM points in our parameter space and that
remaining viable models may be difficult to probe with next generation direct
dark matter searches. Relatively low fine-tuning and good direct detection
prospects are still possible in NUHM scenarios.Comment: 10 pages, 7 figures, to appear in the proceedings of CETUP* 2012. v2:
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Detecting Dark Matter In The MSSM With Non-Universal Higgs Masses
We discuss the direct detection prospects for neutralino dark matter via elastic scattering in variations of the MSSM with non-universal supersymmetry-breaking contributions to the Higgs masses Taking as our starting point the CMSSM, in which supersymmetry-breaking contributions to all scalar masses are universal, we examine scenarios in which both Higgs scalar masses are non-universal by the same amount (NUHM1) and scenarios in which the Higgs scalar masses are independently non-universal (NUHM2)Astronom
Well-Mixed Dark Matter and the Higgs
The breaking of electroweak symmetry through renormalization group flow in
models that have MSSM spectra is found to produce "well-mixed" neutralino dark
matter with a relic density consistent with the WMAP data and elastic
scattering cross section with nuclei consistent with current limits from direct
dark matter searches. These models predict a Higgs boson mass in the range
(125-126) GeV. Well-mixed neutralino dark matter is predominantly bino-like,
but has significant Higgsino and wino content, each with fractions of
comparable size. With a ~1 TeV gluino mass and sizable neutralino-nucleon
scattering cross sections, natural models will be fully tested by both the LHC
and future dark matter direct detection experiments.Comment: 8 pages, 3 figures. V2: Substantial revisions, title change
Varying the Universality of Supersymmetry-Breaking Contributions to MSSM Higgs Boson Masses
We consider the minimal supersymmetric extension of the Standard Model (MSSM)
with varying amounts of non-universality in the soft supersymmetry-breaking
contributions to the Higgs scalar masses. In addition to the constrained MSSM
(CMSSM) in which these are universal with the soft supersymmetry-breaking
contributions to the squark and slepton masses at the input GUT scale, we
consider scenarios in which both the Higgs scalar masses are non-universal by
the same amount (NUHM1), and scenarios in which they are independently
non-universal (NUHM2). We show how the NUHM1 scenarios generalize the (m_{1/2},
m_0) planes of the CMSSM by allowing either mu or m_A to take different (fixed)
values and we also show how the NUHM1 scenarios are embedded as special cases
of the more general NUHM2 scenarios. Generalizing from the CMSSM, we find
regions of the NUHM1 parameter space that are excluded because the LSP is a
selectron. We also find new regions where the neutralino relic density falls
within the range preferred by astrophysical and cosmological measurements,
thanks to rapid annihilation through direct-channel Higgs poles, or
coannihilation with selectrons, or because the LSP composition crosses over
from being mainly bino to mainly Higgsino. Generalizing further to the NUHM2,
we find regions of its parameter space where a sneutrino is the LSP, and others
where neutralino coannihilation with sneutrinos is important for the relic
density. In both the NUHM1 and the NUHM2, there are slivers of parameter space
where the LHC has fewer prospects for discovering sparticles than in the CMSSM,
because either m_{1/2} and/or m_0 may be considerably larger than in the CMSSM.Comment: 39 pages, 16 figure
Black Holes in our Galactic Halo: Compatibility with FGST and PAMELA Data and Constraints on the First Stars
10 to 10^5 solar mass black holes with dark matter spikes that formed in
early minihalos and still exist in our Milky Way Galaxy today are examined in
light of recent data from the Fermi Gamma-Ray Space Telescope (FGST). The dark
matter spikes surrounding black holes in our Galaxy are sites of significant
dark matter annihilation. We examine the signatures of annihilations into
gamma-rays, electrons and positrons, and neutrinos. We find that some
significant fraction of the point sources detected by FGST might be due to dark
matter annihilation near black holes in our Galaxy. We obtain limits on the
properties of dark matter annihilations in the spikes using the information in
the FGST First Source Catalog as well as the diffuse gamma-ray flux measured by
FGST. We determine the maximum fraction of high redshift minihalos that could
have hosted the formation of the first generation of stars and, subsequently,
their black hole remnants. The strength of the limits depends on the choice of
annihilation channel and black hole mass; limits are strongest for the heaviest
black holes and annhilation to and final states. The
larger black holes considered in this paper may arise as the remnants of Dark
Stars after the dark matter fuel is exhausted and thermonuclear burning runs
its course; thus FGST observations may be used to constrain the properties of
Dark Stars. Additionally, we comment on the excess positron flux found by
PAMELA and its possible interpretation in terms of dark matter annihilation
around these black hole spikes.Comment: 34 pages, 11 figures. v2: typos corrected, references added. v3:
updated to match published versio
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