185 research outputs found
Gravitino LSP and leptogenesis after the first LHC results
Supersymmetric scenarios where the lightest superparticle (LSP) is the
gravitino are an attractive alternative to the widely studied case of a
neutralino LSP. A strong motivation for a gravitino LSP arises from the
possibility of achieving higher reheating temperatures and thus potentially
allow for thermal leptogenesis. The predictions for the primordial abundances
of light elements in the presence of a late decaying next-to-LSP (NSLP) as well
as the currently measured dark matter abundance allow us to probe the
cosmological viability of such a scenario. Here we consider a gravitino-stau
scenario. Utilizing a pMSSM scan we work out the implications of the 7 and 8
TeV LHC results as well as other experimental and theoretical constraints on
the highest reheating temperatures that are cosmologically allowed. Our
analysis shows that points with T_R>10^9 GeV survive only in a very particular
corner of the SUSY parameter space. Those spectra feature a distinct signature
at colliders that could be looked at in the upcoming LHC run.Comment: 19 pages + references, 9 eps figures; v2: analysis improved, figures
2-5 updated, conclusions unchanged, presentation improved, references added,
matches journal versio
Interplay of super-WIMP and freeze-in production of dark matter
Non-thermalized dark matter is a cosmologically valid alternative to the
paradigm of weakly interacting massive particles. For dark matter belonging to
a -odd sector that contains in addition a thermalized mediator particle,
dark matter production proceeds in general via both the freeze-in and superWIMP
mechanism. We highlight their interplay and emphasize the connection to
long-lived particles at colliders. For the explicit example of a colored
t-channel mediator model we map out the entire accessible parameter space,
cornered by bounds from the LHC, big bang nucleosynthesis and Lyman-alpha
forest observations, respectively. We discuss prospects for the HL- and HE-LHC.Comment: 9 pages + references, 2 figures; v2: title changed, matches journal
versio
Long-lived staus from strong production in a simplified model approach
We study the phenomenology of a supersymmetric scenario where the
next-to-lightest superparticle is the lighter stau and long-lived due to a very
weakly coupled lightest superparticle, such as the gravitino. We investigate
the LHC sensitivity and its dependence on the superparticle spectrum with an
emphasis on strong production and decay. We do not assume any high-scale model
for SUSY breaking but work along the lines of simplified models. Devising cuts
that yield a large detection efficiency in the whole parameter space, we
determine the LHC's discovery and exclusion potential. This allows us to derive
robust limits on m_stau, m_gluino, a common m_squark, and m_stop1. We briefly
discuss the prospects for observing stopped staus.Comment: 25 pages + references, 27 eps figures; v3: Matches journal version,
typo in table 1 correcte
Probing dark matter annihilation in the Galaxy with antiprotons and gamma rays
A possible hint of dark matter annihilation has been found in Cuoco,
Korsmeier and Kr\"amer (2017) from an analysis of recent cosmic-ray antiproton
data from AMS-02 and taking into account cosmic-ray propagation uncertainties
by fitting at the same time dark matter and propagation parameters. Here, we
extend this analysis to a wider class of annihilation channels. We find
consistent hints of a dark matter signal with an annihilation cross-section
close to the thermal value and with masses in range between 40 and 130 GeV
depending on the annihilation channel. Furthermore, we investigate in how far
the possible signal is compatible with the Galactic center gamma-ray excess and
recent observation of dwarf satellite galaxies by performing a joint global fit
including uncertainties in the dark matter density profile. As an example, we
interpret our results in the framework of the Higgs portal model.Comment: 12 pages + references, 4 figures, v2: References added, minor changes
in presentation, matches journal versio
A global fit of the -ray galactic center excess within the scalar singlet Higgs portal model
We analyse the excess in the -ray emission from the center of our
galaxy observed by Fermi-LAT in terms of dark matter annihilation within the
scalar Higgs portal model. In particular, we include the astrophysical
uncertainties from the dark matter distribution and allow for unspecified
additional dark matter components. We demonstrate through a detailed numerical
fit that the strength and shape of the -ray spectrum can indeed be
described by the model in various regions of dark matter masses and couplings.
Constraints from invisible Higgs decays, direct dark matter searches, indirect
searches in dwarf galaxies and for -ray lines, and constraints from the
dark matter relic density reduce the parameter space to dark matter masses near
the Higgs resonance. We find two viable regions: one where the Higgs-dark
matter coupling is of , and an additional dark matter
component beyond the scalar WIMP of our model is preferred, and one region
where the Higgs-dark matter coupling may be significantly smaller, but where
the scalar WIMP constitutes a significant fraction or even all of dark matter.
Both viable regions are hard to probe in future direct detection and collider
experiments.Comment: 20 pages + references, 12 figures; v2: minor changes in presentation,
references added, improved scan coverage and updated plots in figs. 6, 8, 9,
10 and 12 accordingly, conclusions unchanged, matches journal versio
Solar -rays as a Complementary Probe of Dark Matter
We show that observations of solar -rays offer a novel probe of dark
matter in scenarios where interactions with the visible sector proceed via a
long-lived mediator. As a proof of principle, we demonstrate that there exists
a class of models which yield solar -ray fluxes observable with the
next generation of -ray telescopes, while being allowed by a variety of
current experimental constraints. The parameter space allowed by big bang
nucleosynthesis and beam dump experiments naturally leads to mediator lifetimes
sufficient to produce observable solar -ray signals. The model allows
for solar -ray fluxes up to orders of magnitude larger compared to
dwarf spheroidal galaxies, without reaching equilibrium between dark matter
annihilation and capture rate. Our results suggest that solar -ray
observations are complementary, and in some cases superior, to existing and
future dark matter detection efforts.Comment: 15 pages + references, 7 figures, v3: Fermi-LAT and HERD sensitivity
corrected, minor presentational improvements, matches journal versio
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