2,465 research outputs found
Coloured coannihilations: Dark matter phenomenology meets non-relativistic EFTs
We investigate the phenomenology of a simplified model with a Majorana
fermion as dark matter candidate which interacts with Standard Model quarks via
a colour-charged coannihilation partner. Recently it has been realized that
non-perturbative dynamics, including the Sommerfeld effect, bound state
formation/dissociation and thermal corrections, play an important role in
coannihilations with coloured mediators. This calls for a careful analysis of
thermal freeze-out and a new look at the experimental signatures expected for a
thermal relic. We employ a state of the art calculation of the relic density
which makes use of a non-relativistic effective theory framework and calculate
the effective annihilation rates by solving a plasma-modified Schrodinger
equation. We determine the cosmologically preferred parameter space and
confront it with current experimental limits and future prospects for dark
matter detection.Comment: Published version, references and section on indirect detection adde
Stop Co-Annihilation in the Minimal Supersymmetric Standard Model Revisited
We re-examine the stop co-annihilation scenario of the Minimal Supersymmetric Standard Model, wherein a bino-like lightest supersymmetric particle has a thermal relic density set by co-annihilations with a scalar partner of the top quark in the early universe. We concentrate on the case where only the top partner sector is relevant for the cosmology, and other particles are heavy. We discuss the cosmology with focus on low energy parameters and an emphasis on the implications of the measured Higgs boson mass and its properties. We find that the irreducible direct detection signal correlated with this cosmology is generically well below projected experimental sensitivity, and in most cases lies below the neutrino background. A larger, detectable, direct detection rate is possible, but is unrelated to the co-annihilation cosmology. LHC searches for compressed spectra are crucial for probing this scenario
Pseudoscalar Mediators: A WIMP model at the Neutrino Floor
Due to its highly suppressed cross section (fermionic) dark matter
interacting with the Standard Model via pseudoscalar mediators is expected to
be essentially unobservable in direct detection experiments. We consider both a
simplified model and a more realistic model based on an extended two Higgs
doublet model and compute the leading one-loop contribution to the effective
dark matter- nucleon interaction. This higher order correction dominates the
scattering rate completely and can naturally, i.e. for couplings of order one,
lead to a direct detection cross section in the vicinity of the neutrino floor.
Taking the observed relic density and constraints from low-energy observables
into account we analyze the direct detection prospects in detail and find
regions of parameter space that are within reach of upcoming direct detection
experiments such as XENONnT, LZ, and DARWIN.Comment: 29 pages, 8 figure
An Unfair and Dangerous Process: A Legal Analysis of the Ministerial Deadline to Apply for Asylum and Use of Executive Power in the Legacy Caseload
Astrophysical neutrino point sources as a probe of new physics
Recently, the IceCube collaboration observed a neutrino excess in the
direction of NGC 1068 with high statistical significance. This constitutes the
second detection of an astrophysical neutrino point source after the discovery
of a variable emission originating from the blazar TXS~0506+056. Neutrinos
emitted by these sources traverse huge, well-determined distances on their way
to Earth. This makes them a promising tool to test new physics in the neutrino
sector. We consider secret interactions with the cosmic neutrino background and
discuss their impact on the flux of neutrino point sources. The observation of
emission from NGC 1068 and TXS 0506+056 can then be used to put limits on the
strength of the interaction. We find that our ignorance of the absolute
neutrino masses has a strong impact and, therefore, we present limits in two
benchmark scenarios with the sum of the neutrino masses around their lower and
upper limits.Comment: 7 pages + appendix, 5 figure
Spectral modeling of type II supernovae. I. Dilution factors
We present substantial extensions to the Monte Carlo radiative transfer code
TARDIS to perform spectral synthesis for type II supernovae. By incorporating a
non-LTE ionization and excitation treatment for hydrogen, a full account of
free-free and bound-free processes, a self-consistent determination of the
thermal state and by improving the handling of relativistic effects, the
improved code version includes the necessary physics to perform spectral
synthesis for type II supernovae to high precision as required for the reliable
inference of supernova properties. We demonstrate the capabilities of the
extended version of TARDIS by calculating synthetic spectra for the
prototypical type II supernova SN1999em and by deriving a new and independent
set of dilution factors for the expanding photosphere method. We have
investigated in detail the dependence of the dilution factors on photospheric
properties and, for the first time, on changes in metallicity. We also compare
our results with two previously published sets of dilution factors by Eastman
et al. (1996) and by Dessart & Hillier (2005), and discuss the potential
sources of the discrepancies between studies.Comment: 16 pages, 12 figures, 2 tables, accepted for publication in A&
Equation of motion method for Full Counting Statistics: Steady state superradiance
For the multi-mode Dicke model in a transport setting that exhibits
collective boson transmissions, we construct the equation of motion for the
cumulant generating function. Approximating the exact system of equations at
the level of cumulant generating function and system operators at lowest order,
allows us to recover master equation results of the Full Counting Statistics
for certain parameter regimes at very low cost of computation. The
thermodynamic limit, that is not accessible with the master equation approach,
can be derived analytically for different approximations.Comment: 7 pages, 3 figures, revised version, accepted by PR
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