65 research outputs found
Higgsogenesis
In addition to explaining the masses of elementary particles, the Higgs boson
may have far-reaching implications for the generation of the matter content in
the Universe. For instance, the Higgs plays a key role in two main theories of
baryogenesis, namely electroweak baryogenesis and leptogenesis. In this letter,
we propose a new cosmological scenario where the Higgs chemical potential
mediates asymmetries between visible and dark matter sectors, either generating
a baryon asymmetry from a dark matter asymmetry or vice-versa. We illustrate
this mechanism with a simple model with two new fermions coupled to the Higgs
and discuss associated signatures.Comment: 5 pages, 2 figures; v2: Intro and conclusion improved, clarifications
added, results unchanged. Compared to the PRL version, this arxiv version
contains two extra plots, one additional table and a slightly longer
conclusio
Direct Detection Portals for Self-interacting Dark Matter
Dark matter self-interactions can affect the small scale structure of the
Universe, reducing the central densities of dwarfs and low surface brightness
galaxies in accord with observations. From a particle physics point of view,
this points toward the existence of a 1-100 MeV particle in the dark sector
that mediates self-interactions. Since mediator particles will generically
couple to the Standard Model, direct detection experiments provide sensitive
probes of self-interacting dark matter. We consider three minimal mechanisms
for coupling the dark and visible sectors: photon kinetic mixing, Z boson mass
mixing, and the Higgs portal. Self-interacting dark matter motivates a new
benchmark paradigm for direct detection via momentum-dependent interactions,
and ton-scale experiments will cover astrophysically motivated parameter
regimes that are unconstrained by current limits. Direct detection is a
complementary avenue to constrain velocity-dependent self-interactions that
evade astrophysical bounds from larger scales, such as those from the Bullet
Cluster.Comment: 18 pages, 7 figure
Self-interacting Dark Matter Benchmarks
Dark matter self-interactions have important implications for the
distributions of dark matter in the Universe, from dwarf galaxies to galaxy
clusters. We present benchmark models that illustrate characteristic features
of dark matter that is self-interacting through a new light mediator. These
models have self-interactions large enough to change dark matter densities in
the centers of galaxies in accord with observations, while remaining compatible
with large-scale structure data and all astrophysical observations such as halo
shapes and the Bullet Cluster. These observations favor a mediator mass in the
10 - 100 MeV range and large regions of this parameter space are accessible to
direct detection experiments like LUX, SuperCDMS, and XENON1T.Comment: 4 pages, white paper for Snowmass 2013; v2: finalized version,
figures correcte
Beyond Collisionless Dark Matter: Particle Physics Dynamics for Dark Matter Halo Structure
Dark matter (DM) self-interactions have important implications for the
formation and evolution of structure, from dwarf galaxies to clusters of
galaxies. We study the dynamics of self-interacting DM via a light mediator,
focusing on the quantum resonant regime where the scattering cross section has
a non-trivial velocity dependence. While there are long-standing indications
that observations of small scale structure in the Universe are not in accord
with the predictions of collisionless DM, theoretical study and simulations of
DM self-interactions have focused on parameter regimes with simple analytic
solutions for the scattering cross section, with constant or classical velocity
(and no angular) dependence. We devise a method that allows us to explore the
velocity and angular dependence of self-scattering more broadly, in the
strongly-coupled resonant and classical regimes where many partial modes are
necessary for the achieving the result. We map out the entire parameter space
of DM self-interactions --- and implications for structure observations --- as
a function of the coupling and the DM and mediator masses. We derive a new
analytic formula for describing resonant s-wave scattering. Finally, we show
that DM self-interactions can be correlated with observations of Sommerfeld
enhancements in DM annihilation through indirect detection experiments.Comment: 30 pages, 10 figure
Resonant Dark Forces and Small Scale Structure
A dark force can impact the cosmological history of dark matter (DM), both
explaining observed cores in dwarf galaxies and setting the DM relic density
through annihilation to dark force bosons. For GeV - TeV DM mass, DM
self-scattering in dwarf galaxy halos exhibits quantum mechanical resonances,
analogous to a Sommerfeld enhancement for annihilation. We show that a simple
model of DM with a dark force can accommodate all astrophysical bounds on
self-interactions in halos and explain the observed relic density, through a
single coupling constant.Comment: 5 pages, 3 figure
- …