223 research outputs found
PeV-Scale Dark Matter as a Thermal Relic of a Decoupled Sector
In this letter, we consider a class of scenarios in which the dark matter is
part of a heavy hidden sector that is thermally decoupled from the Standard
Model in the early universe. The dark matter freezes-out by annihilating to a
lighter, metastable state, whose subsequent abundance can naturally come to
dominate the energy density of the universe. When this state decays, it reheats
the visible sector and dilutes all relic abundances, thereby allowing the dark
matter to be orders of magnitude heavier than the weak scale. For concreteness,
we consider a simple realization with a Dirac fermion dark matter candidate
coupled to a massive gauge boson that decays to the Standard Model through its
kinetic mixing with hypercharge. We identify viable parameter space in which
the dark matter can be as heavy as ~1-100 PeV without being overproduced in the
early universe.Comment: 4 pages + appendices, 2 figure
Probing New Physics with Underground Accelerators and Radioactive Sources
New light, weakly coupled particles can be efficiently produced at existing
and future high-intensity accelerators and radioactive sources in deep
underground laboratories. Once produced, these particles can scatter or decay
in large neutrino detectors (e.g Super-K and Borexino) housed in the same
facilities. We discuss the production of weakly coupled scalars via
nuclear de-excitation of an excited element into the ground state in two viable
concrete reactions: the decay of the excited state of O populated
via a reaction on fluorine and from radioactive Ce decay
where the scalar is produced in the de-excitation of Nd, which
occurs along the decay chain. Subsequent scattering on electrons,
, yields a mono-energetic signal that is observable in
neutrino detectors. We show that this proposed experimental set-up can cover
new territory for masses and couplings
to protons and electrons, . This parameter space
is motivated by explanations of the "proton charge radius puzzle", thus this
strategy adds a viable new physics component to the neutrino and nuclear
astrophysics programs at underground facilities.Comment: 5 pages, 2 figure
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