149 research outputs found
The Diphoton and Diboson Excesses in a Left-Right Symmetric Theory of Dark Matter
We explore the possibility that the recently reported diphoton excess at
ATLAS and CMS can be accommodated within a minimal extension of a left-right
symmetric model. Our setup is able to simultaneously explain the Run 2 diphoton
and Run 1 diboson excesses, while providing a standard thermal freeze-out of
weak-scale dark matter. In this scenario, the 750 GeV neutral right-handed
Higgs triplet is responsible for the diphoton excess. Interactions of this
state with the neutral and charged components of dark matter multiplets provide
the dominant mechanisms for production and decay. A striking signature of this
model is the additional presence of missing energy in the diphoton channel.Comment: 19 pages, 3 figure
Inelastic Dark Matter at the LHC Lifetime Frontier: ATLAS, CMS, LHCb, CODEX-b, FASER, and MATHUSLA
Visible signals from the decays of light long-lived hidden sector particles
have been extensively searched for at beam dump, fixed-target, and collider
experiments. If such hidden sectors couple to the Standard Model through
mediators heavier than GeV, their production at low-energy
accelerators is kinematically suppressed, leaving open significant pockets of
viable parameter space. We investigate this scenario in models of inelastic
dark matter, which give rise to visible signals at various existing and
proposed LHC experiments, such as ATLAS, CMS, LHCb, CODEX-b, FASER, and
MATHUSLA. These experiments can leverage the large center of mass energy of the
LHC to produce GeV-scale dark matter from the decays of dark photons in the
cosmologically motivated mass range of GeV. We also provide a
detailed calculation of the radiative dark matter-nucleon/electron elastic
scattering cross section, which is relevant for estimating rates at direct
detection experiments.Comment: 21 pages, 9 figure
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
Mono-Higgs Detection of Dark Matter at the LHC
Motivated by the recent discovery of the Higgs boson, we investigate the
possibility that a missing energy plus Higgs final state is the dominant signal
channel for dark matter at the LHC. We consider examples of higher-dimension
operators where a Higgs and dark matter pair are produced through an off-shell
Z or photon, finding potential sensitivity at the LHC to cutoff scales of
around a few hundred GeV. We generalize this production mechanism to a
simplified model by introducing a Z' as well as a second Higgs doublet, where
the pseudoscalar couples to dark matter. Resonant production of the Z' which
decays to a Higgs plus invisible particles gives rise to a potential mono-Higgs
signal. This may be observable at the 14 TeV LHC at low tan beta and when the
Z' mass is roughly in the range 600 GeV to 1.3 TeV.Comment: 11 page
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