Speaker
Karol Krizka
(University of Chicago (US))
Description
The ATLAS experiment has a rich program of searches for Dark Matter
candidates. Most of them use a simplified model, where the colliding partons
produce a mediator particle that decays into Dark Matter. For vector
mediators, this approach produces limits competitive with direct detection
experiments. However the limits become weaker for Dark Matter masses above 500
GeV, when the heaviest mediator produced in the LHC collisions decay off-
shell. This limitation can be overcome by searching for a dijet resonance
produced by the mediator decaying back into quarks. This method probes all
Dark Matter masses bigger than half the mediator mass and is independent of
the Dark Matter-mediator coupling. The current dijet search from ATLAS using
13 TeV pp collisions sets limits on mediator masses ranging from 1 TeV to 4
TeV. The lower limit is constrained by the high transverse momentum threshold
in the unprescaled jet-based triggers. However the bounds from Dark Matter
relic density prefer lighter mediators. This poster presents a new search
where the mediator mass range probed goes down to 200 GeV, by triggering on
events with an additional particle (jet or photon) coming from initial state
radiation. The presence of the two resonance jets is used to further reduce
the trigger rate in case of photon ISR.
Author
Collaboration ATLAS
(ATLAS)
