Speaker
Louis-Guillaume Gagnon
(Universite de Montreal (CA))
Description
Supersymmetry, a generalisation of the space-time symmetries which
associates a new boson to each Standard Model fermion and vice-versa,
must be obervable near the weak scale in order to solve the hierarchy
problem. If the lepton and baryon numbers are conserved, the lightest
supersymmetric particle is stable and interacts only weakly providing
a viable dark matter candidate. Searches for supersymmetry at the LHC
are thus highly motivated. A search for strong production of pairs of
gluinos, the supersymmetric partner of the gluon, decaying via sbottom
and stop quarks, the supersymmetric partners of the bottom and top
quarks, is reported. A 3.3 fb-1 13 TeV proton-proton LHC dataset,
recorded by the ATLAS detector, is used. This sample is probed for
events containing several high transverse momentum jets, of which at
least 3 must be identified as originating from b-quarks, large missing
transverse momentum, and potentially isolated charged leptons. Massive
large-radius jets, indicating the presence of highly boosted top
quarks, are also used. No significant deviation from the Standard
Model prediction is observed and limits are set in the
gluino-neutralino mass plane in the framework of simplified models of
gluinos decaying via sbottom and stop quarks. Large increase in
cross-sections for gluino pair-production with respect to the 8 TeV
LHC and the recent installation of the Insertable B-Layer at the
center of the ATLAS detector, which appreciably improves the b-jet
identification performance, allows the previous limits to be
significantly increased using the relatively small 2015 LHC dataset.
For neutralino masses below approximately 700 GeV, gluino masses of
less than approximately 1.8 TeV are excluded at the 95% CL in both models,
constituting the current world-wide best limits in these frameworks and
some of the biggest improvements with respect to LHC run 1 searches so
far.
Author
Louis-Guillaume Gagnon
(Universite de Montreal (CA))
