Licentiate Thesis: Calibration of b-tagging e ciency and search for Dark Matter production
Monday 23 May 2016
to 15:00 at
Anna Shcherbakova (Stockholm University, Department of Physics)
The Large Hadron Collider (LHC) is the most powerful and complex particle accelerator
ever built. The ATLAS detector is a general-purpose particle detector at the LHC,
designed to cover a wide range of physics measurements. This thesis presents two
physics studies performed using data of proton-proton collisions collected with the
ATLAS detector at
s = 8 TeV.
The identi cation of jets originating from b quarks (b-tagging) is a crucial tool for
many physics analyses at the LHC. A new technique to calibrate the e ciency of
b-tagging algorithms using high transverse momentum jets is described. This technique
allows to perform the calibration using jets with transverse momenta up to 1200 GeV,
while the current calibration methods only reach approximately 300 GeV. The results
of the calibration are presented.
The second study presented in this thesis is a search for Dark Matter (DM) production
in association with a pair of heavy
avour quarks. A reinterpretation of the results of
the ATLAS search for DM at
s = 8 TeV has been done based on simpli ed models.
A set of simpli ed models with various DM masses, masses of the exchange particle,
that mediates the interaction between DM and the regular matter, and couplings is
considered. This study aims to choose benchmark models to be used in future searches
s = 13 TeV.