Göttingen 2012 – scientific programme
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T: Fachverband Teilchenphysik
T 51: Supersymmetrie 2
T 51.3: Talk
Tuesday, February 28, 2012, 17:15–17:30, ZHG 010
Estimation of the QCD background for searches for Supersymmetry in a channel with zero leptons — •Kathrin Störig1, Sascha Caron1,2, and Gregor Herten1 — 1University of Freiburg — 2University Nijmegen, Netherlands
Although large regions of the supersymmetric parameter space have been excluded
by ATLAS in recent times, there are plenty of possible scenarios left.
Searches, however, do not only need to become smarter, but also (systematic) uncertainties are to be reduced
and background estimates improved.
SUSY searches in general use transfer functions, determined from MC, to
derive a background estimate from several control regions. - Hereby, a crucial ingredient for SUSY searches
without leptons is the precise estimation of the QCD background.
In this talk, a semi-data-driven method will be presented to estimate the
QCD background by measuring the transfer functions directly. An
important variable is the minimum angular separation between jets and the missing transverse energy (ETmiss), called
Δϕmin(jet,ETmiss).
The transfer function is defined as the ratio of events with
Δϕmin < 0.2 (QCD enhanced) and Δϕmin >
0.4 (signal region).
It is evaluated as function of ETmiss in two control
regions. After subtracting the non-QCD background from data,
the QCD transfer functions are fitted and the final numbers are extracted from
an interpolation of the fit into the signal regions. The impact of several systematic
uncertainties, e.g. the jet energy scale and pileup, will be discussed.