Arnold, Hannah
[Author]
;
Jakobs, Karl
[Degree supervisor];
Weiser, Christian
[Degree supervisor]Albert-Ludwigs-Universität Freiburg Fakultät für Mathematik und Physik
Search for a CP-Odd Higgs Boson decaying to Z h in pp collisions at √s
= 13 TeV and development of a b-jet tagging calibration method for c jets at the ATLAS experiment = Search for a CP-Odd Higgs Boson decaying to Zh in pp collisions at sqrt(s) = 13 TeV and development of a b-jet tagging calibration method for c jets at the ATLAS experiment
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Media type:
E-Book
Title:
Search for a CP-Odd Higgs Boson decaying to Z h in pp collisions at √s
Other titles:
13 TeV and development of a b-jet tagging calibration method for c jets at the ATLAS experiment
Search for a CP-Odd Higgs Boson decaying to Zh in pp collisions at sqrt(s)
University thesis:
Dissertation, Universität Freiburg, 2018
Footnote:
Description:
Abstract: In this thesis a search for a CP-odd Higgs boson A decaying into a Z boson and a neutral CP-even Higgs boson h with a mass of 125 GeV is described. <br>The search is based on proton-proton collision data at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector in the years 2015 and 2016 corresponding to an integrated luminosity of 36/fb.<br>Final states, where the Z boson decays into pairs of electrons, muons or neutrinos and the h boson into bottom-quark pairs, are considered. The presence of neutrinos is inferred by a momentum imbalance in the transverse plane, the bottom-quark pairs are reconstructed either as two small-radius or one large-radius calorimeter jet(s). <br>The reconstructed invariant or transverse mass distributions of the Zh candidates are searched for the presence of localised excesses above the expectation from known Standard Model processes.<br>No evidence for an A-boson signal is found. Upper limits on the A-boson production cross-section times the branching fractions for A-boson decays into Zh and h-boson decays to bottom-quark pairs are derived at the 95% confidence level for A bosons with masses between 220 GeV and 2 TeV; they range between 0.0019 pb and 0.81 pb. The results are interpreted in the context of Two-Higgs-Doublet Models.<br><br>Furthermore, a novel method to calibrate the b-tagging efficiency for c-quark jets is described. <br>It is demonstrated for the standard b-tagging algorithm of the ATLAS experiment in Run 1 using proton-proton collision data at a centre-of-mass energy of 7 TeV collected with the ATLAS detector in the year 2011. <br>The calibration uses a sample of c jets obtained from events, where a W boson is produced in association with a single c quark; the resulting c jet is identified by a muon stemming from the semileptonic c-hadron decay. <br>The measured c-jet tagging efficiencies are presented relative to the corresponding efficiencies in simulated W+c events as scale factors. <br>The measured scale factors are extrapolated using a simulation-based and data-supported procedure to obtain scale factors valid for inclusive samples of c jets. Their uncertainties range between 5% and 13 %