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@MASTERSTHESIS{Mbius:641213,
author = {Möbius, Hagen},
othercontributors = {Issever, Cigdem and Pani, Priscilla},
title = {{P}erformance of a soft secondary vertex tagger
usingproton-proton collisions collected at 13.6 {T}e{V}
withthe {ATLAS} detector},
school = {Humboldt-Universit zu Berlin},
type = {Masterarbeit},
reportid = {PUBDB-2025-04944},
pages = {143},
year = {2025},
note = {Masterarbeit, Humboldt-Universit zu Berlin, 2025},
abstract = {This thesis evaluates a b-tagging algorithm optimized to
identify low pT (soft) b-hadrons in theATLAS experiment at
the LHC. The algorithm, called the NewVrtSecInclusiveTool,
reconstructssoft secondary vertices (SSVs), which can be
connected to the decay of a soft b-hadron. Theanalysis
evaluates the properties of these soft secondary vertices
and compares them with theproperties of b-hadrons using a
dileptonic t¯t sample from the Monte Carlo campaign
denotedas mc23a which corresponds to the ATLAS data taking
in 2022. An acceptance definition isintroduced to
specifically test the identification ability of the
algorithm outside of jets. Furthermore,a ΔR matching
procedure is developed to assess if a soft secondary vertex
can be associated tothe decay of a b-hadron. This procedure
divides the SSVs into true SSVs and fake SSVs. Acomparison
of these objects is done and an explanation for the origin
of the fake SSVs is given.The b-hadrons and SSVs in
acceptance, the matched and fake SSVs and the matched
b-hadronsare used to develop an efficiency definition for
the algorithm. Moreover, the average number offake SSVs nF
is introduced to assess how often the algorithm makes a
wrong tagging decision.The efficiency and the average number
of fake SSVs are then analysed as a function of
b-hadronproperties and event variables. Additionally, they
are used to evaluate the 3 working points ofthe algorithm.
The overall efficiency is in the order of 0.2 to 0.25
depending on the working point.The overall average number of
fake SSVs is between 0.01 and 0.04 depending on the
workingpoint. Furthermore, regions which are enhanced in
matched and fake SSVs are constructed and afurther splitting
of these regions is discussed in an effort to enable a
calibration of the algorithmin the future. Finally, Monte
Carlo to data comparisons are performed using data from 2022
and2023 corresponding to the Monte Carlo campaigns denoted
as mc23a and mc23d respective},
cin = {ATLAS / FHTestBeam / $Z_ET$ / $Z_ATUP$ / $Z_ATLAS$},
cid = {I:(DE-H253)ATLAS-20120731 / I:(DE-H253)FHTestBeam-20150203
/ $I:(DE-H253)Z_ET-20210408$ / $I:(DE-H253)Z_ATUP-20210408$
/ $I:(DE-H253)Z_ATLAS-20210408$},
pnm = {611 - Fundamental Particles and Forces (POF4-611)},
pid = {G:(DE-HGF)POF4-611},
experiment = {EXP:(DE-H253)LHC-Exp-ATLAS-20150101},
typ = {PUB:(DE-HGF)19},
url = {https://bib-pubdb1.desy.de/record/641213},
}