eprintid: 23940
rev_number: 12
eprint_status: archive
userid: 3527
dir: disk0/00/02/39/40
datestamp: 2018-01-10 12:52:20
lastmod: 2018-02-27 11:00:16
status_changed: 2018-01-10 12:52:20
type: doctoralThesis
metadata_visibility: show
creators_name: Kolpin, Michael
title: Measurement of the differential branching fraction and angular analysis of the decay $B_s^0\to\phi\mu^+\mu^-$ and determination of the track reconstruction efficiencies at the LHCb experiment
subjects: ddc-530
divisions: i-130200
adv_faculty: af-13
abstract: The measurement of the differential branching fraction and an angular
analysis of the decay B s 0 → φμ + μ − is performed, using a dataset collected by the LHCb
experiment in proton-proton collisions in 2011 and 2012, corresponding to an integrated
luminosity of 3 fb −1 . The results are presented as function of q 2 , the square of the dimuon
invariant mass. A full set of angular observables is extracted for the first time for this
decay mode, where all measured angular coefficients are consistent with Standard Model
expectations. For the range of 1 < q 2 < 6 GeV 2 /c 4 the branching fraction is found to be
more than 3 standard deviations below the Standard Model prediction, which is derived
using a combination of light-cone sum rules and lattice QCD calculations. This tension
is compatible with observations made by other measurements of electroweak penguin
decays mediated by b → s + − transitions in this q 2 region. Possible explanations are
theoretical models which predict new heavy degrees of freedom at the TeV scale, as well
as underestimated contributions from cc-loop corrections in the SM calculations.
An important aspect of the measurements of branching fractions is the determination of
the track reconstruction efficiency. It is determined from J/ψ → μ + μ − decays, where the
data-driven tag-and-probe technique is used. During LHC Run II this measurement is
performed in a “quasi-online” approach, directly after the data has been recorded. For
the 2015 data-taking period of the LHCb experiment, the track reconstruction efficiency is
found to be (96.14 ± 0.03)%, where the uncertainty is statistical only.
date: 2018
id_scheme: DOI
id_number: 10.11588/heidok.00023940
ppn_swb: 1659311179
own_urn: urn:nbn:de:bsz:16-heidok-239409
date_accepted: 2017-12-13
advisor: HASH(0x559e37cfd160)
language: eng
bibsort: KOLPINMICHMEASUREMEN2018
full_text_status: public
citation:   Kolpin, Michael  (2018) Measurement of the differential branching fraction and angular analysis of the decay $B_s^0\to\phi\mu^+\mu^-$ and determination of the track reconstruction efficiencies at the LHCb experiment.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/23940/1/Thesis_kolpin.pdf