The ZZ → 4l process and anomalous triple gauge couplings with ATLAS at the LHC

This thesis is a presentation of an analysis of the $ZZ\rightarrow 4\ell$ (\ell = e,μ) process in proton-proton collisions with centre-of-mass energy $\sqrt{s}$ = 13 TeV at the LHC during 2015 and 2016 (a total integrated luminosity of 36.1 fb^-1), using the ATLAS detector. Candidate $ZZ \rightarrow 4\ell$ events are selected in the three decay channels, $4e$, 2e2μ and 4μ. The cross section of the $ZZ\rightarrow 4\ell$ process is measured in four fiducial regions closely matching the detector acceptance: one for each decay channel ($4e$, 2e2μ and 4μ) and one for the combination of all decay channels. The total cross section of $pp\rightarrow ZZ$ is measured in a phase-space in which both $Z$ bosons have a mass m_Z in the range 66 GeV < m_Z < 116 GeV to be 16.5 $\pm 0.5$ (stat.) $\pm 0.4$ (syst.) $\pm 0.5$ (lumi.) pb which is consistent with a next-to-next-to-leading-order prediction of 16.9^+0.6_-0.5 pb. Observed event yields in four bins of transverse momentum are used to set 95{\%} CL_\text{s} limits on four neutral triple gauge couplings (f^V_i, V=Z,γ, $i=4,5$) which parameterise an effective $ZZV$ vertex (assuming both $Z$ bosons are on shell). The obtained limits are of the order of |f^V_i|<0.0017.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2018

Author dc:creator

• Rosten, Jonatan Hans Niclas

Advisor dc:contributor.advisor

• Batley, John Richard

• High Energy Phyics
• Particle Physics
• Physics

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/0636453b-34ca-4d8a-ab6c-11ffc5028a5a/download
• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

en

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.18842

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/271838