Emir Muhammad - Measurement of the Z boson mass with the LHCb detector

Wednesday 2 Apr 2025, 13:30 → 14:30 UTC

610 (G.O. Jones Building)

Emir Muhammad (University of Warwick)

https://fnal.zoom.us/j/93197574512?pwd=bGlJTHlGTnVtTFFwRnlpYnhrdm5rdz09

About the speaker: Emir is a 4th yeah PhD student from the University of Warwick. During his PhD, he is one of the main propents of the Z mass measurement analysis at LHCb. He is also active in simulation developments, developing a streamlined system to handle simulation productions, as well as developing a versioning framework for LHCb's detector description in context of future upgrades; which led to his recognition with the LHCb Early Careers Award.

Prior to that, he did his integrated masters in the University of Birmingham, with the masters project being a feasibility study of a Higgs to 4 leptons search at the LHeC, with a summer internship at STFC/RAL on ATLAS HLT Trigger studies.

1 Measurement of the Z boson mass with the LHCb detector

In the Standard Model, the Z boson acquires its mass of around 91 GeV through its gauge interaction with the vacuum energy of the Higgs field. Including higher order corrections the Z mass is predicted with a precision of better than 10 MeV, which corresponds to one part in 10,000. The Z mass was measured to 2 MeV by the four LEP experiments in a beam-energy scan of the LEP e+e- collider. Meanwhile, hadron collider experiments have dominated the measurements of the W boson mass, but their studies of the Z boson mass have been primarily in the context of calibrations for the W mass analyses. Here we present the first dedicated Z boson mass measurement in proton-proton collisions. The data were recorded in 2016 by the LHCb experiment and correspond to an integrated luminosity of 1.7 fb-1. The Z mass is determined from a fit to the dimuon mass distribution in Z -> mu+mu- decays. Templates from simulation are used in the fit, with a momentum calibration based on quarkonium resonance decays. The result is compared with previous measurements of the Z mass and with the predicted value from the global electroweak fit.

Speaker: Emir Muhammad (University of Warwick)

20250402_QMUL_seminar-min.pdf