Abstract: The precise measurement of the W boson mass is a sensitive test of the standard model. At hadron colliders, the measurement of the W boson mass is a notorious challenge that requires determining experimental and theoretical sources of uncertainty well below the percent level. The CMS Collaboration has recently measured mW with an uncertainty of 9.9 MeV, the most precise LHC measurement. The result is in close agreement with the expectation from the global electroweak fit under the standard model assumption, and in disagreement with the measurement performed by the CDF Collaboration. The measurement is based on a large data set of 13 TeV proton-proton collisions. Several novel approaches are used to leverage this large data set in order to reduce the impact of theoretical sources of uncertainty. We will discuss the theoretical principles underpinning the W and Z boson transverse momentum modeling and the parton distribution functions, as well as their integration into the CMS measurement, their impact on the analysis, and the estimation of their uncertainties.
About the speakers:
Kenneth Long is an experimental physicist working on the CMS experiment. He joined CMS at the start of his Ph.D in 2013, which he completed in 2019 at the University of Wisconsin-Madison. As a Ph.D. student, he worked on the first 13 TeV diboson measurements, and wrote his thesis on the first measurement of WZ vector boson scattering. Following his Ph.D., he was a CERN fellow from 2019-2021. During this time, he convened the CMS diboson analysis group and joined the W mass analysis team. He moved to MIT as a postdoctoral researcher in 2021, where he has continued to work on standard model precision measurements, especially the measurement of the W boson mass.
Thomas received his PhD at the University of Cambridge and since then he has undertaken postdoctoral positions at University College London and at DESY (theory group) and has just started a position at the University of Antwerp. His research has primarily focused on the development and understanding of global PDFs and their uncertainties. As a key member of the MSHT PDF group he has been actively involved in a range of research from approximate N3LO PDFs to the determination of Standard Model parameters from global PDF fits. Recently he has also studied theory uncertainties from missing higher orders (MHOUs) in perturbation theory using the Theoretical Nuisance Parameter approach. He is therefore interested in the recent work on Standard Model parameter determination by experiments, from the perspective of the evaluation of these PDF and theory uncertainties from missing higher orders.