On 3 June 2026 at 15.15 Maria Naeem will defend her doctoral thesis “First order electroweak radiative corrections to the decay of the polarised W boson” (“Esimest järku elektronõrgad kiirgusparandid polariseeritud W-bosoni lagunemisele”).
Supervisor:
Stefan Groote, Associate Professor in Theoretical Physics, Institute of Physics, University of Tartu, Estonia
Oponent:
Prof. Dr. Ansgar Denner, Chair of Theoretical Physics II, Faculty of Physics and Astronomy, University of W¨ urzburg, Germany
Summary
My work is based on the electroweak (EW) theory. The main feature of this is the unification of the electromagnetic and weak force. The EW theory was formulated by Glashow, Salam and Weinberg (GSW) in 1967. Particle interactions are mediated by photons and W and Z bosons. In nuclear decays weak interactions are found inside the nucleus. The EW theory is a major milestone in modern physics explaining both particle interaction and the origin of mass. Experimental studies of the EW interaction to date show full consistency with the GSW model, which is a building block of what is known as Standard Model (SM). In order to verify the successful SM of elementary physics, described by the interplay of strong and EW interactions, and in order to find out whether or not extensions of this model are necessary, high precision measurements of particle creation and decay processes performed at facilities like the Large Hadron Collider at CERN have to be compared with theory predictions that are of the same precision. The precision and significance of theory predictions can be improved in two ways, namely by taking into account exchanges of virtual particles in the framework of higher order perturbative corrections to a given process, known as radiative corrections, or by taking into account the masses of the particles that participate in process. Looking at effects of polarisation in the process, in the work I present next-to-leading order (NLO) EW radiative corrections to the decay W⁺ (↑) → c + b̄ of the polarised W boson into a pair of heavy quarks by looking at the angular distribution of the decay. I demonstrate the importance of mass effects on the result.
