Asymmetry in flavour changing electromagnetic transitions of vector-like quarks

• Published in: The journal of high energy physics Vol. 2022; no. 5; pp. 15 - 24
• Main Author: Balaji, Shyam
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 03.05.2022; Springer Nature B.V; Springer; SpringerOpen
• Subjects: Apexes; Asymmetry; Beyond Standard Model; Classical and Quantum Gravitation; CP violation; Decay rate; Dipole moments; Elementary Particles; Flavor (particle physics); Heavy Quark Physics; High energy physics; High Energy Physics - Phenomenology; Large Hadron Collider; Mathematical analysis; Particle decay; Phenomenology; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Quarks; Regular Article - Theoretical Physics; Relativity Theory; Standard model (particle physics); String Theory; Heavy Quark Physics; Beyond Standard Model; CP violation; branching ratio; signature; mixing; loop integral; decay; asymmetry; CERN LHC Coll; unitarity; transition; moment; flavor; singlet; electromagnetic; decay rate; quark; polarization; dipole; radiative decay; flavor changing; tree approximation; electroweak interaction
• ISSN: 1029-8479; 1126-6708; 1029-8479
• DOI: 10.1007/JHEP05(2022)015

A bstract Vector-like quarks have been of interest for a plethora of experimentally motivated reasons and have come under increased investigation recently due to their inclusion to the Standard Model (SM) appreciably improving global fits to several flavour physics and precision electroweak measurements. The addition of vector-like quark singlets breaks the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix and enables tree-level flavour changing neutral (FCN) vertices. The resulting radiative flavour changing decays of these particles through the electromagnetic transition dipole moment are a key means to study their properties and search for them at experiments like the Large Hadron Collider (LHC). Despite these radiative decays providing such a clean experimental signature, an explicit analytical study of the branching ratios and CP violation resulting from these loop level processes has thus far evaded attention. We provide the formulation for the decay rates and CP asymmetry resulting from a combination of the imaginary components of the loop integrals and complex phases in the quark mixing matrix. We then apply our analytical results to study phenomenology of these states for several global fits pertaining to vector-like isosinglets t ′ and b ′. We find that clean collider signatures and polarisation observables can be generated for both t ′ and b ′.