Sachin Shain Poruvelil, PhD at Nikhef, will defend his thesis Monday 3 April 2023 at 14.00 at the University of Amsterdam.
“Aspects of strong and new CP violation”
The matter-antimatter asymmetry is evidence of CP violation in nature. The QCD theta term can account for some of the observed matter-antimatter asymmetry indicating beyond the Standard Model (BSM) CP-violating (CPV) sources. Axions are introduced to explain the observed smallness of the theta parameter. We used chiral perturbation theory to study CPV nuclear forces and axion interactions, and dark matter scattering off 4He nuclei. Our results confirmed that the CPV nuclear forces are not properly renormalized at the leading order. The renormalization was restored when we promoted a higher-order contact term to leading order and proposed strategies to compute the associated low energy constant. A Peccei-Quinn mechanism does not remove all CPV from strong and BSM sources, leading to CPV axion interactions. We started with generic dimension six BSM CPV sources and systematically computed the resulting CP-odd couplings of axions to leptons and hadrons. We discuss in detail the phenomenology of the CP-odd axion couplings and compare limits from a wide range of axion searches, spanning axion masses from atto to hecto eV. We studied scalar dark matter interactions and included one- and two-nucleon scattering processes. We found that next-to-leading-order scalar currents are smaller than expected from power counting for scattering off 4He, confirming earlier work. The results for two-nucleon corrections exhibited a linear regulator dependence. We observed a linear correlation between the non-observable D-wave probability of various light nuclei and the scalar two-nucleon matrix elements. These observations indicate potential problems in the applied power counting.
“Aspects of strong and new CP violation” (pdf)
The PhD defense will take place on Monday 3 April 2023, at 14.00 in the Agnietenkapel, Oudezijds Voorburgwal 229 – 231, 1012 EZ Amsterdam.
The PhD defense will be broadcasted online.
More information on the website of the UvA.
Supervisor: dr. W.J. Waalewijn
Co-supervisor: dr. J. de Vries
contact: Sachin Shain