Sachin Shain Poruvelil, promovendus aan het Nikhef, verdedigt zijn proefschrift maandag 3 april 2023 om 14.00 aan de Universiteit van Amsterdam.
“Aspecten van sterke en nieuwe CP-schending”
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)
De promotie vindt plaats op maandag 3 april 2023, om 14.00 in de Agnietenkapel, Oudezijds Voorburgwal 229 – 231, 1012 EZ Amsterdam.
De promotie zal online te volgen zijn.
Meer informatie op de website van de UvA.
Promotor: dr. W.J. Waalewijn
Co-promotor: dr. J. de Vries
contact: Sachin Shain