Precision Flavour Physics: Subleading Contributions to Inclusive Penguin Decays

• Applicant: Professor Dr. Tobias Hurth
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 544892870

The project has the important goal of decisively improving the theoretical prediction of individual key observables of the Belle-II experiment, on the basis of which signs of new physics can be identified. For most observables today, it is the sub-leading non-perturbative corrections that limit the sensitivity to new degrees of freedom. The inclusive penguin decays, as theoretically clean flavour-changing neutral current transitions, are golden modes of the indirect new physics search at the BELLE-II experiment. In the proposed research project we plan to reduce the uncertainty of these modes due to the non-local non-perturbative corrections. The uncertainties due to the so-called resolved contributions are still among the largest uncertainties of these modes. And it is important to adapt the theoretical uncertainty to the high precision of the future BELLE-II measurements. In particular, the semi-leptonic inclusive penguins allow for a theoretically clean crosscheck of the present tensions in corresponding exclusive modes measured by LHCb. The crucial theoretical question is, whether the so-called LHCb anomalies are due to unknown hadronic corrections or due to new physics within the exclusive modes measured at LHCb. The measurement of observables of the semi-leptonic inclusive penguin decays offers the possibilities to resolve this ambiguity. In view of the large scale ambiguity and the large charm mass dependence of the present results, the most important corrections in the non-perturbative contributions that could significantly reduce the uncertainties in the case of the dominant resolved contributions are the corrections due to the strong interaction - including renormalisation group running in order to sum up large logarithms in the final results. The calculations will be done with the help of the effective field theory SCET (soft-collinear-effective theory). Pushing the precision in these inclusive modes by calculating these contributions is the main objective of the proposed project which will significantly increase the new physics sensitivity of these inclusive penguin modes.

• DFG Programme: Research Grants