Higher-twist B-meson light-cone distribution amplitudes: theory and applications to weak decays

• Applicant: Dr. Aleksey Rusov
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 541305755

B-meson light-cone distributions functions (LCDAs) play a crucial role in theoretical studies of various B-meson decays. To make full use of the persistently increasing precision of measurements, corresponding theory improvements are crucial. This includes the investigation of higher-order corrections, in particular, higher-twist effects, in theoretical predictions. Furthermore, the currently observed B-anomalies - tensions between standard model predictions and experimental values for several observables in B-physics - provide an additional strong motivation for analysing these effects in detail. In the proposed project, a study of model-independent properties of the twist-3 and twist-4 two-particle B-meson LCDAs is suggested. The analysis will be performed by employing the operator-product expansion method with an explicit energy cut-off, introduced in the corresponding renormalised moments of the LCDAs, at next-to-leading order in QCD and including contributions up to mass dimension-5. In addition, equation-of-motion relations between the two-particle and the three-particle LCDAs beyond leading order in QCD will be studied. The results of these investigations will then be used in several specific phenomenological applications. First, the semileptonic B \to D and $B \to D^* form factors obtained from light-cone sum rules (LCSR) and consequently the predictions for the lepton-flavour violation (LFU) ratios R(D) and R(D^*) will be updated. Second, the LCSR analysis for several non-leptonic B-meson decays like B \to D K will be revisited. Finally, an updated study of the radiative decay B \to \gamma \ell \nu will be worked out. These new results for higher-twist LCDAs will allow to achieve a higher level of theory accuracy and gain new insights into the QCD dynamics of B-meson decays, which are of great importance in the light of the existing B-anomalies as well as of the rich experimental program by the LHCb and Belle-II collaborations.

• DFG Programme: Research Grants