Probing baryon weak decays - from experiment to lattice QCD
Warsaw, Pasteura 7
Warsaw, Pasteura 7
Andrzej Kupsc(Uppsala University), Artur Ukleja(National Centre for Nuclear Research (PL)), Lars Eklund(Uppsala University (SE)), Patrik Adlarson(Uppsala University (SE)), Varvara Batozskaya(National Centre for Nuclear Research (PL))
We are experimentalists (LHCb and BESIII) and theoreticians from Warsaw, Lund and Uppsala working on weak decays of charm baryons. From an experimental point of view, both LHCb and BELLE-II are ramping up their experimental activities, collecting new world record data sets. In recent years, several breakthroughs have occurred which motivate deeper theoretical explorations and understanding. In the recent report “50 years of Quantum Chromodynamics 50 years” the status of weak baryon decays on the lattice is summarised
"The lattice QCD calculation of form factors for weak decays of baryons
is still in its infancy, because of the extra challenges provided by
the poorer signal-noise. “ (page 108, arXiv:2212.11107).
In light of this, we would like to bring together the expertise in lattice QCD, theory, phenomenology and experiment for an informal workshop in Warsaw, March, 6-7, 2023 to discuss possible joint experimental and theory initiatives related to weak decays of baryons. Such a project would require contributions from lattice QCD and phenomenology to describe the hadronic effects. In particular, we would like to understand the prospects for calculating the properties of weak baryon decays from the lattice in the nearest future.
The main topics of the discussion:
strange, charm and beauty baryon decays: non-leptonic, semi-leptonic, radiative
possible tests of fundamental symmetries
exploration for new projects and future collaboration
Testing the standard model predictions with B -> P P decays
The starting point to our discussion is the ”B → Kπ puzzle”. We show, that although the ”puzzle” can be resolved by a more detailed analysis, there is a more fundamental question that needs to be addressed: Is New Physics necessary to describe the experimentally observed asymmetries and branching fractions of the B → P P decays? We perform a phenomenological analysis based on fits of an model-independent New Physics parameterisation
and obtain exclusion χ2 plots of the two ad-hoc parameters (magnitude and a weak phase) sensitive to New Physics. The results show that the Standard
Model expectation value lies within 2σ with respect to the global minimum but the overall picture is not well constrained by the existing data. Our results are mostly sensitive to the time-dependent asymmetry and branching
fraction of the B 0 → K 0 π 0 decay. New experimental outcomes are highly expected and results of this analysis provide strong hints for improvement of precision in current experiments LHCb and Belle II.
Adam Szabelski(National Centre for Nuclear Research (PL))