Probing baryon weak decays - from experiment to lattice QCD

6 Mar 2023, 09:00 → 7 Mar 2023, 18:00 Europe/Warsaw

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

 

 

Monday 6 March

09:30 → 09:45 Welcome

Speaker: Andrzej Kupsc (Uppsala University)

Kupsc230306Hyp.pdf

09:45 → 10:15 From lattice QCD to experiment - general introduction

Speaker: Johan Bijnens (Lund University)

warsaw23.pdf

10:15 → 10:45 From theory to experiment - introduction

Speaker: Stefan Leupold

CPV-and-all-that.pdf

10:45 → 11:15 Coffee break

11:15 → 11:45 Results on nucleon form factors using lattice QCD simulations at the physical point

Speaker: Constantia Alexandrou

Warsaw.pdf

11:45 → 12:15 Calculations of parton distributions

Speaker: Krzysztof Cichy

cichy-warsaw2023.pdf

12:15 → 12:30 Preliminary discussion

12:30 → 14:00 Lunch

14:00 → 14:30 Nonleptonic decays of heavy baryons - the perspective of theory

Speaker: Stefan Groote (University of Tartu, Institute of Physics)

Stefan Groote - Presentation

15:00 → 15:30 Open discusion

15:30 → 16:00 Coffee break

16:00 → 17:30 Open discussion

17:55 → 18:00 Meeting on the bus (Pasteura 7)

18:30 → 22:00 Dinner

Tuesday 7 March

09:30 → 09:35 Welcome 2nd day

Speaker: Andrzej Kupsc (Uppsala University)

09:35 → 10:00 Semileptonic decays of spin-entangled baryon-antibaryon pairs

Speaker: Varvara Batozskaya (National Centre for Nuclear Research (PL))

WW_Batozskaya_230307_v2.pdf

10:00 → 10:30 Lambda_c --> Lambda X and semileptonic form factors

Speaker: Gunnar Bali (Universität Regensburg)

gunnar.pdf

10:30 → 11:00 Coffee break

11:00 → 11:30 Multihadronic charm baryon decays with Lambda hyperons

Speaker: Joan Ruiz Vidal

JRuiz-Vidal_charmBaryonsToLambda.pdf

11:30 → 12:00 Towards CP violation in baryons from lattice QCD

Speaker: Maxwell Hansen

Warsaw_Hansen.pdf

12:00 → 14:00 Lunch

14:00 → 14:30 Baryon reconstruction at Belle

Speaker: Andrzej Bozek (Polish Academy of Sciences (PL))

wars.pdf

14:30 → 15:00 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.

Speaker: Adam Szabelski (National Centre for Nuclear Research (PL))

B2PP_tests_of_SM_AdamSzabeslki.pdf

15:00 → 15:30 Open discussion

15:30 → 16:00 Coffee break

16:00 → 17:00 Open discussion

17:00 → 17:05 Summary

Speaker: Andrzej Kupsc (Uppsala University)