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



    • 1
      Speaker: Andrzej Kupsc (Uppsala University)
    • 2
      From lattice QCD to experiment - general introduction
      Speaker: Johan Bijnens (Lund University)
    • 3
      From theory to experiment - introduction
      Speaker: Stefan Leupold
    • 10:45
      Coffee break
    • 4
      Results on nucleon form factors using lattice QCD simulations at the physical point
      Speaker: Constantia Alexandrou
    • 5
      Calculations of parton distributions
      Speaker: Krzysztof Cichy
    • 6
      Preliminary discussion
    • 12:30
    • 7
      Nonleptonic decays of heavy baryons - the perspective of theory
      Speaker: Stefan Groote (University of Tartu, Institute of Physics)
    • 8
      Open discusion
    • 15:30
      Coffee break
    • 9
      Open discussion
    • 17:55
      Meeting on the bus (Pasteura 7)
    • 18:30
      Dinner Restaurant "Warszawa Wschodnia by Mateusz Gessler", Mińska 29A

      Restaurant "Warszawa Wschodnia by Mateusz Gessler", Mińska 29A

      Restaurant "Warszawa Wschodnia by Mateusz Gessler", Mińska 29A
  • Tuesday, 7 March
    • 10
      Welcome 2nd day
      Speaker: Andrzej Kupsc (Uppsala University)
    • 11
      Semileptonic decays of spin-entangled baryon-antibaryon pairs
      Speaker: Varvara Batozskaya (National Centre for Nuclear Research (PL))
    • 12
      Lambda_c --> Lambda X and semileptonic form factors
      Speaker: Gunnar Bali (Universität Regensburg)
    • 10:30
      Coffee break
    • 13
      Multihadronic charm baryon decays with Lambda hyperons
      Speaker: Joan Ruiz Vidal
    • 14
      Towards CP violation in baryons from lattice QCD
      Speaker: Maxwell Hansen
    • 12:00
    • 15
      Baryon reconstruction at Belle
      Speaker: Andrzej Bozek (Polish Academy of Sciences (PL))
    • 16
      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))
    • 17
      Open discussion
    • 15:30
      Coffee break
    • 18
      Open discussion
    • 19
      Speaker: Andrzej Kupsc (Uppsala University)