The overarching topic of the workshop is the violation of Baryon-minus-Lepton (B-L) number. B-L number is exactly conserved in the Standard Model, but the observed matter-antimatter asymmetry of the universe hints that beyond the Standard Model B-L violating processes could exist. Proton decay (PDK) experiments set very strong limits on B-violating interactions (though most conserve B-L), pointing towards very high-energy scales around 〖10〗^13 TeV; however, models exist where the proton is stable while B is still not a good symmetry (for instance, if B is only violated by two units, i.e. ΔB=2). Such models lead to unique and powerful experimental signatures such as the transformations of neutrons into antineutrons (n→n ̅, similar to kaon-antikaon oscillations due to strangeness-changing weak interactions) or decays of otherwise stable nuclei via dinucleon annihilation.
Recent years have seen significant theoretical developments of various aspects of these intriguing scenarios, and models have been created that naturally avoid PDK limits while solving other problems within the Standard Model such as the matter-antimatter asymmetry of the universe. Lattice-QCD calculations have made tremendous improvements in calculating QCD matrix elements that connect B-violating quark interactions to observables. Studies in effective field theories for B-violating nuclear interactions have been initiated and applied to light nuclei, while novel intranuclear simulations have been developed to assess whether dinucleon decay processes can be separated from background in medium-heavy nuclei. At the same time, the prospects for future experiments look good: The European Spallation Source, DUNE, PNPI Gatchina, and Hyper-Kamiokande are all expected to attain significantly increased sensitivities to B-L violation.
Despite these recent exciting developments, the collective particle, lattice-QCD, nuclear, and experimental communities are currently rather disjoint and do not meet very often (if at all) to discuss strategy and theoretical necessities for mutualistic progress in the field. A major goal of this workshop is to bring together representatives across these communities to discuss what major challenges exist, what the prospects are for discovering ΔB=2 violation in future experiments, and the interpretation of experimental signals or limits in the broader context of B-L violation.
Furthermore, the US particle physics community is preparing to identify and rank scientific priorities with the goal of shaping the physics program for the next few decades as part of the Snowmass process, which will initiate in the next year. A springtime workshop frame ensures that we can better serve the experimental community interested in BNV by surveying the opportunities in experiment and theory in order to build the foundation for the strategy for Snowmass. This will allow for in-depth planning for both topics and convener strategies in order to be noticed within the broader field.
https://indico.fnal.gov/event/44472/timetable/#20200803
Co-organizers:
Joshua Barrow (University of Tennessee)
Leah Broussard (Oak Ridge National Laboratory)
Jordy de Vries (University of Massachusetts Amherst/Riken Brookhaven)
Michael Wagman (Fermi National Accelerator Laboratory)
