Abstract: Lepton number violation (LNV) as underlying neutrinoless nuclear double beta decay (DBD) and equal-charged lepton pair plus di-jet production in ultra-relativistic hadron collisions are expected to deliver the heavily searched for signatures for physics beyond the standard model (BSM). To study the totally unexplored rank-2 nuclear isotensor spectroscopy inherent to DBD independently, peripheral heavy ion double charge exchange (DCE) reactions, as studied in the NUMEN project, are the proper tool. They include sequential (DCSE) and direct (MDCE) processes formally corresponding to two-neutrino and neutrinoless DBD, respectively. DSCE reactions are the perfect tool for isotensor two-particle – two-hole spectroscopy. MDBD leads to pion potentials as surrogates of the neutrino potentials in neutrinoless DBD. Direct probes for LNV are lepton DCE (LDCE) reactions at accelerators, apparently and surprisingly never considered before. Theoretical concepts are discussed, merging into a second-order approach. As a first application total cross sections of ΔL=+2 (e-,e+) reactions on nuclear targets are estimated. At beam energies beyond 10 GeV, cross sections of magnitudes are predicted which might be measurable at existing facilities.

Seminár sa uskutoční v stredu 29. októbra 2025 o 14:00 hod. prezenčne: V zasadačke KJFB, F1/364, Fakulta matematiky, fyziky a informatiky UK, Mlynská dolina, Bratislava.

S pozdravom, Staníček