New avenues for $|\Delta B| = 2$ processes beyond neutron-antineutron oscillationsBas i Beneito, Arnau (Avtor) Fajfer, Svjetlana (Avtor) Petrov, Alexey A. (Avtor) physics of elementary particlesbeyond the Standard Modelbaryon number violationWe explore baryon-number-violating $(|\Delta B| = 2)$ processes beyond the well-known neutron-antineutron $(n -\overline{n})$ oscillations, focusing on the $\Lambda - \overline{\Lambda}$ system. The presence of a strange quark in the $\Lambda$ baryon introduces a new set of six-quark operators roughly of the form $(uds)^2$, which are different from the $(udd)^2$ operators responsible for $(n -\overline{n})$ oscillations. Using the Standard Model Effective Field Theory (SMEFT), we classify all dimension-9 operators that cause $|\Delta B| = 2$ transitions and study their UV completions mediated by exotic scalar fields with trilinear interactions. We demonstrate that in these models, $\Lambda - \overline{\Lambda}$ oscillations can occur at tree level, with $(n -\overline{n})$ mixing potentially appearing at higher loop levels. We employ a chiral effective theory to constrain the effective mass mixing $\delta m_{\Lambda}$ , deriving bounds from current experimental limits on $(n -\overline{n})$ scillations and dinucleon decays such as $pp \rightarrow K^+K^+$. These bounds indicate that $\Lambda - \overline{\Lambda}$ oscillations probe a complementary parameter space, sensitive to baryon-number violation at scales up to $10^2 - 10^3$ TeV. We show that the existing indirect bounds make it challenging to provide a competitive bound on $\delta m_{\Delta}$ at BESIII. 20262026-03-17 13:13:16Članek v reviji180821UDK: 539.120ISSN pri članku: 1029-8479DOI: 10.1007/JHEP03(2026)124COBISS_ID: 271796995sl