The same-sign top probe for baryon number violation at the LHC

Abstract

Despite strong experimental evidences for their conservation at low energies, the baryon $B$ and lepton $L$ numbers are not expected to be absolute symmetries. Already violated in the Standard Model (SM) by non-perturbative effects (tiny at low temperatures and energies) and not justified by any fundamental principle, $B$ and $L$ appear naturally violated in beyond the Standard Model (BSM) scenarios, e.g. in supersymmetry (SUSY). The fact that any violation remained unobserved at low energies can nonetheless be explained, without pushing the associated characteristic sale beyond the TeV, by using SM flavour symmetries implemented BSM thanks to the Minimal Flavour Violation (MFV) prescription. Violation effects could therefore be observable at the LHC. Same-sign (anti-)tops, sometimes leading to a distinctive predominance of negatively charged lepton pairs over positively charged ones, is a clean signature that is for instance generically present in R-parity violating supersymmetry.