Multi-lepton probes of new physics

Multi-lepton signals provide a relatively clean and rich testing ground for new physics (NP) at the LHC and, in particular, for searching for lepton flavor universality violation (LFUV) effects mediated by new heavy states of an underlying TeV-scale NP. The potential sensitivity of 3rd generation fermions (the top-quark in particular) to TeV-scale NP along with the persistent anomalies in B-decays, the recently confirmed muon g-2 anomaly as well as hints reported recently by ATLAS and CMS of unequal di-muons versus di-electrons production, have led us to explore effects of higher-dimensional $(qq)(\ell \ell)$ 4-Fermi operators involving 3rd generation quarks and muons/electrons, on multi-leptons + jets production at the LHC. We focused on both flavor-changing $(q_3 q_{1,2})(\ell \ell)$ and flavor-diagonal $(q_3 q_3)(\ell \ell)$ scalar, vector and tensor contact interactions and the corresponding "tail-effects" mediated by the new multi-TeV heavy states that generate these 4-Fermi operators. Indeed, with a sufficiently high invariant mass selection on the di-leptons from the $qq\ell\ell$ interaction and additional specific jet-selections designed to minimize the SM background, it is possible to obtain a sensitivity to $\Lambda(q_3 q \ell \ell) \sim {\rm few}~ TeV$ via these $pp \to$ multi-leptons + jets channels already with the current LHC data; significantly better than the current sub-TeV bounds on these type of interactions.

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https://technion.zoom.us/j/96348729779

Meeting ID: 963 4872 9779