Non-resonant new physics search at the LHC for the b → cτν anomalies

Motivated by the b -> c tau(nu) over bar anomalies, we study non-resonant searches for new physics at the large hadron collider (LHC) by considering final states with an energetic and hadronically decaying tau lepton, a b-jet and large missing transverse momentum (pp -> tau(h)(b) over bar + E-T(miss)). Such searches can be useful to probe new physics contributions to b -> c tau(nu) over bar. They are analyzed not only within the dimension-six effective field theory (EFT) but also in explicit leptoquark (LQ) models with the LQ non-decoupled. The former is realized by taking a limit of large LQ mass in the latter. It is clarified that the LHC sensitivity is sensitive to the LQ mass for O(1) TeV even in the search of pp -> tau(h)(b) over bar + E-T(miss). Although the LQ models provide a weaker sensitivity than the EFT limit, it is found that the non-resonant search of pp -> tau(h)(b) over bar + E-T(miss) can improve the sensitivity by approximate to 40% versus a conventional mono-tau search (pp -> tau(h) + E-T(miss)) in the whole LQ mass region. Consequently, it is expected that most of the parameter regions suggested by the b -> c tau(nu) over bar anomalies can be probed at the HL-LHC. Also, it is shown that R-2 LQ scenario is accessible entirely once the LHC Run 2 data are analyzed. In addition, we discuss a charge selection of tau(h) to further suppress the standard-model background, and investigate the angular correlations among b, tau and the missing transverse momentum to discriminate the LQ scenarios.

Automated summary

Motivated by anomalies in b -> c tau(nu) over bar processes, we study non-resonant searches for new physics at the LHC involving tau leptons, b-jets, and missing transverse momentum. The analysis explores both effective field theory frameworks and explicit leptoquark models, finding sensitivity to leptoquark mass and improved detection capabilities over conventional searches. Probing the parameter space suggested by anomalies and investigating angular correlations among particles are key considerations for discriminating between different scenarios.