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

Abstract

Abstract Motivated by the $$ b\to c\tau \overline{v} $$ b → cτ v ¯ 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 τ lepton, a b-jet and large missing transverse momentum $$ \left( pp\to {\tau}_h\overline{b}+{E}_{\mathrm{T}}^{\mathrm{miss}}\right) $$ pp → τ h b ¯ + E T miss . Such searches can be useful to probe new physics contributions to $$ b\to c\tau \overline{v} $$ b → cτ v ¯ . 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 $$ pp\to {\tau}_h\overline{b}+{E}_{\mathrm{T}}^{\mathrm{miss}} $$ pp → τ h b ¯ + E T miss . Although the LQ models provide a weaker sensitivity than the EFT limit, it is found that the non-resonant search of $$ pp\to {\tau}_h\overline{b}+{E}_{\mathrm{T}}^{\mathrm{miss}} $$ pp → τ h b ¯ + E T miss can improve the sensitivity by ≈ 40% versus a conventional mono-τ search $$ \left( pp\to {\tau}_h+{E}_{\mathrm{T}}^{\mathrm{miss}}\right) $$ pp → τ h + E T miss in the whole LQ mass region. Consequently, it is expected that most of the parameter regions suggested by the $$ b\to c\tau \overline{v} $$ b → cτ v ¯ anomalies can be probed at the HL-LHC. Also, it is shown that R2 LQ scenario is accessible entirely once the LHC Run 2 data are analyzed. In addition, we discuss a charge selection of τh to further suppress the standard-model background, and investigate the angular correlations among b, τ and the missing transverse momentum to discriminate the LQ scenarios.