LHC constraints and prospects forS1scalar leptoquark explaining theB¯→D(*

Abstract

Recently, deviations in flavor observables ofB → D ( * ) τν have been shown between the predictions in the Standard Model and the experimental results reported by BaBar, Belle, and LHCb collaborations. One of the solutions to this anomaly is obtained in a class of leptoquark model with a scalar leptoquark boson S 1 , which is a SU (3) c triplet and SU (2) L singlet particle with −1/3 hypercharge interacting with a quarklepton pair. With well-adjusted couplings, this model can explain the anomaly and be compatible with all flavor constraints. In such a case, the S 1 boson can be pair-produced at CERN's Large Hadron Collider (LHC) and subsequently decay as S * 1 → tτ , bν τ , and cτ . This paper explores the current 8 and 13 TeV constraints, as well as the detailed prospects at 14 TeV, of this flavor-motivated S 1 model. From the current available 8 and 13 TeV LHC searches, we obtain constraints on the S 1 boson mass for M S1 < 400 GeV -640 GeV depending on values of the leptoquark couplings to fermions. Then we study future prospects for this scenario at the 14 TeV LHC using detailed cut analyses and evaluate exclusion/discovery potentials for the flavor-motivated S 1 leptoquark model from searches for the (bν)(bν) and (cτ )(cτ ) final states. In the latter case, we consider several scenarios for the identification of charm jets. As a result, we find that the S 1 leptoquark origin of theB → D ( * ) τν anomaly can be probed with M S1 600/800 GeV at the 14 TeV LHC with L = 300/3000 fb −1 of accumulated data. One can also see that the 14 TeV LHC run II with L = 300 fb −1 can exclude the S 1 leptoquark boson up to M S1 ∼ 0.8 TeV at 95% confidence level, whereas a future 14 TeV LHC with L = 3000 fb −1 data has a potential to discover the S 1 leptoquark boson with its mass up to M S1 ∼ 1.1 TeV with over 5σ significance, from the (bν)(bν) and/or (cτ )(cτ ) searches.

Simultaneous explanation of the R K and R D * $$ {R}_{D^{\left(*\right)}} $$ puzzles: a model analysis

“…It is found that the values of the ratios R D ( * ) ≡ B(B → D ( * ) τ −ν τ )/B(B → D ( * ) −ν ) ( = e, µ) considerably exceed their SM predictions. Assuming Gaussian distributions, and taking correlations into account, the experimental results and theoretical predictions can be combined to yield [22,23] The measured values of R D and R D * represent deviations from the SM of 1.7σ and 3.1σ, respectively. These are known as the R D and R D * puzzles.…”

Phenomenology of Λ b → Λ c τ ν ¯ τ $$ {\Lambda}_b\to {\Lambda}_c\tau {\overline{\nu}}_{\tau } $$ using lattice QCD calculations

“…In ref. [65], several leptoquark models are considered that generate scalar, vector, and tensor operators. The SU(3)×SU(2)×U(1) quantum numbers of these models are summarized in table 5.…”

Lepton-flavor universality violation in R K and R D ∗ $$ {R}_{D^{{}_{\left(\ast \right)}}} $$ from warped space

“…Previous analyses in the literature have considered various ad hoc extensions of the Standard Model suitable to accommodate the anomalies, in particular including new gauge bosons [25][26][27][28][29][30][31][32][33][34][35], leptoquarks [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] and general effective field theory frameworks [51][52][53][54][55]. 2 Anomalies in R K , and b → s processes, have also been addressed in Randall-Sundrum [56][57][58] and flat space [59] extra dimensional scenarios.…”