In past years, several hints of lepton flavor universality (LFU) violation have emerged from the b→sl^+l^-and data. More recently, the Belle Collaboration has reported the first measurement of the D^* longitudinal po...In past years, several hints of lepton flavor universality (LFU) violation have emerged from the b→sl^+l^-and data. More recently, the Belle Collaboration has reported the first measurement of the D^* longitudinal polarization fraction in the B→D^*τν decay. Motivated by this intriguing result, along with the recent measurements of and polarization, we present the study of b→cτν decays in supersymmetry (SUSY) with -parity violation (RPV). We consider B→D^(*)τν, Bc→ηcτν, Bc→J/ψτν and modes and focus on the branching ratios, LFU ratios, forward-backward asymmetries, polarizations of daughter hadrons, and the lepton. The RPV SUSY was capable of explaining the RD^(*)anomalies at the 2σ level, after taking into account various flavor constraints. In the allowed parameter space, the differential branching fractions and LFU ratios are largely enhanced by the SUSY effects, especially in the large dilepton invariant mass region. Moreover, a lower bound 10^-6 is obtained. These observables could provide testable signatures at the high-luminosity LHC and SuperKEKB, and correlate with direct searches for SUSY.展开更多
During the past few years, signs of lepton flavor universality (LFU) violation have been observed in b→cτν and sl^+l^- transitions. Recently, the D^* and τ polarization fractions PL^D^* and PL^τ in B→D^*τν dec...During the past few years, signs of lepton flavor universality (LFU) violation have been observed in b→cτν and sl^+l^- transitions. Recently, the D^* and τ polarization fractions PL^D^* and PL^τ in B→D^*τν decay were likewise measured by the Belle collaboration. Motivated by these intriguing results, we revisit the RD^(*) and RK^(*) anomalies in a scalar leptoquark (LQ) model, where two scalar LQs, one of which is a singlet and the other a triplet, are introduced simultaneously. We consider five b→cτν mediated decays,B→D^(*)τν,Bc→ηcτν,Bc→J/ψτν, and ∧cτν, and focus on the LQ effects on the q^2 distributions of the branching fractions, LFU ratios, and various angular observables in these decays. Under the combined constraints of the available data on ,RD^(*),RJ/ψ, and PL^D^*, we perform scans for the LQ couplings and make predictions for a number of observables. Numerically it is found that both the differential branching fractions and LFU ratios are largely enhanced by the LQ effects, with the latter expected to provide testable signatures at the SuperKEKB and High-Luminosity LHC experiments.展开更多
基金Supported by the National Natural Science Foundation of China(11775092,11521064,11435003,11805077)supported in part by the startup research funding from CCNU
文摘In past years, several hints of lepton flavor universality (LFU) violation have emerged from the b→sl^+l^-and data. More recently, the Belle Collaboration has reported the first measurement of the D^* longitudinal polarization fraction in the B→D^*τν decay. Motivated by this intriguing result, along with the recent measurements of and polarization, we present the study of b→cτν decays in supersymmetry (SUSY) with -parity violation (RPV). We consider B→D^(*)τν, Bc→ηcτν, Bc→J/ψτν and modes and focus on the branching ratios, LFU ratios, forward-backward asymmetries, polarizations of daughter hadrons, and the lepton. The RPV SUSY was capable of explaining the RD^(*)anomalies at the 2σ level, after taking into account various flavor constraints. In the allowed parameter space, the differential branching fractions and LFU ratios are largely enhanced by the SUSY effects, especially in the large dilepton invariant mass region. Moreover, a lower bound 10^-6 is obtained. These observables could provide testable signatures at the high-luminosity LHC and SuperKEKB, and correlate with direct searches for SUSY.
基金Supported by the National Natural Science Foundation of China(11775092,11521064,11435003,11805077)supported in part by the startup research funding from CCNU
文摘During the past few years, signs of lepton flavor universality (LFU) violation have been observed in b→cτν and sl^+l^- transitions. Recently, the D^* and τ polarization fractions PL^D^* and PL^τ in B→D^*τν decay were likewise measured by the Belle collaboration. Motivated by these intriguing results, we revisit the RD^(*) and RK^(*) anomalies in a scalar leptoquark (LQ) model, where two scalar LQs, one of which is a singlet and the other a triplet, are introduced simultaneously. We consider five b→cτν mediated decays,B→D^(*)τν,Bc→ηcτν,Bc→J/ψτν, and ∧cτν, and focus on the LQ effects on the q^2 distributions of the branching fractions, LFU ratios, and various angular observables in these decays. Under the combined constraints of the available data on ,RD^(*),RJ/ψ, and PL^D^*, we perform scans for the LQ couplings and make predictions for a number of observables. Numerically it is found that both the differential branching fractions and LFU ratios are largely enhanced by the LQ effects, with the latter expected to provide testable signatures at the SuperKEKB and High-Luminosity LHC experiments.
