The semileptonic and nonleptonic decays of the b-flavor vector mesons B_(u,d,s)^(*) and B_(c)^(*) are investigated within the covariant light-front quark model(CLFQM).By calculating the form factors of the transitions...The semileptonic and nonleptonic decays of the b-flavor vector mesons B_(u,d,s)^(*) and B_(c)^(*) are investigated within the covariant light-front quark model(CLFQM).By calculating the form factors of the transitions B_(u,d,s)^(*)→P under the CLFQM,with P denoting a pseudoscalar meson,i.e.,π,K,η_(c)(1S,2S),D_((s)),B_((s)),we predict and discuss several physical observables,including the branching ratios,polarization fractions f_(L),f_(∥),and forward-backward asymmetries A_(FB).The total widths of the single-photon radiative decay channels for these b-flavor vector mesons are estimated using their partial widths.In these considered decays,one can find that the semileptonic decays B_(s)_(*0)→D_(s)^(-)l′+ν_(l′)and B_(c)^(*+)→B_(s)^(0)l′+ν_(l′),η_(c)l′+ν_(l′),with l′being e orτ,and the nonleptonic channels B*+c→B0sπ+,B0sρ+have the largest branching ratios,which can reach up to the 10^(-7) order,and are most likely to be accessible at the future high-luminosity LHCb and Belle-II experiments.展开更多
In past years,several hints of lepton flavor universality（LFU）violation have emerged from the b→ct■,and b→sl+l-data.More recently,the Belle Collaboration has reported the first measurement of the D* longitudinal ...In past years,several hints of lepton flavor universality（LFU）violation have emerged from the b→ct■,and b→sl+l-data.More recently,the Belle Collaboration has reported the first measurement of the D* longitudinal polarization fraction in the B→D*τV decay.Motivated by this intriguing result,along with the recent measurements of RJ/Ψand τ polarization,we present the study of b→ct■ decays in supersymmetry（SUSY）with R-parity violation（RPV）.We consider B→D（*）t■,Bc→ηct■,Bc→J/ψt■ and ∧b→∧ct■ modes and focus on the branching ratios,LFU ratios,forward-backward asymmetries,polarizations of daughter hadrons,and the τ 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 B（B+→K+vv）>7.37×10-6 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
We discuss the implications of the recently reported R_K and R_（K＊） anomalies, the lepton flavor nonuniversality in the B → Kl~＋l^-and B → K~＊l~＋~l- decay channels. Using two sets of hadronic inputs of form fa...We discuss the implications of the recently reported R_K and R_（K＊） anomalies, the lepton flavor nonuniversality in the B → Kl~＋l^-and B → K~＊l~＋~l- decay channels. Using two sets of hadronic inputs of form factors, we perform a fit of new physics to the R_K and R_（K＊） data, and significant new physics contributions are found. We suggest the study of lepton flavor universality in a number of related rare B,Bs,Bc and Λb decay channels, and in particular we give predictions for the μ-to-e ratios of decay widths with different polarizations of the final state particles, and of the b → dl~＋l^- processes, which are presumably more sensitive to the structure of the underlying new physics. With the new physics contributions embedded in the Wilson coefficients, we present theoretical predictions for lepton flavor non-universality in these processes.展开更多
Based on a data sample of 384 million BB pairs collected with the BABAR detector at the PEP-Ⅱ asymmetric e ＋ e ￣ storage ring,we measure branching fractions,direct CP,isospin and lepton-flavor asymmetries for the r...Based on a data sample of 384 million BB pairs collected with the BABAR detector at the PEP-Ⅱ asymmetric e ＋ e ￣ storage ring,we measure branching fractions,direct CP,isospin and lepton-flavor asymmetries for the rare decays B → K （＊） l ＋ l￣ in two di-lepton mass bins above and below the J/ψ resonance.For the B → K＊ l ＋ l￣ decay,we also measure the K＊ longitudinal polarization fraction and the di-lepton forwardbackward asymmetry.展开更多
基金partly supported by the National Natural Science Foundation of China(11347030)the Program for Science and Technology Innovation Talents in Universities of Henan Province(14HASTIT037)the Natural Science Foundation of Henan Province,China(232300420116)。
文摘The semileptonic and nonleptonic decays of the b-flavor vector mesons B_(u,d,s)^(*) and B_(c)^(*) are investigated within the covariant light-front quark model(CLFQM).By calculating the form factors of the transitions B_(u,d,s)^(*)→P under the CLFQM,with P denoting a pseudoscalar meson,i.e.,π,K,η_(c)(1S,2S),D_((s)),B_((s)),we predict and discuss several physical observables,including the branching ratios,polarization fractions f_(L),f_(∥),and forward-backward asymmetries A_(FB).The total widths of the single-photon radiative decay channels for these b-flavor vector mesons are estimated using their partial widths.In these considered decays,one can find that the semileptonic decays B_(s)_(*0)→D_(s)^(-)l′+ν_(l′)and B_(c)^(*+)→B_(s)^(0)l′+ν_(l′),η_(c)l′+ν_(l′),with l′being e orτ,and the nonleptonic channels B*+c→B0sπ+,B0sρ+have the largest branching ratios,which can reach up to the 10^(-7) order,and are most likely to be accessible at the future high-luminosity LHCb and Belle-II experiments.
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→ct■,and b→sl+l-data.More recently,the Belle Collaboration has reported the first measurement of the D* longitudinal polarization fraction in the B→D*τV decay.Motivated by this intriguing result,along with the recent measurements of RJ/Ψand τ polarization,we present the study of b→ct■ decays in supersymmetry（SUSY）with R-parity violation（RPV）.We consider B→D（*）t■,Bc→ηct■,Bc→J/ψt■ and ∧b→∧ct■ modes and focus on the branching ratios,LFU ratios,forward-backward asymmetries,polarizations of daughter hadrons,and the τ 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 B（B+→K+vv）>7.37×10-6 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 National Natural Science Foundation of China(11575110,11655002,11735010)Natural Science Foundation of Shanghai(15DZ2272100,15ZR1423100)+1 种基金Young Thousand Talents PlanKey Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Education
文摘We discuss the implications of the recently reported R_K and R_（K＊） anomalies, the lepton flavor nonuniversality in the B → Kl~＋l^-and B → K~＊l~＋~l- decay channels. Using two sets of hadronic inputs of form factors, we perform a fit of new physics to the R_K and R_（K＊） data, and significant new physics contributions are found. We suggest the study of lepton flavor universality in a number of related rare B,Bs,Bc and Λb decay channels, and in particular we give predictions for the μ-to-e ratios of decay widths with different polarizations of the final state particles, and of the b → dl~＋l^- processes, which are presumably more sensitive to the structure of the underlying new physics. With the new physics contributions embedded in the Wilson coefficients, we present theoretical predictions for lepton flavor non-universality in these processes.
文摘Based on a data sample of 384 million BB pairs collected with the BABAR detector at the PEP-Ⅱ asymmetric e ＋ e ￣ storage ring,we measure branching fractions,direct CP,isospin and lepton-flavor asymmetries for the rare decays B → K （＊） l ＋ l￣ in two di-lepton mass bins above and below the J/ψ resonance.For the B → K＊ l ＋ l￣ decay,we also measure the K＊ longitudinal polarization fraction and the di-lepton forwardbackward asymmetry.
