Investigation on the New Physics effects of the vector leptoquark on semileptonic (ar{B}^*ightarrow V au ^-ar{u _{au }}) decays

摘要

In recent years, the experimental results about the ratio of the branching ratios $$R_{D^{(*)}}$$ R D ( ? ) and $$R_{K^{(*)}}$$ R K ( ? ) , which are in the semileptonic $$bightarrow c l ar{u }_{l}$$ b → c l ν ˉ l and $$bightarrow s l^+l^-$$ b → s l + l - decays, have been observed to deviate from the Standard Model prediction by $$1.4sigma $$ 1.4 σ , $$2.5sigma $$ 2.5 σ , $$2.4sigma $$ 2.4 σ and $$2.2sigma $$ 2.2 σ respectively. Motivated by these anomalies and by the abundant $$B^*$$ B ? data samples, we investigate possible New Physics effects of the vector leptoquark in the semileptonic decay $$ar{B}^*_{u,d,s,c} ightarrow V au ^-ar{u }_{au }$$ B ˉ u , d , s , c ? → V τ - ν ˉ τ ( $$V=D^*_{u,d,s},J/psi $$ V = D u , d , s ? , J / ψ ). which is induced by $$bightarrow c au ^-ar{u }_{au }$$ b → c τ - ν ˉ τ at the quark level. Using the best fit solutions for the new operator Wilson coefficients and the relevant form factors which are obtained in the light-front quark model, we find that (i) the contributions of the vector leptoquark to $$d{arGamma }^{(L)}/dq^2(ar{B}^*_{u,d,s,c} ightarrow V au ^-ar{u }_{au })$$ d Γ ( L ) / d q 2 ( B ˉ u , d , s , c ? → V τ - ν ˉ τ ) and $$R^{*(L)}_{V}(q^2)$$ R V ? ( L ) ( q 2 ) to be significant; (ii) the two best fit solutions in the vector leptoquark are indistinguishable from each other and give similar amounts of enhancements to these two observables; (iii) both two cases of the vector leptoquark give nearly same results as those of the Standard Model for $$A_{FB}^{au }(q^2)$$ A FB τ ( q 2 ) , $$P_{au }(q^2)$$ P τ ( q 2 ) and $$F_{L}^{*V}(q^2)$$ F L ? V ( q 2 ) . We hope that the numerical results in this work will be tested in the future high energy experiments.