Semileptonic neutral currents decays of $Ξ_b$ with dileptons or dineutrinos in the final state

Abstract: We perform a detailed analysis of semileptonic $Ξ<em>b$ decays mediated by flavor-changing neutral currents ($b\to s$ and $b\to d$) with dilepton or dineutrino final states within the perturbative QCD framework. All independent form factors including vector, axial-vector, tensor, and pseudotensor currents are calculated and are used to analyze the decay branching fractions and angular distributions. Our numerical results for the branching fractions of $Ξ_b\to Ξ\ell<sup>+\ell<sup>-$ decays suggest they are within measurable reach for the LHCb experiment in the near future. Furthermore, we show that a measurement of the ratio $$\mathcal{B}(Ξ_b^-\to Σ^- μ^{+μ^-)} / \mathcal{B}(Ξ_b^-\to Ξ^- μ<sup>+μ<sup>-)$$ will allow for an independent determination of $|V</em>{td}/V_{ts}|$. For the case of unpolarized $Ξ_b$ baryons, we derive several angular observables, which can provide new and complementary constraints on Wilson coefficients in semileptonic FCNC transitions compared to those from mesonic decays. Finally, we present a combined analysis of dilepton and dineutrino channels, comparing various observables in detail. Our results offer further insights into the long-standing anomalies observed in $B$ meson decays.