Heavy to Light Meson Semileptonic Decays Form Factors

Abstract

Like the two-photon and two-gluon decays of the P-wave charmonium state for which the Born term produces a very simple decays amplitude, the Born term for the processes cd‾→(π,K)ℓν and bd‾→(π,K)ℓν, could also produce a simple expression for D and B meson semileptonic decays with a light meson π, K in the final state. The pole term at q2=mB2+mπ2 for B → π and at q2=mD2+mK2 for D → K form factor, are generated by the Born term and given as: f+(0)/(1−q2/(mH2+mπ2)), with H = D, B for D, B → π form factors, and f+(0)/(1−q2/(mH2+mK2)) for B, D → K form factor. These pole dominance terms describe rather well the q2-behavior of the form factors observed in the BaBar, Belle and BESIII measurements and in lattice simulation. In particular, the D → K form factors are in good agreement with the measured values in the whole range of q2 showing evidence for S U(3) breaking with the presence of the mK2 term in the quark propagator, but some corrections to the Born term are needed at large q2 for D, B → π form factors.