Heavy to Light Meson Semileptonic Decays Form Factors

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 c (d) over bar -> (pi, K)lv and b (d) over bar -> (pi, K)lv, could also produce a simple expression for D and B meson semileptonic decays with a light meson pi, K in the final state. The pole term at q(2) = m(B)(2) + m(pi)(2) for B -> pi and at q(2) = m(D)(2) + m(K)(2) for D -> K form factor, are generated by the Born term and given as : f(+)(0)/(1 - q(2)/(m(H)(2) + m(pi)(2))) with H = D, B for D, B -> pi form factors, and f(+)(0)/(1 - q(2)/(m(H)(2) + m(K)(2))) for B, D -> K form factor. These pole dominance terms describe rather well the q(2)-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 q(2) showing evidence for S U(3) breaking with the presence of the m(K)(2) term in the quark propagator, but some corrections to the Born term are needed at large q(2) for D, B -> pi form factors.