Resonant and nonresonantD+→K−π+

Abstract

We analyze the semileptonic decay D ϩ →K Ϫ ϩ l ϩ l using an effective Lagrangian developed previously to describe the decays D→ Pl l and D→Vl l . Light vector mesons are included in the model which combines the heavy quark effective Lagrangian and chiral perturbation theory approach. The nonresonant and resonant contributions are compared. With no new parameters the model correctly reproduces the measured ratio ⌫ nres /⌫ nres ϩ res . We also present useful nonresonant decay distributions. Finally, a similar model, but with a modified current which satisfies the soft pion theorems at the expense of introducing another parameter, is analyzed and the results of the models are compared. ͓S0556-2821͑98͒02017-7͔

Penguin operators in nonresonantB−→MM¯π−Fajfer1, Oakes2, Pham3 1999Phys. Rev. DSelf Cite411450View full textAdd to dashboardCite

“…The experimental result for the branching ratio of the nonresonant D + → K − π + lν decay was successfully reproduced within a hybrid framework [15] which combines the heavy quark effective theory (HQET) and the chiral Lagrangian (CHPT) approach. The combination of heavy quark symmetry and chiral symmetry has also been quite successful in other analyses of D meson semileptonic decays [16] - [22].…”

“…For the calculation of the matrix element < MM |(ūb) V −A |B − > we extend the results obtained in [15], where the nonresonant D + → K − π + lν decay was analyzed. The experimental result for the branching ratio of the nonresonant D + → K − π + lν decay was successfully reproduced within a hybrid framework [15] which combines the heavy quark effective theory (HQET) and the chiral Lagrangian (CHPT) approach.…”

“…Our modification is quite straightforward: we retain the usual HQET Feynman rules for the vertices near and outside the zero-recoil region, but we include the complete propagators instead of using the usual HQET propagator. This quite reasonable modification of the hybrid HQET and CHPT model enabled us to use it successfully over the entire kinematic region of the D meson weak decays [15,21,22].…”

“…The quark currents required in the weak Hamiltonian (1) can be expressed in terms of the meson fields, as previously described explicitly in [4,15,21]. The operator O 6 can be rewritten as the product of the density operators.…”

“…It is really only known that the combination of HQET and CHPT is valid at small recoil momentum. To take into account the larger recoil energies of the light mesons in our previous work [15,21], we modified the hybrid model of [16] - [20] to describe the semileptonic decays of D mesons into one light vector or pseudoscalar meson. Our modification is quite straightforward: we retain the usual HQET Feynman rules for the vertices near and outside the zero-recoil region, but we include the complete propagators instead of using the usual HQET propagator.…”