Eur. Phys. J. C (2007) 52: 967-973
https://doi.org/10.1140/epjc/s10052-007-0422-4

Regular Article - Theoretical Physics

Form factors, branching ratio and forward–backward asymmetry in B→K₁ℓ⁺ℓ^- decays

¹ Department of Physics and National Centre for Physics, Quaid-i-Azam University, Islamabad, Pakistan
² Department of Physics, COMSATS Institute of Information Technology, CHAK SHAH2AD Campus, Islamabad, Pakistan

^* e-mail: jamil@ncp.edu.pk

Received: 30 June 2007
Revised: 19 August 2007
Published online: 16 October 2007

Abstract

We study long-distance effects in the rare exclusive semileptonic decays B→K₁ℓ⁺ℓ^-, where K₁ is the axial vector meson. The form factors describing the meson transition amplitudes of the effective Hamiltonian are calculated using the Ward identities, which are then used to calculate the branching ratio and the forward–backward asymmetry in these decay modes. The zero of the forward–backward asymmetry is of special interest and provides us with a precision test of the standard model.