Factorization in Color-Favored B Meson Decays to Charm.pdf

a r X i v : h e p - p h / 0 1 0 1 0 8 9 v 4 2 2 J u n 2 0 0 1 Factorization in Color-Favored B-Meson Decays to Charm 1 Zumin Luo 2 and Jonathan L. Rosner 3 Enrico Fermi Institute and Department of Physics University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637 Improved B meson decay data have permitted more incisive tests of fac- torization predictions. A concurrent benefit is the ability to constrain the Cabibbo-Kobayashi-Maskawa matrix element |Vcb|. Using a simulta- neous fit to differential distributions dΓ(B 0 → D(?)+l?ν?l)/dq2 and the rates for the color-favored decays B 0 → D(?)+(π?, ρ?, a?1 ), we find |Vcb| = 0.0415± 0.0022. The slope of the universal Isgur-Wise form factor is de- scribed by a parameter found to be ρ2 = 1.52±0.11. Taking the Ds meson decay constant from the world average of direct measurements, we predict satisfactorily the branching ratios for B 0 → D(?)+D(?)?s . Ratios of helicity amplitudes for color-favored processes are also found to be in accord with predictions. PACS Categories: 13.25.Hw, 14.40.Nd, 14.65.Fy, 12.39.Hg 1Enrico Fermi Institute preprint EFI 01-02, hep-ph/0101089. Submitted to Physical Review D. 2zuminluo@ 3rosner@ 1 I Introduction Semileptonic weak hadron decays provide useful information on form factors of the weak current. The lepton pair can then be replaced with a hadron, permitting the calculation of nonleptonic decays. Although this hadron can re-interact with the rest of the system, the effects of this re-interaction sometimes can be neglected or evaluated. In such cases one is employing the factorization hypothesis. An early version of this hypothesis [1] was recently justified for certain decays of hadrons containing heavy quarks [2]. In the present paper we update and test some factorization predictions first made a number of years ago [3]. We compare values of the Cabibbo-Kobayashi-Maskawa ma- trix element |Vcb| and form factor shapes obtained from (1) the differential distribution dΓ(B 0 → D(?)+l?ν