Phenomenological Analysis of D Meson Lifetimes.pdfVIP

Phenomenological Analysis of D Meson Lifetimes Hai-Yang Cheng and Kwei-Chou Yang Institute of Physics, Academia Sinica, Taipei, Taiwan 115, R.O.C. Abstract 9 9 9 The QCD-based operator-product-expansion technique is systematically ap- 1 plied to the study of charmed meson lifetimes. We stress that it is crucial y a to take into account the momentum of the spectator light quark of charmed M mesons, otherwise the destructive Pauli-interference effect in D+ decays will 2 lead to a negative decay width for the D+ . We have applied the QCD sum 1 rule approach to estimate the hadronic matrix elements of color-singlet and 1 color-octet 4-quark operators relevant to nonleptonic inclusive D decays. The v + 0 3 lifetime of Ds is found to be longer than that of D because the latter receives 1 a constructive W -exchange contribution, whereas the hadronic annihilation 3 5 and leptonic contributions to the former are compensated by the Pauli inter- 0 + 0 ference. We obtain the lifetime ratio τ (Ds )/τ (D ) ≈ 1.08 ± 0.04, which is 9 9 larger than some earlier theoretical estimates, but still smaller than the recent / h measurements by CLEO and E791. p - p e h : v i PACS numbers: 13.25.Hw, 12.38.Lg, 11.55.Hx, 12.39.Hg X r a Typeset using REVT X