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QCD factorization for B->PP and B->PV decays

Martin Beneke, Matthias Neubert

Abstract

A comprehensive study of exclusive hadronic B-meson decays into final states containing two pseudoscalar mesons (PP) or a pseudoscalar and a vector meson (PV) is presented. The decay amplitudes are calculated at leading power in Lambda_{QCD}/m_b and at next-to-leading order in alpha_s using the QCD factorization approach. The calculation of the relevant hard-scattering kernels is completed. Important classes of power corrections, including ``chirally-enhanced'' terms and weak annihilation contributions, are estimated and included in the phenomenological analysis. Predictions are presented for the branching ratios of the complete set of the 96 decays of B^-, B^0, and B_s mesons into PP and PV final states, and for most of the corresponding CP asymmetries. Several decays and observables of particular phenomenological interest are discussed in detail, including the magnitudes of the penguin amplitudes in PP and PV final states, an analysis of the pi-rho system, and the time-dependent CP asymmetry in the K phi and K eta' final states.

QCD factorization for B->PP and B->PV decays

Abstract

A comprehensive study of exclusive hadronic B-meson decays into final states containing two pseudoscalar mesons (PP) or a pseudoscalar and a vector meson (PV) is presented. The decay amplitudes are calculated at leading power in Lambda_{QCD}/m_b and at next-to-leading order in alpha_s using the QCD factorization approach. The calculation of the relevant hard-scattering kernels is completed. Important classes of power corrections, including ``chirally-enhanced'' terms and weak annihilation contributions, are estimated and included in the phenomenological analysis. Predictions are presented for the branching ratios of the complete set of the 96 decays of B^-, B^0, and B_s mesons into PP and PV final states, and for most of the corresponding CP asymmetries. Several decays and observables of particular phenomenological interest are discussed in detail, including the magnitudes of the penguin amplitudes in PP and PV final states, an analysis of the pi-rho system, and the time-dependent CP asymmetry in the K phi and K eta' final states.

Paper Structure

This paper contains 34 sections, 141 equations, 13 figures, 24 tables.

Table of Contents

  1. Introduction
  2. Two-body decay amplitudes
  3. The QCD factorization approach
  4. Flavor operators
  5. Distribution amplitudes
  6. Coefficients of the decay operators in QCD factorization
  7. Leading order (Figure \ref{['figlo']}).
  8. Vertex terms (Figure \ref{['figvertex']}).
  9. Penguin terms (Figure \ref{['figpenguin']}).
  10. Hard spectator terms (Figure \ref{['fighardspec']}).
  11. Input parameters
  12. Analysis strategy for $B^-$ and $\bar{B}^0$ decays
  13. Outline
  14. Simplified expressions for the decay amplitudes
  15. The $B^-\to\pi^-\pi^0$ tree amplitude
  16. ...and 19 more sections

Figures (13)

  • Figure 1: Graphical representation of the factorization formula (\ref{['fact']}). Only one of the two form-factor terms is shown for simplicity.
  • Figure 2: Leading-order contribution to the coefficients $a_i^p$. The weak decay of the $b$ quark through a four-fermion operator is represented by the black square. The $b$-quark line comes in from the left. The outgoing line to the right represents the quark in $M_1$. The two lines directed upward represent the meson $M_2$. The spectator antiquark is not drawn, because it does not participate in the hard scattering.
  • Figure 3: Next-to-leading order vertex contribution to the coefficients $a_i^p$. The meaning of the external lines is the same as in Figure \ref{['figlo']}.
  • Figure 4: Next-to-leading order penguin contribution to the coefficients $a_i^p$.
  • Figure 5: Hard spectator-scattering contribution to the coefficients $a_i^p$. The meaning of the external lines is the same as in Figure \ref{['figlo']}, but the spectator-quark line is now included in the drawing.
  • ...and 8 more figures