## Abstract

We investigate the light-front zero-mode contribution to the weak transition form factors between pseudoscalar and vector mesons using a covariant fermion field theory model in (3+1) dimensions. In particular, we discuss the form factors a-(q^{2}) and f(q^{2}) which have been suspected to have the zero-mode contribution in the q^{+}=0 frame. While the zero-mode contribution in principle depends on the form of the vector meson vertex Γ^{μ}=γ^{μ}-(2k-P_{V})^{μ}/D, the form factor f(q^{2}) is found to be free from the zero mode if the denominator D contains the term proportional to the light-front longitudinal momentum fraction factor (1/x)^{n} of the struck quark with the power n>0. Although the form factor a-(q^{2}) is not free from the zero mode, the zero-mode contribution comes only either from the simple vertex Γ^{μ}=γ^{μ} term or from the other term just with a constant D (i.e. n=0), but not with the momentum-dependent denominator (i.e. D~(1/x)^{n} with n>0). We identify the zero-mode contribution to a-(q^{2}) and incorporate it as a convolution of the zero-mode operator with the initial- and final-state light-front wave functions. The covariance (i.e. frame independence) of our model has been checked by performing the light-front calculations both in the q^{+}=0 and q^{+}>0 frames. We present our numerical result of the B→ρ transition for an explicit demonstration of our findings.

Original language | English |
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Pages (from-to) | 95-111 |

Number of pages | 17 |

Journal | Nuclear Physics A |

Volume | 856 |

Issue number | 1 |

DOIs | |

State | Published - 15 Apr 2011 |

## Keywords

- Analytic continuation
- Light-front zero mode
- Semileptonic decays
- Weak form factors