Light-cone expansion of heavy-to-light form factors

TL;DR

This paper investigates the light-cone expansion of heavy-to-light form factors within a scalar constituent model, revealing the behavior and suppression of higher-twist contributions in the 1/m_Q expansion.

Contribution

It provides a systematic analysis of higher-twist effects and their suppression parameters, highlighting the unique behavior of leading and subleading twists.

Findings

Higher-twist contributions share the same behavior in 1/m_Q expansion.

Suppression parameter of higher-twist effects is generally the inverse Borel parameter.

Leading and subleading twists are of the same order in 1/β due to additional suppression.

Abstract

We present the results of our recent systematic study of the light-cone expansion of heavy-to-light transition form factors in a model with scalar constituents [1]. We show that the higher-twist contributions (represented in this model by off-light-cone effects) all have the same behaviour in the 1/m_Q expansion. The suppression parameter of the higher-twist contributions compared to the lower-twist contributions is, in general, the inverse Borel parameter \beta. The only exception here is the case of the leading and the subleading twists: they are of the same order in 1/\beta because of an extra suppression of the leading-twist contribution to the form factor.