Eur. Phys. J. C (2005) 42: 163-168
https://doi.org/10.1140/epjc/s2005-02289-6

Theoretical Physics

On BLM scale fixing in exclusive processes

¹ Bogoliubov Laboratory of Theoretical Physics, JINR, 141980, Dubna, Russia
² CPHT (Unité mixte 8627 du CNRS.), École Polytechnique, 91128, Palaiseau, France
³ Soltan Institute for Nuclear Studies, Warsaw, Poland
⁴ LPT (Unité mixte 8627 du CNRS.), Université Paris-Sud, 91405, Orsay, France
⁵ Phys. Théor. Fondam., Inst. de Physique, Univ. de Liége, 4000, Liége, Belgium

Abstract

We discuss the BLM scale fixing procedure in exclusive electroproduction processes in the Bjorken regime with rather large x _B. We show that in the case of vector meson production dominated in this case by quark exchange the usual way to apply the BLM method fails due to singularities present in the equations fixing the BLM scale. We argue that the BLM scale should be extracted from the squared amplitudes which are directly related to observables.