Diffractive beauty photoproduction as a short distance probe of QCD pomeron

摘要

High-energy open beauty photoproduction probes the vacuum exchange at distances similar to 1/m(b) and detects significant corrections to the BFKL asymptotics coming from the subleading vacuum poles. We show that the interplay of leading and subleading vacuum exchanges gives rise to the cross section sigma (b (b) over bar)(W) growing much faster than it is prescribed by the exchange of the leading pomeron trajectory with intercept alpha (P)(0) - 1 = Delta (P) = 0.4. Our calculations within the color dipole BFKL model are in agreement with the recent determination of sigma (b (b) over bar)(W) by th, H1 Collaboration. The comparative analysis of diffractive photoproduction of beauty, charm and light quarks exhibits the hierarchy of pre-asymptotic pomeron intercepts which follows the hierarchy of corresponding hardness scales, We comment on the phenomenon of decoupling of soft and subleading BFKL singularities at the scale of elastic gamma (1S)-photoproduction which results in precocious color dipole BFKL asymptotics of the process gammap --> gammap. (C) 2001 Published by Elsevier Science B.V. [References: 26]