Beauty, charm, and FL at HERA: New data vs. Early predictions
One of the well-known effects of the asymptotic freedom is splitting of the leading-log BFKL pomeron into a series of isolated poles in complex angular momentum plane. Following our earlier works we explore the phenomenological consequences of the emerging BFKL-Regge factorized expansion for the small-x charm (F2c) and beauty (F2b) structure functions of the proton. As we found earlier, the colordipole approach to the BFKL dynamics predicts uniquely decoupling of subleading hard BFKL exchanges from F2c at moderately large Q2. We predicted precocious BFKL asymptotics of F2c (x,Q2) with intercept of the rightmost BFKL pole αP(0) − 1 = ΔP ≈ 0.4. High-energy open beauty photo- and electroproduction probes the vacuum exchange at much smaller distances and detects significant corrections to the BFKL asymptotics coming from the subleading vacuum poles. In view of the accumulation of the experimental data on small −xF2c and F2b we extended our early predictions to the kinematical domain covered by new HERA measurements. Our structure functions obtained in 1999 agree well with the determination of both F2c and F2b by the H1 published in 2006 but contradict very recent (2008, preliminary)H1 results on F2b. We present also comparison of our early predictions for the longitudinal structure function FL with recent H1 data (2008) taken at very low Bjorken x. We comment on the electromagnetic corrections to the Okun-Pomeranchuk theorem.
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