Beauty, charm, and F L at HERA: New data vs. Early predictions
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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 (F 2 c ) and beauty (F 2 b ) 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 F 2 c at moderately large Q 2. We predicted precocious BFKL asymptotics of F 2 c (x,Q 2) with intercept of the rightmost BFKL pole α P(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 −x F 2 c and F 2 b 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 F 2 c and F 2 b by the H1 published in 2006 but contradict very recent (2008, preliminary)H1 results on F 2 b . We present also comparison of our early predictions for the longitudinal structure function F L with recent H1 data (2008) taken at very low Bjorken x. We comment on the electromagnetic corrections to the Okun-Pomeranchuk theorem.
KeywordsAtomic Nucleus Regge Expansion Open Charm BFKL Equation Longitudinal Structure Function
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- 1.L. B. Okun, and I. Ya. Pomeranchuk, Zh. Eksp. Teor. Fiz. 30, 307 (1956) [Sov. Phys. JETP 3, 307 (1956)].Google Scholar
- 3.L. N. Lipatov, Sov. Phys. JETP 63, 904 (1986).Google Scholar
- 10.L. N. Lipatov, Sov. J. Nucl. Phys. 23, 338 (1976); E. A. Kuraev, L. N. Lipatov, and V. S. Fadin, Sov. Phys. JETP 44, 443 (1976); 45, 199 (1977); Ya. Ya. Balitsky and L. N. Lipatov, Sov. J. Nucl. Phys. 28, 882 (1978).Google Scholar
- 11.N. N. Nikolaev, B. G. Zakharov, and V. R. Zoller, Zh. Eksp. Teor. Fiz. 105, 1498 (1994) [JETP 78, 806 (1994)].Google Scholar
- 18.H1 Collab. (preliminary), in Proc. of the 34th Intern. Conf. on High Energy Physics (ICHEP 2008), Philadelphia, 30 Jul.–5 Aug. 2008.Google Scholar
- 28.N. N. Nikolaev, Comments Nucl. Part. Phys. 21, 41 (1992); B. Z. Kopeliovich, J. Nemchik, N. N. Nikolaev, and B. G. Zakharov, Phys. Lett. B 309, 179 (1993); 324, 469 (1994); J. Nemchik, N. N. Nikolaev, and B. G. Zakharov, Phys. Lett. B 341, 228 (1994).Google Scholar