Beauty, charm and $F_L$ at HERA: new data vs. early predictions

Abstract

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 color dipole 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 $α_{\Pom}(0)-1=Δ_{\Pom}\approx 0.4$. High-energy open beauty photo- and electro-production 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 to 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.

16 pages, 4 figures. The contribution to the volume in honor of Lev Okun's 80 birthday

References in corpus (6)

• Gauge-invariant field-strength correlators in pure Yang-Mills and full QCD at finite temperature
• Measurement of the Proton Structure Function F_L at Low x
• Measurement of F_2^{c\bar{c}} and F_2^{b\bar{b}} at Low Q^2 and x using the H1 Vertex Detector at HERA
• Evidence for the Discrete Asymptotically-Free BFKL Pomeron from HERA Data
• A Variable Flavour Number Scheme for Heavy Quark Production at Small x
• Diffractive beauty photoproduction as a short distance probe of QCD pomeron

Cited by in corpus (14)

• Longitudinal structure function from logarithmic slopes of $F_2$ at low $x$
• Geometrical scaling behavior of the top structure functions ratio at the LHeC
• Top structure function at the LHeC
• The ratio of the beauty structure functions $R^b=F_L^b/F_2^b$ at low x
• Longitudinal structure function from the parton parameterization
• Ratio of the structure functions and the color dipole model bound
• The behavior of the heavy-quarks structure functions at small-$x$
• The study of the gluon distribution function and reduced cross section behavior using the proton structure function
• Importance of the heavy-quarks longitudinal structure function measurements at future circular collider energies
• Influence of gluon behavior on heavy-quark pair production
• Heavy quark structure functions from unifying the color dipole picture and double asymptotic scaling approaches
• Heavy quarks structure functions $F_2^{q\bar{q}}(x,Q^2)$ and $F_L^{q\bar{q}}(x,Q^2)$ at the NLO approximation
• Collinear approach for top quark production at ep colliders
• Geometrical scaling of heavy-quark contributions in the low $x$ region