相关论文: Beauty, charm and $F_L$ at HERA: new data vs. earl…
A precise proton structure function F_2 at low x is measured. The data is interpreted in the framework of QCD with an extraction of gluon density xg. The charm contribution to F_2 is determined in an extended kinematic range. Neutral and…
It is shown that in the leading twist approximation of the Wilson operator product expansion with "frozen" and analytic strong coupling constants, Bessel-inspired behavior of the structure functions F2 and F2cc and also the derivative d(ln…
Measurements are presented of inclusive charm and beauty cross sections in e^+p collisions at HERA for values of photon virtuality Q^2 > 150 GeV^2 and of inelasticity 0.1 < y < 0.7. The charm and beauty fractions are determined using a…
We use the hard (Lipatov) pomeron for the low-x gluon distribution and provide a compact formula for the ratio $R^{c} =F_{L}^{c}/F_{2}^{c}$ that is useful to extract the charm structure function from the reduced charm cross-section, in…
The color dipole gBFKL phenomenology of a diffraction cone for photo- and electroproduction $\gamma^{*}N \to VN$ of heavy vector mesons (charmonium & bottonium) at HERA and in fixed target experiments is presented. A substantial shrinkage…
Results on open charm and beauty production and on the search for top production in high-energy electron-proton collisions at HERA are reviewed. This includes a discussion of relevant theoretical aspects, a summary of the available…
The transition from the low $Q^2$ region in deep inelastic scattering where charm production is described by photon-gluon fusion to a region where the charm structure function $F_2^c$ is largely generated by a charm quark density should be…
The results from a recent analysis on beauty production in deep inelastic scattering at HERA using decays into electrons from the ZEUS collaboration are presented. The fractions of events containing b quarks were extracted from a likelihood…
In this paper we consider the influence of non-perturbative corrections on the large $ b $ (impact parameter) behavior of the BFKL amplitude. This is done in the framework of a model where such ``soft'' corrections are taken into account in…
The drastic rise of the proton structure function F_2(x,Q^2) when the Bj\"orken variable x decreases, seen at HERA for a large span of Q^2, negative values for the 4-momentum transfer, may be damped when Q^2 increases beyond several…
We perform a numerical study of various improvements of the LO BFKL prediction for the gamma^* gamma^* total cross section in the kinematical region of the L3 detector at LEP. In particular, we study the effects of a massive charm quark and…
The low $x$ limit of deep inelastic electron proton scattering is considered using methods of perturbative QCD. In the first part we investigate the phenomenological consequences of the resummation of leading logarithms in $1/x$ given by…
Using the analytical expression for transverse momentum dependent (TMD) gluon density in a proton, a self-consistent simultaneous description of low $Q^2$ data on proton structure function $F_2(x,Q^2)$, reduced cross section for the…
The small-$x$ evolution of protons is determined from numerical solutions of the JIMWLK equations, starting from an initial condition at moderate $x$ for a finite size proton. The resulting dipole amplitude is used to calculate the total…
Based on the QCD dipole picture of the BFKL Pomeron, we investigate the role played by the saturation scale, Q_{sat}, in obtaining physical values for the affective strong coupling in phenomenological fits to small-x HERA data. The…
We investigate the production of a quark-antiquark pair in diffractive photon- proton scattering, approximating soft pomeron exchange by the exchange of two nonperturbative gluons. In deep inelastic scattering at HERA, events with two jets…
A method allowing for a direct comparison of data with theoretical predictions is proposed for forward jet production at HERA and Mueller-Navelet jets at Tevatron and LHC. An application to the determination of the effective Pomeron…
The $F_{2}$, $F_{G}$, $R=F_{L}/F_{T}$ proton structure functions are derived in the QCD dipole picture of BFKL dynamics. We get a three parameter fit describing the 1994 H1 proton structure function $F_{2}$ data in the low $x$, moderate…
It has been observed recently that a consistent LO BFKL gluon evolution leads to a steep growth of F_2(x,Q^2) for x -> 0 almost independently of Q^2. We show that current data from the DESY HERA collider are precise enough to finally rule…
Measurements are presented of inclusive charm and beauty cross sections in e^+p collisions at HERA for values of photon virtuality 12 \le Q^2 \le 60 GeV^2 and of the Bjorken scaling variable 0.0002 \le x \le 0.005. The fractions of events…