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In the leading twist approximation of the Wilson operator product expansion with standard and "frozen" versions of strong copling constant we show that the Bessel-inspired behavior of the structure function $F_2$ at small $x$, obtained for…

High Energy Physics - Phenomenology · Physics 2008-12-31 A. Yu. Illarionov , A. V. Kotikov

We present a set of formulae to extract the longitudinal deep inelastic structure function $F_L$ from the transverse structure function $F_2$ and its derivative $dF_2/dlnQ^2$ at small $x$. Using $F_2$ HERA data we obtain $F_L$ in the range…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. V. Kotikov , G. Parente

The experimental data on F2 structure functions of the proton and deuteron were used to construct their moments. In particular, recent measurements performed with CLAS detector at Jefferson Lab allowed to extend our knowledge of structure…

High Energy Physics - Phenomenology · Physics 2014-11-18 M. Osipenko , S. Simula , S. Kulagin , G. Ricco , CLAS Collaboration

We derive a unitarity relationship between the spin structure function $g_{LT}(x,Q^{2})=g_{1}(x,Q^{2})+g_{2}(x,Q^{2})$, the LT interference diffractive structure function and the spin-flip coupling of the pomeron to nucleons. Our…

High Energy Physics - Phenomenology · Physics 2009-10-31 I. P. Ivanov , N. N. Nikolaev , A. V. Pronyaev , W. Schäfer

I present a full leading-order calculation of F_2(x,Q^2) and F_L(x,Q^2), including contributions not only from leading order in \alpha_s, but also from the leading power of \alpha_s for each order in ln(1/x). The calculation is ordered…

High Energy Physics - Phenomenology · Physics 2009-10-30 Robert S. Thorne

The charm quark structure function $F^c_2$ and the longitudinal structure function $F_l^p$ are directly sensitive to the gluon content of proton and therefore are crucial in understanding of proton structure function, in particular at low…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Modarres , M. M. Yazdanpanah

We study the heavy-quark contributions to the proton structure functions $F_2^i(x,Q^2)$ and $F_L^i(x,Q^2)$, with $i=c,b$, for small values of Bjorken's $x$ variable and provide compact formulas for their ratios $R_i=F_L^i/F_2^i$ that are…

High Energy Physics - Phenomenology · Physics 2008-12-31 A. Yu. Illarionov , B. A. Kniehl , A. V. Kotikov

We present a simultaneous extraction of the moments of $F_2$ and $F_L$ structure functions of the proton for a range of photon virtuality, $Q^2$. This is achieved by computing the forward Compton amplitude on the lattice utilizing the…

We show that a unified approach to the perturbative evolution of structure functions which sums all logarithms of Q^2 and 1/x at leading and next-to-leading order yields results in full agreement with the 1993 HERA data for F_2. This makes…

High Energy Physics - Phenomenology · Physics 2007-05-23 R. D. Ball , S. Forte

We propose a modified Balitsky-Fadin-Kuraev-Lipatov equation from the viewpoint of the resummation technique, which contains an intrinsic dependence on momentum transfer Q, and satisfies the unitarity bound. The idea is to relax the strong…

High Energy Physics - Phenomenology · Physics 2016-09-06 Hsiang-nan Li

We discuss the evolution of F_2^p at small x, emphasizing the uncertainties related to expansion, fitting, renormalization and factorization scheme dependence. We find that perturbative extrapolation from the measured region down to smaller…

High Energy Physics - Phenomenology · Physics 2007-05-23 R. D. Ball , S. Forte

We present the first measurement of the Q^2-dependence of the neutron spin structure function g_2^n at five kinematic points covering 0.57 (GeV/c)^2 <= Q^2 <= 1.34 (GeV/c)^2 at x~0.2. Though the naive quark-parton model predicts g_2=0,…

Nuclear Experiment · Physics 2008-11-26 K. Kramer

We perform a perturbative QCD analysis of the nucleon's Pauli form factor $F_2(Q^2)$ in the asymptotically large $Q^2$ limit. We find that the leading contribution to $F_2(Q^2)$ has a $1/Q^6$ power behavior, consistent with the well-known…

High Energy Physics - Phenomenology · Physics 2009-11-07 Andrei V. Belitsky , Xiangdong Ji , Feng Yuan

A model for the longitudinal structure function $F_L$ at low $x$ and low $Q^2$ is presented, which includes the kinematical constraint $F_L \sim Q^4$ as $Q^2 \rightarrow 0$. It is based on the photon-gluon fusion mechanism suitably…

High Energy Physics - Phenomenology · Physics 2007-05-23 B. Badelek , J. Kwiecinski , A. Stasto

The $F_2$, $F_G$, $R = F_L/F_T$ proton structure functions are derived in the QCD dipole picture. Assuming $k_T$ and renormalization-group factorization, we relate deep-inelastic proton scattering to deep-inelastic onium scattering. We get…

High Energy Physics - Phenomenology · Physics 2008-11-26 H. Navelet , R. Peschanski , Ch. Royon , S. Wallon

We analyse the available data on the polarized asymmetries $A_1$ for proton, neutron and deuteron targets. We use a homogeneous and updated set of unpolarized structure functions to derive $g_1$ from $A_1$, and we accurately correct for the…

High Energy Physics - Phenomenology · Physics 2009-10-22 G. Altarelli , P. Nason , G. Ridolfi

First results of a non--singlet QCD analysis of the structure function $F_2(x,Q^2)$ in 3--loop order based on the non--singlet world data are presented. Correlated errors are determined and their propagation through the evolution equations…

High Energy Physics - Phenomenology · Physics 2009-11-10 J. Blümlein , H. Böttcher , A. Guffanti

We report a semi-analytical approach for the solution of the nonlinear Gribov-Levin-Ryskin-Mueller-Qiu (GLR-MQ) evolution equation for sea quark distribution and investigate the effect of gluon shadowing on the small-x and moderate-Q^2…

High Energy Physics - Phenomenology · Physics 2018-08-09 Mayuri Devee

The QCD dipole picture allows to build an unified theoretical description -based on BFKL dynamics- of the total and diffractive nucleon structure functions. We use a four parameter fit to describe the 1994 H1 proton structure function F2…

High Energy Physics - Phenomenology · Physics 2007-05-23 C. Royon

In the framework of conventional Regge theory we present a common description of total photon-proton cross-section and proton structure functions in the region $0 \leq Q^2 \leq 5 \ {\rm GeV}^2$. Using it as an initial condition in the…

High Energy Physics - Phenomenology · Physics 2009-10-28 A. Capella , A. Kaidalov , C. Merino , J. Tran Thanh Van