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Related papers: Small x resummations confronted with F_2(x,Q^2) da…

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We calculate DIS-scheme splitting and coefficient functions for electromagnetic deep inelastic scattering with small x resummations, as given by the NLL BFKL equation with running coupling and approximate NLL resummed impact factors. The…

High Energy Physics - Phenomenology · Physics 2008-11-26 C. D. White , R. S. Thorne

We discuss the inclusion of running coupling effects in perturbative small x evolution equations. We show that a running coupling BFKL-like x-evolution equation is fully compatible, up to higher twist corrections, with the standard…

High Energy Physics - Phenomenology · Physics 2008-11-26 Guido Altarelli , Richard D. Ball , Stefano Forte

It is well understood that the leading logarithmic approximation for the amplitudes of high energy processes is insufficient and that the next-to-leading logarithmic effects are very large and lead to instability of the solution. The…

High Energy Physics - Phenomenology · Physics 2020-04-22 Michal Deak , Leonid Frankfurt , Mark Strikman , Anna Stasto

We construct an anomalous dimension for small x evolution which goes beyond standard fixed order perturbative evolution by including resummed small x logarithms deduced from the leading order BFKL equation with running coupling.…

High Energy Physics - Phenomenology · Physics 2008-11-26 Guido Altarelli , Richard D. Ball , Stefano Forte

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…

High Energy Physics - Phenomenology · Physics 2012-12-18 A. V. Kotikov

We show that a resummation model for the evolution kernel at small x creates a bridge between the weak and strong couplings. The resummation model embodies DGLAP and BFKL anomalous dimensions at leading logarithmic orders, as well as a…

High Energy Physics - Phenomenology · Physics 2010-03-25 Anna M. Stasto

We perform the fit to the structure function $F_2$ data from HERA including terms due to the resummation at small $x$. The equation for the unintegrated gluon density is solved, previously established within the renormalization group…

High Energy Physics - Phenomenology · Physics 2022-07-13 Wanchen Li , Anna M. Stasto

I review recent results by Fadin,Lipatov and collaborators and by our group,leading to the almost complete calculation of the next-to-leading BFKL kernel,of its eigenvalues,and of the resummed gluon anomalous dimension. Qualitative…

High Energy Physics - Phenomenology · Physics 2007-05-23 Marcello Ciafaloni

We propose a systematic approximation scheme for solving GLAP evolution equations at small Bjorken-$x$. The approximate solutions interpolate smoothly between hard (singular as $x^{-(1+\lambda)}$, $\lambda> 0$) and soft (singular at most as…

High Energy Physics - Phenomenology · Physics 2007-05-23 L. Mankiewicz , A. Saalfeld , T. Weigl

We propose an improvement of the splitting functions at small x which overcomes the apparent problems encountered by the BFKL approach. We obtain a stable expansion for the x-evolution function chi(M) near M=0 by including in it a sequence…

High Energy Physics - Phenomenology · Physics 2008-11-26 Guido Altarelli , Richard D. Ball , Stefano Forte

We compare two Monte Carlo implementations of resummation schemes for the description of parton evolution at small values of Bjorken x. One of them is based on the Balitsky-Fadin-Kuraev-Lipatov (BFKL) evolution equation and generates fully…

High Energy Physics - Phenomenology · Physics 2015-03-18 G. Chachamis , M. Deak , A. Sabio Vera , P. Stephens

We show that, provided that the non-perturbative input is regular at the right of the $\omega=0$ singularity of the dominant DGLAP anomalous dimension, the rise of $F_2$ at small $x,$ experimentally measured by the averaged observable…

High Energy Physics - Phenomenology · Physics 2010-03-25 H. Navelet , R. Peschanski , Ch. Royon , L. Schoeffel , S. Wallon

We critically examine the QCD predictions for the $Q^2$ dependence of the electron-proton deep-inelastic structure function $F_2(x,Q^2)$ in the small $x$ region, which is being probed at HERA. The standard results based on next-to-leading…

High Energy Physics - Phenomenology · Physics 2010-03-25 A. J. Askew , K. Golec , J. Kwiecinski , A. D. Martin , P. J. Sutton

We propose a matrix evolution equation in (x,kt)-space for flavour singlet, unintegrated quark and gluon densities, which generalizes DGLAP and BFKL equations in the relevant limits. The matrix evolution kernel is constructed so as to…

High Energy Physics - Phenomenology · Physics 2010-03-25 M. Ciafaloni , D. Colferai , G. P. Salam , A. M. Stasto

We review the current understanding of the behaviour of inclusive cross sections at small x and large Q^2 in terms of Altarelli-Parisi evolution, the BFKL equation, and Regge theory, asking in particular to what extent they are mutually…

High Energy Physics - Phenomenology · Physics 2010-03-25 R. D. Ball , P. V. Landshoff

We show that the next-to-leading-order renormalization-group-improved asymptotically-free BFKL Pomeron provides a good fit to HERA data on virtual photoproduction at small x and large Q^2. The leading discrete Pomeron pole reproduces…

High Energy Physics - Phenomenology · Physics 2008-11-26 J. Ellis , H. Kowalski , D. A. Ross

We review the current status of small x resummation of evolution of parton distributions and of deep-inelastic coefficient functions. We show that the resummed perturbative expansion is stable, robust upon different treatments of subleading…

High Energy Physics - Phenomenology · Physics 2015-05-13 Stefano Forte , Guido Altarelli , Richard D. Ball

We investigate factorisation at small x using a variety of analytical and numerical techniques. Previous results on factorisation in collinear models are generalised to the case of the full BFKL equation, and illustrated in the example of a…

High Energy Physics - Phenomenology · Physics 2009-10-31 Marcello Ciafaloni , Dimitri Colferai , Gavin P. Salam

Using the leading-twist approximation of the Wilson operator product expansion with "frozen" and analytic versions of the strong-coupling constant, we show that the Bessel-inspired behavior of the structure function F_2 and its slope\break…

High Energy Physics - Phenomenology · Physics 2009-10-02 G. Cvetic , A. Yu. Illarionov , B. A. Kniehl , A. V. Kotikov

The Balitskii-Fadin-Kuraev-Lipatov (BFKL) and the Gribov-Lipatov- Dokshitzer-Altarelli-Parisi (GLDAP) evolution equations for the diffractive deep inelastic scattering at ${1\over x} \gg 1$ are shown to have a common solution in the weak…

High Energy Physics - Phenomenology · Physics 2016-08-14 N. N. Nikolaev , B. G. Zakharov