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We describe the gluon parton distribution function (PDF) in the proton, deduced by data from the ATLAS and HERA experiments, in the framework of the parton statistical model. The best fit parameters involved in the Planck formula that…

High Energy Physics - Phenomenology · Physics 2023-07-12 Loredana Bellantuono , Roberto Bellotti , Franco Buccella

We consider the gluon propagator in the Landau gauge at low spacelike momenta and with the dressing function $Z(Q^2)$ at the two-loop order. We incorporate the nonperturbative effects by making the (noninteger) powers of the QCD coupling in…

High Energy Physics - Phenomenology · Physics 2014-09-01 Pedro Allendes , Cesar Ayala , Gorazd Cvetič

We present a consistent calculation of the structure functions within a light-front constituent quark model of the nucleon. Relativistic effects and the relevance of the covariance constraints are analyzed for polarized parton…

High Energy Physics - Phenomenology · Physics 2007-05-23 P. Faccioli , F. Cano , M. Traini , V. Vento

Parton distribution functions (DFs) have long been recognised as key measures of hadron structure. Today, theoretical prediction of such DFs is becoming possible using diverse methods for continuum and lattice analyses of strong interaction…

High Energy Physics - Phenomenology · Physics 2024-11-12 Yang Yu , Craig D. Roberts

We consider the ratio of the top structure functions $R^{t}(\tau_{t})$ in top pair production as a probe of the top content of the proton at the LHeC project. We study the top structure functions with the geometrical scaling of gluon…

High Energy Physics - Phenomenology · Physics 2015-04-07 G. R. Boroun

We study the scaled-energy (x_B) distribution of bottom-flavored hadrons (B) inclusively produced in top-quark decays at next-to-leading order (NLO) in the general-mass variable-flavor-number scheme endowed with realistic, nonperturbative…

High Energy Physics - Phenomenology · Physics 2015-06-05 Bernd A. Kniehl , Gustav Kramer , Seyed M. Moosavi Nejad

We present a first calculation of the heavy flavor contribution to the longitudinally polarized deep-inelastic scattering structure function $g_1^{Q}$, differential in the transverse momentum or the rapidity of the observed heavy quark $Q$…

High Energy Physics - Phenomenology · Physics 2021-08-04 Felix Hekhorn , Marco Stratmann

Nuclear parton distributions are studied in a parton model with rescaling and recombination mechanisms. Parton x distributions are first calculated at Q^2=1 GeV^2 by the model, and they are evolved to larger Q^2 in order to be compared with…

High Energy Physics - Phenomenology · Physics 2007-05-23 S. Kumano , K. Umekawa

New type of parametrization for parton distribution functions, based on an exact their Q^2-evolution at large and small x values, is constructed for valence quarks. It preserves exactly the low x and large x asymptotics of the solution of…

High Energy Physics - Phenomenology · Physics 2011-02-18 A. Yu. Illarionov , A. V. Kotikov , S. S. Parzycki , D. V. Peshekhonov

We present the third-order contributions to the quark-gluon and gluon-quark timelike splitting functions for the evolution of fragmentation functions in perturbative QCD. These quantities have been derived by studying physical evolution…

High Energy Physics - Phenomenology · Physics 2015-05-28 A. A. Almasy , A. Vogt , S. Moch

A recently proposed strategy to quantify the role of the charm quark mass in the $\Delta I=1/2$ rule is reviewed. Results for the low-energy couplings of the $\Delta S=1$ chiral effective Hamiltonian in a theory with a light charm quark…

High Energy Physics - Lattice · Physics 2008-11-26 P. Hernandez

We present the next-to-next-to-leading order (NNLO) contributions to the main splitting functions for the evolution of longitudinally polarized parton densities of hadrons in perturbative QCD. The quark-quark and gluon-quark splitting…

High Energy Physics - Phenomenology · Physics 2015-06-22 S. Moch , J. A. M. Vermaseren , A. Vogt

We argue that the difference between the structure functions corresponding to deep inelastic scattering with and without heavy quarks in the current fragmentation region scales at high $Q^2$ and fixed (low) $x_{Bj}$. The lower bound on…

High Energy Physics - Phenomenology · Physics 2011-01-25 A. V. Kisselev , V. A. Petrov

Within a QCD-based eikonal model with a dynamical infrared gluon mass scale we discuss how the small $x$ behavior of the gluon distribution function at moderate $Q^{2}$ is directly related to the rise of total hadronic cross sections. In…

High Energy Physics - Phenomenology · Physics 2008-11-26 E. G. S. Luna , A. A. Natale , C. M. Zanetti

Using the QCD dipole picture of the hard BFKL Pomeron, we perform a 3 parameter fit analysis of the recent inclusive structure function experimental measurements at small-$x$ and intermediate $Q^2$. As a byproduct, the longitudinal…

High Energy Physics - Phenomenology · Physics 2009-11-10 A. Lengyel , M. V. T. Machado

Recent accurate data on F_2(x,Q) and on F_2^c(x,Q) from HERA at small-x require a more precise treatment of charm production in the global QCD analysis of parton distributions. We improve on existing global analyses by implementing the…

High Energy Physics - Phenomenology · Physics 2007-05-23 H. L. Lai , W. K. Tung

We investigate the nucleon and pion gluon distribution functions in the framework of holographic QCD, focusing on the small Bjorken x region. Based on an approximate relation, the gluon distributions are extracted from structure functions…

High Energy Physics - Phenomenology · Physics 2020-06-24 Akira Watanabe , Takahiro Sawada , Mei Huang

We introduce a new family of Generalised Parton Distribution models able to fulfil by construction all the theoretical properties imposed by QCD. These models are built on standard Parton Distribution Functions and extended to off-forward…

The common view that structure functions measured in deep inelastic lepton scattering are determined by the probability of finding quarks and gluons in the target is not correct in gauge theory. We show that gluon exchange between the fast,…

High Energy Physics - Phenomenology · Physics 2009-09-11 Stanley J. Brodsky , Paul Hoyer , Nils Marchal , Stephane Peigne , Francesco Sannino

The double parton distribution functions are investigated in the region of small longitudinal momentum fractions in the leading logarithm approximation of perturbative QCD. It is shown that these functions have the factorization property in…

High Energy Physics - Phenomenology · Physics 2011-03-23 A. M. Snigirev