Related papers: Nuclear Gluon Distributions in a Parton Model
The low $x$ behaviour of the gluon density $xg(x,\mu^2)$ at scale $\mu^2=2.4$ GeV$^2$ is determined using exclusive $J/\psi$ production data from HERA and LHCb within the framework of collinear factorisation at next-to-leading order (NLO).…
It has been shown recently that there exist analytical solutions of the Yang-Mills equations for non-Abelian Weizs\"acker-Williams fields which describe the distribution of gluons in large nuclei at small x. These solutions however depend…
Parton distributions in the virtual photon target are investigated in perturbative QCD up to the next-to-next-to-leading order (NNLO). In the case $\Lambda^2 \ll P^2 \ll Q^2$, where $-Q^2$ ($-P^2$) is the mass squared of the probe (target)…
At high energies a quark-gluon plasma is expected to be formed in heavy ion collisions at RHIC and LHC. The theoretical description of these processes is directly associated to a complete knowledge of the details of medium effects in the…
We gauge the impact of soft-gluon resummation on quark distributions by performing a simple fit of Deep Inelastic Scattering structure function data using next-to-leading order (NLO) and next-to-leading-logarithmic (NLL)-resummed…
We analyze the capability of prompt photon production in pp and pp(bar) collisions to constrain the gluon distribution of the proton, considering data from fixed-target experiments as well as collider measurements. Combined fits are…
The nuclear shadowing and antishadowing effects are explained by a unitarized BFKL equation. The $Q^2$- and $x$-variations of the nuclear parton distributions are detailed based on the level of the unintegrated gluon distribution. In…
We present a new set of parton distributions obtained at NNLO. These differ from the previous sets available at NNLO due to improvements in the theoretical treatment. In particular we include a full treatment of heavy flavours in the region…
The nuclear modification factor $R_{pA}(p_T)$ provides information on the small-$x$ gluon distribution of a nucleus at hadron colliders. Several experiments have recently measured the nuclear modification factor not only in minimum bias but…
In these proceedings we discuss recent progress in nucleon structure using lattice QCD simulations at or near the physical value of the pion mass. Main focus will be given in observables such as the nucleon axial charge and the first…
We present a study of the contribution of antishadowing effects on the gluon distribution functions $G(x,Q^2)$ in light of the Gribov-Levin-Ryskin-Mueller-Qiu, Zhu-Ruan-Shen (GLR-MQ-ZRS) nonlinear equation at small-$x$, where $x$ is the…
We study the operator description of the gluon spin contribution ($\Gamma$) to the nucleon's spin as it is measured in deep inelastic processes. $\Gamma$ can be related to the forward matrix element of a local gluon operator in $A^+=0$…
In this paper we re-analyse the situation with the shadowing corrections (SC) in QCD for the proton deep inelastic structure functions. We reconsider the Glauber - Mueller approach for the SC in deep inelastic scattering (DIS) and suggest a…
In order to overcome the shortcoming of nonconservation of nuclear momentum existing in the original $Q^2$-rescaling model(O$Q^2$RM) and avoid introducing nuclear shadowing factor, we proposed a double $Q^2$-rescaling model(D$Q^2$RM) for…
We study the global analysis for parton distributions as a function of the QCD strong coupling strength alpha_s, and present a new series of distributions that span the range 0.110 < alpha_s(m_Z) < 0.128. We use these distributions to…
We argue that the collinear factorization of the fragmentation functions in high energy nuclear collisions breaks down at transverse momenta $p_T \lesssim Q_s/g$ due to high parton densities in the colliding hadrons and/or nuclei. We find…
Nuclear shadowing in the structure function $F_3$ is investigated as a possible test of shadowing models. The $F_3$ shadowing is studied in two different theoretical models: a parton-recombination model with $Q^2$ rescaling and an…
Exclusive J/psi production, gamma* p -> J/psi p, offers a unique opportunity to determine the gluon density of the proton in the small x domain. We use the available HERA data to determine the gluon distribution in the region 10^{-4} <~ x…
We show how exclusive vector meson production off light ions can be used to probe the spatial distribution of small-$x$ gluons in the deuteron and $^3$He wave functions. In particular, we demonstrate how short range repulsive…
We show that various nucleon "radii" that appear in the literature, e.g."charge", "gravitational", "mass" or "mechanical, do not have a direct geometric meaning and do not give an idea of the physical size of the nucleon. In the framework…