Global Analysis of Nuclear Parton Distributions

Impact of nuclear dependence ofR=σL/σTon antishadowing in nuclear structure functions

“…7 where we present the ratio of leading order gluon distributions in 40 Ca to that in the free proton, g A (x)/g N (x), as a function of x at fixed Q 2 = 3 GeV 2 . In the figure, the solid curve is the result of the EPS09 fit [16]; the dotted curve is the result of the HKN07 fit [15]; the dot-dashed curve is the nDS parameterization [14], whose results are quantitatively similar to those of [17]. For the EPS09 and HKN07 fits, we showed only the central values; the theoretical uncertainty on these predictions is quite large essentially in the entire range of x.…”

“…In the framework of the leading twist formalism, global QCD fits to the available data [13][14][15][16][17] show that the small enhancement of σ A /σ D in the antishadowing region translates into an enhancement of the valence quark and possibly gluon distributions in nuclei compared to those in the free proton. One should emphasize that these analyses assumed no nuclear dependence of R, i.e., R = 0.…”

“…In the leading twist formalism, the small enhancement of σ A /σ D in the antishadowing region translates into an enhancement of the valence quark and possibly gluon distributions in nuclei in this region [13][14][15][16][17]. However, the pattern and especially the magnitude of nuclear modifications of the gluon distribution in nuclei are very poorly constrained by present data.…”

The LHC p+Pb run from the nuclear PDF perspective

“…However, a bit surprisingly, the shape of this distribution around the central rapidities does not appear to receive large NLO corrections as demonstrated in the right-hand panel of Figure 1 where the absolute distribution has been normalized by the total cross section. In Figure 2, the preliminary CMS data [2] for this normalized distribution is compared to the calculations with no nuclear effects (only CT10NLO), and with various nuclear PDFs (nPDFs), HKN07 [5], DSSZ [6] and EPS09 [7]. From these, only EPS09 is capable to systematically reproduce the the data.…”

Nuclear effects in photoproduction of heavy quarks and vector mesons in ultraperipheral PbPb andpPb collisions at energies available at the CERN Large Hadron Collider

“…Earlier global analyses [32][33][34][35] relied heavily on fixed-target nuclear deep-inelastic scattering (DIS) and Drell-Yan (DY) lepton-pair production data. Incorporation of additional data from inclusive hadron production in deuteron-gold collisions and neutrino-iron processes has been implemented in [36][37][38][39][40][41]. The approach in [42,43] utilizes the Gribov picture of shadowing and data from diffractive processes to generate nuclear modifications.…”