Nuclear parton distributions in the DGLAP approach

Determination of the nuclear parton distributions within the framework of perturbative QCD, the DGLAP equations in particular, is discussed. Scale and flavour dependent nuclear effects in the parton distributions are compared with the scale and flavour independent parametrizations of HIJING and of the Hard Probe Collaboration. A comparison with the data from deep inelastic lepton-nucleus scattering and the Drell-Yan process in proton-nucleus collisions is shown.Comment: 19 pages, 6 eps-figures, to appear in the Proceedings of the Hard Probe Collaboratio

Constraints for nuclear gluon shadowing from DIS data

The $Q^2$ dependence of the ratios of the cross sections of deep inelastic lepton--nucleus scattering is studied in the framework of leading twist, lowest order perturbative QCD. The $\log Q^2$ slope of the ratio $F_2^{\rm Sn}/F_2^{\rm C}$ is computed by using the DGLAP evolution equations, and shown to be sensitive to the nuclear gluon distribution functions. Four different parametrizations for the nuclear effects of parton distributions are studied. We show that the NMC data on the $Q^2$ dependence of $F_2^{\rm Sn}/F_2^{\rm C}$ rule out the case where nuclear shadowing (suppression) of gluons at $x\sim 0.01$ is much larger than the shadowing observed in the ratio $F_2^A/F_2^{\rm D}$. We also show that the possible nonlinear correction terms due to gluon fusion in the evolution equations do not change this conclusion. Some consequences for computation of RHIC multiplicities, which probe the region x\gsim0.01, are also discussed.Comment: 11 pages, 3 eps figure

Global DGLAP fit analyses of the nPDF: EKS98 and HKM

The DGLAP analyses of the nuclear parton distribution functions (nPDF) based on the global fits to the data are reviewed, and the results from EKS98 and HKM are compared. The usefulness of measuring hard probes in $pA$ collisions, at the LHC in particular, is demonstrated.Comment: 10 pages, 3 figures. Contribution to CERN Yellow Report on Hard Probes in Heavy Ion Collisions at the LH

Constraints for nuclear gluon densities from DIS data

The $Q^2$ dependence of the ratios of nuclear structure functions $F_2^A$ is studied by performing QCD evolution of nuclear parton distribution functions. The log $Q^2$ slope of these ratios is very sensitive to the nuclear gluon distribution function. Taking different parametrizations, we show that the NMC data on the $Q^2$ dependence of $F_2^{\rm Sn}/F_2^{\rm C}$ rule out the case where nuclear shadowing (suppression) of gluons at $x\sim 0.01$ is much larger than the shadowing observed in the ratio $F_2^A/F_2^{\rm D}$. We also take into account modifications to the DGLAP evolution by including gluon fusion terms and see that the effect is small at present energies, and, in any case, a strong gluon shadowing is not favored. The region studied ($x \sim 0.01$) is the most relevant for RHIC multiplicities.Comment: 4 pages, 3 postscript figures. Contributed to 37th Rencontres de Moriond on QCD and Hadronic Interactions, Les Arcs, France, 16-23 Mar 200

DGLAP analyses of nPDF: constraints from data

We explain how the constraints from present experimental data can be used to obtain the nPDF in the framework of LO DGLAP evolution. We will also compare the only two available sets of this type and comment on the important information that neutrino factories could provide.Comment: 1 pages, 1 postscript figure. Invited talk at the NuFact'02 workshop (Neutrino Factories based on Muon Storage Rings), London, July 200

Cross-sectional area of the paraspinal muscles and its association with muscle strength among fighter pilots : A 5-year follow-up

Background: A small cross sectional area (CSA) of the paraspinal muscles may be related to low back pain among military aviators but previous studies have mainly concentrated on spinal disc degeneration. Therefore, the primary aim of the study was to investigate the changes in muscle CSA and composition of the psoas and paraspinal muscles during a 5-year follow up among Finnish Air Force (FINAF) fighter pilots. Methods: Study population consisted of 26 volunteered FINAF male fighter pilots (age: 20.6 (±0.6) at the baseline). The magnetic resonance imaging (MRI) examinations were collected at baseline and after 5 years of follow-up. CSA and composition of the paraspinal and psoas muscles were obtained at the levels of 3-4 and 4-5 lumbar spine. Maximal isometric strength tests were only performed on one occasion at baseline. Results: The follow-up comparisons indicated that the mean CSA of the paraspinal muscles increased (p <0.01) by 8% at L3-4 level and 7% at L4-5 level during the 5-year period. There was no change in muscle composition during the follow-up period. The paraspinal and psoas muscles' CSA was positively related to overall maximal isometric strength at the baseline. However, there was no association between LBP and muscle composition or CSA. Conclusions: The paraspinal muscles' CSA increased among FINAF fighter pilots during the first 5 years of service. This might be explained by physically demanding work and regular physical activity. However, no associations between muscle composition or CSA and low back pain (LBP) experienced were observed after the five-year follow-up. © 2019 The Author(s).Peer reviewe

RHIC-tested predictions for low-pTp_T and high-pTp_T hadron spectra in nearly central Pb+Pb collisions at the LHC

We study the hadron spectra in nearly central $A$+$A$ collisions at RHIC and LHC in a broad transverse momentum range. We cover the low-$p_T$ spectra using longitudinally boost-invariant hydrodynamics with initial energy and net-baryon number densities from the perturbative QCD (pQCD)+saturation model. Build-up of the transverse flow and sensitivity of the spectra to a single decoupling temperature \Tdec are studied. Comparison with RHIC data at \ssNN=130 and 200 GeV suggests a rather high value \Tdec=150 MeV. The high-$p_T$ spectra are computed using factorized pQCD cross sections, nuclear parton distributions, fragmentation functions, and describing partonic energy loss in the quark-gluon plasma by quenching weights. Overall normalization is fixed on the basis of p+$\bar{\rm p}$(p) data and the strength of energy loss is determined from RHIC Au+Au data. Uncertainties are discussed. With constraints from RHIC data, we predict the $p_T$ spectra of hadrons in 5 % most central Pb+Pb collisions at the LHC energy \ssNN=5500 GeV. Due to the closed framework for primary production, we can also predict the net-baryon number at midrapidity, as well as the strength of partonic energy losses at the LHC. Both at the LHC and RHIC, we recognize a rather narrow crossover region in the $p_T$ spectra, where the hydrodynamic and pQCD fragmentation components become of equal size. We argue that in this crossover region the two contributions are to a good approximation mutually independent. In particular, our results suggest a wider $p_T$-region of applicability for hydrodynamical models at the LHC than at RHIC.Comment: 45 pages, 16 eps-figure

Enhanced charm hadroproduction due to nonlinear corrections to the DGLAP equations

We have studied the effects of nonlinear scale evolution of the parton distribution functions to charm production in $pp$ collisions at center-of-mass energies of 5.5, 8.8 and 14 TeV. We find that the differential charm cross section can be enhanced up to a factor of 4-5 at low $p_T$. The enhancement is quite sensitive to the charm quark mass and the renormalization/factorization scales.Comment: 4 pages, 3 eps-figures. To appear in the proceedings of the seventeenth international conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004