Search results for "Parto"

Agreement of Neutrino Deep Inelastic Scattering Data with Global Fits of Parton Distributions

2013

The compatibility of neutrino-nucleus deep inelastic scattering data within the universal, factorizable nuclear parton distribution functions has been studied independently by several groups in the past few years. The conclusions are contradictory, ranging from a violation of the universality up to a good agreement, most of the controversy originating from the use of the neutrino-nucleus data from the NuTeV Collaboration. Here, we pay attention to non-negligible differences in the absolute normalization between different neutrino data sets. We find that such variations are large enough to prevent a tensionless fit to all data simultaneously and could therefore misleadingly point towards non…

Suppression of Back-to-Back Hadron Pairs at Forward Rapidity ind+AuCollisions atsNN=200  GeV

2011

Back-to-back hadron pair yields in d + Au and p + p collisions at root S-NN = 200 GeV were measured with the PHENIX detector at the Relativistic Heavy Ion Collider. Rapidity separated hadron pairs were detected with the trigger hadron at pseudorapidity vertical bar eta vertical bar < 0: 35 and the associated hadron at forward rapidity (deuteron direction, 3.0< eta < 3.8). Pairs were also detected with both hadrons measured at forward rapidity; in this case, the yield of back-to-back hadron pairs in d + Au collisions with small impact parameters is observed to be suppressed by a factor of 10 relative to p + p collisions. The kinematics of these pairs is expected to probe partons in the Au nu…

Hyperon polarization asymmetry: Polarized beams andΩ−production

1985

The parton recombination model relates polarizations in inclusive baryon fragmentation to those of the underlying constituent subprocesses. Measurements of spin-spin correlations in experiments using polarized beams will provide detailed information on the quark spin dynamics in the color-confining recombination process. We present a large number of predictions for the octet baryon\ensuremath{\rightarrow}octet baryon transitions. We discuss the production of polarized ${\ensuremath{\Omega}}^{\mathrm{\ensuremath{-}}}$'s, required to measure the magnetic moment of the ${\ensuremath{\Omega}}^{\mathrm{\ensuremath{-}}}$. We also review the data from unpolarized beam experiments, and find very sa…

Erratum to: Moments of polarized parton distribution functions

2003

Lepton jets from radiating dark matter

2015

Journal of High Energy Physics 2015.7 (2015): 045 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)

EPPS16 : Bringing nuclear PDFs to the LHC era

2018

We report on EPPS16, the first global analysis of nuclear parton distribution functions (nPDFs) to include LHC data. Also for the first time, a full flavour dependence of nPDFs is allowed. While the included Z and W data are found to have insufficient statistics to yield stringent constraints, the CMS 5.02 TeV proton-lead dijet data prove crucial in setting the shape of nuclear gluon modifications. With these and other observables being measured in proton-lead runs, we are experiencing a shift of nPDFs to the LHC precision era.

Quadrupole Anisotropy in Dihadron Azimuthal Correlations in Centrald+AuCollisions atsNN=200  GeV

2013

The PHENIX collaboration at the Relativistic Heavy Ion Collider (RHIC) reports measurements of azimuthal dihadron correlations near midrapidity in d + Au collisions at root s(NN) = 200 GeV. These measurements complement recent analyses by experiments at the Large Hadron Collider (LHC) involving central p + Pb collisions at root s(NN) = 5.02 TeV, which have indicated strong anisotropic long-range correlations in angular distributions of hadron pairs. The origin of these anisotropies is currently unknown. Various competing explanations include parton saturation and hydrodynamic flow. We observe qualitatively similar, but larger, anisotropies in d + Au collisions at RHIC compared to those seen…

Nuclear PDFS today

2018

I review the current status of global analysis of nuclear parton distributions and discuss some near-future prospects. I also advocate proton-nucleus (p-$A$) measurements at the LHC with $A\ll 208$ from the viewpoint of nuclear parton distributions.

LHC data challenges the contemporary parton-to-hadron fragmentation functions

2014

We discuss the inclusive high-pT charged-particle production in proton-proton collisions at the LHC. The experimental data are compared to the NLO perturbative QCD calculations employing various sets of parton-to-hadron fragmentation functions. Most of the theoretical predictions are found to disastrously overpredict the measured cross sections, even if the scale variations and PDF errors are accounted for. The problem appears to arise from the presently too hard gluon-to-hadron fragmentation functions.

Electron-ion physics with the LHeC

2015

The Large Hadron Electron Collider (LHeC) project is the proposal to use the existing LHC proton/ion beams and construct a new electron beam line to perform high-energy electron-proton/ion collisions. In this talk, we consider some of the physics topics that could be studied in the electron-ion mode. In particular, we estimate how much the current nuclear parton distribution fits could be improved with the deeply inelastic scattering measurements at the LHeC by including pseudodata into a global analysis. In addition, we discuss briefly other topics that would help to better understand some aspects of heavy-ion collisions, namely small-$x$ physics and hadron production with a nuclear target.