Do we understand the single-spin asymmetry for $\pi^0$ inclusive production in pp collisions?

Bourrely, Claude; Soffer, Jacques

doi:10.1140/epjc/s2004-01956-4

Cited by 64 publications

(75 citation statements)

References 24 publications

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“…This belief is supported by the successful perturbative QCD description of the cross sections for pion production at RHIC, which describes the scattering as the hard scattering of the gluons and quarks in each beam. However, a similar pattern of transverse spin asymmetry is seen at fixed target energy [7], where the measured cross section is considerably higher than the pQCD description [8]. Production by a polarized neutron beam would reverse the roles of the valence u and d quarks in the beam, compared to polarized protons.…”

Section: Polarized Neutrons In Rhic?mentioning

confidence: 62%

High Energy Hadron Polarimetry

Bunce¹

2008

AIP Conference Proceedings

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Section: Polarized Neutrons In Rhic?mentioning

confidence: 62%

High Energy Hadron Polarimetry

Bunce¹

2008

AIP Conference Proceedings

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“…These latter processes are akin to hadroproduction from proton+proton (p+p) collisions such as those at RHIC or at the LHC, where the partons from the incoming beam interact with the target(beam) partons. Measurements of hadron production proceeding from p+p data have been compared to pQCD calculations at different √ s ranges [3]. Results of these comparisons have shown that the pQCD calculations have not correctly described hadron production at decreasing √ s. Only high √ s seemed to be properly described by these models.…”

Section: Hadron Cross-sections At √ S = 17 Gevmentioning

confidence: 99%

Hadron production from μ–Deuteron scattering at s=17 GeV at COMPASS

Morreale

2011

Nuclear Physics B - Proceedings Supplements

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Abstract.Hadrons proceeding from quasi-real photo-production are one of the many probes accesible at the Common Muon Proton Apparatus for Structure and Spectroscopy (COMPASS) at CERN. These hadrons provide information on the scattering between photon and partons through γ-gluon(g) direct channels as well as q-g resolved processes. Comparisons of unpolarized differential cross section measurements to next-to-leading order (NLO) pQCD calculations are essential to develop our understanding of proton-proton and lepton-nucleon scattering at varying center of mass energies. These measurements are important to asses the applicability of NLO pQCD in interpreting polarized processes. In this talk we will present the unidentified charged separated hadron cross-sections measured by the COMPASS experiment at center of mass energy of √ s = 17 GeV , low Q 2 (Q 2 < 0.1 GeV 2 /c 2 ) and high transverse momenta (pT > 1.0 GeV /c.) IntroductionCross-sections of final state inclusive and semi-inclusive particles are benchmark measurements which may elucidate information on polarized and unpolarized photon-parton and parton-parton interactions. While perturbative quantum chromo dynamics (pQCD) is a well established theory of strong interactions, it does not provide an exact analytical calculation. In a pQCD factorized framework, a hadron cross-section can be defined as the convolution of three main ingredients (Eq. 1) from which only one is fully calculable:

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“…It was pointed out recently [5] that the standard collinear approach is not able to describe very forward production of π 0 . In Fig.1 Clearly, the standard collinear approach fails badly in the very forward region.…”

Section: From Partons To Hadronsmentioning

confidence: 99%

Unintegrated parton distributions and pion production in pp collisions at RHIC energies

Czech¹,

Szczurek²

2006

J. Phys. G: Nucl. Part. Phys.

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We compare results of 2 → 1 k t -factorization approach with Kwieciński unintegrated parton distributions and the standard collinear factorization approach at RHIC and slightly smaller energies. Our approach contains only one free parameter responsible for internal parton motion in nucleons. In contrast to recent works in the literature our k t -factorization approach includes also quark degrees of freedom in addition to purely gluonic terms. Both mid and forward rapidity regions are considered. We discuss uncertainties due to fragmentation functions. In general, the k t -factorization approach gives a better description of the p t ∼ 1 -4 GeV region both at mid and forward rapidity regions. Our approach leads to asymmetry in the production of π + and π − , very similar to the one observed very recently by the BRAHMS collaboration.

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Do we understand the single-spin asymmetry for $\pi^0$ inclusive production in pp collisions?

Cited by 64 publications

References 24 publications

High Energy Hadron Polarimetry

High Energy Hadron Polarimetry

Hadron production from μ–Deuteron scattering at s=17 GeV at COMPASS

Unintegrated parton distributions and pion production in pp collisions at RHIC energies

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