Do the E866 Drell Yan data change our picture of the chiral structure of the nucleon ?

Abstract

We revisit the evaluation of the pionic mechanism of the $\bar{u}-\bar{d}$-asymmetry in the proton structure function. Our analysis is based on the extended AGK unitarity relation between contributions of different mechanisms to the inclusive particle production and the total photoabsorption cross-section (i.e. the proton structure function). We reanalyze the role of isovector reggeons in inclusive production of nucleons and Delta isobars in hadronic reactions. We find rather large contribution of reggeon-exchange induced production of Delta isobars. This leaves much less room for the pion-exchange induced mechanism of $\Delta$ production and provides a constraint on the $\pi N\Delta$ form factor. The production of leading pions in proton-proton collisions at ISR puts additional constraints on the $\pi NN$ vertex form factors. An extension of the AGK-rules to reggeon exchange suggests a negligible contribution to the proton structure function from DIS off the exchanged $\rho ,a_2$ reggeons. All these constraints are used then to estimate the pion content of the nucleon and allow to calculate parameter-free the $x$-dependence of $\bar{d}-\bar{u}$. We discuss the violation of the Gottfried Sum Rule and $\bar{d}$-$\bar{u}$ asymmetry and compare to the one obtained from the E866 experiment at Fermilab. We estimate the background to the pion structure function being determined by the ZEUS and H1 collaborations at HERA from leading neutron experiments.

18 pages, 8 figures included (epsfig)

References in corpus (14)

• Measurement of the Light Antiquark Flavor Asymmetry in the Nucleon Sea
• Flavor Asymmetry of Antiquark Distributions in the Nucleon
• The triple-pomeron regime and the structure function of the pomeron in the diffractive deep inelastic scattering at very small x
• Flavour and Spin of the Proton and the Meson Cloud
• dbar/ubar Asymmetry and the Origin of the Nucleon Sea
• Dynamics of Light Antiquarks in the Proton
• Parton Distributions for Low Q^2
• On the Flavor Structure of the Constituent Quark
• Testing the meson cloud in the nucleon in Drell-Yan processes
• Leading proton spectrum from DIS at HERA
• Reggeon and pion contributions in semi-exclusive diffractive processes at HERA
• Non universality of structure functions and measurement of the strange sea density
• Pion Content of the Nucleon as seen in the NA51 Drell-Yan experiment
• Subleading Reggeons in Deep Inelastic Diffractive Scattering at HERA

Cited by in corpus (43)

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• Leading neutron production in $e^{+}p$ collisions at HERA
• Revealing the structure of light pseudoscalar mesons at the Electron-Ion Collider
• Novel Phenomenology of Parton Distributions from the Drell-Yan Process
• Leading proton production in e^+p collisions at HERA
• The color dipole BFKL-Regge expansion: from DIS on protons to pions to rise of hadronic cross sections
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• Damping of forward neutrons in pp collisions
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• Measurement of dijet cross sections for events with a leading neutron in photoproduction at HERA
• Valence quark distributions of the proton from maximum entropy approach
• Exclusive production of $\omega$ meson in proton-proton collisions at high energies
• Parton Distribution of Proton in a Simple Statistical Model
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• Sea quark contents of octet baryons
• Low mass Drell-Yan production of lepton pairs at forward directions at the LHC: a hybrid approach
• Gluon saturation and Feynman scaling in leading neutron production
• Sea flavor content of octet baryons and intrinsic five-quark Fock states
• Flavor Structure of the Nucleon Sea
• Collinear parton distributions and the structure of the nucleon sea in a light-front meson-cloud model
• Exclusive processes with a leading neutron in $ep$ collisions
• Parton distributions in the proton and pion
• Nuclear dependence of the transverse-single-spin asymmetry for forward neutron production in polarized $p$$+$$A$ collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV
• Does the $D^{-}/D^{+}$ production asymmetry decrease at large $x_F$?
• Orbital Angular Momentum in the Nucleon
• Total ${\pi }^{+}p$ cross section extracted from the leading neutron spectra at the LHC
• On the energy dependence of the D^+/D^- production asymmetry
• Sigma Meson Cloud and Proton's Light Flavor Sea Quarks
• Testing the Meson Cloud Model in Inclusive Meson Production
• Sea Quark Flavor Asymmetry of Hadrons in Statistical Balance Model
• Pion-Exchange and Fermi-Motion Effects on the Proton-Deuteron Drell-Yan Process
• Pion fluctuation in deep inelastic scattering
• $\bar{d}-\bar{u}$ asymmetry and semi-inclusive production of pions in DIS
• Multi-quark components in baryons
• Gluon saturation: survival probability for leading neutrons in DIS
• Estimating proton radius and proportion of other non-perturbative components in the proton by the Maximum Entropy Method
• A determination of the flavor asymmetric sea quarks in the proton