Abundant φ-meson production in annihilation at rest and strangeness in the nucleon

Abstract

A large apparent violation of the OZI rule has recently been found in many channels inpp annihilation at LEAR. An interpretation of these data in terms of the "shakeout" and "rearrangement" of an intrinsicss component of the nucleon wave function is proposed. This gives a channel-dependent, non-universal modification of the naïve OZI prediction. Within this approach, we interpret the strong excess of φ production in S-wavepp annihilations in terms of the polarization of the nucleon'sss component indicated by deep inelastic lepton-nucleon scattering experiments. This interpretation could be tested by measurements of the f ′ 2 (1525)/f 2 (1270) production ratio in P-wave annihilations and by experiments with polarized beams and polarized targets. We also propose a test of the intrinsic strangeness hypothesis in φ production in high-momentum transfer processes, via a difference in constituent counting rules from gluon-mediated production.

$\Lambda$ and $\overline{\Lambda}$ polarization in lepton induced processes

“…A negative spin transfer from u and d quarks of −0.09 was also predicted in [8] using an effective QCD Lagrangian, and in the covariant quark -di-quark model of [13]. This effect can be understood qualitatively even if the spin of the Λ is determined by its constituent s quark only: in some cases the fragmenting u or d quark will become a sea quark of the constituent s quark, and the spin of the constituent s quark will be anti-correlated to the spin of the fragmenting quark [23,7]. Another possibility occurs when the Λ is produced as a second rank particle in the fragmentation of a u or d quark.…”

Polarization observables in the reactionNN→NNφ

“…Indeed, the recent experiments on the proton annihilation at rest, pp → ΦX (cf. [12] for a compilation of data), point to a large apparent violation of the OZI rule, which is interpreted [12] as a hint to an intrinsic ss component in the proton. Analyses of the πN sigma term [13] also suggest that the proton might contain a strange quark admixture as large as 20%.…”

Photoproduction ofφmesons from the proton: Polarization observables and strangeness in the nucleon

“…Recent experiments on vector meson production through pp annihilation at rest [17][18][19] report a strong violation of the OZI rule. It can be accounted for by the presence of an intrinsic ss component in the nucleon wave function [8,20], which contributes to the process through the rearrangement and shake-out diagrams [21][22][23][24]. On the other hand, it was also claimed that this OZI violation could be explained through modified meson exchange models [25,26] without any strangeness content of the nucleon.…”