Photoproduction of Ξ off nucleons

Abstract

The photoproduction reaction γN → KKΞ is investigated based on a relativistic meson-exchange model of hadronic interactions. The production amplitude is calculated in the tree-level approximation from relevant effective Lagrangians, whose (coupling constant) parameters are mostly fixed from the empirical data and/or quark models together with SU(3) symmetry considerations. Gauge invariance of the resulting amplitude is maintained by introducing the contact currents by extending the gauge-invariant approach of Haberzettl for one-meson photoproduction to two-meson photoproduction. The role of the intermediate low-lying hyperons and of the intermediate higher-mass hyperon resonances are analyzed in detail. In particular, the basic features of the production of Ξ − (1318) in γp → K + K + Ξ − and their possible manifestations in the forthcoming experimental data are discussed.

Cascade production in the reactionsγp→K+K+(X)andGuo1, Weygand2, Kubarovsky3 et al. 2007Phys. Rev. C

“…It is possible to probe the production mechanism through various differential cross sections, such as dσ Although the quark-diquark fusion mechanism was used to explain earlier − inclusive photoproduction data, hadronic degrees of freedom are of more relevance at the energy range of this experiment. Partly owing to the lack of data, there have been no theoretical predictions of the cascade production in exclusive photon-nucleon reactions until the production model developed by Nakayama et al [14] for Although Ref. [14] includes predictions using many variations of the parameters, the best agreement with our data requires t-channel processes involving at least one J = 3 2 hyperon.…”

“…Partly owing to the lack of data, there have been no theoretical predictions of the cascade production in exclusive photon-nucleon reactions until the production model developed by Nakayama et al [14] for Although Ref. [14] includes predictions using many variations of the parameters, the best agreement with our data requires t-channel processes involving at least one J = 3 2 hyperon. Therefore, the more interesting differential cross sections would be dσ/dM(K + − ).…”

“…3) peak significantly higher, at positions shifting according to the the photon energies. Whether these enhancements [14]. The solid curves correspond to the predictions with the pv-coupling choice; the dashed curves correspond to the ps-coupling choice.…”

“…[14]. The possibility of producing other excited cascade states in photon-proton reactions is also discussed.…”

“…However, such a model is more appropriate for inclusive reactions at high energies where partonic degrees of freedom are more relevant, and it is not applicable for exclusive reactions at low to intermediate energies compared with the threshold (E thres γ = 2.37 GeV). Recently, Nakayama et al [14] developed a production model for the exclusive reaction γ N → KK from an effective Lagrangian that incorporates various t-, u-, and s-channel processes, taking into account intermediate hyperon and nucleon resonances. (Details of the model will be discussed later in this paper.)…”