Regge phenomenology of pion photoproduction off the nucleon at forward angles

Role ofω-meson exchange in scaling of theγp→π0pprocess from a Regge-type model with resonances

“…In the Regge realm beyond E γ =3 GeV, of course, the cross section coincides with that from the pure Regge pole exchanges as described in Ref. [8]. tial cross section at the third peak due to N (1680), the resonance ∆(1700) together with N (1650) play the role to fit to Σ.…”

“…For a better agreement with the beam asymmetry Σ at high energy the exchanges of b 1 and the h 1 are further introduced with the constant phase taken [8].…”

“…the Regge framework where the production mechanism of the π 0 process is dominated by the ω exchange, the bump structure around W ≈ 2.2 GeV, in essence, results from the deep-dip pattern that arises from the nonsense wrong signature zero (NWSZ) of the ω trajectory α ω (t) = 0 [7,8]. This in fact leads to the vanishing of the amplitude at W ≈ 1.58 GeV at the angle θ = 90…”

Tensor meson contribution to γp → K[sup +]Λ(Σ;[sup 0]) at high energies

“…Since the photoproduction current in the model is given by the Born approximation for the t-channel meson exchange, gauge invariance of the photoproduction amplitude is easily prescribed for the pion Regge pole exchange as Guidal, Laget and Vanderhaeghen (GLV) illustrated [4]. It is, therefore, advantageous to work with the Regge poles in the SCHA in that one exploits the effective Lagrangians for estimating the coupling constants of the exchanged meson from the decay width or from the symmetry consideration [5]. As shown in Table 1 below, however, the meson-baryon coupling constants of the K * in models of Refs.…”

“…Here we discuss the possibility of the Regge model without fit parameters for kaon photoproduction based on our previous analysis [5]. Therefore, it is of interest to investigate the K * 2 Regge pole with an expectation that it could help reducing the coupling constants of the K * to acceptable values.…”