${\eta }^{\prime }$ photoproduction near threshold

Abstract

In this work, the ${\eta }^{\prime }$ meson photoproduction near threshold is studied in the quark model framework. A pseudovector effective Lagrangian is introduced for the ${\eta }^{\prime }NN$ coupling and the newly published data from the SAPHIR Collaboration provide good constraints to this parameter. Corrections of order $O(1/m_q^2)$ for the electromagnetic interaction vertex are taken into account, which produce corrections of order $O(1/m_q^3)$ to the transition amplitude for $\gamma p\to {\eta }^{\prime }p$. Some low-lying resonances, $S_{11}(1535)$, $P_{13}(1720)$, and $P_{13}(1900)$ are found to have significant contributions. A bump structure around $E_{\gamma }\approx$ 2 GeV is found arising from the $n=3$ terms in the harmonic oscillator basis. The beam polarization asymmetries are predicted and can be tested against the forthcoming data from GRAAL.

Comments: Revtex, 3 eps figures, 1 table; Resubmitted to Phys. Rev. C