Angular Dependence of Meson Production for Different Photon Beam Energies

The dependence of -meson photoproduction on the polar angle is investigated in the framework of a multisource thermal model. We present a detailed comparison between our results and experimental data of the neutral decay mode in the reaction . The results are in good agreement with the experimental data. It is found that the movement factor increases linearly with the photon beam energies. 1. Introduction More than 20 years ago, strangeness enhancement was predicted to be a unique signature of the quark-gluon plasma (QGP) formation in high energy collisions [1]. So far, many experimental results from the Super Proton Synchrotron (SPS) and Relativistic Heavy Ion Collider (RHIC) have shown the enhancement of strange particles [2]. At low photon energies, strangeness production starting from threshold is also helpful to understand underlying photoproduction mechanisms because it is far below the region of perturbative Quantum Chromodynamics (QCD) and is an energy domain well above the region controlled by low energy theorems [3–5]. As a particle with hidden strangeness, meson can be produced without an associated hyperon. Recently, in the reaction , a photoproduction cross-section of the meson in its neutral decay mode was measured by the CLAS Collaboration. The experiment is conducted by a tagged photon beam of energy ？GeV on a liquid hydrogen target at the Thomas Jefferson National Accelerator Facility (TJNAF) [6]. In order to explain the abundant experimental data, some phenomenological models of initial-coherent multiple interactions and particle transport were proposed and developed in recent years [7–12]. The dynamics of the system evolution has been studied by the azimuthal anisotropy of final-state particles produced in high energy collisions. In our previous work [13], the multisource thermal model has been used to describe the elliptic flows of final-state hadrons produced in nucleus-nucleus collisions at RHIC energies. It involves the anisotropic expansion of the participant area in the transverse momentum space. The model is successful in the description of (pseudo)rapidity and multiplicity distributions of produced particles [14]. In the present work, we focus our attention on the dependence of meson photoproduction on the polar angle. A purpose of this paper is to check whether the model can fit the angular dependence of meson photoproduction. The paper is organized as follows: in Section 2, the multisource thermal model is introduced; in Section 3, we present our results, which are compared with the experimental data; at the end, we provide