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Understanding the hadron spectrum is one of the primary goals of non-perturbative QCD. Many predictions have experimentally been confirmed, others still remain under experimental investigation. Of particular interest is how gluonic excitations give rise to states with constituent glue. One class of such states are hybrid mesons that are predicted by theoretical models and Lattice QCD calculations. Searching for and understanding the nature of these states is a primary physics goal of the GlueX experiment at the CEBAF accelerator at Jefferson Lab. A search for a JPC = 1−− hybrid meson candidate, the Y(2175), in φ(1020)π+π+ and φ(1020)f0(980) channels in photoproduction on a proton target has been conducted. A first measurement of non-resonant φ(1020)π+π+ and φ(1020)f0(980) total cross sections in photoproduction has been performed. An upper limit on the resonance production cross section for the Y (2175) → φ(1020)π+π+ and Y (2175) → φ(1020)f0(980) channels are estimated. Since the analysis essentially depends on the quality of the charged kaon identification, also an optimization of particle identification through an improvement of the energy loss estimation in the central drift chamber by a truncated mean method has been investigated.
In the last two decades, new unpredicted charmonium-like states with extraordinary characteristics have been observed experimentally. These states also known as the XYZ states, e.g., the Y(4260) or the X(3872), are mostly interpreted as QCD allowed exotic hadrons. One of the leading hadron physics experiments in the world, the Beijing Electron Spectrometer III (BESIII) at the Beijing Electron-Positron Collider II (BEPCII) is aiming towards revealing the internal structure of these states. It has brought numerous breakthrough discoveries including the discovery of the charged Zc(3900). In order to understand the nature of the Y(4260) state and its decay patterns, an inclusive analysis is performed for different recoil systems (π+π−,K+K− and K±π∓) using the BESIII data samples for center of mass energies above 4 GeV collected between 2013 and 2019. The aim of this analysis is twofold: on one hand, we search for new unobserved charmonium-like decay channels using the missing mass technique and on the other hand, it provides an accurate inclusive cross section measurement for e+e−→X π+π−, with the X being the J/ψ, hc and ψ(2S), respectively. Two resonant structures, the Y(4220) and the Y(4390), are observed in the inclusive energy dependent Born cross section of e+e−→hc π+π−, which is consistent with the BESIII exclusive measurements. Moreover, the energy dependent cross section of e+e−→J/ψ π+π− is investigated, in which two resonances have consistently been observed with the previous BESIII exclusive studies, namely, the Y(4220) and the Y(4320). In the (K±π±) recoil system, possible Y(4260) open charm decay channels are investigated. Two enhancements are observed in the inclusive energy dependent cross section of e+e−→DD above 4.13GeV, which could possibly be the ψ(4160)and the ψ(4415).