Investigation of electromagnetic form factors of Zcs(3985) exotic meson

In recent years, the discovery of more than 50 exotic hadrons has been regarded as a significant development in the field of particle physics. These exotic resonances have been detected in numerous experiments, and their physical properties, such as masses, decay widths, quark content, and quantum numbers, have been measured in detail. However, the internal structures of these particles remain largely unknown. This thesis focuses on understanding the structure of exotic mesons, which possess quantum numbers not found in the quark model that successfully explains many hadrons and classifies them into two families: mesons and baryons. Specifically, a detailed calculation has been carried out on the example of the charged hidden-charm $Z_{cs}^+(3985)$ particle, observed by the BESIII collaboration in 2021 during electron-positron collisions through the process $(e^+e^- \to K^+(D_s^- D^{0} + D_s^{-}D^0))$. This particle has a quark structure of $c \bar c s \bar u$, quantum numbers of $J^{PC}=1^{+-}$, a mass of approximately $4.681\;GeV$, and a decay width of $12.8\;MeV$. Three-point QCD sum rules were used as the method, and calculations were performed on the electromagnetic form factors of the $Z_{cs}(3985)$ particle. The results are presented through numerical analyses. Additionally, the electric charge radius of the $Z_{cs}^+(3985)$ particle was calculated, contributing to a more detailed understanding of the particle's structure.\\This study aims to shed light on new approaches that may go beyond the limits of current particle physics theories by providing new insights into the structure of exotic hadrons. The findings can be considered an important step toward better understanding exotic mesons and hadronic structures in general. This work may open new paths for the discovery and understanding of physical processes beyond the quark model. Keywords: QCD sum Rules, Exotic mesons, QCD phenomenology, Tetraquarks, Electromagnetic form factors.