Physics and detector design of polarized Electron Ion Collider in China (EicC)

Abstract

<p indent=0mm>The innermost exploration regime of visible matter involves the nucleon structure. High-energy electron-nucleon scattering, regarded as a modern “Rutherford” experiment, is an ideal platform to conduct investigations of the nucleon structure, which improves our understanding of matter and aids the common interests of nuclear and particle physicists. Electron Ion Colliders (EICs) are super electron microscopes that can take clear images of the inner structure of a nucleon; hence, they are effective tools for gaining insights into the fundamental constituents of matter, e.g., structures of a nucleon and nuclei. An Electron Ion Collider in China (EicC) project is proposed for the heavy ion analytical facility. This project will provide a large integrated experimental platform to propel the development of nuclear and particle physics and other relevant fields in China. The energy of an EicC is confined in the region where the contributions of sea-quarks are dominant. However, this region is well suited for the study of the origin of the nucleon mass and its 3D structure. Additionally, it can fill the gap between the energy regions of current electron scattering experiments and future EIC (for instance, in the US). In this study, we review the rich physics highlights of EicC, including the precise measurements of 1D and 3D sea-quark structures, such as TMDs and GPDs. Comparisons of the projected EicC precision with current data are presented. Moreover, this work reviews the significance of EicC for the study of the origin of proton mass, nuclear medium effects, π-structure functions, and the first conceptual design of an EicC detector. The EicC facility will promote our understanding of many fundamental questions including the origin of proton spin and mass and mechanism of quark-gluon confinement.