Electron-ion collider in China

Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a polarization of similar to 80%) and protons (with a polarization of similar to 70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2-3) x 10(33) cm(-2) . s(-1). Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.

Automated summary

The EicC project in China proposes to construct an Electron-ion collider based on an upgraded heavy-ion accelerator, providing highly polarized electrons and protons with variable center of mass energies. The main goals include precise measurements of nucleon structure, partonic structure of nuclei, interaction with nuclear environment, and exotic states with heavy flavor quark contents. A hermetical detector system with cutting-edge technologies will be constructed to achieve these physics goals.