Quark star matter in heavy quark stars Peng-Cheng Chu, Yi Zhou, Yao-Yao Jiang, Hong-Yang Ma, He Liu, Xiao-Min Zhang and Xiao-Hua Li Eur. Phys. J. C, 81 1 (2021) 93 Published online: 29 January 2021 DOI: 10.1140/epjc/s10052-020-08800-3