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Muhammad Ibrahim Abdulhamid, Bassam Aboona, Jaroslav Adam, Leszek Adamczyk, Joseph R. Adams, Ishu Aggarwal, Madan Mohan Aggarwal, Zubayer Ahammed, Derek M. Anderson, Elke Caroline Aschenauer, Sameer Aslam, J. Atchison, Vipul Bairathi, W. Baker, J.G. Ball Cap, Kenneth Barish, Rene Bellwied, P. Bhagat, Anju Bhasin, S. Bhatta, Jaroslav Bielčík, Jana Bielčíková, James D. Brandenburg, X.Z. Cai, Helen Louise Caines, Manuel Calderón de la Barca Sánchez, Daniel A. Cebra, J. Ceska, Irakli Chakaberia, Petr Chaloupka, B.K. Chan, Z. Chang, A. Chatterjee, D. Chen, J. Chen, J.H. Chen, Z. Chen, J. Cheng, Y. Cheng, Subikash Choudhury, William Christie, X. Chu, Henry J. Crawford, Máté Csanád, G. Dale-Gau, A. Das, M. Daugherity, Ingo Martin Deppner, A. Dhamija, L. Di Carlo, Lidia Didenko, P. Dixit, X. Dong, James Lucus Drachenberg, E. Duckworth, James C. Dunlop, Jon M. Engelage, Geary Wareham Eppley, ShinIchi Esumi, Olga Y. Evdokimov, A. Ewigleben, Kjeld Oleg Eyser, Renee H. Fatemi, Salvatore Fazio, C.J. Feng, Y. Feng, Evan Finch, Yuri V. Fisyak, F.A. Flor, C. Fu, Carl A. Gagliardi, Tetyana Galatyuk, Frank Geurts, N. Ghimire, Adam Gibson, Krishan Gopal, X. Gou, David P. Grosnick, Anik Gupta, Włodzimierz Guryn, Ahmed M. Hamed, Y. Han, S. Harabasz, M.D. Harasty, John W. Harris, H. Harrison-Smith, W. He, X.H. He, Y. He, Norbert Herrmann, Lukáš Holub, C. Hu, Q. Hu, Y. Hu, H. Huang, H.Z. Huang, Shengli Huang, T. Huang, X. Huang, Y. Huang, Y. Huang, Thomas J. Humanic, D. Isenhower, M. Isshiki, William W. Jacobs, A. Jalotra, Chitrasen Jena, Alexander Jentsch, Y. Ji, J. Jia, C. Jin, X. Ju, Eleanor G. Judd, Sonia Kabana, M.L. Kabir, Skipper Kagamaster, Dmitry Kalinkin, K. Kang, David Kapukchyan, Declan Keane, Matthew Kelsey, Yevheniia V. Khyzhniak, Daniel P. Kikoła, B. Kimelman, D. Kincses, Ivan Kisel, A. Kiselev, Anders Garritt Knospe, H.S. Ko, Leszek Krzysztof Kosarzewski, L. Kramarik, Lokesh Kumar, Shyam Kumar, R. Kunnawalkam Elayavalli, Roy Alphanso Lacey, Jeffery M. Landgraf, Jerome Lauret, Alexei Lebedev, J.H. Lee, Y.H. Leung, N. Lewis, C. Li, W. Li, X. Li, Y. Li, Y. Li, Z. Li, X. Liang, Y. Liang, Robert Licenik, T. Lin, Michael A. Lisa, C. Liu, F. Liu, G. Liu, H. Liu, H. Liu, L. Liu, T. Liu, X. Liu, Y. Liu, Z. Liu, Tonko A. Ljubicic, William Joseph Llope, O. Lomicky, Ronald S. Longacre, E.M. Loyd, T. Lu, N.S. Lukow, X.F. Luo, L. Ma, R. Ma, Yu-Gang Ma, Niseem Magdy Abdelwahab Abdelrahman, Dukhishyam Mallick, Spyridon Margetis, Christina Markert, Howard S. Matis, Joel Anthony Mazer, G. McNamara, K. Mi, Saskia Mioduszewski, Bedangadas Mohanty, Mriganka Mouli Mondal, Isaac A. Mooney, A. Mukherjee, M.I. Nagy, A.S. Nain, J.D. Nam, M. Nasim, D. Neff, John M. Nelson, Daniel B. Nemes, M. Nie, Takafumi Niida, R. Nishitani, Toshihiro Nonaka, G. Odyniec, Akio Ogawa, Saehanseul Oh, K. Okubo, Brian S. Page, R. Pak, Jinjin Pan, A. Pandav, Ashutosh Kumar Pandey, T. Pani, A. Paul, Bogdan Pawlik, Diana Pawłowska, Chris Perkins, Jan Marian Pluta, B.R. Pokhrel, Matthew Posik, Tristan Protzman, V. Prozorova, Navneet Kumar Pruthi, Mariusz Przybycien, Jörn H. Putschke, Z. Qin, H. Qiu, Amilkar Quintero, Cameron Racz, Sooraj Krishnan Radhakrishnan, N. Raha, Robert L. Ray, Rosi Jan Reed, Hans Georg Ritter, C.W. Robertson, M. Robotkova, M.A. Rosales Aguilar, D. Roy, P. Roy Chowdhury, L. Ruan, A.K. Sahoo, Nihar Ranjan Sahoo, H. Sako, Sevil Salur, S. Sato, William B. Schmidke, Norbert Schmitz, F.-J. Seck, Janet Elizabeth Seger, Richard Seto, Peter Seyboth, N. Shah, Prashanth V. Shanmuganathan, T. Shao, M. Sharma, Natasha Sharma, R. Sharma, S.R. Sharma, Ashik Ikbal Sheikh, D.Y. Shen, K. Shen, S.S. Shi, Y. Shi, Q.Y. Shou, F. Si, J. Singh, Subhash Singha, P. Sinha, M.J. Skoby, Nikolai Smirnov, Y. Söhngen, Y. Song, B. Srivastava, T. D. Shirvel Stanislaus, Maria Stefaniak, David J. Stewart, Blair Stringfellow, Y. Su, Alexandre Alarcon do Passo Suaide, Michal Šumbera, C. Sun, X. Sun, Y. Sun, Y. Sun, Bernd Surrow, Z.W. Sweger, Paweł Szymański, A. Tamis, Aihong Tang, Z. Tang, Terence J. Tarnowsky, James H. Thomas, Anthony Robert Timmins, David Tlusty, Takahito Todoroki, C.A. Tomkiel, Stephen Trentalange, Robert E. Tribble, Prithwish Tribedy, T. Truhlar, Barbara Antonina Trzeciak, Oleg D. Tsai, C.Y. Tsang, Z. Tu, J. Tyler, Thomas Ullrich, David G. Underwood, Isaac Upsal, Gene Van Buren, Jan Vanek, Iouri Vassiliev, Veronica Verkest, Flemming Videbæk, Sergei Voloshin, F. Wang, G. Wang, J.S. Wang, X. Wang, Y. Wang, Y. Wang, Y. Wang, Z. Wang, Jason C. Webb, P.C. Weidenkaff, Gary D. Westfall, D. Wielanek, Howard Wieman, G. Wilks, Scott W. Wissink, Richard Witt, J. Wu, J. Wu, X. Wu, Y. Wu, B. Xi, Z.G. Xiao, Guannan Xie, W. Xie, H. Xu, N. Xu, Q.H. Xu, Y. Xu, Y. Xu, Z. Xu, Z. Xu, G. Yan, Z. Yan, C. Yang, Q. Yang, S. Yang, Y. Yang, Z. Ye, Z. Ye, L. Yi, K. Yip, Y. Yu, Hanna Paulina Zbroszczyk, W. Zha, C. Zhang, D. Zhang, J. Zhang, S. Zhang, W. Zhang, X. Zhang, Y. Zhang, Y. Zhang, Y. Zhang, Z.J. Zhang, Z. Zhang, Z. Zhang, F. Zhao, J. Zhao, M. Zhao, C. Zhou, J. Zhou, S. Zhou, Y. Zhou, X. Zhu, M. Zurek, Maksym Zyzak

• We report on new measurements of elliptic flow (v2) of electrons from heavy-flavor hadron decays at mid-rapidity (|y|<0.8) in Au+Au collisions at sNN−−−√ = 27 and 54.4 GeV from the STAR experiment. Heavy-flavor decay electrons (eHF) in Au+Au collisions at sNN−−−√ = 54.4 GeV exhibit a non-zero v2 in the transverse momentum (pT) region of pT< 2 GeV/c with the magnitude comparable to that at sNN−−−√=200 GeV. The measured eHF v2 at 54.4 GeV is also consistent with the expectation of their parent charm hadron v2 following number-of-constituent-quark scaling as other light and strange flavor hadrons at this energy. These suggest that charm quarks gain significant collectivity through the evolution of the QCD medium and may reach local thermal equilibrium in Au+Au collisions at sNN−−−√=54.4 GeV. The measured eHF v2 in Au+Au collisions at sNN−−−√= 27 GeV is consistent with zero within large uncertainties. The energy dependence of v2 for different flavor particles (π,ϕ,D0/eHF) shows an indication of quark mass hierarchy in reaching thermalization in high-energy nuclear collisions.