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arXiv · 1905.02052

First observation of the directed flow of $D^{0}$ and $\overline{D^0}$ in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200~GeV

STAR Collaboration·J. Adam·L. Adamczyk·J. R. Adams·J. K. Adkins·G. Agakishiev·M. M. Aggarwal·Z. Ahammed·I. Alekseev·D. M. Anderson·R. Aoyama·A. Aparin·D. Arkhipkin·E. C. Aschenauer·M. U. Ashraf·F. Atetalla·A. Attri·G. S. Averichev·V. Bairathi·K. Barish·A. J. Bassill·A. Behera·R. Bellwied·A. Bhasin·A. K. Bhati·J. Bielcik·J. Bielcikova·L. C. Bland·I. G. Bordyuzhin·J. D. Brandenburg·A. V. Brandin·J. Bryslawskyj·I. Bunzarov·J. Butterworth·H. Caines·M. Calderón~de~la~Barca~Sánchez·D. Cebra·I. Chakaberia·P. Chaloupka·B. K. Chan·F-H. Chang·Z. Chang·N. Chankova-Bunzarova·A. Chatterjee·S. Chattopadhyay·J. H. Chen·X. Chen·J. Cheng·M. Cherney·W. Christie·H. J. Crawford·M. Csanád·S. Das·T. G. Dedovich·I. M. Deppner·A. A. Derevschikov·L. Didenko·C. Dilks·X. Dong·J. L. Drachenberg·J. C. Dunlop·T. Edmonds·N. Elsey·J. Engelage·G. Eppley·R. Esha·S. Esumi·O. Evdokimov·J. Ewigleben·O. Eyser·R. Fatemi·S. Fazio·P. Federic·J. Fedorisin·Y. Feng·P. Filip·E. Finch·Y. Fisyak·L. Fulek·C. A. Gagliardi·T. Galatyuk·F. Geurts·A. Gibson·K. Gopal·D. Grosnick·A. Gupta·W. Guryn·A. I. Hamad·A. Hamed·J. W. Harris·L. He·S. Heppelmann·N. Herrmann·L. Holub·Y. Hong·S. Horvat·B. Huang·H. Z. Huang·S. L. Huang·T. Huang
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Abstract

We report the first measurement of rapidity-odd directed flow ($v_{1}$) for $D^{0}$ and $\overline{D^{0}}$ mesons at mid-rapidity ($|y| < 0.8$) in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200\,GeV using the STAR detector at the Relativistic Heavy Ion Collider. In 10--80\% Au+Au collisions, the slope of the $v_{1}$ rapidity dependence ($dv_{1}/dy$), averaged over $D^{0}$ and $\overline{D^{0}}$ mesons, is -0.080 $\pm$ 0.017 (stat.) $\pm$ 0.016 (syst.) for transverse momentum $p_{\rm T}$ above 1.5~GeV/$c$. The absolute value of $D^0$-meson $dv_1/dy$ is about 25 times larger than that for charged kaons, with 3.4$σ$ significance. These data give a unique insight into the initial tilt of the produced matter, and offer constraints on the geometric and transport parameters of the hot QCD medium created in relativistic heavy-ion collisions.

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STAR Collaboration, J. Adam, L. Adamczyk, J. R. Adams, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, F. Atetalla, A. Attri, G. S. Averichev, V. Bairathi, K. Barish, A. J. Bassill, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. D. Brandenburg, A. V. Brandin, J. Bryslawskyj, I. Bunzarov, J. Butterworth, H. Caines, M. Calderón~de~la~Barca~Sánchez, D. Cebra, I. Chakaberia, P. Chaloupka, B. K. Chan, F-H. Chang, Z. Chang, N. Chankova-Bunzarova, A. Chatterjee, S. Chattopadhyay, J. H. Chen, X. Chen, J. Cheng, M. Cherney, W. Christie, H. J. Crawford, M. Csanád, S. Das, T. G. Dedovich, I. M. Deppner, A. A. Derevschikov, L. Didenko, C. Dilks, X. Dong, J. L. Drachenberg, J. C. Dunlop, T. Edmonds, N. Elsey, J. Engelage, G. Eppley, R. Esha, S. Esumi, O. Evdokimov, J. Ewigleben, O. Eyser, R. Fatemi, S. Fazio, P. Federic, J. Fedorisin, Y. Feng, P. Filip, E. Finch, Y. Fisyak, L. Fulek, C. A. Gagliardi, T. Galatyuk, F. Geurts, A. Gibson, K. Gopal, D. Grosnick, A. Gupta, W. Guryn, A. I. Hamad, A. Hamed, J. W. Harris, L. He, S. Heppelmann, N. Herrmann, L. Holub, Y. Hong, S. Horvat, B. Huang, H. Z. Huang, S. L. Huang, T. Huang. 2019-05-06. First observation of the directed flow of $D^{0}$ and $\overline{D^0}$ in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200~GeV. https://doi.org/10.1103/physrevlett.123.162301

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