Observation of Directed Flow of Hypernuclei <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">H</mml:mi></mml:mrow><mml:mprescripts/><mml:mrow><mml:mi mathvariant="normal">Λ</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">H</mml:mi></mml:mrow><mml:mprescripts/><mml:mrow><mml:mi mathvariant="normal">Λ</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msqrt><mml:mrow><mml:msub><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mi>NN</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:msqrt><mml:mo>=</mml:mo><mml:mn>3</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>GeV</mml:mi></mml:mrow></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>Au</mml:mi><mml:mo>+</mml:mo><mml:mi>Au</mml:mi></mml:mrow></mml:math> Collisions at RHIC
B. E. Aboona, J. Adam, J. R. Adams, G. Agakishiev, I. Aggarwal, M. M. Aggarwal, Z. Ahammed, A. Aitbaev, I. I. Alekseev, D. M. Anderson, A. Aparin, Jennifer Atchison, G. S. Averichev, V. Bairathi, W. Baker, J. G. Ball, K. Barish, P. Bhagat, A. Bhasin, S. Bhatta, I. G. Bordyuzhin, J. D. Brandenburg, A. V. Brandin, X. Z. Cai, H. Caines, M. Calderon De La Barca Sanchez, D. Cebra, J. Ceska, I. Chakaberia, B. K. Chan, Z. Chang, D. Chen, J. Chen, J. H. Chen, Z. Chen, Ji-Gui Cheng, Y. Cheng, S. Choudhury, W. Christie, X. Chu, H. J. Crawford, G. Dale-Gau, Arkaprava Das, M. Daugherity, T. G. Dedovich, I. M. Deppner, A. A. Derevschikov, A. Dhamija, L. Di Carlo, L. Didenko, P. Dixit, X. Dong, J. L. Drachenberg, E. Duckworth, J. C. Dunlop, J. Engelage, G. Eppley, S. Esumi, O. Evdokimov, A. Ewigleben, O. Eyser, R. Fatemi, S. Fazio, C. J. Feng, Y. Feng, Emily Finch, Y. Fisyak, F. A. Flor, C. Fu, F. J. M. Geurts, N. Ghimire, S. M. Gibson, K. Gopal, Xiaohua Gou, D. Grosnick, A. Gupta, A. Hamed, Y. L. Han, M. D. Harasty, J. W. Harris, H. Harrison, Wei-bo He, X. H. He, Yuqing He, Chenguo Hu, Q. Hu, Y. Hu, H. Z. Huang, H. Z. Huang, S. L. Huang, T. Huang, Xinhui Huang, Y. Huang, Y. Huang, T. J. Humanic, D. Isenhower, M. Isshiki, W. W. Jacobs, A. Jalotra, C. Jena
Abstract
We report here the first observation of directed flow (${v}_{1}$) of the hypernuclei $_{\mathrm{\ensuremath{\Lambda}}}^{3}\mathrm{H}$ and $_{\mathrm{\ensuremath{\Lambda}}}^{4}\mathrm{H}$ in mid-central $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{\mathrm{NN}}}=3\text{ }\text{ }\mathrm{GeV}$ at RHIC. These data are taken as part of the beam energy scan program carried out by the STAR experiment. From $165\ifmmode\times\else\texttimes\fi{}{10}^{6}$ events in 5%--40% centrality, about 8400 $_{\mathrm{\ensuremath{\Lambda}}}^{3}\mathrm{H}$ and 5200 $_{\mathrm{\ensuremath{\Lambda}}}^{4}\mathrm{H}$ candidates are reconstructed through two- and three-body decay channels. We observe that these hypernuclei exhibit significant directed flow. Comparing to that of light nuclei, it is found that the midrapidity ${v}_{1}$ slopes of $_{\mathrm{\ensuremath{\Lambda}}}^{3}\mathrm{H}$ and $_{\mathrm{\ensuremath{\Lambda}}}^{4}\mathrm{H}$ follow baryon number scaling, implying that the coalescence is the dominant mechanism for these hypernuclei production in the 3 GeV $\mathrm{Au}+\mathrm{Au}$ collisions.