Anomalous centrality evolution of two-particle angular correlations from Au-Au collisions at $\sqrt{s_{\rm NN}}$ = 62 and 200 GeV
Abstract
We present two-dimensional (2D) two-particle angular correlations on relative pseudorapidity and azimuth for charged particles from Au-Au collisions at and 200 GeV with transverse momentum GeV/, and azimuth. Observed correlations include a {same-side} (relative azimuth ) 2D peak, a closely-related away-side azimuth dipole, and an azimuth quadrupole conventionally associated with elliptic flow. The same-side 2D peak and away-side dipole are explained by semihard parton scattering and fragmentation (minijets) in proton-proton and peripheral nucleus-nucleus collisions. Those structures follow N-N binary-collision scaling in Au-Au collisions until mid-centrality where a transition to a qualitatively different centrality trend occurs within a small centrality interval. Above the transition point the number of same-side and away-side correlated pairs increases rapidly {relative to} binary-collision scaling, the width of the same-side 2D peak also increases rapidly ( elongation) and the width actually decreases significantly. Those centrality trends are more remarkable when contrasted with expectations of jet quenching in a dense medium. Observed centrality trends are compared to {\sc hijing} predictions and to the expected trends for semihard parton scattering and fragmentation in a thermalized opaque medium. We are unable to reconcile a semihard parton scattering and fragmentation origin for the observed correlation structure and centrality trends with heavy ion collision scenarios which invoke rapid parton thermalization. On the other hand, if the collision system is effectively opaque to few-GeV partons the observations reported here would be inconsistent with a minijet picture.
Keywords
Cite
@article{arxiv.1109.4380,
title = {Anomalous centrality evolution of two-particle angular correlations from Au-Au collisions at $\sqrt{s_{\rm NN}}$ = 62 and 200 GeV},
author = {STAR Collaboration and G. Agakishiev and M. M. Aggarwal and Z. Ahammed and A. V. Alakhverdyants and I. Alekseev and J. Alford and B. D. Anderson and C. D. Anson and D. Arkhipkin and G. S. Averichev and J. Balewski and D. R. Beavis and R. Bellwied and M. J. Betancourt and R. R. Betts and A. Bhasin and A. K. Bhati and H. Bichsel and J. Bielcik and J. Bielcikova and L. C. Bland and I. G. Bordyuzhin and W. Borowski and J. Bouchet and E. Braidot and A. V. Brandin and S. G. Brovko and E. Bruna and S. Bueltmann and I. Bunzarov and T. P. Burton and X. Z. Cai and H. Caines and M. Calderon and D. Cebra and R. Cendejas and M. C. Cervantes and P. Chaloupka and S. Chattopadhyay and H. F. Chen and J. H. Chen and J. Y. Chen and L. Chen and J. Cheng and M. Cherney and A. Chikanian and W. Christie and P. Chung and M. J. M. Codrington and R. Corliss and J. G. Cramer and H. J. Crawford and X. Cui and A. Davila Leyva and L. C. De Silva and R. R. Debbe and T. G. Dedovich and J. Deng and A. A. Derevschikov and R. Derradi de Souza and L. Didenko and P. Djawotho and X. Dong and J. L. Drachenberg and J. E. Draper and C. M. Du and J. C. Dunlop and L. G. Efimov and M. Elnimr and J. Engelage and G. Eppley and M. Estienne and L. Eun and O. Evdokimov and R. Fatemi and J. Fedorisin and R. G. Fersch and P. Filip and E. Finch and V. Fine and Y. Fisyak and C. A. Gagliardi and D. R. Gangadharan and F. Geurts and P. Ghosh and Y. N. Gorbunov and A. Gordon and O. G. Grebenyuk and D. Grosnick and A. Gupta and S. Gupta and W. Guryn and B. Haag and O. Hajkova and A. Hamed and L-X. Han and J. W. Harris and J. P. Hays-Wehle and S. Heppelmann and A. Hirsch and G. W. Hoffmann and D. J. Hofman and B. Huang and H. Z. Huang and T. J. Humanic and L. Huo and G. Igo and W. W. Jacobs and C. Jena and J. Joseph and E. G. Judd and S. Kabana and K. Kang and J. Kapitan and K. Kauder and H. W. Ke and D. Keane and A. Kechechyan and D. Kettler and D. P. Kikola and J. Kiryluk and A. Kisiel and V. Kizka and S. R. Klein and D. D. Koetke and T. Kollegger and J. Konzer and I. Koralt and L. Koroleva and W. Korsch and L. Kotchenda and P. Kravtsov and K. Krueger and L. Kumar and M. A. C. Lamont and J. M. Landgraf and S. LaPointe and J. Lauret and A. Lebedev and R. Lednicky and J. H. Lee and W. Leight and M. J. LeVine and C. Li and L. Li and W. Li and X. Li and X. Li and Y. Li and Z. M. Li and L. M. Lima and M. A. Lisa and F. Liu and T. Ljubicic and W. J. Llope and R. S. Longacre and Y. Lu and E. V. Lukashov and X. Luo and G. L. Ma and Y. G. Ma and D. P. Mahapatra and R. Majka and O. I. Mall and R. Manweiler and S. Margetis and C. Markert and H. Masui and H. S. Matis and D. McDonald and T. S. McShane and A. Meschanin and R. Milner and N. G. Minaev and S. Mioduszewski and M. K. Mitrovski and Y. Mohammed and B. Mohanty and M. M. Mondal and B. Morozov and D. A. Morozov and M. G. Munhoz and M. K. Mustafa and M. Naglis and B. K. Nandi and Md. Nasim and T. K. Nayak and L. V. Nogach and S. B. Nurushev and G. Odyniec and A. Ogawa and K. Oh and A. Ohlson and V. Okorokov and E. W. Oldag and R. A. N. Oliveira and D. Olson and M. Pachr and B. S. Page and S. K. Pal and Y. Pandit and Y. Panebratsev and T. Pawlak and H. Pei and T. Peitzmann and C. Perkins and W. Peryt and P. Pile and M. Planinic and J. Pluta and D. Plyku and N. Poljak and J. Porter and C. B. Powell and D. Prindle and C. Pruneau and N. K. Pruthi and P. R. Pujahari and J. Putschke and H. Qiu and R. Raniwala and S. Raniwala and R. L. Ray and R. Redwine and R. Reed and H. G. Ritter and J. B. Roberts and O. V. Rogachevskiy and J. L. Romero and L. Ruan and J. Rusnak and N. R. Sahoo and I. Sakrejda and S. Salur and J. Sandweiss and E. Sangaline and A. Sarkar and J. Schambach and R. P. Scharenberg and J. Schaub and A. M. Schmah and N. Schmitz and T. R. Schuster and J. Seele and J. Seger and I. Selyuzhenkov and P. Seyboth and N. Shah and E. Shahaliev and M. Shao and M. Sharma and S. S. Shi and Q. Y. Shou and E. P. Sichtermann and F. Simon and R. N. Singaraju and M. J. Skoby and N. Smirnov and D. Solanki and P. Sorensen and U. G. de Souza and H. M. Spinka and B. Srivastava and T. D. S. Stanislaus and S. G. Steadman and J. R. Stevens and R. Stock and M. Strikhanov and B. Stringfellow and A. A. P. Suaide and M. C. Suarez and M. Sumbera and X. M. Sun and Y. Sun and Z. Sun and B. Surrow and D. N. Svirida and T. J. M. Symons and A. Szanto de Toledo and J. Takahashi and A. H. Tang and Z. Tang and L. H. Tarini and T. Tarnowsky and D. Thein and J. H. Thomas and J. Tian and A. R. Timmins and D. Tlusty and M. Tokarev and T. A. Trainor and S. Trentalange and R. E. Tribble and P. Tribedy and B. A. Trzeciak and O. D. Tsai and T. Ullrich and D. G. Underwood and G. Van Buren and G. van Nieuwenhuizen and J. A. Vanfossen, and R. Varma and G. M. S. Vasconcelos and A. N. Vasiliev and F. Videbaek and Y. P. Viyogi and S. Vokal and M. Wada and M. Walker and F. Wang and G. Wang and H. Wang and J. S. Wang and Q. Wang and X. L. Wang and Y. Wang and G. Webb and J. C. Webb and G. D. Westfall and C. Whitten and H. Wieman and S. W. Wissink and R. Witt and W. Witzke and Y. F. Wu and Z. Xiao and W. Xie and H. Xu and N. Xu and Q. H. Xu and W. Xu and Y. Xu and Z. Xu and L. Xue and Y. Yang and Y. Yang and P. Yepes and K. Yip and I-K. Yoo and M. Zawisza and H. Zbroszczyk and W. Zhan and J. B. Zhang and S. Zhang and W. M. Zhang and X. P. Zhang and Y. Zhang and Z. P. Zhang and F. Zhao and J. Zhao and C. Zhong and X. Zhu and Y. H. Zhu and Y. Zoulkarneeva},
journal= {arXiv preprint arXiv:1109.4380},
year = {2015}
}
Comments
26 pages, 8 figures, 2 tables