PHENIX results on collectivity tests in high-multiplicity p + p and p + Au collisions at

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• 作者：Itaru Nakagawa^a ; ^b ; for the PHENIX Collaboration¹
• 关键词：QGP ; small systems ; collective effect ; elliptic flow ; RHIC ; PHENIX ; high-multiplicity ; trigger
• 刊名：Nuclear Physics A
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：956
• 期：Complete
• 页码：765-768
• 全文大小：399 K

文摘

The observation of possible collective effects in high-multiplicity p+p and p+Pb collisions at the LHC and in d+Au and ³He+Au collisions at RHIC challenge our understanding of the ingredients necessary for quark-gluon plasma formation. For further investigation of these effects, the PHENIX collaboration has taken high statistics data in p+p and p+Au and p  +Al collisions in 2015. For these data sets, high-multiplicity triggers were implemented using the forward silicon detector (FVTX) and the beam-beam counter (BBC) covering pseudo-rapidity formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0375947416301774&_mathId=si2.gif&_user=111111111&_pii=S0375947416301774&_rdoc=1&_issn=03759474&md5=3e7d37f0de0118e2a544b1e06508a0b1" title="Click to view the MathML source">1.0<|η|<3.0$1.0<|\eta |<3.0$ and formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0375947416301774&_mathId=si3.gif&_user=111111111&_pii=S0375947416301774&_rdoc=1&_issn=03759474&md5=df3995754d857da37c53273eebbe596c" title="Click to view the MathML source">3.1<|η|<3.9$3.1<|\eta |<3.9$, respectively. The multi-hundred million high-multiplicity event samples recorded enable highly differential analysis to look for collective effects. We report results on large pseudo-rapidity separation correlations to elucidate if the so-called ridge phenomena exists in certain p+p event classes at RHIC. The flow coefficients from azimuthal anisotropies in p+Au are extracted and compared with theoretical expectations in various models, including viscous hydrodynamics where the elliptic flow strength is expected to be substantially smaller than in d+Au and ³He+Au at the same energy due to the smaller initial spatial eccentricity.