Dihadron azimuthal correlations containing a high transverse momentum(pr)trigger particle are sensit-ive to the properties of the nuclear medium created at RHIC through the strong interactions occurring between the tr...Dihadron azimuthal correlations containing a high transverse momentum(pr)trigger particle are sensit-ive to the properties of the nuclear medium created at RHIC through the strong interactions occurring between the traversing parton and the medium,ie.jet-quenching.Previous measurements revealed a strong modification to di-hadron azimuthal correlations in Au+Au collisions with respect to ptp and d+Au collisions.The modification in-creases with the collision centrality,suggesting a path-length or energy density dependence to the je-quenching ef-fect.This paper reports STAR measurements of dihadron azimuthal correlations in mid-central(20%-60%)Au+Au collisions at√^(S)NN=200 GeV as a function of the trigger particle's azimuthal angle relative to the event plane,Ф_(s)=|Ф_(t)-ψ_(Ep)|.The azimuthal correlation is studied as a function of both the trigger and associated particle pr.The subtractions of the combinatorial background and anisotropic flow,assuming Zero Yield At Minimum(ZYAM),are described.The correlation results are first discussed with subtraction of the even harmonic(elliptic and quadrangu-lar)flow backgrounds.The away-side correlation is strongly modifed,and the modification varies withФ_(s),with a double-peak structure for out-of-plane trigger particles.The near-side ridge(long range pseudo-rapidity△_(η)correla-tion)appears to drop with increasingФ_(s)while the jet-like component remains approximately constant.The correla-tion functions are further studied with the subtraction of odd harmonic triangular flow background arising from fluc-tuations.It is found that the triangular flow,while responsible for the majority of the amplitudes,is not sufficient to explain theφs-dependence of the ridge or the away-side double-peak structure.The dropping ridge withФ_(s)could be attributed to aФ_(s)-dependent lliptie anisotropy;however,the physics mechanism of the ridge remains an open ques-tion.Even with aФ_(s)-dependent elliptic flow,the away-side correlation structure is robust.These results,with extens-ive systematic studies of the dihadron correlations as a function ofФ_(s),trigger and associated particle pT,and the pseudo-rapidity range△_(η),should provide stringent inputs to help understand the underlying physics mechanisms of jet-medium interactions in high energy nuclear collisions.展开更多
团簇结构可以稳定存在于原子核的内部。研究原子核的α团簇结构及其影响在核物理与天体物理中是一个十分重要的课题。在过去几十年里,原子核的团簇结构效应在重离子核反应中有了较多的研究。本文主要总结了在核反应与相对论重离子碰撞...团簇结构可以稳定存在于原子核的内部。研究原子核的α团簇结构及其影响在核物理与天体物理中是一个十分重要的课题。在过去几十年里,原子核的团簇结构效应在重离子核反应中有了较多的研究。本文主要总结了在核反应与相对论重离子碰撞中对原子核的α团簇结构效应的研究。例如,通过原子核的巨共振来研究原子核的团簇结构。通过核反应中的粒子(包括中子、质子以及光子)的发射与关联、集体流等研究原子核的团簇结构。进一步,我们把原子核的团簇效应延伸推广到相对论重离子碰撞中,比如,对集体流及其涨落、HBT(Hanbury Brown and Twiss)关联、多重性关联、双强子方位角关联、电磁场等的研究。展开更多
基金Supported in part by the Offices of NP and HEP within the U.S.DOE Office of Sciencethe U.S.NSF+18 种基金the Sloan Foundationthe DFG cluster of excellence‘Origin and Structure of the Universe’of Germany,CNRS/IN2P3STFC and EPSRC of the United KingdomFAPESP CNPq of Brazil,Ministry of Ed.Sci.of the Russian FederationNNSFCCASMoSTMoE of ChinaGA and MSMT of the Czech RepublicFOM and NWO of the NetherlandsDAEDSTCSIR of IndiaPolish Ministry of Sci.Higher Ed.,Korea Research Foundation,Ministry of Sci.,Ed.Sports of the Rep.Of CroatiaRussian Ministry of Sci.and TechRos-Atom of Russia。
文摘Dihadron azimuthal correlations containing a high transverse momentum(pr)trigger particle are sensit-ive to the properties of the nuclear medium created at RHIC through the strong interactions occurring between the traversing parton and the medium,ie.jet-quenching.Previous measurements revealed a strong modification to di-hadron azimuthal correlations in Au+Au collisions with respect to ptp and d+Au collisions.The modification in-creases with the collision centrality,suggesting a path-length or energy density dependence to the je-quenching ef-fect.This paper reports STAR measurements of dihadron azimuthal correlations in mid-central(20%-60%)Au+Au collisions at√^(S)NN=200 GeV as a function of the trigger particle's azimuthal angle relative to the event plane,Ф_(s)=|Ф_(t)-ψ_(Ep)|.The azimuthal correlation is studied as a function of both the trigger and associated particle pr.The subtractions of the combinatorial background and anisotropic flow,assuming Zero Yield At Minimum(ZYAM),are described.The correlation results are first discussed with subtraction of the even harmonic(elliptic and quadrangu-lar)flow backgrounds.The away-side correlation is strongly modifed,and the modification varies withФ_(s),with a double-peak structure for out-of-plane trigger particles.The near-side ridge(long range pseudo-rapidity△_(η)correla-tion)appears to drop with increasingФ_(s)while the jet-like component remains approximately constant.The correla-tion functions are further studied with the subtraction of odd harmonic triangular flow background arising from fluc-tuations.It is found that the triangular flow,while responsible for the majority of the amplitudes,is not sufficient to explain theφs-dependence of the ridge or the away-side double-peak structure.The dropping ridge withФ_(s)could be attributed to aФ_(s)-dependent lliptie anisotropy;however,the physics mechanism of the ridge remains an open ques-tion.Even with aФ_(s)-dependent elliptic flow,the away-side correlation structure is robust.These results,with extens-ive systematic studies of the dihadron correlations as a function ofФ_(s),trigger and associated particle pT,and the pseudo-rapidity range△_(η),should provide stringent inputs to help understand the underlying physics mechanisms of jet-medium interactions in high energy nuclear collisions.
文摘团簇结构可以稳定存在于原子核的内部。研究原子核的α团簇结构及其影响在核物理与天体物理中是一个十分重要的课题。在过去几十年里,原子核的团簇结构效应在重离子核反应中有了较多的研究。本文主要总结了在核反应与相对论重离子碰撞中对原子核的α团簇结构效应的研究。例如,通过原子核的巨共振来研究原子核的团簇结构。通过核反应中的粒子(包括中子、质子以及光子)的发射与关联、集体流等研究原子核的团簇结构。进一步,我们把原子核的团簇效应延伸推广到相对论重离子碰撞中,比如,对集体流及其涨落、HBT(Hanbury Brown and Twiss)关联、多重性关联、双强子方位角关联、电磁场等的研究。
