Observation of sequential Υ suppression in PbPb collisions

Workshop for Young Scientists on the Physics of Ultrarelativistic Nucleus–Nucleus Collisions 2012

Hu, Zhen^1

Purdue University, West Lafayette, IN 47906, United States^1

关键词: Integrated luminosity;    Nucleon-nucleon collisions;    Pb-Pb collisions;    Upper limits;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/446/1/012043/pdf
DOI  :  10.1088/1742-6596/446/1/012043

来源: IOP

【 摘 要 】

The sequential suppression of the individual υ states in PbPb collisions with respect to their yields in pp data has been measured. The PbPb and pp datasets used in these proceedings correspond to integrated luminosities of 150/μb and 230/nb, respectively, collected by the CMS experiment at the LHC at 2.76 TeV in 2011. The relative suppression of the excited υ states has been measured with respect to the υ(1S) ground state, expressed as a double ratio [υ(nS)/υ(1S)]pbPb/[υ(nS)/υ(1S)]pp. The absolute suppression of the υ(nS) yields in PbPb relative to the yields in pp scaled by the number of nucleon-nucleon collisions, RAA, is measured as a function of the collision centrality. Integrated over centrality, the RAAvalues for υ(1S), υ(2S), and the upper limit of υ(3S) RAAare reported in this proceeding, which demonstrate the sequential suppression of the υ(nS) states in PbPb collisions at LHC energies.