Measurements of fragmentation functions for jets associated with an isolated photon are presented for the first time in pp and Pb-Pb collisions. The analysis uses data collected with the CMS detector at the CERN LHC at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Fragmentation functions are obtained for jets with pTjet>30 GeV/c in events containing an isolated photon with pTγ>60 GeV/c, using charged tracks with transverse momentum pTtrk>1 GeV/c in a cone around the jet axis. The association with an isolated photon constrains the initial pT and azimuthal angle of the parton whose shower produced the jet. For central Pb-Pb collisions, modifications of the jet fragmentation functions are observed when compared to those measured in pp collisions, while no significant differences are found in the 50% most peripheral collisions. Jets in central Pb-Pb events show an excess (depletion) of low (high) pT particles, with a transition around 3 GeV/c. This measurement shows for the first time the in-medium shower modifications of partons (quark dominated) with well-defined initial kinematics. It constitutes a new well-controlled reference for testing theoretical models of the parton passage through the quark-gluon plasma.

Observation of Medium-Induced Modifications of Jet Fragmentation in Pb-Pb Collisions at sNN =5.02 TeV Using Isolated Photon-Tagged Jets / Sirunyan, A.M., Tumasyan, A., Adam, W., Ambrogi, F., Asilar, E., Bergauer, T., Brandstetter, J., Brondolin, E., Dragicevic, M., Ero, J., Escalante Del Valle, A., Flechl, M., Friedl, M., Fruhwirth, R., Ghete, V.M., Grossmann, J., Hrubec, J., Jeitler, M., Konig, A., Krammer, N., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 121:24(2018), p. 242301.242301. [10.1103/PhysRevLett.121.242301]

Observation of Medium-Induced Modifications of Jet Fragmentation in Pb-Pb Collisions at sNN =5.02 TeV Using Isolated Photon-Tagged Jets

Creanza D.;De Filippis N.;Iaselli G.;Pugliese G.;
2018

Abstract

Measurements of fragmentation functions for jets associated with an isolated photon are presented for the first time in pp and Pb-Pb collisions. The analysis uses data collected with the CMS detector at the CERN LHC at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Fragmentation functions are obtained for jets with pTjet>30 GeV/c in events containing an isolated photon with pTγ>60 GeV/c, using charged tracks with transverse momentum pTtrk>1 GeV/c in a cone around the jet axis. The association with an isolated photon constrains the initial pT and azimuthal angle of the parton whose shower produced the jet. For central Pb-Pb collisions, modifications of the jet fragmentation functions are observed when compared to those measured in pp collisions, while no significant differences are found in the 50% most peripheral collisions. Jets in central Pb-Pb events show an excess (depletion) of low (high) pT particles, with a transition around 3 GeV/c. This measurement shows for the first time the in-medium shower modifications of partons (quark dominated) with well-defined initial kinematics. It constitutes a new well-controlled reference for testing theoretical models of the parton passage through the quark-gluon plasma.
2018
Observation of Medium-Induced Modifications of Jet Fragmentation in Pb-Pb Collisions at sNN =5.02 TeV Using Isolated Photon-Tagged Jets / Sirunyan, A.M., Tumasyan, A., Adam, W., Ambrogi, F., Asilar, E., Bergauer, T., Brandstetter, J., Brondolin, E., Dragicevic, M., Ero, J., Escalante Del Valle, A., Flechl, M., Friedl, M., Fruhwirth, R., Ghete, V.M., Grossmann, J., Hrubec, J., Jeitler, M., Konig, A., Krammer, N., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 121:24(2018), p. 242301.242301. [10.1103/PhysRevLett.121.242301]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11589/210457
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