Observation of nuclear modification of energy-energy correlators inside jets in heavy ion collisions
V. Chekhovsky, Aram Hayrapetyan, Vladimir Makarenko, A. Tumasyan, Wolfgang Adam, Janik Walter Andrejkovic, L. Benato, T. Bergauer, S. Chatterjee, K. Damanakis, M. Dragicevic, Priya Sajid Hussain, M. Jeitler, Natascha Krammer, A. Li, D. Liko, Ivan Mikulec, J. Schieck, R. Schöfbeck, D. Schwarz, M. Sonawane, W. Waltenberger, Claudia-Elisabeth Wulz, X. Janssen, Hyejin Kwon, T. Van Laer, Pierre van Mechelen, Nordin Breugelmans, J. D’Hondt, Soumya Dansana, A. De Moor, M. Delcourt, Felix Heyen, Y. Hong, Steven Lowette, I. Makarenko, Denise Müller, Stefaan Tavernier, M. Tytgat, G. P. Van Onsem, S. Van Putte, D. Vannerom, Bugra Bilin, Barbara Clerbaux, Aloke Kumar Das, Isabelle de Bruyn, G. De Lentdecker, Hugues Evard, Laurent Favart, P. Gianneios, Mohammad A. Khalilzadeh, Fakhri Alam Khan, K. Lee, A. Malara, Muhammad Aamir Shahzad, Laurent Thomas, M. Vanden Bemden, Catherine Vander Velde, P. Vanlaer, M. De Coen, D. Dobur, G. Gökbulut, J. Knolle, Luka Lambrecht, David Marckx, K. Skovpen, N. Van Den Bossche, Jan van der Linden, Liam Wezenbeek, S. Bein, A. Benecke, A. Bethani, G. Bruno, C. Caputo, J. De Favereau De Jeneret, C. Delaere, I. S. Donertas, A. Giammanco, Ahmet Oguz Guzel, Sandhya Jain, Vincent Lemaître, J. Lidrych, Paola Mastrapasqua, Tu Thong Tran, S. Turkcapar, G.A. Alves, E. Coelho, Gilson Correia Silva, Carsten Hensel, T. Menezes De Oliveira, C. Mora Herrera, P. Rebello Teles, M. Soeiro, E. J. Tonelli Manganote, A. Vilela Pereira, W. L. Aldá Júnior, M. Barroso Ferreira Filho, H. Brandao Malbouisson, W. Carvalho, Jose Chinellato
Abstract
Energy-energy correlators are constructed by averaging the number of charged particle pairs within jets, weighted by the product of their transverse momenta, as a function of the angular separation of the particles within a pair. They are sensitive to a multitude of perturbative and nonperturbative quantum chromodynamics phenomena in high-energy particle collisions. Using lead-lead data recorded with the CMS detector, energy-energy correlators inside high transverse momentum jets are measured in heavy ion collisions for the first time. The data are obtained at a nucleon-nucleon center-of-mass energy of 5.02 TeV and correspond to an integrated luminosity of 1.70 nb − 1 . A similar analysis is done for proton-proton collisions at the same center-of-mass energy to establish a reference. The ratio of lead-lead to proton-proton energy-energy correlators reveals significant jet substructure modifications in the quark-gluon plasma. The results are compared to different models that incorporate either color coherence or medium response effects, where the two effects predict similar substructure modifications.