Predictions for boson-jet observables and fragmentation function ratios from a hybrid strong/weak coupling model for jet quenching

• Main Authors: Casalderrey-Solana, Jorge (Author), Gulhan, Doga Can (Contributor), Milhano, José Guilherme (Author), Pablos, Daniel (Author), Rajagopal, Krishna (Contributor)
• Other Authors: Massachusetts Institute of Technology. Center for Theoretical Physics (Contributor), Massachusetts Institute of Technology. Department of Physics (Contributor), Massachusetts Institute of Technology. Laboratory for Nuclear Science (Contributor)
• Format: Article
• Language: English
• Published: Springer Berlin Heidelberg/International School for Advanced Studies (SISSA), 2016-06-07T14:49:19Z.
• Subjects: Article
• Online Access: Get fulltext

We have previously introduced a hybrid strong/weak coupling model for jet quenching in heavy ion collisions in which we describe the production and fragmentation of jets at weak coupling, using Pythia, and describe the rate at which each parton in the jet shower loses energy as it propagates through the strongly coupled plasma, dE/dx, using an expression computed holographically at strong coupling. The model has a single free parameter that we fit to a single experimental measurement. We then confront our model with experimental data on many other jet observables, focusing in this paper on boson-jet observables, finding that it provides a good description of present jet data. Next, we provide the predictions of our hybrid model for many measurements to come, including those for inclusive jet, dijet, photon-jet and Z-jet observables in heavy ion collisions with energy [squareroot s] = 5:02 ATeV coming soon at the LHC. As the statistical uncertainties on near-future measurements of photon-jet observables are expected to be much smaller than those in present data, with about an order of magnitude more photon-jet events expected, predictions for these observables are particularly important. We find that most of our pre- and post-dictions do not depend sensitively on the form we choose for the rate of energy loss dE/dx of the partons in the shower. This gives our predictions considerable robustness. To better discriminate between possible forms for the rate of energy loss, though, we must turn to intrajet observables. Here, we focus on ratios of fragmentation functions. We close with a suggestion for a particular ratio, between the fragmentation functions of inclusive and associated jets with the same kinematics in the same collisions, which is particularly sensitive to the x- and E-dependence of dE/dx, and hence may be used to learn which mechanism of parton energy loss best describes the quenching of jets.
Marie Curie Career Integration Grant (FP7-PEOPLE-2012-GIG-333786)
Spain. Ministerio de Economía y Competitividad (grant FPA2013-46570)
Spain. Ministerio de Economía y Competitividad (grant FPA2013-40360-ERC)
Spain. Ministerio de Economía y Competitividad (grant MDM-2014-0369 of ICCUB (Unidad de Excelencia Mara de Maeztu))
Programa Consolider-Ingenio 2010, Spain (grant 2014-SGR-104, Generalitat de Catalunya)
United States. Dept. of Energy (Contract Number DE-SC0011088)
United States. Dept. of Energy (Contract Number DE-SC0011090)
Fundação para a Ciência e a Tecnologia (Portugal) (project CERN/FP/123596/2011)
Fundação para a Ciência e a Tecnologia (Portugal) (contract Investigador FCT | Development Grant)