Parton propagation in cold and hot QCD media – PARTONPROP

This program first requires the understanding of energy loss effects in cold nuclear matter. The systematic study of various hard QCD processes, where associated gluon radiation and the resulting parton energy loss play a dominant role, will allow to improve the current understanding of cold nuclear effects and to provide accurate predictions for the case of hot matter, in the pQCD framework. From a theoretical perspective, we will study gluon radiation associated to various hard partonic processes. The notion of energy loss associated to a hard process should provide a unified approach, making the link between kinematical conditions looking otherwise drastically different. From a phenomenological perspective, we plan to obtain predictions for various observables sensitive to energy loss effects. Making realistic predictions will first require the understanding of p-p collisions. The next step will be to elaborate realistic models for p-A and A-A collisions, and predict the effect of medium-induced energy loss for a wide class of observables. On the experimental side, we will focus on LHC data taken by the CMS experiment and various aspects such as feasibility issues, simulations and data analysis. We will mostly use quarkonium and heavy flavour production (and related measurements) in A-A collisions to test the theory of parton energy loss.

- An energy loss model has been developed which describes the suppression of heavy-quarkonium states in proton-nucleus collisions
- Predictions in p-Pb collisions at LHC have been made.

- Extend the model to nucleus-nucleus collisions
- Extend the model at fixed impact parameter
- Predict the expected suppression in other canals e.g. the production of light and heavy hadrons

F. Arleo and S. Peigné, 1204.4609 to appear in Physical Review Letters

The goal of the project is to investigate systematically, in perturbative Quantum ChromoDynamics (pQCD), parton propagation and radiation effects in cold and hot QCD media. The research will be carried out from various and complementary perspectives, theoretical, phenomenological, and experimental. Our main motivation is to study jet and heavy flavour quenching observed in heavy-ion collisions at RHIC and LHC, which is a prominent signal for Quark-Gluon Plasma (QGP) formation. A detailed understanding of energy loss processes in a hot environment is crucial to determine the nature (perturbative or non-perturbative) of QGP.

This program first requires the understanding of energy loss effects in cold nuclear matter. The systematic study of various hard QCD processes, where associated gluon radiation and the resulting parton energy loss play a dominant role, will allow to improve the current understanding of cold nuclear effects and to provide accurate predictions for the case of hot matter, in the pQCD framework. From a theoretical perspective, we will study gluon radiation associated to various hard partonic processes. The notion of energy loss associated to a hard process should provide a unified approach, making the link between kinematical conditions looking otherwise drastically different. From a phenomenological perspective, we plan to obtain predictions for various observables sensitive to energy loss effects. Making realistic predictions will first require the understanding of p-p collisions. The next step will be to elaborate realistic models for p-A and A-A collisions, and predict the effect of medium-induced energy loss for a wide class of observables. On the experimental side, we will focus on LHC data taken by the CMS experiment and various aspects such as feasibility issues, simulations and data analysis. We will mostly use quarkonium and heavy flavour production (and related measurements) in A-A collisions to test the theory of parton energy loss.

In summary, our project will exploit the most recent theoretical developments in pQCD as well as the richness of the LHC, in conjunction with the results already obtained, with an emphasis on collisions involving heavy nuclei. It will allow for a comprehensive phenomenology, based on the understanding of energy loss processes, leading to supplementary experimental studies as well as new measurements at the LHC.