# Sujet de thèse pour la rentrée 2017

## Calcul des sections efficaces et développement d'une théorie de transport basée sur le lagrangien NJL

In the last years we have studied the time evolution of a plasma created in relativistic heavy ion collisions (studied for example at LHC at CERN)using a transport theory based on the Nambu Jona-Lasinio (NJL) Lagrangian.

This Lagrangian, which shares the symmetries of the QCD Lagragian, has been proven in the past to be very useful to calculate the properties of mesons and baryons in a hot and dense environment. It allows as well for the calculation of the cross sections among partons and hadrons, as well as for hadronization. Based on only a few parameters which are adjusted to static cold matter properties like masses a complete transport theory can be formulated.

This is of special interest because the NJL Lagragian shows a cross over from the parton to the hadron phase for vanishing chemical potential, whereas for large chemical potentials, expected to be the region of the upcoming FAIR experiments in Darmstadt (Germany), the phase transition is of first order. The transport theory allows therefore for a study of how a finite size system passes a first order phase transition.

In the framework of this thesis we want to study this phase transition. For this purpose one has to calculate the equation of state, the masses and the cross sections at finite chemical potential and implement these results in the presently existing transport approach. These calculations are mathematically demanding therefore a solid knowledge in field theory, functional analysis and statistical physics is considered as advantage.

The high energy-energy theory group is composed of 8 permanent senior researchers, 2 postdocs and 4 PhD students. Further general information can be found on our website http://www-subatech.in2p3.fr

Candidates should send a CV, a statement of their research interests and two letters of recommendation to Prof. J. Aichelin , (Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser., tel +33 2 51 85 84 09) with whom the candidate will work.

Deadline to apply: April 30th 2017