Influence of the ion mass on quantum electrodynamics processes with the next generation high power lasers*

The construction of a number of new multi-petawatt laser facilities in Europe, USA and China has generated intense interest in the exploration of new physical regimes involving ultra-strong electromagnetic fields in which a significant amount of the laser energy is converted into high energy synchrotron radiation and in which electron-positron pairs can be produced. These new laser facilities will enable experimental exploration of this science for the first time. From an ultra-intense laser pulse (I > 10$^{23}$ W/cm$^2$) interacting with a plasma, we bring out the impact of the ion collective dynamics on the basic quantum electrodynamics processes such as high energy synchrotron radiation generation and the production of electron-positron pairs in the non-linear Breit-Wheeler process. Relevant cases are qualitatively discussed as well as potential future experiments.