Thursday, March 21, 2013, 16:00
WHGA/Auditorium
S. Schlesser, U. Groningen
Abstract:
This work is motivated by the proton radius puzzle, namely, the discrepancy observed between the measurements of the proton radius using different probes. In particular, the muonic hydrogen spectroscopy measured the proton radius more than 4.4 standard deviations away from what had been obtained using standard hydrogen. So far, no explanation has been found, and there is need for more measurements in different elements (deuterium, helium...) which could help to identify patterns, correlations, and rule out or promote some hypothesis, among which we can mention beyond the standard model physics.
We need accurate theoretical predictions for the energy levels of the muonic helium ion, which implies to calculate in particular the effects of the polarizability of the nucleus. For this, we use pionless effective field theory, describing properly the dynamics at low energy of strongly interacting nucleons.