Seminars this week

We construct a chiral effective Lagrangian for e.-m. transitions between vector and pseudoscalar mesons (PVgamma). Based on an organization scheme in 1/Nc and the quark masses, we fit up to 12 decays and compare the results of our model with the experimental values given in PDG2018. We will extend our framework to the Dalitz decays PVl+l- and compare the calculated decay rates and transition form factors with recent experimental results.

The short-range interaction between particles many times shows a strong repulsion that strongly correlated the many-body system. In the particular case of a two-body shallow state, very extended compared to the range of the interaction, the three-body system has universal behavior. There is an infinite number of states geometrically accumulated at E=0. This is the Efimov effect predicted by V. Efimov in 1970 and experimentally verified more than 25 years later. I will discuss how universal behavior emerges in strongly correlated systems as liquid drops or light nuclear systems and how this behavior propagates as the number of particle increases.

Exciting an atom or molecule into a high-lying electronic state, a Rydberg state, changes its properties in a drastic, but very well-understood way. While the binding energy of the Rydberg electron decrease with the principal quantum number n as 1/n^2, the orbital radius and transition dipole moments increase as n^2. This results in the electric polarizability increasing as n^7. I will present recent experiments in which we have exploited these scaling laws and exaggerated properties to perform precision measurements of ionization energies with relative accuracies up to 10^11, to characterize precisely static and alternating electric fields, and to reduce the detrimental role of stray fields in applications of Rydberg atoms. In a second part, I’ll discuss our progress towards extracting accurate scattering phase shifts from the spectroscopy of hetero-nuclear long-range Rydberg molecules, which are bound by the interaction of the Rydberg electron with ground-state atoms within its orbit, and how we plan to exploit the exotic properties of long-range Rydberg molecules to create ultracold, strongly correlated plasmas.