A constraint on antigravity of antimatter from precision spectroscopy of   simple atoms
  Consideration of antigravity for antiparticles is an attractive target for various experimental projects. There are a number of theoretical arguments against it but it is not quite clear what kind of experimental data and theoretical suggestions are involved. In this paper we present straightforward arguments against a possibility of antigravity based on a few simple theoretical suggestions and some experimental data. The data are: astrophysical data on rotation of the Solar System in respect to the center of our galaxy and precision spectroscopy data on hydrogen and positronium. The theoretical suggestions for the case of absence of the gravitational field are: equality of electron and positron mass and equality of proton and positron charge. We also assume that QED is correct at the level of accuracy where it is clearly confirmed experimentally. 
Savely G. Karshenboim (Max-Planck-Institut fuer Quantenoptik, Garching   and D.I. Mendeleev Institute for Metrology, St.Pete...