On Gravity and Mass

Motivated mainly by the fact that no charged elementary particles having zero mass have been observed up to now, we investigate the question whether the mass of the elementary particles is connected with their electric charge and whether gravity can be derived from QED. The graviton is considered as a two-photon bound state. A relation between mass and charge of elementary particles is derived. Masses of the light quarks $d$ and $u$ are calculated from the electron mass, assuming that $d$, $u$ and $e$ are all fundamental and not composite. In this picture, the heavier quarks and leptons are considered as not fundamental, the massive neutral gauge bosons (and then their charged partners) are composite. The here calculated $u$ and $d$ quark masses, result in quark-mass ratios which display interesting regularities. The lightest quark mass turns out to be quite small. This may be interesting in connection to the strong CP problem.