Stueckelberg Redux: How Classical Gravity Can Induce Changes in Particle   Lifetimes
  ECG Stueckelberg (1905-1984) often published important theories years before those who would receive the Nobel Prize for their discoery. Perhpas other jewels may remain the work of this prescient genius. In a short paper in 1957--coming shortly on the heels of the suggestion and experimental confirmation of parity non-conservation by the weak force--Stueckelberg noted that sine there exist completely antisymmetric four-tensors (e) with covariant derivative zero, non-parity conserving forces can readily be accomodated by general relativity as the product of such a tensor and the non-parity conserving terms. Stueckelberg also pointed out that in classical general relativity the covariant derivative, D, of e is De=(-g)^1/2*d[e(-g)^-1/2]=0, where g is the determinant of the metric tensor, and d is an ordinary derivative. Since g is non-zero, if g is constant, e is a constant and mean proper particle lifetimes are the same in all Lorenz frames. I point out that Stueckelberg's paper has three further deep and important implications. (1) We see how gravity-- matter--can influence particle lifetimes by forcing the e tensor to be non-constant to have to "adjust" so that d[e(-g)^-1/2] is zero, and we can get some quantitative feel for the magnitude of this effect. (2) If any difference in the lifetimes of particles and antiparticles are to occur, in the absence of Lorenz invariance violation, it would be in regions where dg is non-zero. (3) If indeed, differences in particle and antiparticle lifetimes are found, before they can be ascibed to effects of quantum gravity, supersymmetry, or string theory, the effects of classical gravity need to be accounted for. 
Eric Lewin Altschuler