Quantum physics and equivalence principle

[exponent137]

I read some articles, where equivalence principle is no more valid in quantum area. One example are neutrinos, changing colours (electron, muon, tauon neutrino). But formulae are not derived from fundaments, so I do not understand, where it is the catch.

I read also about COW experiment, this is experiment with neutrons in gravitational field. Phase difference at this experiment is dependent from neutron mass. But behavior in gravitational field should be independent from gravitational field. So, hot it is with this?

Are here any clear and simple suggestins, what should happens with equivalence principle in quantum area?

But I am aware that experiment which would violate equivalence principle because of quantum physics, will be revolutionary for quantum gravity. But now it does not exist idea, how to do some measurement in quantum gravity area.

Best regards

 

[exponent137]

I will try with one more specific question: In http://en.wikipedia.org/wiki/Equivalence_principle
it is written that
"The need to continue testing Einstein's theory of gravity may seem superfluous, as the theory is elegant and is compatible with almost all observations to date (except for instance the Pioneer anomaly). However, no quantum theory of gravity is known, and most suggestions violate one of the equivalence principles at some level. String theory, supergravity and even quintessence, for example, seem to violate the weak equivalence principle because they contain many light scalar fields with long Compton wavelengths. These fields should generate fifth forces and variation of the fundamental constants. There are a number of mechanisms that have been suggested by physicists to reduce these violations of the equivalence principle to below observable levels.
"
Can someone explain this or find links with explanations?