Quantum gravity and the fate of Lorentz invariance in the standard model

The most important problem of fundamental Physics is the quantization of the gravitational field. Experimental tests that discriminate among the theories proposed to quantize gravity are difficult due to the smallness of the new effects involved. So the violation of a well tested symmetry such as Lorentz invariance could be a good arena to explore the implications of the quantized gravitational field. Here we review recent work where we showed that the Standard Model(SM) itself contains tiny Lorentz invariance violation(LIV) terms coming from QG. All terms depend on one arbitrary parameter a that set the scale of QG effects.alpha can be estimated using the spectrum of Ultra High Energy Cosmic Rays.