Quantum Gravity and Lorentz invariance violation in the Standard Model
  The most important problem of fundamental Physics is the quantization of the gravitational field. A main difficulty is the lack of available experimental tests that discriminate among the theories proposed to quantize gravity. Recently, Lorentz invariance violation by Quantum Gravity(QG) have been the source of a growing interest. However, the predictions depend on ad-hoc hypothesis and too many arbitrary parameters. Here we show that the Standard Model(SM) itself contains tiny Lorentz invariance violation(LIV) terms coming from QG. All terms depend on one arbitrary parameter $\alpha$ that set the scale of QG effects. This parameter can be estimated using data from the Ultra High Energy Cosmic Rays spectrum to be $|\alpha|<\sim 10^{-22}-10^{-23}$. 
Jorge Alfaro