Testing Lorentz Violation Using Propagating UHECRs
  Lorentz invariant violation (LIV) test is very important to study in the new physics. All the known astrophysical constraints either have a very small examinable parameter space, or are only suitable for some special theoretical models. Here we suggest that it is possible to detect the time-delay of ultra-high-energy cosmic-rays (UHECRs) directly. We discuss some difficulties in our method, including the intergalactic magnetic fields. It seems that none of them are crucial, hence this method could give a larger examinable parameter space and a stronger constraint on LIV. 
Cong-Xin Qiu, Zi-Gao Dai