Bounds on Stringy Quantum Gravity from Low Energy Existing Data

We show that existing low energy experiments, searching for the breaking of local Lorentz invariance, set bounds upon string theory inspired quantum gravity models that induce corrections to the propagation of fields. In the D-particle recoil model we find M > 1.2 x 10^5 M_P and v < 2 x 10^{-27}c for the mass and recoil speed of the D-particle, respectively. These bounds are ~10^8 times stronger than the latest astrophysical bounds. These results indicate that the stringy scenario for modified dispersion relations is as vulnerable to these types of tests as the loop quantum gravity schemes.