Constraints on Lorentz violation from clock-comparison experiments - art. no. 116010

Constraints from clock-comparison experiments on violations of Lorentz and CPT symmetry are investigated in the context of a general Lorentz-violating extension of the standard model. The experimental signals are shown to dep end on the atomic and ionic species used as clocks. Certain experiments usu ally regarded as establishing comparable bounds are in this context sensiti ve to different types of Lorentz violation. Some considerations relevant to possible future measurements are presented. All these experiments are pote ntially sensitive to Lorentz-violating physics at the Planck scale. [S0556- 2821(99)01223-0].