Test of special relativity by a determination of the Lorentz limiting velocity: DoesE=mc2?

We describe a method by which existing precision measurements may be used to provide a new laboratory test of the special theory of relativity. In this test the speed of light ${\mathit{c}}_{\mathrm{em}}$ is compared to the limiting velocity of massive particles, ${\mathit{c}}_{\mathit{m}}$. Although it is conventionally assumed that ${\mathit{c}}_{\mathrm{em}}$=${\mathit{c}}_{\mathit{m}}$ieqc, this need not be the case in phenomenological alternatives to special relativity. Our results impose limits on the quantity (1-${\mathit{c}}_{\mathit{m}}$/${\mathit{c}}_{\mathrm{em}}$). Unlike null tests of special relativity, this limit does not depend on assumptions concerning the motion of the laboratory with respect to a preferred frame.