Search forPandTviolations in the hyperfine structure of thallium fluoride

Abstract

A molecular-beam experiment using TlF is described. The experiment searched for a $P$- and $T$-violating interaction of the form ${\mathcal{H}}_{\mathrm{PT}}=d{\overrightarrow{\sigma }}_{\mathrm{Tl}}·{\overrightarrow{\lambda }}_{\mathrm{TlF}}$, where $d$ is a coupling constant, ${\overrightarrow{\sigma }}_T$ is a unit vector parallel to the thallium nuclear spin, and ${\overrightarrow{\lambda }}_{\mathrm{TlF}}$ is a unit vector parallel to the internuclear axis. The experiment yields the null result $\frac{d}{h}=8\mathrm{}\pm 12$ mHz. Interpreting the interaction in terms of an electric dipole moment on the proton, $D_p$, or in terms of a possible weak neutral-current tensor interaction with a coupling constant $C_T$, this result corresponds to $D_p=(1.3\mathrm{}\pm 2.0)\times {10}^{-21\mathrm{}} e$ cm and $C_T=(6\mathrm{}\pm 9)\times {10}^{-6\mathrm{}}{G}_F$, where the errors incorporate unexplained systematic effects as well as statistical errors.