title: New limit on Lorentz- and CPT-violating neutron spin interactions.
abstract: We performed a search for neutron spin coupling to a Lorentz- and CPT-violating background field using a magnetometer with overlapping ensembles of K and ³He atoms. The comagnetometer is mounted on a rotary platform for frequent reversal of its orientation. We measure sidereal oscillations in the signal to search for anomalous spin coupling of extra-solar origin. We determine the equatorial components of the background field interacting with the neutron spin to be b˜Xn=(0.1 ± 1.6) × 10⁻³³ GeV and b˜Yn=(2.5 ± 1.6) × 10⁻³³ GeV, improving on the previous limit by a factor of 30. This measurement represents the highest energy resolution of any spin anisotropy experiment.
authors.affiliation: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Brown
authors.forename: S J
authors.initials: SJ
authors.lastname: Smullin
authors.forename: T W
authors.initials: TW
authors.lastname: Kornack
authors.forename: M V
authors.initials: MV
authors.lastname: Romalis