Rotation, Equivalence Principle, and GP-B Experiment

TL;DR

This paper uses Gravity Probe B data to test the Weak Equivalence Principle II, achieving four orders of magnitude improvement in constraints on the free-fall Eötvös parameter for rotating bodies and setting bounds on anomalous torques.

Contribution

It provides the first high-precision experimental constraints on WEP II parameters using GP-B data, including the free-fall Eötvös parameter and anomalous torque parameters.

Findings

Eötvös parameter eta <= 10^(-11), four orders better than previous.

Constraints on anomalous torque per unit angular momentum lambda in three directions.

Limits on frequency-dependence parameter kappa with improved precision.

Abstract

The ultra-precise Gravity Probe B experiment measured the frame-dragging effect and geodetic precession on four quartz gyros. We use this result to test WEP II (Weak Equivalence Principle II) which includes rotation in the universal free-fall motion. The free-fall E\"otv\"os parameter eta for rotating body is < = 10**(-11) with four-order improvement over previous results. The anomalous torque per unit angular momentum parameter lambda is constrained to (-0.05 +- 3.67) \times 10**(-15) s-1, (0.24 +- 0.98) \times 10**(-15) s-1, and (0 +- 3.6) \times 10**(-13) s-1 respectively in the directions of geodetic effect, frame-dragging effect and angular momentum axis; the dimensionless frequency-dependence parameter {\kappa} is constrained to (1.75 +- 4.96) \times 10**(-17), (1.80 +- 1.34) \times 10**(-17), and (0 +- 3) \times 10**(-14) respectively.