title: Improved tests of local position invariance using 87Rb and 133Cs fountains.
abstract: We report tests of local position invariance based on measurements of the ratio of the ground state hyperfine frequencies of 133Cs and 87Rb in laser-cooled atomic fountain clocks. Measurements extending over 14 years set a stringent limit to a possible variation with time of this ratio: d ln(ν(Rb)/ν(Cs))/dt=(-1.39±0.91)×10(-16) yr(-1). This improves by a factor of 7.7 over our previous report [H. Marion et al., Phys. Rev. Lett. 90, 150801 (2003)]. Our measurements also set the first limit to a fractional variation of the Rb/Cs frequency ratio with gravitational potential at the level of c(2)d ln(ν(Rb)/ν(Cs))/dU=(0.11±1.04)×10(-6), providing a new stringent differential redshift test. The above limits equivalently apply to the fractional variation of the quantity α(-0.49)(g(Rb)/g(Cs)), which involves the fine-structure constant α and the ratio of the nuclear g-factors of the two alkalis. The link with variations of the light quark mass is also presented together with a global analysis combining other available highly accurate clock comparisons.
authors.affiliation: LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 75014 Paris, France.
authors.forename: J
authors.initials: J
authors.lastname: Guéna
authors.forename: M
authors.initials: M
authors.lastname: Abgrall
authors.forename: D
authors.initials: D
authors.lastname: Rovera
authors.forename: P
authors.initials: P
authors.lastname: Rosenbusch
authors.forename: M E
authors.initials: ME
authors.lastname: Tobar
authors.forename: Ph
authors.initials: P
authors.lastname: Laurent
authors.forename: A
authors.initials: A
authors.lastname: Clairon
authors.forename: S
authors.initials: S
authors.lastname: Bize