title: Limits on variations in fundamental constants from 21-cm and ultraviolet Quasar absorption lines.
abstract: Quasar absorption spectra at 21-cm and UV rest wavelengths are used to estimate the time variation of x [triple-bond] alpha(2)g(p)mu, where alpha is the fine structure constant, g(p) the proton g factor, and m(e)/m(p) [triple-bond] mu the electron/proton mass ratio. Over a redshift range 0.24 < or = zeta(abs) < or = 2.04, (Deltax/x)(weighted)(total) = (1.17 +/- 1.01) x 10(-5). A linear fit gives x/x = (-1.43 +/- 1.27) x 10(-15) yr(-1). Two previous results on varying alpha yield the strong limits Deltamu/mu = (2.31 +/- 1.03) x 10(-5) and Deltamu/mu=(1.29 +/- 1.01) x10(-5). Our sample, 8 x larger than any previous, provides the first direct estimate of the intrinsic 21-cm and UV velocity differences 6 km s(-1).
authors.affiliation: School of Physics, The University of New South Wales, Sydney, Australia. pana@phys.unsw.edu.au
authors.forename: P
authors.initials: P
authors.lastname: Tzanavaris
authors.forename: J K
authors.initials: JK
authors.lastname: Webb
authors.forename: M T
authors.initials: MT
authors.lastname: Murphy
authors.forename: V V
authors.initials: VV
authors.lastname: Flambaum
authors.forename: S J
authors.initials: SJ
authors.lastname: Curran