Related papers: Does the fine structure constant vary? A detailed …
Comparison of quasar absorption spectra with laboratory spectra allow us to probe possible variations in the fundamental constants over cosmological time-scales. In a companion paper we present an analysis of Keck/HIRES spectra and report…
The Keck telescope's HIRES spectrograph has previously provided evidence for a smaller fine-structure constant, alpha, compared to the current laboratory value, in a sample of 143 quasar absorption systems: da/a=(-0.57+/-0.11)x10^{-5}. This…
[Abridged] We previously presented evidence for a varying fine-structure constant, alpha, in two independent samples of Keck/HIRES QSO spectra. Here we present a detailed many-multiplet analysis of a third Keck/HIRES sample containing 78…
We report preliminary results from a third sample of quasar absorption line spectra from the Keck telescope which has been studied to search for any possible variation of the fine structure constant, alpha. This third sample, which is…
We describe the results of a search for time variability of the fine structure constant, alpha, using absorption systems in the spectra of distant quasars. Three large optical datasets and two 21cm/mm absorption systems provide four…
An experimental search for variation in the fundamental coupling constants is strongly motivated by modern high-energy physics theories. Comparison of quasar absorption line spectra with laboratory spectra provides a sensitive probe for…
We present a short review of the current quasar (QSO) absorption line constraints on possible variation of the fine structure constant, alpha = e^2/(hbar*c). Particular attention is paid to recent optical Keck/HIRES spectra of 49 absorption…
We critically review the current null results on a varying fine-structure constant, alpha, derived from VLT/UVES quasar absorption spectra, focusing primarily on the many-multiplet analysis of 23 absorbers from which Chand et al. (2004)…
Attempts to measure the variability of the fine structure constant alpha over cosmological time, using spectra of high redshift quasars have produced conflicting results. We use the Many Multiplet (MM) method with Mg II and Fe II lines on…
A method offering an order of magnitude sensitivity gain is described for using quasar spectra to investigate possible time or space variation in the fine structure constant, alpha. Applying the technique to a sample of 30 absorption…
We present evidence for variations in the fine-structure constant from Keck/HIRES spectra of 143 quasar absorption systems over the redshift range 0.2 < z_abs < 4.2. This includes 15 new systems, mostly at high-z (z_abs > 1.8). Our most…
(abridged) Quasar absorption lines provide a precise test of the assumed constancy of the fundamental constants of physics. We have investigated potential changes in the fine-structure constant, alpha, and the proton-to-electron mass ratio,…
Calculation of the Dirac hydrogen atom spectrum in the framework of dynamical fine structure constant (alpha) variability discloses a small departure in the laboratory from Sommerfeld's formula for the fine structure shifts, possibly…
Observations of the redshift z=7.085 quasar J1120+0641 have been used to search for variations of the fine structure constant, alpha, over the redshift range 5.5 to 7.1. Observations at z=7.1 probe the physics of the universe when it was…
In their Letter [Phys. Rev. Lett. 92, 121302 (2004)] (also [Astron. Astrophys. 417, 853 (2004)]), Srianand et al. analysed optical spectra of heavy-element species in 23 absorption systems along background quasar sight-lines, reporting…
We present an analysis of 23 absorption systems along the lines of sight towards 18 quasars in the redshift range of $0.4 \leq z_{abs} \leq 2.3$ observed on the Very Large Telescope (VLT) using the Ultraviolet and Visual Echelle…
(Abridged) Many-multiplet (MM) method applied to three inhomogeneous samples of Keck/HIRES quasar absorption spectra gives a shift in the value of the fine-structure constant of Delta alpha/alpha = (-5.4+/-1.2) 10^{-6} in the redshift range…
Murphy et al. (2003a, MNRAS, 345, 609) claim to find evidence of cosmological variations of the fine structure constant $\alpha$ in the spectra of intervening QSO absorption line systems. We find that this result is affected by systematic…
There are indications from the study of quasar absorption spectra that the fine structure constant $\alpha$ may have been measurably smaller for redshifts $z>2.$ Analyses of other data ($^{149}$Sm fission rate for the Oklo natural reactor,…
At redshifts z_abs < 2, quasar absorption-line constraints on space-time variations in the fine-structure constant, alpha, rely on the comparison of MgII and FeII transition wavelengths. One potentially important uncertainty is the relative…