Search for Cosmological -Variation from High-Redshift H 2 Absorption; A Status Report

Observations of H2 spectra in the line-of-sight of distant quasars may reveal a variation of the proton-electron mass ratioD mp=me at high redshift, typically for z >2 . Currently four high-quality systems (Q0347-383, Q0405-443, Q0528-250 and J2123-050) have been analyzed returning a constraint ��=� < 1 � 10 � 5 . We present data and a � -variation analysis of another system, Q2348- 011 at redshift zabs D 2:42, delivering ��=� D.� 1:5 ˙ 1:6/ � 10 � 5 . In addition to observational data the status of the laboratory measurements is reviewed. The future possibilities of deriving a competitive constraint on ��=� from the known high-redshift H2 absorbers is investigated, resulting in the identification of a number of potentially useful systems for detecting � -variation.