Search for cosmological mu variation from high redshift H2 absorption; a status report

TL;DR

This paper reports on the analysis of high-redshift quasar spectra to detect possible variations in the proton-electron mass ratio, presenting new data, reviewing laboratory measurements, and identifying promising systems for future constraints.

Contribution

It provides new measurements of mu variation at high redshift, reviews laboratory data, and identifies potential systems for improved future constraints.

Findings

Measured dmu/mu = (-1.5 ± 1.6) x 10^{-5} for system Q2348-011

Reviewed laboratory measurements relevant to mu variation

Identified promising high-redshift systems for future studies

Abstract

Observations of H2 spectra in the line-of-sight of distant quasars may reveal a variation of the proton-electron mass ratio mu=m_p/m_e at high redshift, typically for z>2. Currently four high-quality systems (Q0347-383, Q0405-443, Q0528-250 and J2123-005) have been analyzed returning a constraint Dmu/mu < 1 x 10^{-5}. We present data and a mu-variation analysis of another system, Q2348-011 at redshift z_{abs}=2.42, delivering dmu/mu = (-1.5 \pm 1.6) x 10^{-5}. In addition to observational data the status of the laboratory measurements is reviewed. The future possibilities of deriving a competitive constraint on Dmu/mu from the known high-redshift H2 absorbers is investigated, resulting in the identification of a number of potentially useful systems for detecting mu-variation.