# Strong Limit on a Variable Proton-to-Electron Mass Ratio from Molecules in the Distant Universe

@article{Murphy2008StrongLO,
title={Strong Limit on a Variable Proton-to-Electron Mass Ratio from Molecules in the Distant Universe},
author={Michael T. Murphy and Victor V. Flambaum and S{\'e}bastien Muller and Christian Henkel},
journal={Science},
year={2008},
volume={320},
pages={1611 - 1613}
}
• Published 18 June 2008
• Physics
• Science
The Standard Model of particle physics assumes that the so-called fundamental constants are universal and unchanging. Absorption lines arising in molecular clouds along quasar sightlines offer a precise test for variations in the proton-to-electron mass ratio, μ, over cosmological time and distance scales. The inversion transitions of ammonia are particularly sensitive to μ as compared to molecular rotational transitions. Comparing the available ammonia spectra observed toward the quasar B0218…
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## References

SHOWING 1-10 OF 48 REFERENCES
The kinetic temperature of a molecular cloud at redshift 0.7: ammonia in the gravitational lens B0218+357
Context. Little is known about the structure of the interstellar medium and the nature of individual clouds in galaxies at intermediate redshifts. The gravitational lens toward PKS 1830–211 offers
Astronomical constraints on the cosmic evolution of the fine structure constant and possible quantum dimensions.
• Physics
Physical review letters
• 2000
Measurements of absorption by the 21 cm hyperfine transition of neutral hydrogen toward radio sources at substantial look-back times are presented to set limits on the evolution of the fine structure constant.
Constraining variations in the fine-structure constant, quark masses and the strong interaction
• Physics
• 2003
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 1.8). Our most robust estimate is a weighted
Indication of a cosmological variation of the proton-electron mass ratio based on laboratory measurement and reanalysis of H2 spectra.
• Physics
Physical review letters
• 2006
A new set of sensitivity coefficients K(i) is derived for all lines in the H2 spectrum, representing the dependence of their transition wavelengths on a possible variation of the proton-electron mass ratio mu, indicating that mu could have decreased in the past 12 Gyr.
Limit on the cosmological variation of mp/me from the inversion spectrum of ammonia.
• Physics
Physical review letters
• 2007
We obtain the limit on the space-time variation of the ratio of the proton mass to the electron mass, mu=m(p)/m(e), based on comparison of quasar absorption spectra of NH3 with CO, HCO+ and HCN
A new constraint on the time dependence of the proton-to-electron mass ratio - Analysis of the Q 0347-383 and Q 0405-443 spectra
• Physics
• 2005
A new limit on the possible cosmological variation of the proton-to-electron mass ratio $\mu=m_{\rm p}/m_{\rm e}$ is estimated by measuring wavelengths of H 2 lines of Lyman and Werner bands from two
Probing the cosmological variation of the fine - structure constant: Results based on VLT - UVES sample
• Physics
• 2004
Development of fundamental physics relies on the constancy of various fundamental quantities such as the fine- structure constant. Detecting or constraining the possible time variations of these
Redshifted formaldehyde from the gravitational lens B0218+357
• Physics
• 2007
Context. Little is known about individual molecular clouds at high redshifts. The gravitational lens toward B0218+357 offers the unique possibility to study cool moderately dense gas with high
Neutral hydrogen 21 centimeter absorption at Z = 0.6847 toward the 'smallest Einstein ring'
• Physics
• 1993
We detect neutral hydrogen 21 cm absorption toward the smallest Einstein ring, 0218+357, at a redshift of 0.6847. The implied H I column density is N(H I)=4×10 18 (T s /f) cm −2 , where T s is the
Formaldehyde Absorption at z=0.685 toward the
• Physics
• 1996
We report VLA observations of absorption in the 211 → 212 transition of formaldehyde (H2CO) at a redshift of 0.68466 toward the Einstein ring gravitational lens system B0218+357. We observe the H2CO