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A stringent constraint on the fractional change of proton g-factor

Renzhi Su, Stephen J. Curran, Jeremy Darling, Minfeng Gu, J. N. H. S. Aditya, Ningyu Tang, Di Li, Zheng Zheng

TL;DR

This study targets cosmological changes in the proton g-factor $g_p$ by comparing HI $21$ cm and OH $18$ cm line redshifts toward PKS 1413+135 at $z=0.24671$ using FAST. Leveraging simultaneous HI and OH observations, the authors derive stringent constraints on $\frac{\Delta g_p}{g_p}$ and on combinations involving $\alpha$ and $\mu$, finding results consistent with no variation over ~2.9 Gyr. The work dramatically improves prior limits by over two orders of magnitude and demonstrates the efficacy of multi-transition, high-SNR spectroscopy for probing fundamental constants, with strong implications for grand unified theories and future SKA-era measurements.

Abstract

We report a constraint on the cosmological variation of the proton g-factor, $g_p$. By comparing the measured redshifts between \mbox{H\,{\sc i}} 21 cm and OH 18 cm lines observed with the newly commissioned Five-hundred-meter Aperture Spherical radio Telescope (FAST) toward PKS 1413+135 at $z$ = 0.24671, we obtain $Δg_{p}/g_{p} = (-4.3\pm2.5)\times10^{-5}$, which is more than two orders of magnitude more sensitive than previous constraints. In addition, we obtain sensitive constraints of $Δ(μα^{2})/(μα^{2}) = (2.0\pm1.2)\times10^{-5}$ and $Δ(μα^{2}g_{p}^{0.64})/(μα^{2}g_{p}^{0.64}) = (-4.7\pm1.9)\times10^{-6}$.

A stringent constraint on the fractional change of proton g-factor

TL;DR

This study targets cosmological changes in the proton g-factor by comparing HI cm and OH cm line redshifts toward PKS 1413+135 at using FAST. Leveraging simultaneous HI and OH observations, the authors derive stringent constraints on and on combinations involving and , finding results consistent with no variation over ~2.9 Gyr. The work dramatically improves prior limits by over two orders of magnitude and demonstrates the efficacy of multi-transition, high-SNR spectroscopy for probing fundamental constants, with strong implications for grand unified theories and future SKA-era measurements.

Abstract

We report a constraint on the cosmological variation of the proton g-factor, . By comparing the measured redshifts between \mbox{H\,{\sc i}} 21 cm and OH 18 cm lines observed with the newly commissioned Five-hundred-meter Aperture Spherical radio Telescope (FAST) toward PKS 1413+135 at = 0.24671, we obtain , which is more than two orders of magnitude more sensitive than previous constraints. In addition, we obtain sensitive constraints of and .

Paper Structure

This paper contains 9 sections, 5 equations, 2 figures.

Table of Contents

  1. Introduction
  2. Observations and data reduction
  3. Spectra and redshift measurements
  4. Systematic errors
  5. Evolution of fundamental constants
  6. Summary
  7. Acknowledgements
  8. Conflict of interest
  9. Data availability

Figures (2)

  • Figure 1: The FAST H i and OH spectra in the source rest frame with respect to $z$ = 0.24671. The dotted lines show the Gaussian fits. While the OH lines are fitted with single Gaussian profile, the H i line is best fit with four, labeled as H i-g1, H i-g2, H i-g3 and H i-g4 with decreasing peak absorption.
  • Figure 2: Overlay of the H i and OH spectra shifted to the source rest frame. The strength of 1612, 1720 and H i lines are divided by a factor of 4, -4 and 400, respectively. The inset shows the sum of the 1612 and 1720 lines, with the red vertical lines marking the range of the absorption which is consistent with the noise, as expected from the conjugate nature.