Computational molecular spectroscopy towards new physics
Abstract
There is a divide in physics, a chasm between the physics of the small (quantum mechanics and the Standard Model of Matter) and the heavy (general relativity). Unifying these theories requires new fundamental physics theories, of which there are several competing theories. Astrophysical molecular spectroscopy is an important method of searching for new physics through probing the variation of the proton-to-electron mass ratio, $\mu$, with existing constraints limiting possible variation to a fractional change of less than 10$^{-17}$/year. Being able to more accurately measure the variation of the proton-to-electron mass ratio could revolutionise physics by allowing us to filter through the currently competing fundamental physics theories. To aid the improvement of existing measurements, we have computationally looked at rovibronic spectral transitions from 11 different diatomics and identified transitions that might allow a very high sensitivity measurement, if observable. This was done using spectroscopic models for these diatomics, along with the program DUO to solve the nuclear motion Schrodinger equation to produce high accuracy linelists. We utilise these high-level calculations to simulate a small shift in the proton-to-electron mass ratio, to determine key transitions. Most previous theoretical studies have focused on finding large sensitivity while not explicitly considering a range of other criteria that affects the sensitivity of the astrophysical measurement, for example; the intensity of the spectral line, its frequency, available telescopes and their resolution, and the molecule's astrophysical abundance. This insight has enabled screening of all astrophysical diatomics as potential probes of proton-to-electron mass variation, with CN, CP, SiN and SiC being the most promising candidates for further investigation for sensitivity in rovibronic transitions. Our ultimate goal is to determine the optimal molecules and spectral transitions of high astrophysical observations could be made to test whether the proton-to-electron mass ratio has changed over cosmological time.
- Publication:
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43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E2152S