Finding New Physics
Looking for New Physics in space using Spectroscopy
Keywords: Beyond Standard Model, Computational Chemistry, Rovibronic Spectroscopy
New theories of physics that attempt to unify gravity and the standard model of matter often predict variation in the proton-to-electron mass ratio. This variation can be measured astrophysically through transitions in molecules. CP, SiN and SiP are as yet unexplored astrophysical diatomic molecules that have the potential to be used as molecular probes of proton-to-electron mass variation. In this project, you will be creating a rovibronic line list of the energy levels and transition intensities for these molecules using sophisticated quantum chemistry packages and available experimental data. Beyond the primary objective, this data will also be used to look for these molecules in other astrophysical bodies such as stars, planets and exoplanets; the presence of unusual molecules give essential knowledge about the chemistry and physics of their environment (e.g. phosphine on Venus).
Using Molecular Spectroscopy to find New Physics
At its heart, fundamental physics has a problem: general relativity describing heavy objects and quantum mechanics (generalised to the standard model of matter) describing small objects do not work together and we cannot describe heavy small objects like black holes. The Large Hadron Collider has not yet produced new physics. Therefore, alternate experiments are imperative. One such experiment involves measuring whether the proton-to-electron mass ratio has varied over time or over space. Note that though this is a fundamental constant in our current understanding, many theories beyond the standard model predict variations – this variation can be measured through a shift in the spectral frequency of some transition frequencies. Spectroscopic measurements are the most accurate measurement humans can currently make and thus ideal for this high accuracy measurement. Measurement accuracy can be optimised by careful selection of a molecule and transition. Theoretical support is vital in both finding this molecule and transition, and in connecting a change in the observed spectroscopic measurement to a variation in this mass ratio.
This project will involve establishing a comprehensive set of criteria for a good target transition for experiments investigating proton-to-electron mass ratio variation for both astronomy and/or laboratory experiments. These criteria will then be applied to analyse the suitability of transitions in a small number of molecular systems.