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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - NEWPHYS-MOLECULES (Probing Physics beyond the Standard Model from Molecules)

Teaser

Summary

The Standard Model of physics is incomplete. Gravity is not understood at the quantum level, dark matter and dark energy are not explained, and (string)-theories searching to cover these shortcomings are only consistent in higher-dimensional spaces, while only four of those dimensions are observed. The mystery of finely tuned strengths of the fundamental forces, providing us with a Universe of complexity, remains unexplained. This calls for new physics that can be explored also at the atomic scale in the low energy domain. That is the paradigm underlying the present proposal: Effects of new physics - either related to hitherto unknown particles or to symmetry-breaking phenomena - will manifest themselves as minute shifts in the quantum level structures of atoms and molecules, in minute drifts over time or dependencies on environmental conditions.

I propose to perform precision metrology measurements on the H2 molecule in a search for new physics. Deviations between experimental results and QED-theory will scan unexplored territory beyond the Standard Model. Molecular metrology results of the fundamental ground tone vibration in H2 will be confronted with QED-theory calculations to search for the existence of new forces at the Angstrom length scale. If extra dimensions beyond the known 3+1 would be compactified at the same length scale of 1 A, this would lead to strongly enhanced gravitational effects, measurable in a molecule. Our current research on experimental probes for varying constants on a cosmological time scale, is redirected into the investigation of chameleon scenarios: by studying H2 molecules in white dwarf stars by uv-astronomy, and by studying methanol molecules in our own galaxy by radio astronomy, searching for a possible dependence of fundamental constants on strong gravity or on density.

If any of these targeted phenomena could be uncovered, it would have great impact on science as a whole, and on our view on the Universe and its origin.

Work performed

\"Precision measurements on the hydrogen molecule, on H2 and its isotopologues are being investigated. Results have been obtained in three directions:
1) The dissociation energy of the H2 molecule has recently been measured to an accuracy of one part-per-billion, hence seven orders of magnitude more accurate than the first measurement about a century ago. The measurements was made possible by performing a pulsed laser experiment at a short wavelength (179 nm), that could be prodiced by implementing a special KBBF crystal in the setup, obtained via a collaboration with a grouo from China.
2) An infrared transition in the HD molecule has been measured a thousand times more accurate then previously. For this an entirely new measurement setup has been built allowing us to measure a \"\"Lamb-dip\"\" so that the Doppler effect could be nullified in a laser experiment.
3) For the first time laser precision measurements could be performed on Tritium molecules, a special form of havy hydrogen. these measurements were made possible through a collaboration with the Tritium Laboratory at KIT-Karsruhe.
The measured values are all more accurate than their theoretical evaluation and the results have spurred activity by theorists, now performing calculations on the hydrogen isotopes, including relativistic and QED effects. A comparison between the highly accurate experiments and the new calculatiosn being performed might produce hints of new physics beyond the Standard Model, if any discrepancies between the two would be revealed.\"