Precise spectroscopy of the antihydrogen atom for comparison to it’s matter counternpart, the hydrogen atom, is motivated by searches for New Physics in particular to shed light on the baryon assymetry puzzle. CPT symmetry, the combination of the three discrete symmetries: Charge conjugation, Parity, and Time reversal, dictates hydrogen and antihydrogen spectra to be identical.
Precise comparisons of antihydrogen and hydrogen spectra are thus powerful methods to test CPT invariance; a cornerstone of quantum field theory, which, if found to be violated, would be a definite sign of New Physics.
The Standard Model Extension (SME), an effective field theory that generalises the Standard Model (SM) Lagrangian by adding terms violating CPT and Lorentz symmetry, constitues a framework that allows the comparison of different experimental constraints. In this context, the precise measurement of the antihydrogen ground state hyperfine splitting (H̄ GSHFS) has the potential to provide the most stringent test of CPT symmetry.
The ASACUSA collaboration proposed the measurement of the H̄ GSHFS in a beam. Unlike other proposed measurements in a magnetic trap, the Rabi-type beam method allows for measurements at very low and controlled magnetic fields. We have developed and tested with hydrogen a H̄ Rabi-spectrometer that reached an absolute precision of 3.8 Hz on the 1.42 GHz transition. I will report on new measurements which improved on this result and allowed to puts first constraints on a set of coefficients of the Standard Model Extension, which were not measured by previous experiments.
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Test of CPT and Lorentz invariance with a cold (anti)hydrogen beam
Precise spectroscopy of the antihydrogen atom for comparison to it’s matter counternpart, the hydrogen atom, is motivated by searches for New Physics in particular to shed… (more)