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A. W. Hauser

Publications and source records attributed to A. W. Hauser.

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Effect of alpha variation on the vibrational spectrum of Sr_2

We consider the effect of $α$ variation on the vibrational spectrum of Sr$_2$ in the context of a planned experiment to test the stability of $μ\equiv m_e/m_p$ using optically trapped Sr$_2$ molecules [Zelevinsky et al., Phys. Rev. Lett. {\bf 100}, 043201; Kotochigova et al., Phys. Rev. A {\bf 79}, 012504]. We find the prospective experiment to be 3 to 4 times less sensitive to fractional variation in $α$ as it is to fractional variation in $μ$. Depending on the precision ultimately achieved by the experiment, this result may give justification for the neglect of $α$ variation or, alternatively, may call for its explicit consideration in the interpretation of experimental results.

physics.atom-ph

Rotational spectrum of molecular ion NH^+ as a probe for alpha- and m_e/m_p-variation

We identify the molecular ion NH^+ as a potential candidate for probing variations in the fine structure constant alpha and electron-to-proton mass ratio mu. NH^+ has an anomalously low-lying excited Sigma state, being only a few hundred cm^-1 above the ground Pi state. Being a light molecule, this proximity is such that rotational levels of the respective states are highly intermixed for low angular momenta. We find that several low-frequency transitions within the collective rotational spectrum experience enhanced sensitivity to alpha- and mu-variation. This is attributable to the close proximity of the Pi and Sigma states, as well as the ensuing strong spin-orbit coupling between them. Suggestions that NH^+ may exist in interstellar space and recent predictions that trapped-ion precision spectroscopy will be adaptable to molecular ions make NH^+ a promising system for future astrophysical and laboratory studies of alpha- and mu-variation.

physics.atom-ph