PRECISION SPECTROSCOPY OF MOLECULAR HYDROGEN AND THE SEARCH FOR NEW PHYSICS

The hydrogen molecule is the smallest neutral chemical entity and a benchmark system of molecular spectroscopy. The comparison between highly accurate measurements of transition frequencies and level energies with quantum calculations including all known phenomena (relativistic, vacuum polarization and self energy) provides a tool to search for physical phenomena in the realm of the unknown: are there forces beyond the three included in the Standard Model of physics plus gravity [1], are there extra dimensions beyond the 3+1 describing space time [2] ? Comparison of laboratory wavelengths of transitions in hydrogen may be compared with the lines observed during the epoch of the early Universe to verify whether fundamental constants of Nature have varied over cosmological time [3]. These concepts, as well as the precision laboratory experiments and the astronomical observations used for such searches of new physics [4] will be discussed._x000d_ _x000d_ [1] E.J. Salumbides, J.C.J. Koelemeij, J. Komasa, K. Pachucki, K.S.E. Eikema, W. Ubachs, emph{Bounds on fifth forces from precision measurements on molecules}, Phys. Rev. D87, 112008 (2013)._x000d_ _x000d_ [2] E.J. Salumbides, A.N. Schellekens, B. Gato-Rivera, W. Ubachs_x000d_ emph{Constraints on extra dimensions from molecular spectroscopy},_x000d_ New. J. Phys. 17, 033015 (2015)._x000d_ _x000d_ [3] W. Ubachs, J. Bagdonaite, E.J. Salumbides, M.T. Murphy, L. Kaper,_x000d_ emph{Search for a drifting proton-electron mass ratio from H$_2$},_x000d_ Rev. Mod. Phys. 88, 021003 (2016)._x000d_ _x000d_ [4] W. Ubachs, J.C.J. Koelemeij, K.S.E. Eikema, E.J. Salumbides,_x000d_ emph{Physics beyond the Standard Model from hydrogen spectroscopy},_x000d_ J. Mol. Spectr. 320, 1 (2016)