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12–17 Sept 2016
Szczecin, Poland
Europe/Warsaw timezone

Search for varying constants and new physics from molecular hydrogen

13 Sept 2016, 10:00
1h

Speaker

Wim Ubachs (VU University Amsterdam)

Description

The spectroscopy of molecular hydrogen can be used for a search into physics beyond the Standard Model. Differences between the absorption spectra of the Lyman and Werner bands of H2 as observed at high redshift and those measured in the laboratory can be interpreted in terms of possible variations of the proton-electron mass ratio μ=mp/me over cosmological history. Investigation of some ten of such absorbers in the redshift range z=2.04.2 yields a constraint of |Δμ/μ|<5×106 at 3σ, as was recently reported in a review [1]. Observation of H2 from the photospheres of white dwarf stars inside our Galaxy delivers a constraint of similar magnitude on a dependence of μ on a gravitational potential 104 times as strong as on the Earth's surface [2].

While such astronomical studies aim at finding quintessence in an indirect manner, laboratory precision measurements target such additional quantum fields in a direct manner. Laser-based precision measurements of dissociation energies, vibrational splittings and rotational level energies in H2 molecules and their deuterated isotopomers HD and D2 produce values for the rovibrational binding energies fully consistent with quantum ab initio calculations including relativistic and quantum electrodynamical (QED) effects [3]. Similarly, precision measurements of high-overtone vibrational transitions of HD+ ions, also result in transition frequencies fully consistent with calculations including QED corrections [4].
These comprehensive results of laboratory precision measurements on neutral and ionic hydrogen molecules can be interpreted to set bounds on the existence of possible fifth forces [5] and of higher dimensions [6], phenomena describing physics beyond the Standard Model.

[1] W. Ubachs, J. Bagdonaite, E.J. Salumbides, M.T. Murphy, L. Kaper, Rev. Mod. Phys. 88, 021003 (2016).

[2] J. Bagdonaite, E.J. Salumbides, S.P. Preval, M.A. Barstow, J.D. Barrow, M.T. Murphy, W. Ubachs, Phys. Rev. Lett. 113, 123002 (2014).

[3] W. Ubachs, J.C.J. Koelemeij, K.S.E. Eikema, E.J. Salumbides, J. Mol. Spectr. 320, 1 (2016).

[4] J. Biesheuvel, J.-Ph. Karr, L. Hilico, K.S.E. Eikema, W. Ubachs, J.C.J. Koelemeij, Nat. Comm. 7, 10385 (2016).

[5] E.J. Salumbides, J.C.J. Koelemeij, J. Komasa, K. Pachucki, K.S.E. Eikema, W. Ubachs,
Phys. Rev. D87, 112008 (2013).

[6] E.J. Salumbides, A.N. Schellekens, B. Gato-Rivera, W. Ubachs, New. J. Phys. 17, 033015 (2015).

Author

Wim Ubachs (VU University Amsterdam)

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