Thursday, August 1, 2013

1307.8266 (S. A. Levshakov et al.)

Limits on the space-time variations of fundamental constants    [PDF]

S. A. Levshakov, C. Henkel, D. Reimers, P. Molaro
We report on new tests that improve our previous (2009-2010) estimates of the electron-to-proton mass ratio variation, mu = m_e/m_p. Subsequent observations (2011-2013) at the Effelsberg 100-m telescope of a sample of eight molecular cores from the Milky Way disk reveal systematic errors in the measured sky frequencies varying with an amplitude +/-0.01 km/s during the exposure time. The averaged offset between the radial velocities of the NH3(1,1), HC3N(2-1), HC5N(9-8), HC7N(16-15), HC7N(21-20), and HC7N(23-22) transitions gives Delta V = 0.002 +/- 0.015 km/s (3 sigma C.L.). This value, when interpreted in terms of Delta mu/mu = (mu_obs - mu_lab)/mu_lab constraints the mu-variation at the level of Delta mu/mu < 2x10^{-8} (3 sigma C.L.), which is the most stringent limit on the fractional changes in mu based on radio astronomical observations. If variation of the fine-structure constant alpha is coupled with mu, then within the grand unification model one may expect locally the spacial changes |Delta alpha/alpha| < 10^{-10} (1 sigma C.L.)-- a restriction four orders of magnitude tighter than that obtained from optical spectra of quasars.
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