Seminar Title: |
Searching for Chameleon-like Scalar Fields |
Speaker: |
Prof. Sergei Levshakov |
Affiliation: |
(Ioffe Physical-Technical Institute, St. Petersburg, Russia) |
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When: |
Wednesday Morning, Dec. 22th, 10:00 a.m |
Where: |
Room 327, Office Block, 2 West Beijing Road (PMO, CAS) |
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Welcome to Attend |
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( PMO Academic Committee & Academic Circulating committee) |
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Abstract
Using the 32-m Medicina, 45-m Nobeyama, and 100-m Effelsberg telescopes we found a statistically significant velocity offset ΔV =27 ± 3 m/s (1δ) between the inversion transition in NH3(1,1) and low-J rotational transitions in N2H+(1-0) and HC3N(2-1) arising in cold and dense molecular cores in the Milky Way. Systematic shifts of the line centers caused by turbulent motions and velocity gradients, possible non-thermal hyperfine structure populations, pressure and optical depth effects are shown to be lower than or about 1 m/s and thus can be neglected in the total error budget.
The reproducibility of ΔV at the same facility (Effelsberg telescope) on a year-to-year basis is found to be very good. Since the frequencies of the inversion and rotational transitions have different sensitivities to variations in the electron-to-proton mass ratio, μ = me/mp, the revealed non-zero ΔV may imply that μ changes when measured at high (terrestrial) and low (interstellar) matter densities as predicted by chameleon-like scalar field models - candidates to the dark energy carrier. Thus we are testing whether scalar field models have chameleon-type interactions with ordinary matter. The measured velocity offset corresponds to the ratio Δμ/μ= (μspace - μlab)/ μlab of (26 ± 3)×10-9 (1δ).