The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Hendrick L. Bethlem - One of the best experts on this subject based on the ideXlab platform.
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On a variation of the proton-Electron Mass ratio
2017Co-Authors: Wim Ubachs, Hendrick L. Bethlem, R. Buning, Edcel J. Salumbides, S. Hannemann, D. Bailly, M. Vervloet, Lex Kaper, Michael T. MurphyAbstract:Recently indication for a possible variation of the proton-to-Electron Mass ratio μ=mp/me was found from a comparison between laboratory H2 spectroscopic data and the same lines in quasar spectra. This result will be put in perspective of other spectroscopic activities aiming at detection of variation of fundamental constants, on a cosmological as well as on a laboratory time scale. Furthermore the opportunities for obtaining improved laboratory wavelength positions of the relevant H2 absorption lines, as well as the prospects for obtaining a larger data set of H2 absorptions at high redshift will be presented. Also an experiment to detect Δμ on a laboratory time scale will be discussed.
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Constraints on changes in the proton–Electron Mass ratio using methanol lines
Monthly Notices of the Royal Astronomical Society, 2015Co-Authors: Nissim Kanekar, Wim Ubachs, Karl M. Menten, Julija Bagdonaite, Andreas Brunthaler, Christian Henkel, Sebastien Muller, Hendrick L. Bethlem, M. DapraAbstract:We report Karl G. Jansky Very Large Array (VLA) absorption spectroscopy in four methanol (CH3OH) lines in the z = 0.885 82 gravitational lens towards PKS1830-211. Three of the four lines have very different sensitivity coefficients K-mu to changes in the proton-Electron Mass ratio mu; a comparison between the line redshifts thus allows us to test for temporal evolution in mu. We obtain a stringent statistical constraint on changes in mu by comparing the redshifted 12.179 and 60.531 GHz lines, [Delta mu/mu] 4 sigma significance). The sensitivity of the above result, and that of all earlier CH3OH studies, is thus likely to be limited by unknown systematic errors, probably arising due to the frequency-dependent structure of PKS1830-211. A robust result is obtained by combining the three lines at similar frequencies, 48.372, 48.377 and 60.531 GHz, whose line profiles are found to be in good agreement. This yields the 2 sigma constraint [Delta mu/mu] less than or similar to 4 x 10(-7), the most stringent current constraint on changes in mu. We thus find no evidence for changes in the proton-Electron Mass ratio over a lookback time of approximate to 7.5 Gyr.
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constraints on changes in the proton Electron Mass ratio using methanol lines
Monthly Notices of the Royal Astronomical Society, 2015Co-Authors: Nissim Kanekar, Wim Ubachs, Karl M. Menten, Julija Bagdonaite, Andreas Brunthaler, Christian Henkel, Sebastien Muller, Hendrick L. Bethlem, M. DapraAbstract:We report Karl G. Jansky Very Large Array (VLA) absorption spectroscopy in four methanol (CH3OH) lines in the z = 0.885 82 gravitational lens towards PKS1830-211. Three of the four lines have very different sensitivity coefficients K-mu to changes in the proton-Electron Mass ratio mu; a comparison between the line redshifts thus allows us to test for temporal evolution in mu. We obtain a stringent statistical constraint on changes in mu by comparing the redshifted 12.179 and 60.531 GHz lines, [Delta mu/mu] 4 sigma significance). The sensitivity of the above result, and that of all earlier CH3OH studies, is thus likely to be limited by unknown systematic errors, probably arising due to the frequency-dependent structure of PKS1830-211. A robust result is obtained by combining the three lines at similar frequencies, 48.372, 48.377 and 60.531 GHz, whose line profiles are found to be in good agreement. This yields the 2 sigma constraint [Delta mu/mu] less than or similar to 4 x 10(-7), the most stringent current constraint on changes in mu. We thus find no evidence for changes in the proton-Electron Mass ratio over a lookback time of approximate to 7.5 Gyr.
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Sensitivity to a possible variation of the proton-to-Electron Mass ratio torsion-wagging-rotation transitions in methylamine CH3NH2
Physical Review A, 2012Co-Authors: Vadim V. Ilyushin, Wim Ubachs, Paul Jansen, Mikhail G. Kozlov, Sergei A. Levshakov, Isabelle Kleiner, Hendrick L. BethlemAbstract:We determine the sensitivity to a possible variation of the proton-to-Electron Mass ratio μ for torsion-wagging-rotation transitions in the ground state of methylamine (CH
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methanol as a sensitive probe for spatial and temporal variations of the proton to Electron Mass ratio
Physical Review Letters, 2011Co-Authors: Paul Jansen, I Kleiner, W Ubachs, Hendrick L. BethlemAbstract:The 6.7 and 12.2 GHz masers, corresponding to the 5(1) → 6(0)A+ and 2(0) → 3(-1)E transitions in methanol (CH3OH), respectively, are among the brightest radio objects in the sky. We present calculations for the sensitivity of these and other transitions in the ground state of methanol to a variation of the proton-to-Electron Mass ratio. We show that the sensitivity is greatly enhanced due to a cancellation of energies associated with the hindered internal rotation and the overall rotation of the molecule. We find sensitivities of K(μ) = -42 and K(μ) = -33, for the 5(1) → 6(0)A+ and 2(0) → 3(-1)E transitions, respectively. The sensitivities of other transitions in the different isotopologues of methanol range from -88 to 330. This makes methanol a sensitive probe for spatial and temporal variations of the proton-to-Electron Mass ratio.
Paul Jansen - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity to a possible variation of the proton-to-Electron Mass ratio torsion-wagging-rotation transitions in methylamine CH3NH2
Physical Review A, 2012Co-Authors: Vadim V. Ilyushin, Wim Ubachs, Paul Jansen, Mikhail G. Kozlov, Sergei A. Levshakov, Isabelle Kleiner, Hendrick L. BethlemAbstract:We determine the sensitivity to a possible variation of the proton-to-Electron Mass ratio μ for torsion-wagging-rotation transitions in the ground state of methylamine (CH
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methanol as a sensitive probe for spatial and temporal variations of the proton to Electron Mass ratio
Physical Review Letters, 2011Co-Authors: Paul Jansen, I Kleiner, W Ubachs, Hendrick L. BethlemAbstract:The 6.7 and 12.2 GHz masers, corresponding to the 5(1) → 6(0)A+ and 2(0) → 3(-1)E transitions in methanol (CH3OH), respectively, are among the brightest radio objects in the sky. We present calculations for the sensitivity of these and other transitions in the ground state of methanol to a variation of the proton-to-Electron Mass ratio. We show that the sensitivity is greatly enhanced due to a cancellation of energies associated with the hindered internal rotation and the overall rotation of the molecule. We find sensitivities of K(μ) = -42 and K(μ) = -33, for the 5(1) → 6(0)A+ and 2(0) → 3(-1)E transitions, respectively. The sensitivities of other transitions in the different isotopologues of methanol range from -88 to 330. This makes methanol a sensitive probe for spatial and temporal variations of the proton-to-Electron Mass ratio.
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Methanol as a sensitive probe for spatial and temporal variations of the proton-to-Electron Mass ratio.
Physical Review Letters, 2011Co-Authors: Paul Jansen, Wim Ubachs, Isabelle Kleiner, Hendrick L. BethlemAbstract:The 6.7 and 12.2 GHz masers, corresponding to the 5{sub 1}{yields}6{sub 0}A{sup +} and 2{sub 0}{yields}3{sub -1}E transitions in methanol (CH{sub 3}OH), respectively, are among the brightest radio objects in the sky. We present calculations for the sensitivity of these and other transitions in the ground state of methanol to a variation of the proton-to-Electron Mass ratio. We show that the sensitivity is greatly enhanced due to a cancellation of energies associated with the hindered internal rotation and the overall rotation of the molecule. We find sensitivities of K{sub {mu}=}-42 and K{sub {mu}=}-33, for the 5{sub 1}{yields}6{sub 0}A{sup +} and 2{sub 0}{yields}3{sub -1}E transitions, respectively. The sensitivities of other transitions in the different isotopologues of methanol range from -88 to 330. This makes methanol a sensitive probe for spatial and temporal variations of the proton-to-Electron Mass ratio.
W Ubachs - One of the best experts on this subject based on the ideXlab platform.
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analysis of molecular hydrogen absorption toward qso b0642 5038 for a varying proton to Electron Mass ratio
The Astrophysical Journal, 2014Co-Authors: Julija Bagdonaite, Michael T. Murphy, W Ubachs, J B WhitmoreAbstract:Rovibronic molecular hydrogen (H2) transitions at redshift z abs 2.659 toward the background quasar B0642–5038 are examined for a possible cosmological variation in the proton-to-Electron Mass ratio μ. We utilize an archival spectrum from the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph (UVES) with a signal-to-noise ratio of ~35 per 2.5 km s–1 pixel at the observed H2 wavelengths (335-410 nm). Some 111 H2 transitions in the Lyman and Werner bands have been identified in the damped Lyα system for which a kinetic gas temperature of ~84 K and a molecular fraction log f = –2.18 ± 0.08 are determined. The H2 absorption lines are included in a comprehensive fitting method, which allows us to extract a constraint on a variation of the proton-Electron Mass ratio Δμ/μ from all transitions at once. We obtain Δμ/μ = (17.1 ± 4.5stat ± 3.7sys) × 10–6. However, we find evidence that this measurement has been affected by wavelength miscalibration errors recently identified in UVES. A correction based on observations of objects with solar-like spectra gives a smaller Δμ/μ value and contributes to a larger systematic uncertainty: Δμ/μ = (12.7 ± 4.5stat ± 4.2sys) × 10–6.
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methanol as a sensitive probe for spatial and temporal variations of the proton to Electron Mass ratio
Physical Review Letters, 2011Co-Authors: Paul Jansen, I Kleiner, W Ubachs, Hendrick L. BethlemAbstract:The 6.7 and 12.2 GHz masers, corresponding to the 5(1) → 6(0)A+ and 2(0) → 3(-1)E transitions in methanol (CH3OH), respectively, are among the brightest radio objects in the sky. We present calculations for the sensitivity of these and other transitions in the ground state of methanol to a variation of the proton-to-Electron Mass ratio. We show that the sensitivity is greatly enhanced due to a cancellation of energies associated with the hindered internal rotation and the overall rotation of the molecule. We find sensitivities of K(μ) = -42 and K(μ) = -33, for the 5(1) → 6(0)A+ and 2(0) → 3(-1)E transitions, respectively. The sensitivities of other transitions in the different isotopologues of methanol range from -88 to 330. This makes methanol a sensitive probe for spatial and temporal variations of the proton-to-Electron Mass ratio.
Anne Amy-klein - One of the best experts on this subject based on the ideXlab platform.
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Stability of the proton-to-Electron Mass ratio.
Physical Review Letters, 2008Co-Authors: Alexander Shelkovnikov, Christian Chardonnet, Robert James Butcher, Anne Amy-kleinAbstract:We report a limit on the fractional temporal variation of the proton-to-Electron Mass ratio as (1/(m{sub P}/m{sub e}))({partial_derivative}/{partial_derivative}t)(m{sub P}/m{sub e})=(-3.8{+-}5.6)x10{sup -14} yr{sup -1}, obtained by comparing the frequency of a rovibrational transition in SF{sub 6} with the fundamental hyperfine transition in Cs. The SF{sub 6} transition was accessed using a CO{sub 2} laser to interrogate spatial 2-photon Ramsey fringes. The atomic transition was accessed using a primary standard controlled with a Cs fountain. This result is direct and model-free.
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Stability of the proton-to-Electron Mass ratio
Physical Review Letters, 2008Co-Authors: Alexander Shelkovnikov, Robert James Butcher, Christian Chardonnet, Anne Amy-kleinAbstract:We report a limit on the fractional temporal variation of the proton-to-Electron Mass ratio as , obtained by comparing the frequency of a rovibrational transition in SF6 with the fundamental hyperfine transition in Cs. The SF6 transition was accessed using a CO2 laser to interrogate spatial 2-photon Ramsey fringes. The atomic transition was accessed using a primary standard controlled with a Cs fountain. This result is direct and model-free.
Florence Boillot - One of the best experts on this subject based on the ideXlab platform.
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Electron Mass Predicted From Substructure Stability in Electrodynamical Model
Frontiers in Physics, 2020Co-Authors: Stéphane Avner, Florence BoillotAbstract:Modern physics has characterized spacetime, the interactions between particles, but not the nature of the particles themselves. Previous models of the Electron have not specified its substance nor justified its cohesion. Here we present a relativistic electrodynamical model of the Electron at rest, founded on natural interpretations of observables. Essentially intertwined positively and negatively charged subparticles revolve at light velocity in coplanar circular orbits, forming some coherent "envelope"and "nucleus", possibly responsible for its wavelike and corpuscular behaviors, respectively. We show that the model can provide interpretations of fundamental constants, satisfy the Virial theorem, and exhibit cohesion and stability without invoking Poincare stresses. Remarkably, the stability condition allows predicting Electron Mass, regarded as being a manifestation of its total (kinetic and potential) electromagnetic cohesion energy, and muon Mass, directly from the substructure. Our study illustrates the possibility of constructing causal and objectively realist models of particles beneath the Compton scale. Finally, wave-corpuscle duality and the relation to quantum mechanics are discussed in the light of our Electron model.