Measuring the electric dipole moment of the electron in BaF Aggarwal, Parul; Bethlem, Hendrick L.; Borschevsky, Anastasia ...
The European physical journal. D, Atomic, molecular, and optical physics,
11/2018, Letnik:
72, Številka:
11
Journal Article
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We investigate the merits of a measurement of the permanent electric dipole moment of the electron (
e
EDM) with barium monofluoride molecules, thereby searching for phenomena of
CP
violation beyond ...those incorporated in the standard model (SM) of particle physics. Although the BaF molecule has a smaller enhancement factor in terms of the effective electric field than other molecules used in current studies (YbF, ThO and ThF
+
), we show that a competitive measurement is possible by combining Stark-deceleration, laser-cooling and an intense primary cold source of BaF molecules. With the long coherent interaction times obtainable in a cold beam of BaF, a sensitivity of 5 × 10
−30
e⋅cm for an
e
EDM is feasible. We describe the rationale, the challenges and the experimental methods envisioned to achieve this target.
Graphical abstract
Frequency combs and cavity-enhanced optical techniques have revolutionized molecular spectroscopy: their combination allows recording saturated Doppler-free lines with ultrahigh precision. Network ...theory, based on the generalized Ritz principle, offers a powerful tool for the intelligent design and validation of such precision-spectroscopy experiments and the subsequent derivation of accurate energy differences. As a proof of concept, 156 carefully-selected near-infrared transitions are detected for H
O, a benchmark system of molecular spectroscopy, at kHz accuracy. These measurements, augmented with 28 extremely-accurate literature lines to ensure overall connectivity, allow the precise determination of the lowest ortho-H
O energy, now set at 23.794 361 22(25) cm
, and 160 energy levels with similarly high accuracy. Based on the limited number of observed transitions, 1219 calibration-quality lines are obtained in a wide wavenumber interval, which can be used to improve spectroscopic databases and applied to frequency metrology, astrophysics, atmospheric sensing, and combustion chemistry.
The standard model of physics is built on the fundamental constants of nature, but it does not provide an explanation for their values, nor require their constancy over space and time. Here we set a ...limit on a possible cosmological variation of the proton-to-electron mass ratio μ by comparing transitions in methanol observed in the early universe with those measured in the laboratory. From radio-astronomical observations of PKS1830-211, we deduced a constraint of Δμ/μ = (0.0 ± 1.0) × 10 -7 at redshift z = 0.89, corresponding to a look-back time of 7 billion years. This is consistent with a null result.
Abstract
A Grüneisen relationship is defined for gases, following the formulation of the original microscopic Grüneisen ratio
γ
= (d ln
ω
)/(d ln
V
) for solids. In the case of gases acoustic ...excitations represent the modes at frequency
ω
to be considered. By comparing to measured Brillouin shifts in various gases (SF
6
, N
2
O, and CO
2
) under various conditions of pressure and temperature, a specific value of the defined ratio
γ
0
= 0.064 ± 0.004 is found to provide a universal description of the active modes in a gas. This finding of such universal gas law may find application in extrapolation of properties of ideal gases to regimes where those cannot be measured easily, like the acoustics and shocks at extremely high temperatures.
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