Determination of the Scalar and Vector Polarizabilities of the Cesium 6sS21/2→

Abstract

Using recent high-precision measurements of electric dipole matrix elements of atomic cesium, we make an improved determination of the scalar (α) and vector (β) polarizabilities of the cesium 6s 2 S 1/2 → 7s 2 S 1/2 transition calculated through a sum-over-states method. We report values of α = −268.82 (30) a 3 0 and β = 27.139 (42) a 3 0 with the highest precision to date. We find a discrepancy between our value of β and the past preferred value, resulting in a significant shift in the value of the weak charge Qw of the cesium nucleus. Future work to resolve the differences in the polarizability will be critical for interpretation of parity non-conservation measurements in cesium, which have implications for physics beyond the Standard Model.

Global fits of the SM parameters

“…Another change affected the extraction from the APV measurement in 133 Cs [15], for which the Stark vector transition polarizability needs to be known. The latter has been re-measured [21] very recently, shifting |Q W ( 133 Cs)| which was 1.4 σ lower than what was expected from the SM much closer to the prediction (see the lower part of Figure 1).…”

First-generation new physics in simplified models: from low-energy parity violation to the LHC

“…Experimentally, the ratio of the PV amplitude over the Stark vector transition polarizability β is measured (with the most precise results currently available for 133 Cs [112,113]), which then needs to be combined with atomic-theory calculations and independent input for β. The latter can be determined semi-empirically either via a measurement together with another hyperfine amplitude [114,115] or the scalar polarizability [116][117][118], leading to the recommendation β = 27.064 (25) exp (21) th a 3 B [88] in units of the Bohr radius a B , but the uncertainty of this average does not include an error inflation to account for the 2.7σ tension between the two methods. Similarly, the coefficient of the atomic structure calculation has been under debate in the literature [119][120][121][122][123][124], with ref.…”

Testing the Standard Model at the Precision Frontier with the Qweak Experiment

“…We note that the authors of [10] have recently reported using new precision data and an alternate technique to determine the vector polarizability β needed to extract the (APV) weak charge of cesium. Their result differs from the currently accepted value of β, which shifts the extracted weak charge of cesium (and thus the corresponding sin 2̂) closer to the SM value than shown in Figure 4.…”