Improved measurement of the shape of the electron

By J. Hudson, Dhiren M. Kara, I. Smallman, B. Sauer, M. Tarbutt, E. Hinds. Nature, 2011

670 citations recorded by the source corpus.

The electron is predicted to be slightly aspheric, with a distortion characterized by the electric dipole moment (EDM), de. No experiment has ever detected this deviation. The standard model of particle physics predicts that de is far too small to detect, being some eleven orders of magnitude smaller than the current experimental sensitivity. However, many extensions to the standard model naturally predict much larger values of de that should be detectable. This makes the search for the electron EDM a powerful way to search for new physics and constrain the possible extensions. In particular, the popular idea that new supersymmetric particles may exist at masses of a few hundred GeV/c2 (where c is the speed of light) is difficult to reconcile with the absence of an electron EDM at the present limit of sensitivity. The size of the EDM is also intimately related to the question of why the Universe has so little antimatter. If the reason is that some undiscovered particle interaction breaks the symmetry between matter and antimatter, this should result in a measurable EDM in most models of particle physics. Here we use cold polar molecules to measure the electron EDM at the highest level of precision reported so far, providing a constraint on any possible new interactions. We obtain de = (−2.4 ± 5.7stat ± 1.5syst) × 10−28e cm, where e is the charge on the electron, which sets a new upper limit of |de| < 10.5 × 10−28e cm with 90 per cent confidence. This result, consistent with zero, indicates that the electron is spherical at this improved level of precision. Our measurement of atto-electronvolt energy shifts in a molecule probes new physics at the tera-electronvolt energy scale.

Subfields: Instrumentation, Nuclear and High Energy Physics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/ad0c5db7c0648b106d1c5aefe0e9e8f286cafa38

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In Instrumentation

Igor G. Irastorza

In Nuclear and High Energy Physics

In Statistical and Nonlinear Physics

Citations in the corpus

New frontiers for quantum gases of polar molecules (2016, background): “Polar molecules are especially favorable for electron electric dipole moment searches because a small electric field in the lab produces a huge effective electric field in the molecule [105, 106, 107].”
Electric Dipole Moments of Nucleons, Nuclei, and Atoms: The Standard Model and Beyond (2013, background): “r strong coupling (evaluated at the scale ). For k= em Eq.(6.194) gives d f ˘sin˚ CPV m f MeV 1 TeV M 2 10 13 efm : (6.195) The present limit on the EDM of the electron, jd ej<10:5 10 15 efm [147] obtained from an experiment on the Yb-F molecule, then implies that jsin˚ CPVj. ( =2 TeV) 2 : (6.1”
Effective Lagrangian for a light Higgs-like scalar (2013, background): “In the lepton sector, the current measurements and SM predictions of the muon [43, 44] and electron [45, 46] anomalous magnetic moments and the limits on their EDMs [47–49] imply the following 95% probability bounds:”
Baryogenesis from the weak scale to the grand unification scale (2020, background): “The analysis of Espinosa et al. (2012) was carried out while assuming the upper bound (Hudson et al., 2011) de < 1.05× 10−27 e cm .”
Lepton number and flavour violation in TeV-scale left-right symmetric theories with large left-right mixing (2013, background): “(64) In addition, the experimental limit of |de| < 10 e cm [86] on the electric dipole moment of”
Physics beyond colliders at CERN: beyond the Standard Model working group report (2019, background): “Further improvements are expected soon from projects using these and also further molecules, such as YbF [147] and BaF [148] It is highly realistic to expect that within the coming decade sensitivities better than 10−30 ecm will be achieved for the EDM on the electron.”
Quantum transport and electroweak baryogenesis (2013, background): “pole moments that constrain new sources of CP violation. Often the induced electric 4 MODELS 36 dipole moments arise only at two loop. Still, current bounds on the electron EDM, de <1.05×10−27 ecm [63], and neutron EDM, dn <2.9×10−26 ecm [64], heavily constrain realistic models of electroweak ”
Electric dipole moments in two-Higgs-doublet models (2013, methodology): “The combination with previous measurements, performed with thallium (Tl) atoms and ytterbium fluoride (YbF) molecules [72, 73] allows for a model-independent determination of the electron EDM, which improves significantly using in addition information from the mercury (Hg) system [23], see figure 1.”
Electric dipole moments of atoms, molecules, nuclei, and particles (2017, methodology): “Our YbF molecular beam, illustrated in Fig.”
Measuring the electric dipole moment of the electron in BaF (2018, methodology): “to be discovered particles and the eEDM value in dierent types of models is illustrated in Fig. 1. The blue and green lines show the limits on the eEDM set by experiments with molecular beams of YbF [7] and ThO [8], respectively. The purple line shows the limit aimed at in our experiment with BaF. I”
Search for New Physics with Atoms and Molecules (2017, methodology): “Earlier experiments, one using a beam of YbF molecules (Hudson et al., 2011) and the other using side-by-side beams of both Tl and sodium (Na, Z=11) atoms (Regan et al.”