An improved bound on the electron’s electric dipole moment

Abstract

The imbalance of matter and antimatter in our Universe provides compelling motivation to search for undiscovered particles that violate charge-parity symmetry. Interactions with vacuum fluctuations of the fields associated with these new particles will induce an electric dipole moment of the electron (eEDM). We present the most precise measurement yet of the eEDM using electrons confined inside molecular ions, subjected to a huge intramolecular electric field, and evolving coherently for up to 3 seconds. Our result is consistent with zero and improves on the previous best upper bound by a factor of ~2.4. Our results provide constraints on broad classes of new physics above 10 13 electron volts, beyond the direct reach of the current particle colliders or those likely to be available in the coming decades.

Experimental perspectives on the matter–antimatter asymmetry puzzle: developments in electron EDM and H¯ experiments

“…[61]. However, thanks to the work of J. D. Weinstein's group, on alkali atoms in para hydrogen, Ne and Ar matrix [62][63][64] there has been renewed interest in using matrix isolation spectroscopy for EDM searches [19]. Indeed, recent achievements regarding high dopant density approximately 1 × 10 18 cm 3 , while maintaining long spin coherence time (as long as 0.1 s) and good optical pumping capacity, are all very positive first steps toward an initial EDM measurement or spin alignment [65][66][67][68].…”

“…While its HfF + measurement holds since recently the tightest bound on an eEDM, i.e. |d e | < 4.1 × 10 −30 e cm [19,20], the next generation JILA experiment will replace HfF + with ThF + . This is motivated by the higher Z in (radioactive) Th and, thus, larger E eff as well as a longer coherence time reflecting that the EDM sensitivity is found in the electronic ground state of the molecule [21].…”

Fundamental Physics with the Thermodynamically Stable Diatomic Trication UF3+

“…This renders UF 3+ and similar systems with simpler electronic structure [3] interesting candidates for the search for $${P,T}$$ ‐violation in the nucleus. The high charge could be advantageous in trapping experiments and the open‐shells could be favorable for polarisation [21,45] of this molecule. The possibility of subsequent laser cooling has to be analysed in order to pave the way for high‐precision spectroscopy.…”

“…The high sensitivity to an eEDM stems from the orbital of high s character, which is polarized by admixture of p$${{}_{1/2}}$$ , as the eEDM interaction is very short‐ranged and requires electron density in the vicinity of the nucleus. Recently the ThO experiment was outperformed by an experiment with HfF + , which resembles the electronic structure of ThO and has an eEDM sensitive meta‐stable $${{}^{3}{{\rm \Delta }}_{1}}$$ state as well [21] . This HfF + experiment shall in future be improved by using the heavier ThF + , which is isoelectronic to ThO but in which the sensitive $${{}^{3}{{\rm \Delta }}_{1}}$$ state forms the electronic ground state [22–24] …”

The cosmological constant and scale hierarchies with emergent gauge symmetries

“…Other ideas relating the sizes of the cosmological constant scale and neutrino mass are discussed in[92][93][94] 7. This measurement of H 0 from the cosmic microwave background is in tension with recent late-time, low-redshift measurements[95] which give a value of H 0 about 0.73 km s −1 Mpc −1 -a present open puzzle in cosmology 8. Axions are a candidate to explain the strong CP puzzle (why gluon topological effects do not induce extra CP violation in QCD)[107][108][109] though this might also be associated with confinement related phenomena[110].…”