Enhancement factor for the electric dipole moment of the electron in the BaOH and YbOH molecules

Abstract

Polyatomic polar molecules are promising systems for future experiments that search for violation of time-reversal and parity symmetries due to their advantageous electronic and vibrational structure, which allows laser cooling, full polarisation of the molecule, and reduction of systematic effects [I. Kozyryev and N.R. Hutzler, Phys, Rev. Lett. 119, 133002 (2017)]. In this work we investigate the enhancement factor of the electric dipole moment of the electron (E eff ) in the triatomic monohydroxide molecules BaOH and YbOH within the high-accuracy relativistic coupled cluster method. The recommended E eff values of the two systems are 6.65 ± 0.15 GV/cm and 23.4 ± 1.0 GV/cm, respectively. We compare our results with similar calculations for the isoelectronic diatomic molecules BaF and YbF, which are currently used in experimental search for P, T -odd effects in molecules. The E eff values prove to be very close, within about 1.5 % difference in magnitude between the diatomic and the triatomic compounds. Thus, BaOH and YbOH have a similar enhancement of the electron electric dipole moment, while benefiting from experimental advantages, and can serve as excellent candidates for next-generation experiments.

Enhanced P,T-violating nuclear magnetic quadrupole moment effects in laser-coolable molecules

“…Such an anomalous trend was already seen for another P, T -odd property, the eEDM enhancement factor (E eff ) in Ref. 9 , which also undergoes an increase and then a decrease upon enlarging the basis set. A possible explanation for the lack of saturation with respect to the basis set could be in that these basis set were not optimised for calculations of properties on the coupled cluster level.…”

“…Thus, one would naturally look for diatomic molecules already employed in eEDM experiments that contain heavy quadrupole-deformed nuclei. An alternative is to turn towards the analogous triatomic molecules that were recently identified as even more promising candidates for the search for P, T -odd interactions [8][9][10] . Due to their favourable vibrational structure, these molecules possess internal comagnetometer states and they can be fully polarised in comparatively low electric fields.…”

The Role of Relativistic Many-Body Theory in Electron Electric Dipole Moment Searches Using Cold Molecules

“…The result is similar to that of YbF. Also, there were two other works on linear geometry, at about the same time as ours on YbOH: Gaul and Berger (who used a zeroth order regular approximation) [47,74], and Denis et al (who also employ a relativistic coupled cluster method) [75]. For an excited bent mode, specifically a (010) mode, we do not know beforehand the degree to which the molecule is bent, and therefore, we estimate the effective electric field at the DF level for various values of Θ, which is the angle formed by O-Yb, with respect to H-O, as Figure 2 shows.…”

Laser-cooled polyatomic molecules for improved electron electric dipole moment searches

“…Thus, a class of molecules has been identified where a precision measurement with trapped polyatomic molecules, e.g. 174 YbOH, could probe CP-violating BSM physics at the PeV scale in a near-term experiment [13,23,24]. Trapped molecules present many other practical advantages to future eEDM experiments.…”