Catalog · EDM / neutrino · E001

E001 $d_e$

Electron electric dipole moment

Status SUBTLETY-ADDED VERIFIED High Code: NO Priority High

PDG / equivalent values

Observable	Value	Year	Experiment / source	Provenance
Electron electric dipole moment	4.1e-30 e cm	2026	PDG Live 2026 S003EDM electron electric dipole moment datablock	source ↑
Electron electric dipole moment, HfF+ molecular ions	-1.3 10^-30 e cm	2023	Roussy et al., Science 381, 46 (2023); arXiv:2212.11841	source ↑
Electron electric dipole moment, ThO benchmark	1.1e-29 e cm	2018	ACME Collaboration, Andreev et al., Nature 562, 355 (2018)	source ↑

Why this constrains the RS scan

The electron EDM constrains the imaginary part of a CP-odd lepton dipole, schematically $\mathcal{L}\supset -i d_e\,\bar e\sigma_{\mu\nu}\gamma_5 e F^{\mu\nu}/2$. In warped lepton extensions, anarchic Yukawas and new CP phases can feed this operator through loop matching. The constraint is therefore a direct diagnostic of CP alignment in the charged-lepton sector, and it is especially relevant when the neutrino sector or bulk Higgs dynamics introduce additional complex spurions. It does not directly constrain the current quark-only $\Delta F=2$ scan.

What's changed since the original paper

Relative to the 2008 CFW RS-flavor reference point (CsakiFalkowskiWeiler:RSFlavor2008), the experimental EDM frontier changed qualitatively. ACME 2018 (ACME:ElectronEDM2018) set the previous molecular ThO limit at $1.1\times10^{-29}\ e\,\mathrm{cm}$, already strong enough to motivate EFT treatments of CP-violating electron dipoles. Roussy et al. 2023 (Roussy:ElectronEDM2023) then improved the previous best upper bound by about $2.4$ using trapped HfF${}^+$ molecular ions, yielding the current PDG value above. The post-ACME EFT literature, represented here by Panico, Pomarol, and Riembau 2019 (PanicoPomarolRiembau:ElectronEDM2019), treats electron EDMs as constraints on CP-violating dipole operators and their two-loop anomalous dimensions, the natural language for a future Wilson-coefficient implementation.

Validity and model dependence

The experimental null limit is robust as a bound on the effective electron EDM extracted from paramagnetic molecular spectroscopy. Model interpretation is less automatic: paramagnetic systems can also be sensitive to semileptonic CP-odd electron-nucleon interactions, and an RS implementation must specify which SMEFT or low-energy CP-odd operator basis is being matched. As a catalog constraint this is a lepton-extension and EDM-adjacent loop bound, not a standalone exclusion in the existing quark pipeline. For anarchic CP phases, EDM constraints should be reviewed jointly with the flavor branching rows that share the same Wilson coefficients (relevant cross-refs: K001, K003, B011, B033, B034), not as an isolated appendix.

Code coverage in this repo

NO. The required catalog greps and a focused implementation grep for electron.?EDM, eEDM, electric dipole, and d\_e over quarkConstraints/, qcd/, flavorConstraints/, neutrinos/, yukawa/, warpConfig/, solvers/, scanParams/, and tests/ found no electron-EDM implementation. The only adjacent dipole code is the off-diagonal $\mu\to e\gamma$ bound in flavorConstraints/muToEGamma.py:1, :3, :20--21, and :81; scanParams/scan.py:32--33 sets a MEG II branching-fraction limit for that different process.

Implementation difficulty

HIGH. A live implementation needs a new flavor-diagonal CP-odd lepton dipole observable, matching from the model's lepton/KK sector to the dipole Wilson coefficient, and likely SMEFT-to-low-energy running. The existing $\Delta F=2$ operator basis and the $\mu\to e\gamma$ NDA helper do not provide the needed CP-odd $d_e$ calculation.

Reason: Requires a new flavor-diagonal CP-odd lepton dipole observable, model-to-Wilson matching in the lepton/KK sector, and likely SMEFT/LEFT running. Existing $\Delta F = 2$ and $\mu \to e \gamma$ utilities do not provide d_e.

Key references

Process-local source keys before bibliography consolidation: PDG2026:ElectronEDM, Roussy:ElectronEDM2023, ACME:ElectronEDM2018, PanicoPomarolRiembau:ElectronEDM2019, and CsakiFalkowskiWeiler:RSFlavor2008.

value_summary |d_e| < 4.1 x 10^-30 e cm at 90% CL

RESOLVED

Match snapshot line 20

L17: Current PDG-used limit:
L18: ROUSSY 2023, technique ESR, electrons in intramolecular electric field:
L19: VALUE <0.041, CL 90%.
L20: Equivalent value: |d_e| < 4.1e-30 e cm at 90% CL.
L21: PDG footnote: ROUSSY 2023 gives the measurement
L22: (-1.3 +/- 2.0 +/- 0.6) x 10^-30 e cm corresponding to this limit.
L23:

measurement_summary d_e = (-1.3 +/- 2.0_stat +/- 0.6_syst) x 10^-30 e cm; |d_e| < 4.1 x 10^-30 e cm at 90% confidence

RESOLVED

Match snapshot line 23

L20: constraints on broad classes of new physics above 10^13 eV.
L21: 
L22: Extract from pdftotext of arXiv PDF:
L23: de = (-1.3 +/- 2.0_stat +/- 0.6_syst) x 10^-30 e cm.
L24: The corresponding upper bound is |de| < 4.1 x 10^-30 e cm at 90% confidence.
L25: 
L26: Notes:

value_summary |d_e| < 1.1 x 10^-29 e cm at 90% CL

RESOLVED

Match snapshot line 24

L21: measurements.
L22: 
L23: Numerical value as recorded by the PDG S003EDM datablock:
L24: ACME/Andreev 2018 gives |d_e| < 1.1e-29 e cm at 90% CL, corresponding to
L25: (4.3 +/- 3.1 +/- 2.6) x 10^-30 e cm.