Flavor Catalog v0.4
102 entries
Catalog · EDM / neutrino · E002

E002 $d_\mu$

Muon electric dipole moment
Status REVIEWED VERIFIED High Code: NO Priority Low

PDG / equivalent values

Observable Value Year Experiment / source Provenance
PSI frozen-spin muEDM proposal muon momentum 125 MeV/c 2021 Adelmann2021:E002:muon_momentum source ↑
PSI frozen-spin muEDM proposal magnetic field magnitude 3 T 2021 Adelmann2021:E002:magnetic_field source ↑
PSI frozen-spin muEDM proposal rest-frame electric field 1 GV/m 2021 Adelmann2021:E002:rest_frame_electric_field source ↑
PSI frozen-spin muEDM proposal expected EDM sensitivity 6e-23 e cm 2021 Adelmann2021:E002:sensitivity source ↑
PSI muEDM status first-phase feasibility target 2026 calendar year 2024 Renga2024:E002:first_phase_target_year source ↑
PSI muEDM status ultimate sensitivity-improvement goal 100 improvement factor 2024 Renga2024:E002:ultimate_improvement_factor source ↑
PSI muEDM status ultimate-goal period early 2030s time period 2024 Renga2024:E002:ultimate_goal_period source ↑

Why this constrains the RS scan

A nonzero \(d_\mu\) probes the imaginary part of the flavor-diagonal muon dipole operator, schematically \(\bar\mu\sigma_{\alpha\beta}\gamma_5\mu F^{\alpha\beta}\). In warped lepton extensions, anarchic charged-lepton and neutrino Yukawa structures can generate such dipoles through loop matching involving KK leptons, Higgs dynamics, or gauge-sector phases. The process therefore diagnoses CP alignment in the muon sector, complementary to \(\mu\to e\gamma\), but it does not directly constrain the existing quark-only scan.

What's changed since the original paper

Relative to the 2008 CFW warped-flavor reference point (CsakiFalkowskiWeiler:RSFlavor2008), the key direct experimental development is the BNL E821 publication in 2009. That analysis used muon \(g-2\) storage-ring spin-precession data and remains the basis of the PDG direct limit. The major post-2008 prospective change is the dedicated PSI muEDM program. The 2021 PSI letter of intent auxiliary\_values.psi\_frozen\_spin\_projection (Adelmann:MuonEDMPSI2021) proposes a frozen-spin search with \(p=125~\mathrm{MeV}/c\), \(|B|=3~\mathrm{T}\), a rest-frame electric field of \(1~\mathrm{GV/m}\), and an expected sensitivity \(\sigma(d_\mu)\leq6\times10^{-23}\ e\,\mathrm{cm}\). The auxiliary\_values.psi\_2024\_status entry (Renga:MuonEDMStatus2024) describes a first phase aimed at demonstrating feasibility by 2026, with an ultimate goal of improving the sensitivity by a factor of \(100\) by the early 2030s.

Validity and model dependence

The PDG number is a robust direct storage-ring bound on a static muon EDM. Its interpretation in RS is model-dependent: a live constraint requires the lepton-sector CP phases, the dipole matching scale, and the treatment of SMEFT/low-energy running to be fixed. The PSI entries are projections and should be treated as roadmap information, not current exclusions.

Code coverage in this repo

NO. Focused greps for muEDM, muon.?EDM, muon electric dipole, d\_mu, and dmu over quarkConstraints/, qcd/, flavorConstraints/, neutrinos/, yukawa/, warpConfig/, solvers/, scanParams/, and tests/ found no muon-EDM implementation. The nearby dipole code is the off-diagonal \(\mu\to e\gamma\) helper in flavorConstraints/muToEGamma.py:3, :21, and :81, with the MEG II branching-fraction default at scanParams/scan.py:33; that is a different observable.

Implementation difficulty

HIGH. A production implementation needs a new flavor-diagonal CP-odd lepton dipole observable, loop matching from the lepton/KK sector, and likely SMEFT-to-low-energy running. The existing \(\Delta F=2\) basis and the \(\mu\to e\gamma\) NDA helper do not calculate \(d_\mu\).

Reason: Requires a new flavor-diagonal CP-odd lepton dipole observable, lepton/KK loop matching, and likely SMEFT-to-low-energy running. Existing $\Delta F = 2$ utilities and the $\mu \to e \gamma$ NDA helper do not compute d_mu.

Key references

Process-local source keys before bibliography consolidation: PDG2026:MuonEDM, Bennett:MuonEDM2009, Adelmann:MuonEDMPSI2021, Renga:MuonEDMStatus2024, and CsakiFalkowskiWeiler:RSFlavor2008.
Source SHAs
5 snapshot(s) tracked in flavor_catalog/processes/edm_neutrino/E002.yaml
Access dates
2026-05-16
Worklog
flavor_catalog/worklogs/E002/
LaTeX source
flavor_catalog/processes/edm_neutrino/E002.tex
Anchors generated
2026-05-17T21:55:00-04:00

canonical_direct_limit

https://pdgprod.lbl.gov/pdgprod/pdgLive/DataBlock.action?cl=T&desig=&init=0&node=S004EDM&parCode=S004EDM
accessed 2026-05-16 sha 2918e0eb7819... snapshot E002/pdg2026_muon_edm_datablock.txt RESOLVED
value_summary |d_mu| < 1.8 x 10^-19 e cm at 95% CL
RESOLVED
Match snapshot line 19 
L16: Canonical direct experimental result:
L17:   <1.8, CL = 95%, Bennett 2009, method MUG2 +/- storage ring.
L18: Converted value:
L19:   |d_mu| < 1.8 x 10^-19 e cm at 95% CL.
L20: 
L21: PDG notes on the Bennett 2009 entries:
L22:   The canonical limit is the combination of the mu+ and mu- Bennett 2009 measurements.
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.

pdg_combined_measurement

https://pdgprod.lbl.gov/pdgprod/pdgLive/DataBlock.action?cl=T&desig=&init=0&node=S004EDM&parCode=S004EDM
accessed 2026-05-16 sha 2918e0eb7819... snapshot E002/pdg2026_muon_edm_datablock.txt RESOLVED
value_summary d_mu = (0.0 +/- 0.9) x 10^-19 e cm
RESOLVED
Match snapshot line 23 
L20: 
L21: PDG notes on the Bennett 2009 entries:
L22:   The canonical limit is the combination of the mu+ and mu- Bennett 2009 measurements.
L23:   The combined result is also presented as a measurement of (0.0 +/- 0.9) x 10^-19 e cm.
L24:   The mu+ entry is -0.1 +/- 1.0 in units of 10^-19 e cm, also reported as |d(mu+)| < 2.1 x 10^-19 e cm at 95% CL.
L25:   The mu- entry is -0.1 +/- 0.7 in units of 10^-19 e cm, also reported as |d(mu-)| < 1.5 x 10^-19 e cm at 95% CL.
L26:
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.

primary_bnl_measurement

https://arxiv.org/abs/0811.1207
accessed 2026-05-16 sha 16ce7a84e7ba... snapshot E002/bennett2009_arxiv0811_1207.txt RESOLVED
value_uncertainty_fallback -0.1 +/- 0.9 10^-19 e cm
RESOLVED
Match snapshot line 19 
L16:   from the Brookhaven National Laboratory E821 muon g-2 storage ring.
L17: 
L18: Numerical results from the arXiv abstract:
L19:   Combined measurement: d = -0.1(0.9) x 10^-19 e cm.
L20:   Published direct limit: |d| < 1.9 x 10^-19 e cm at 95% CL.
L21:   The abstract states that this is a factor-5 improvement over the previous best muon-EDM limit.
L22:
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.

Adelmann2021:E002:muon_momentum

https://arxiv.org/abs/2102.08838
accessed 2026-05-16 sha bc86e027b5ee... snapshot E002/adelmann2021_arxiv2102_08838.txt RESOLVED
value_units_fallback 125 MeV/c
RESOLVED
Match snapshot line 17 
L14:   committee in January 2021. It proposes a frozen-spin muon-EDM search at PSI.
L15: 
L16: Numerical proposal values from the arXiv abstract:
L17:   Muon momentum: p = 125 MeV/c.
L18:   Magnetic field magnitude: |B| = 3 T.
L19:   Rest-frame electric field: E = 1 GV/m.
L20:   Expected sensitivity at the PSI muE1 beam line: sigma(d_mu) <= 6 x 10^-23 e cm.
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.

Adelmann2021:E002:magnetic_field

https://arxiv.org/abs/2102.08838
accessed 2026-05-16 sha bc86e027b5ee... snapshot E002/adelmann2021_arxiv2102_08838.txt RESOLVED
value_units_fallback 3 T
RESOLVED
Match snapshot line 18 
L15: 
L16: Numerical proposal values from the arXiv abstract:
L17:   Muon momentum: p = 125 MeV/c.
L18:   Magnetic field magnitude: |B| = 3 T.
L19:   Rest-frame electric field: E = 1 GV/m.
L20:   Expected sensitivity at the PSI muE1 beam line: sigma(d_mu) <= 6 x 10^-23 e cm.
L21:   Current direct limit quoted in the abstract: |d_mu| <= 1.8 x 10^-19 e cm at 95% CL.
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.

Adelmann2021:E002:rest_frame_electric_field

https://arxiv.org/abs/2102.08838
accessed 2026-05-16 sha bc86e027b5ee... snapshot E002/adelmann2021_arxiv2102_08838.txt RESOLVED
value_units_fallback 1 GV/m
RESOLVED
Match snapshot line 19 
L16: Numerical proposal values from the arXiv abstract:
L17:   Muon momentum: p = 125 MeV/c.
L18:   Magnetic field magnitude: |B| = 3 T.
L19:   Rest-frame electric field: E = 1 GV/m.
L20:   Expected sensitivity at the PSI muE1 beam line: sigma(d_mu) <= 6 x 10^-23 e cm.
L21:   Current direct limit quoted in the abstract: |d_mu| <= 1.8 x 10^-19 e cm at 95% CL.
L22:
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.

Adelmann2021:E002:sensitivity

https://arxiv.org/abs/2102.08838
accessed 2026-05-16 sha bc86e027b5ee... snapshot E002/adelmann2021_arxiv2102_08838.txt RESOLVED
value_limit_fallback <= 6e-23 e cm
RESOLVED
Match snapshot line 20 
L17:   Muon momentum: p = 125 MeV/c.
L18:   Magnetic field magnitude: |B| = 3 T.
L19:   Rest-frame electric field: E = 1 GV/m.
L20:   Expected sensitivity at the PSI muE1 beam line: sigma(d_mu) <= 6 x 10^-23 e cm.
L21:   Current direct limit quoted in the abstract: |d_mu| <= 1.8 x 10^-19 e cm at 95% CL.
L22: 
L23: Use in E002:
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.

Renga2024:E002:first_phase_target_year

https://arxiv.org/abs/2409.20050
accessed 2026-05-16 sha c9c8a8cb2c32... snapshot E002/renga2024_arxiv2409_20050.txt RESOLVED
observable_value_fallback PSI muEDM status first-phase feasibility target 2026 calendar year
RESOLVED
Match snapshot line 20 
L17:   would indicate a nonzero EDM.
L18: 
L19: Numerical/prospect statements from the arXiv abstract:
L20:   The first phase is intended to demonstrate feasibility by 2026 while reaching
L21:   sensitivity competitive with parasitic measurements in muon g-2 experiments.
L22:   The ultimate goal is to improve that sensitivity by a factor of 100 by the early 2030s.
L23:
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.

Renga2024:E002:ultimate_improvement_factor

https://arxiv.org/abs/2409.20050
accessed 2026-05-16 sha c9c8a8cb2c32... snapshot E002/renga2024_arxiv2409_20050.txt RESOLVED
value_units_fallback 100 improvement factor
RESOLVED
Match snapshot line 22 
L19: Numerical/prospect statements from the arXiv abstract:
L20:   The first phase is intended to demonstrate feasibility by 2026 while reaching
L21:   sensitivity competitive with parasitic measurements in muon g-2 experiments.
L22:   The ultimate goal is to improve that sensitivity by a factor of 100 by the early 2030s.
L23: 
L24: Use in E002:
L25:   This is a status/prospect source for the post-2008 subsection, not a measured
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.

Renga2024:E002:ultimate_goal_period

https://arxiv.org/abs/2409.20050
accessed 2026-05-16 sha c9c8a8cb2c32... snapshot E002/renga2024_arxiv2409_20050.txt RESOLVED
value_units_fallback early 2030s time period
RESOLVED
Match snapshot line 22 
L19: Numerical/prospect statements from the arXiv abstract:
L20:   The first phase is intended to demonstrate feasibility by 2026 while reaching
L21:   sensitivity competitive with parasitic measurements in muon g-2 experiments.
L22:   The ultimate goal is to improve that sensitivity by a factor of 100 by the early 2030s.
L23: 
L24: Use in E002:
L25:   This is a status/prospect source for the post-2008 subsection, not a measured
Snapshots live under flavor_catalog/references/<process_id>/. Source-line anchoring is automated; the status pill reflects match confidence, not editorial review.