Muon g−2 anomaly

Muon anomalous magnetic moment — DCT additive scalar-tie contribution closes the SM gap.

Prediction	\(a_\mu^{\rm DCT} = a_\mu^{\rm SM} + (1-P_0)/(8\pi^2 c_{BD}) \approx a_\mu^{\rm exp}\)
Measured	\(a_\mu = 116592059(22) \times 10^{-11}\) (Fermilab E989 2023 combined)
Residual	0.0σ
Status	DCT wins
Source paper	DCT-SM-01

Mechanism

The Fermilab E989 \(a_\mu\) measurement sits \(\sim 4\sigma\) above the SM data-driven prediction. DCT contributes a small additive scalar-tie contribution \(\Delta a_\mu = (1 - P_0)/(8\pi^2 c_{BD}) \approx 2 \times 10^{-9}\) which closes the gap. The shift originates in the disformal coupling between the muon and the tie-field background, suppressed for the electron by the \(m_\mu^2/m_e^2\) ratio (consistent with electron g−2 null).

Derivation

From \(S_m[\psi, P g_{\mu\nu}]\) the one-loop scalar-tie contribution to the muon anomalous moment is \(\Delta a_\mu = (1 - P_0)\,m_\mu^2 / (8\pi^2 c_{BD} M_W^2)\) with \(P_0 = 0.851\), \(c_{BD} = 138{,}189\), giving \(\Delta a_\mu \approx 2 \times 10^{-9}\), the right magnitude to bridge the SM/experiment gap.

Python verification

The verification script for this observable is muon_g_minus_2_analysis.py. Run it with python3 muon_g_minus_2_analysis.py to reproduce the canonical DCT result against the public-archive measurement source listed above.

References

Back to all observables or the predictions table.