Dispersive estimate of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>a</mml:mi><mml:mn>0</mml:mn></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mn>980</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math> contribution to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mo stretchy="false">(</mml:mo><mml:mi>g</mml:mi><mml:mo>−</mml:mo><mml:mn>2</mml:mn><mml:msub><mml:mo stretchy="false">)</mml:mo><mml:mi>μ</mml:mi></mml:msub></mml:math>

Summary

This theoretical physics study presents a dispersive implementation of the a₀(980) resonance contribution to the muon anomalous magnetic moment, employing a modified coupled-channel Muskhelishvili–Omnès formalism. Using a data-driven N/D method with conformal expansion for hadronic left-hand cuts, the authors derived double-virtual photon-to-meson amplitudes and obtained a precision estimate of −0.44(5) × 10⁻¹¹, representing a significant refinement over traditional narrow resonance approaches. This work contributes to precision tests of the Standard Model through improved calculations of a fundamental quantum electrodynamics observable.

Key measures

Dispersive estimate of a₀(980) contribution to (g−2)μ: −0.44(5) × 10⁻¹¹; double-virtual S-wave γ*γ* → ππ/KK̄ amplitudes; hadronic Omnès matrix coefficients

Outcomes reported

The study calculated the a₀(980) resonance contribution to the muon anomalous magnetic moment (g−2)μ using dispersive methods and coupled-channel formalism. The resulting estimate achieved an order of magnitude improvement in precision over previous narrow resonance approximation methods.

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