Longitudinal short-distance constraints for the hadronic light-by-light contribution to (g − 2)μ with large-Nc Regge models

• DOI: 10.1007/jhep03(2020)101
• Publication Date: 2020-03-18T11:59:53Z
• Authors: Gilberto Colangelo; Franziska Hagelstein; Martin Hoferichter; Laetitia Laub; Peter Stoffer
• Keywords: Operator product expansion

A bstract While the low-energy part of hadronic light-by-light (HLbL) tensor can be constrained from data using dispersion relations, for a full evaluation its contribution to anomalous magnetic moment muon ( g − 2) μ also mixed- and high-energy regions need estimated. Both addressed within operator product expansion (OPE), either configurations where all photon virtualities become large or one them remains finite. Imposing such short-distance constraints (SDCs) on HLbL is thus major aspect model-independent approach towards scattering. Here, we focus longitudinal SDCs, which concern amplitudes containing pseudoscalar-pole contributions π 0 , η η′ . Since these conditions cannot fulfilled by finite number pseudoscalar poles, consider tower excited pseudoscalars, constraining their masses transition form factors Regge theory, OPE, phenomenology. Implementing matching resulting expressions onto perturbative QCD quark loop, are able further constrain our calculation significantly reduce model dependence. We find that especially corresponding increase much smaller than previous prescriptions in literature would imply. Overall, estimate SDCs $$ \varDelta {a}_{\mu}^{\mathrm{LSDC}}=13(6) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Δ</mml:mi> <mml:msubsup> <mml:mi>a</mml:mi> <mml:mi>μ</mml:mi> <mml:mtext>LSDC</mml:mtext> </mml:msubsup> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mfenced> <mml:mn>6</mml:mn> </mml:mfenced> </mml:math> × 10 -11 This does not include charm quark, {a}_{\mu}^{c- quark} <mml:mrow> <mml:mi>c</mml:mi> <mml:mo>−</mml:mo> <mml:mtext>quark</mml:mtext> </mml:mrow> = 3(1) 11