Tensor amplitudes for elastic photon-photon scattering

Leo, R. A.; Soliani, G.; Minguzzi, Anna

doi:10.1007/bf02730173

Cited by 22 publications

(19 citation statements)

References 9 publications

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“…The generalization of this derivation to D-waves requires the analog of (2.23) for the full HLbL tensor. We derived such a basis along the lines described in [41][42][43], and will provide a full version of the dispersive system including a complete treatment of D-waves in a subsequent publication [33].…”

Section: Calculate the Helicity Projections Ofãmentioning

confidence: 99%

Dispersive approach to hadronic light-by-light scattering

Colangelo

Hoferichter

Procura

et al. 2014

J. High Energ. Phys.

192

140

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Based on dispersion theory, we present a formalism for a model-independent evaluation of the hadronic light-by-light contribution to the anomalous magnetic moment of the muon. In particular, we comment on the definition of the pion pole in this framework and provide a master formula that relates the effect from ππ intermediate states to the partial waves for the process γ * γ * → ππ. All contributions are expressed in terms of onshell form factors and scattering amplitudes, and as such amenable to an experimental determination.

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Section: Calculate the Helicity Projections Ofãmentioning

confidence: 99%

Dispersive approach to hadronic light-by-light scattering

Colangelo

Hoferichter

Procura

et al. 2014

J. High Energ. Phys.

192

140

View full text Add to dashboard Cite

show abstract

“…The HLbL tensor can be written a priori in terms of 138 basic Lorentz structures built out of the metric tensor and the four-momenta [26]. Our first task is to write the HLbL tensor in terms of Lorentz structures that satisfy the WT identities, while at the same time the scalar functions that multiply these structures must be free of kinematic singularities and zeros.…”

Section: Lorentz Structure Of the Hlbl Tensormentioning

confidence: 99%

Dispersion relations for hadronic light-by-light scattering and the muon g – 2

et al. 2018

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Abstract. The largest uncertainties in the Standard Model calculation of the anomalous magnetic moment of the muon (g − 2) µ come from hadronic effects, and in a few years the subleading hadronic light-by-light (HLbL) contribution might dominate the theory error. We present a dispersive description of the HLbL tensor, which is based on unitarity, analyticity, crossing symmetry, and gauge invariance. This opens up the possibility of a data-driven determination of the HLbL contribution to (g − 2) µ with the aim of reducing model dependence and achieving a reliable error estimate.Our dispersive approach defines unambiguously the pion-pole and the pion-box contribution to the HLbL tensor. Using Mandelstam double-spectral representation, we have proven that the pion-box contribution coincides exactly with the one-loop scalar-QED amplitude, multiplied by the appropriate pion vector form factors. Using dispersive fits to high-statistics data for the pion vector form factor, we obtain a π-box µ = −15.9(2) × 10 −11 . A first model-independent calculation of effects of ππ intermediate states that go beyond the scalar-QED pion loop is also presented. We combine our dispersive description of the HLbL tensor with a partial-wave expansion and demonstrate that the known scalar-QED result is recovered after partial-wave resummation. After constructing suitable input for the γ * γ * → ππ helicity partial waves based on a pion-pole left-hand cut (LHC), we find that for the dominant charged-pion contribution this representation is consistent with the two-loop chiral prediction and the COMPASS measurement for the pion polarizability. This allows us to reliably estimate S -wave rescattering effects to the full pion box and leads to a π-box µ + a ππ,π-pole LHC µ,J=0 = −24(1) × 10 −11 .⋆

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“…The HLbL tensor can be written a priori in terms of 138 basic Lorentz structures built out of the metric tensor and the four-momenta [17]. Our first task is to write the HLbL tensor in terms of Lorentz structures that satisfy the WT identities, while requiring at the same time that the scalar functions that multiply these structures be free of kinematic singularities and zeros.…”

Section: Lorentz Structure Of the Hlbl Tensormentioning

confidence: 99%

Dispersion relation for hadronic light-by-light scattering and the muon g-2

Colangelo¹,

Stoffer²,

Hoferichter³

et al. 2016

Proceedings of the 8th International Workshop on Chiral Dynamics — PoS(CD15)

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The largest uncertainties in the Standard Model calculation of the anomalous magnetic moment of the muon (g − 2) µ come from hadronic contributions. In particular, it can be expected that in a few years the subleading hadronic light-by-light (HLbL) contribution will dominate the theory uncertainty. We present a dispersive description of the HLbL tensor, which is based on unitarity, analyticity, crossing symmetry, and gauge invariance. Such a model-independent approach opens up an avenue towards a data-driven determination of the HLbL contribution to (g − 2) µ . The dispersive approach defines unambiguously the pion-pole and the pion-box contribution to the HLbL tensor. Using Mandelstam's double-spectral representation, we have proven that the pion-box contribution coincides exactly with the one-loop scalar QED amplitude, multiplied by the appropriate pion vector form factors.

show abstract

Tensor amplitudes for elastic photon-photon scattering

Cited by 22 publications

References 9 publications

Dispersive approach to hadronic light-by-light scattering

Dispersive approach to hadronic light-by-light scattering

Dispersion relations for hadronic light-by-light scattering and the muon g – 2

Dispersion relation for hadronic light-by-light scattering and the muon g-2

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