Prospects for precise predictions of $a_μ$ in the Standard Model

Colangelo, G.; Davier, M.; El-Khadra, A. X.; Hoferichter, M.; Lehner, C.; Lellouch, L.; Mibe, T.; Roberts, B. L.; Teubner, T.; Wittig, H.; Ananthanarayan, B.; Bashir, A.; Bijnens, J.; Blum, T.; Boyle, P.; Bray-Ali, N.; Caprini, I.; Calame, C. M. Carloni; Catà, O.; Cè, M.; Charles, J.; Christ, N. H.; Curciarello, F.; Danilkin, I.; Das, D.; Deineka, O.; Della Morte, M.; Denig, A.; DeTar, C. E.; Dominguez, C. A.; Eichmann, G.; Fischer, C. S.; Gérardin, A.; Giusti, D.; Golterman, M.; Gottlieb, Steven; Gülpers, V.; Hagelstein, F.; Hayakawa, M.; Hermansson-Truedsson, N.; Hoid, B. -L.; Holz, S.; Izubuchi, T.; Jüttner, A.; Keshavarzi, A.; Knecht, M.; Kronfeld, A. S.; Kubis, B.; Kupść, A.; Lahert, S.; Liu, K. F.; Lüdtke, J.; Lynch, M.; Malaescu, B.; Maltman, K.; Marciano, W.; Marinković, M. K.; Masjuan, P.; Meyer, H. B.; Müller, S. E.; Neil, E. T.; Passera, M.; Pepe, M.; Peris, S.; Petrov, A. A.; Procura, M.; Raya, K.; Rebhan, A.; Risch, A.; Rodríguez-Sánchez, A.; Roig, P.; Sánchez-Puertas, P.; Simula, S.; Stoffer, P.; Stokes, F. M.; Sugar, R.; Tsang, J. T.; van de Water, R. S.; Avilés-Casco, A. Vaquero; Venanzoni, G.; von Hippel, G. M.; Zhang, Z.

doi:10.48550/arxiv.2203.15810

Cited by 18 publications

(23 citation statements)

References 148 publications

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“…e + e − → hadrons cross-section data. While the detailed comparison to lattice QCD as well as related observables defines an important path forward [60][61][62][63][64][65][66][67], so does renewed scrutiny of the data-driven approach.…”

Section: Introductionmentioning

confidence: 99%

Isospin-breaking effects in the two-pion contribution to hadronic vacuum polarization

Colangelo

Hoferichter

Kubis³

et al. 2022

J. High Energ. Phys.

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Isospin-breaking (IB) effects in the two-pion contribution to hadronic vacuum polarization (HVP) can be resonantly enhanced, if related to the interference of the ρ(770) and ω(782) resonances. This particular IB contribution to the pion vector form factor and thus the line shape in e+e−→ π+π− can be described by the residue at the ω pole — the ρ-ω mixing parameter ϵω. Here, we argue that while in general analyticity requires this parameter to be real, the radiative channels π0γ, ππγ, ηγ can induce a small phase, whose size we estimate as δϵ = 3.5(1.0)° by using a narrow-width approximation for the intermediate-state vector mesons. We then perform fits to the e+e−→ π+π− data base and study the consequences for the two-pion HVP contribution to the anomalous magnetic moment of the muon, its IB part due to ρ-ω mixing, and the mass of the ω resonance. We find that the global fit does prefer a non-vanishing value of δϵ = 4.5(1.2)°, close to the narrow-resonance expectation, but with a large spread among the data sets, indicating systematic differences in the ρ-ω region.

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Section: Introductionmentioning

confidence: 99%

Isospin-breaking effects in the two-pion contribution to hadronic vacuum polarization

Colangelo

Hoferichter

Kubis³

et al. 2022

J. High Energ. Phys.

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show abstract

“…An excellent summary of all these discussions was recently presented, see slides of [142], and for details, we refer to ref. [129,[143][144][145] and references therein. Some of these hadronic light-by-light contributions, as well as those contributions to (g−2) µ involve related processes where transition form factors play an important role.…”

Section: Selected Applications Of Chiral Perturbative Theorymentioning

confidence: 99%

Chiral Perturbation Theory Reflections on Effective Theories of the Standard Model

Ananthanarayan¹,

Khan²,

Wyler³

2023

Preprint

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The pseudoscalar particles pions, kaons and the η-particle are considerably lighter than the other hadrons such as protons or neutrons. Their lightness was understood as a consequence of approximate chiral symmetry breaking. This led to current algebra, a way to express the relations imposed by the symmetry breaking. It was realized by Weinberg that because of their low mass, it is possible to formulate a purely pionic (effective) field theory at experimental energies, which carries all information on the (non-perturbative) dynamics, symmetries, and their spontaneous breaking of quantum chromodynamics (QCD) and allows for systematic calculations of observables. In this review, we trace these developments and present recent activities in this field. We make the connection to other effective theories, more generally introduced by Wilson, as approximate field theories at low energies. Indeed, principles and paradigms introduced first for pions have become ubiquitous in particle physics and the standard model. Lastly, we turn to the latest development where the present (fundamental) standard model itself is considered as an effective field theory of a -yet to be formulated -even more fundamental theory. We also discuss important techniques that were developed in order to turn chiral perturbation theory into a predictive framework and briefly review some connections between lattice QCD and chiral perturbation theory (ChPT).

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“…An excellent summary of all these discussions was recently presented (see slides of [142]), and for details, we refer to ref. [129,[143][144][145] and references therein. Some of these hadronic light-by-light contributions, as well as those contributions to ðg À 2Þ l involve related processes where transition form factors play an important role.…”

Section: Selected Applications Of Chiral Perturbative Theorymentioning

confidence: 99%

Chiral perturbation theory: reflections on effective theories of the standard model

2023

View full text Add to dashboard Cite

The pseudoscalar particles pions, kaons and the g-particle are considerably lighter than the other hadrons such as protons or neutrons. Their lightness was understood as a consequence of approximate chiral symmetry breaking. This led to current algebra, a way to express the relations imposed by the symmetry breaking. It was realized by Weinberg that because of their low mass, it is possible to formulate a purely pionic (effective) field theory at experimental energies, which carries all information on the (non-perturbative) dynamics, symmetries, and their spontaneous breaking of quantum chromodynamics (QCD) and allows for systematic calculations of observables. In this review, we trace these developments and present recent activities in this field. We make the connection to other effective theories, more generally introduced by Wilson, as approximate field theories at low energies. Indeed, principles and paradigms introduced first for pions have become ubiquitous in particle physics and the standard model. Lastly, we turn to the latest development where the present (fundamental) standard model itself is considered as an effective field theory of a-yet to be formulated-even more fundamental theory. We also discuss important techniques that were developed in order to turn chiral perturbation theory into a predictive framework and briefly review some connections between lattice QCD and chiral perturbation theory (ChPT).

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Prospects for precise predictions of $a_μ$ in the Standard Model

Abstract: We discuss the prospects for improving the precision on the hadronic corrections to the anomalous magnetic moment of the muon, and the plans of the Muon g − 2 Theory Initiative to update the Standard Model prediction.

Cited by 18 publications

References 148 publications

Isospin-breaking effects in the two-pion contribution to hadronic vacuum polarization

Isospin-breaking effects in the two-pion contribution to hadronic vacuum polarization

Chiral Perturbation Theory Reflections on Effective Theories of the Standard Model

Chiral perturbation theory: reflections on effective theories of the standard model

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