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A dispersive implementation of the $a_0(980)$ resonance to $(g-2)_\mu$ requires the knowledge of the double-virtual $S$-wave $\gamma^*\gamma^*\to\pi\eta / K\bar{K}_{I=1}$ amplitudes. To obtain these amplitudes we used a modified…

High Energy Physics - Phenomenology · Physics 2023-09-06 Oleksandra Deineka , Igor Danilkin , Marc Vanderhaeghen

We compute the hadronic light-by-light scattering contributions to the muon anomalous magnetic moment, $\amulbl$, in chiral perturbation theory that are enhanced by large logarithms and a factor of $N_C$. They depend on a low-energy…

High Energy Physics - Phenomenology · Physics 2009-11-07 M. Ramsey-Musolf , Mark B. Wise

We report on our preliminary results from the lattice-QCD computation of the hadronic light-by-light (HLbL) contribution to the anomalous magnetic moment of the muon. We use twisted-mass $N_f = 2 + 1 + 1$ gauge ensembles at the physical…

High Energy Physics - Lattice · Physics 2024-12-18 Nikolaos Kalntis , Gurtej Kanwar , Marcus Petschlies , Simone Romiti , Urs Wenger

We present a detailed analysis of $e^+e^-\to\pi^+\pi^-$ data up to $\sqrt{s}=1\,\text{GeV}$ in the framework of dispersion relations. Starting from a family of $\pi\pi$ $P$-wave phase shifts, as derived from a previous Roy-equation analysis…

High Energy Physics - Phenomenology · Physics 2019-02-06 Gilberto Colangelo , Martin Hoferichter , Peter Stoffer

The hadronic light-by-light scattering contribution to the muon anomalous magnetic moment, $(g-2$)/2, is computed in the infinite volume QED framework with lattice QCD. We report $a_\mu^\text{HLbL}=12.47(1.15)(0.95) \times 10^{-10}$ where…

High Energy Physics - Lattice · Physics 2024-12-09 Thomas Blum , Norman Christ , Masashi Hayakawa , Taku Izubuchi , Luchang Jin , Chulwoo Jung , Christoph Lehner , Cheng Tu

We review the Hadronic Light-by-Light (HLbL) contribution to the muon anomalous magnetic moment. Upcoming measurements will reduce the experimental uncertainty of this precision observable by a factor of four, thus breaking the current…

High Energy Physics - Phenomenology · Physics 2024-04-12 Daniel Melo-Porras , Edilson Alfonso Reyes Rojas , Angelo Raffaele Fazio

We present a new strategy for the dispersive evaluation of the hadronic light-by-light contribution to the anomalous magnetic moment of the muon $a_\mu$. The new approach directly applies in the kinematic limit relevant for $a_\mu$: one of…

High Energy Physics - Phenomenology · Physics 2023-04-28 Jan Lüdtke , Massimiliano Procura , Peter Stoffer

Recently it was pointed out that for the evaluation of the numerically dominant pion-exchange contribution to the hadronic light-by-light scattering correction in the muon g-2, a fully off-shell pion-photon-photon form factor should be…

High Energy Physics - Phenomenology · Physics 2010-04-21 Andreas Nyffeler

We report a lattice QCD calculation of the hadronic light-by-light contribution to the muon anomalous magnetic moment at physical pion mass. The calculation includes the connected diagrams and the leading, quark-line-disconnected diagrams.…

High Energy Physics - Lattice · Physics 2017-01-18 Thomas Blum , Norman Christ , Masashi Hayakawa , Taku Izubuchi , Luchang Jin , Chulwoo Jung , Christoph Lehner

This thesis investigates the Hadronic Light by Light (HLL) scattering contribution to the muon $g-2$, which is one of the most important low energy hadronic effects and consists mainly of the quark loop, the pion pole and the charged pion…

High Energy Physics - Phenomenology · Physics 2012-08-14 Mehran Zahiri Abyaneh

In this thesis, I present dispersive treatments of two hadronic processes: the semileptonic kaon decay $K_{\ell4}$ and hadronic light-by-light scattering. The $K_{\ell4}$ decay is one of the best sources of information on some of the…

High Energy Physics - Phenomenology · Physics 2014-12-18 Peter Stoffer

The calculation of the hadronic light-by-light scattering contribution to the muon g-2 currently relies entirely on models. Measurements of the form factors which describe the interactions of hadrons with photons can help to constrain the…

High Energy Physics - Phenomenology · Physics 2013-06-26 Andreas Nyffeler

We determine the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon using the framework of Dyson-Schwinger and Bethe-Salpeter equations of QCD. Our result for the pseudoscalar ($\pi^0, \eta, \eta'$)…

High Energy Physics - Phenomenology · Physics 2015-03-17 Tobias Goecke , Christian S. Fischer , Richard Williams

We briefly review the current status of the hadronic light-by-light scattering correction to the muon g-2. Then we present our semi-analytical evaluation of the pion-pole contribution, using a description of the pion-photon-photon…

High Energy Physics - Phenomenology · Physics 2009-11-07 Andreas Nyffeler

We present a lattice QCD calculation of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon using $N_f=2+1+1$ flavors of staggered quarks with masses tuned to their physical values. Our final…

High Energy Physics - Lattice · Physics 2024-11-19 Zoltan Fodor , Antoine Gerardin , Laurent Lellouch , Kalman K. Szabo , Balint C. Toth , Christian Zimmermann

We present updated results for the hadronic light-by-light (HLbL) contribution to the muon anomalous magnetic moment. The calculations are based on ETMC's $N_f=2+1+1$ Wilson-clover twisted-mass ensembles at the physical point. We perform…

High Energy Physics - Lattice · Physics 2025-12-25 N. Kalntis , G. Kanwar , M. Petschlies , S. Romiti , U. Wenger

We think that phenomenological resonance Lagrangian models, constrained by global fits from low energy hadron reaction data, can help to improve muon g-2 predictions. The main issue are those contributions which cannot be calculated by…

High Energy Physics - Phenomenology · Physics 2013-12-17 Fred Jegerlehner

The hadronic light-by-light contribution to a_{mu}, the anomalous magnetic moment of the muon, is discussed from the point of view of an effective low-energy theory. As an application, the coefficient of the leading logarithm arising from…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Knecht , A. Nyffeler , M. Perrottet , E. de Rafael

The hadronic corrections to the muon anomalous magnetic moment, due to the full gauge-invariant set of diagrams with dynamical quark loop and intermediate pseudoscalar and scalar states light-by-light scattering insertions, are calculated…

High Energy Physics - Phenomenology · Physics 2015-11-19 A. S. Zhevlakov , A. E. Dorokhov , A. E. Radzhabov

We comment on the theoretical uncertainties involved in estimating the hadronic effects on the light-by-light scattering contribution to the anomalous magnetic moment of the muon, especially based on the analysis and results of T.…

High Energy Physics - Phenomenology · Physics 2009-10-22 Martin B. Einhorn