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Status of the Hadronic Light-by-Light Contribution to the Muon Anomalous Magnetic Moment
Bijnens, Johan;Prades, Joaquim
High Energy Physics - Phenomenology , 2007,
Abstract: We review the present status of the hadronic light-by-light contribution to muon g-2 and critically compare recent calculations.
Status of the Hadronic Light-by-Light Contribution to the Muon Anomalous Magnetic Moment  [PDF]
Johan Bijnens,Joaquim Prades
Physics , 2007,
Abstract: We review the present status of the hadronic light-by-light contribution to muon g-2 and critically compare recent calculations.
Hadronic Light-by-light Scattering Contribution to Muon $ g - 2 $  [PDF]
M. Hayakawa,T. Kinoshita,A. I. Sanda
Physics , 1996, DOI: 10.1103/PhysRevD.54.3137
Abstract: The hadronic light-by-light scattering contribution to muon $g-2$ is examined based on the low energy effective theories of QCD, the Nambu-Jona-Lasinio model and hidden local symmetry approach, supplemented by a general information concerning the asymptotic behavior of QCD. Our result is $- 52 \times 10^{-11}$ with an uncertainty of $\pm 18 \times 10^{-11}$, which includes our best estimate of model dependence. This is within the expected measurement uncertainty of $40\times 10^{-11}$ in the forthcoming experiment at Brookhaven National Laboratory. Our result removes one of the main theoretical obstacles in verifying the existence of the weak contribution to the muon $g-2$.
Hadronic Light-by-Light Contribution to the Muon $g-2$  [PDF]
Johan Bijnens,Elisabetta Pallante,Joaquim Prades
Physics , 1995, DOI: 10.1103/PhysRevLett.75.1447
Abstract: Mistake in FORTRAN program corrected. The numerical results and conclusions are changed significantly: We present a calculation of the hadronic light-by-light contributions to the muon $g-2$ in the $1/N_c$ expansion. We have used an Extended NJL model and introduced an explicit cut-off for the high energy region. We have then critically studied the relative size of the high energy contributions. Although we find them large we can give a conservative estimate of the light-by-light contribution to $a_\mu$ which is $-(11\pm5) \cdot 10^{-10}$. This is between two and three sigmas the expected experimental uncertainty at the forthcoming BNL experiment.
Pseudoscalar pole terms in the hadronic light-by-light scattering contribution to muon $ g - 2 $  [PDF]
M. Hayakawa,T. Kinoshita
Physics , 1997, DOI: 10.1103/PhysRevD.66.019902
Abstract: The pseudoscalar pole contribution is the dominant source of the $ {\cal O}(\alpha^3) $ hadronic light-by-light scattering effect in muon $g - 2$. We have examined this contribution taking account of the off-shell structure of the pseudoscalar-photon-photon anomaly vertex deduced from available experimental data. Our work leads to an improved estimate, $ -79.2 (15.4) \times 10^{-11}$, for the total hadronic light-by-light scattering contribution to the muon $g - 2$.
Hadronic light-by-light scattering contribution to the muon g-2 from lattice QCD : Methodology  [PDF]
Masashi Hayakawa,Thomas Blum,Taku Izubuchi,Norikazu Yamada
Physics , 2005,
Abstract: The hadronic light-by-light scattering contribution to the muon g-2 is the most troublesome component of its theoretical prediction; (1) it cannot be determined from the other measurable quantities, (2) the dimensional argument and the estimation based on hadronic models imply that the magnitude of this contribution may be comparable to the discrepancy between the standard model prediction and the experimental value. The direct approach to evaluate the hadronic light-by-light scattering contribution requires the evaluation of the correlation function of {\it four} hadronic electromagnetic currents, and the summation of it over two independent four-momenta of off-shell photons, which is far from the reach of direct lattice simulation. Here we propose an alternative method using combined (QCD + QED) lattice simulations to evaluate the hadronic light-by-light scattering contribution.
Hadronic light-by-light scattering contribution to the muon anomalous magnetic moment from lattice QCD  [PDF]
Thomas Blum,Saumitra Chowdhury,Masashi Hayakawa,Taku Izubuchi
Physics , 2014, DOI: 10.1103/PhysRevLett.114.012001
Abstract: The form factor that yields the light-by-light scattering contribution to the muon anomalous magnetic moment is computed in lattice QCD+QED and QED. A non-perturbative treatment of QED is used and is checked against perturbation theory. The hadronic contribution is calculated for unphysical quark and muon masses, and only the diagram with a single quark loop is computed. Statistically significant signals are obtained. Initial results appear promising, and the prospect for a complete calculation with physical masses and controlled errors is discussed.
The Hadronic Light-by-Light Contribution to the Muon Anomalous Magnetic Moment: Where do we stand?
Bijnens, Johan;Prades, Joaquim
High Energy Physics - Phenomenology , 2007, DOI: 10.1142/S0217732307022992
Abstract: We review the status of the hadronic light-by-light contribution to the muon anomalous magnetic moment and critically compare recent calculations. We also study in detail which momentum regions the pi^0 exchange main contribution originates. We also argue that a_\mu^{light-by-light} = (11 \pm 4) \times 10^{-10} encompasses the present understanding of this contribution and comment on some directions to improve on that.
Lattice Calculation of the Connected Hadronic Light-by-Light Contribution to the Muon Anomalous Magnetic Moment  [PDF]
Luchang Jin,Thomas Blum,Norman Christ,Masashi Hayakawa,Taku Izubuchi,Christoph Lehner
Physics , 2015,
Abstract: The anomalous magnetic moment of muon, $g-2$, is a very precisely measured quantity. However, the current measurement disagrees with standard model by about 3 standard deviations. Hadronic vacuum polarization and hadronic light by light are the two types of processes that contribute most to the theoretical uncertainty. I will describe how lattice methods are well-suited to provide a first-principle's result for the hadronic light by light contribution, the various numerical strategies that are presently being used to evaluate it, our current results and the important remaining challenges which must be overcome.
Hadronic light-by-light scattering contribution to the muon g-2: an effective field theory approach  [PDF]
M. Knecht,A. Nyffeler,M. Perrottet,E. de Rafael
Physics , 2001, DOI: 10.1103/PhysRevLett.88.071802
Abstract: 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 the two-loop graphs involving two anomalous vertices is computed, and found to be positive. This corresponds to a positive sign for the pion-pole contribution to the hadronic light-by-light correction to a_{mu}, and to a sizeable reduction of the discrepancy between the present experimental value of a_{mu} and its theoretical counterpart in the standard model.
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