A dispersive estimate of scalar contributions to hadronic light-by-light scattering

Author(s)
Igor Danilkin, Martin Hoferichter, Peter Stoffer
Abstract

We consider the contribution of scalar resonances to hadronic light-by-light scattering in the anomalous magnetic moment of the muon. While the f0(500) has already been addressed in previous work using dispersion relations, heavier scalar resonances have only been estimated in hadronic models so far. Here, we compare an implementation of the f0(980) resonance in terms of the coupled-channel S-waves for γγ→ππ/K¯K to a narrow-width approximation, which indicates aμHLbL[f0(980)]=−0.2(2)×10−11. With a similar estimate for the a0(980), the combined effect is thus well below 1×10−11 in absolute value. We also estimate the contribution of heavier scalar resonances. In view of the very uncertain situation concerning their two-photon couplings we suggest to treat them together with other resonances of similar mass when imposing the matching to short-distance constraints. Our final result is a refined estimate of the S-wave rescattering effects in the ππ and K¯K channel up to about 1.3 GeV and including a narrow-width evaluation of the a0(980): aμHLbL[scalars]=−9(1)×10−11.

Organisation(s)
Particle Physics
External organisation(s)
Johannes Gutenberg-Universität Mainz, Universität Bern, University of Washington, University of California, San Diego
Journal
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume
820
No. of pages
8
ISSN
0370-2693
DOI
https://doi.org/10.1016/j.physletb.2021.136502
Publication date
09-2021
Peer reviewed
Yes
Austrian Fields of Science 2012
103034 Particle physics, 103012 High energy physics
ASJC Scopus subject areas
Nuclear and High Energy Physics
Portal url
https://ucris.univie.ac.at/portal/en/publications/a-dispersive-estimate-of-scalar-contributions-to-hadronic-lightbylight-scattering(e5037677-ac3f-412f-937a-5c059a49ff97).html