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Two-pion low-energy contribution to the muon g-2 with improved precision from analyticity and unitarity

Ananthanarayan, B and Caprini, Irinel and Das, Diganta and Imsong, Sentitemsu I (2014) Two-pion low-energy contribution to the muon g-2 with improved precision from analyticity and unitarity. In: PHYSICAL REVIEW D, 89 (3).

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Official URL: http://dx.doi.org/10.1103/PhysRevD.89.036007


The two-pion contribution from low energies to the muon magnetic moment anomaly, although small, has a large relative uncertainty since in this region the experimental data on the cross sections are neither sufficient nor precise enough. It is therefore of interest to see whether the precision can be improved by means of additional theoretical information on the pion electromagnetic form factor, which controls the leading-order contribution. In the present paper, we address this problem by exploiting analyticity and unitarity of the form factor in a parametrization-free approach that uses the phase in the elastic region, known with high precision from the Fermi-Watson theorem and Roy equations for pi pi elastic scattering as input. The formalism also includes experimental measurements on the modulus in the region 0.65-0.70 GeV, taken from the most recent e(+)e(-) ->pi(+)pi(-) experiments, and recent measurements of the form factor on the spacelike axis. By combining the results obtained with inputs from CMD2, SND, BABAR, and KLOE, we make the predictions a(mu)(pi pi,LO)2m(pi), 0.30 GeV] = (0.553 +/- 0.004) x 10(-10) and a(mu)(pi pi,LO)0.30 GeV; 0.63 GeV] = (133.083 +/- 0.837) x 10(-10). These are consistent with the other recent determinations and have slightly smaller errors.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the AMER PHYSICAL SOC, USA
Department/Centre: Division of Physical & Mathematical Sciences > Centre for High Energy Physics
Date Deposited: 19 May 2014 05:17
Last Modified: 19 May 2014 05:19
URI: http://eprints.iisc.ac.in/id/eprint/48916

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