Study of the process e+e-\to \mu+\mu- in the energy region \sqrt{s}=980, 1040 -- 1380 MeV

TL;DR

This study precisely measured the e+e- to mu+mu- cross section in the 980 to 1380 MeV energy range, confirming the theoretical predictions and determining the electromagnetic coupling constant with high accuracy.

Contribution

The paper provides new experimental data on the e+e- to mu+mu- process in a specific energy range, validating theoretical models and extracting the electromagnetic coupling constant.

Findings

Measured cross section closely matches theoretical predictions.

Determined the electromagnetic coupling constant in the studied energy range.

Confirmed the validity of QED in the energy region.

Abstract

The cross section of the process e+e-\to\mu+\mu- was measured in the SND experiment at the VEPP-2M e+e- collider in the energy region \sqrt{s}=980, 1040 -- 1380 MeV. The event numbers of the process e+e-\to\mu+\mu- were normalized to the integrated luminosity measured using e+e-\to e+e- and e+e-\to\gamma\gamma processes. The ratio of the measured cross section to the theoretically predicted value is 1.006\pm 0.007 \pm 0.016 and 1.005 \pm 0.007 \pm 0.018 in the first and second case respectively. Using results of the measurements, the electromagnetic running coupling constant \alpha in the energy region \sqrt{s}=1040 -- 1380 MeV was obtained <1/\alpha> = 134.1\pm 0.5 \pm 1.2 and this is in agreement with theoretical expectation.