Measurement of the Electromagnetic Coupling at Large Momentum Transfer
We report the first purely electroweak measurement of the strengthening of the electromagnetic coupling, αQED with increasing momentum transfer Q2, by comparing the process e+e--->μ+μ- with the process e+e--->e+e-μ+μ-. The data were accumulated at an average center-of-mass energy <s> = 57.77 GeV using the TOPAZ detector at the TRISTAN e+e- collider. We measure α-1QED\(Q2) to change from its known value of α-1QED≅137.0 at Q2 = 0 to 128.5+/-1.8\(stat\)+/-0.7\(syst\) at Q2 = \(57.77 GeV/c\)2. This result agrees with electroweak predictions.
Physical Review Letters
- Pub Date:
- January 1997