R Values in Low Energy e+e− Annihilation
نویسنده
چکیده
whereQf is the fractional charge of the quark, and the factor of 3 in front counts the three colors for each flavor. The cross section of the pure QED process is σ(e+e− → μ+μ−) = 4πα2/3s. The value of R, which counts directly the number of quarks, both flavor and colors, is expected to be constant so long as the centerof-mass (cm) energy of the annihilated e+e− does not overlap with resonances or thresholds for the production of new quark flavors. One has
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