Low-energy gluon contributions to the vacuum polarization of heavy quarks
نویسنده
چکیده
We calculate a correction to the electromagnetic current induced by a heavy quark loop. The contribution of this correction to the vacuum polarization function appears at the O(αs) order of perturbation theory and has a qualitatively new feature – its absorptive part starts at zero energy in contrast to other contributions where the absorptive parts start at the two-particle threshold. Our result imposes a constraint on the order n of the moments used in the heavy-quark sum rules, n < 4. PACS: 11.40.-q, 12.20.-m, 12.38.Bx, 02.70.Hm
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