Dispersive derivation of the trace anomaly
نویسنده
چکیده
We present a simple derivation of the one-loop trace anomaly in spinor QED through dispersion relations, avoiding completely any ultraviolet regu-larization. The anomaly can be expressed as a convergent sum rule for the imaginary part of a relevant formfactor. In the massless limit, the imaginary part produces a delta-function singularity at zero external momentum squared. Such a treatment reveals an "infrared face" of the trace anomaly, in striking similarity with the well-known case of the axial anomaly.
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