Analysis of the Z^0 Resonant Amplitude in General R_ξGauges

Abstract

The Z^0 resonant amplitude is discussed in general R_ξgauges. When the original on-shell definition of the Z^0 mass M is employed, a gauge dependence of M emerges in the next-to-leading approximation which, although small, is of the same magnitude as the current experimental error. In the following order of expansion, these unphysical effects are unbounded. The gauge dependence of M disappears when modified, previously proposed definitions of mass or self-energies, are used. The relevance of these considerations to the concept of the mass of unstable particles is pointed out.

7 pages, LaTeX. Slightly modified version (to improve clarity of presentation). To be published in Phys. Rev. Letters

References in corpus (3)

• Gauge Invariance and Unstable Particles
• A Gauge-Independent Approach to Resonant Transition Amplitudes
• Gauge-Invariant Resummation Formalism for Two-Point Correlation Functions

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