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arXiv · hep-th/0005149

Width and Partial Widths of Unstable Particles

P. A. Grassi·B. A. Kniehl·A. Sirlin
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Abstract

In the gauge theory context, a definition of branching ratios and partial widths of unstable particles is proposed that satisfies the basic principles of additivity and gauge independence. A simpler definition, similar to the conventional one, is examined in the Z^0-boson case. In order to establish contact with experiment, we show that it leads to a peak cross section that justifies the expression used by the LEP Electroweak Working Group through next-to-next-to-leading order, provided that the pole rather than the on-shell mass and width of the Z^0 boson are employed.

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P. A. Grassi, B. A. Kniehl, A. Sirlin. 2000-08-29. Width and Partial Widths of Unstable Particles. https://doi.org/10.1103/physrevlett.86.389

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