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Main Author: Willenbrock, Scott
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2503.07866
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author Willenbrock, Scott
author_facet Willenbrock, Scott
contents It has been known since the 1950's that an unstable particle is associated with a complex pole in the propagator. This had to be rediscovered twice: in the early 1970's in the context of hadronic resonances, and in the early 1990's in the context of the $Z$ boson. The physical mass of the particle is the real part of the pole in the complex energy plane. In hadronic physics, this replaced the ``Breit-Wigner mass,'' which was found to depend on the parameterization of the ``energy-dependent width.'' In $Z$ physics, it replaced the ``on-shell'' mass, which was found to be gauge dependent. Although the mass defined from the complex pole position has been widely discussed in the literature, it has not yet made its way into quantum field theory textbooks.
format Preprint
id arxiv_https___arxiv_org_abs_2503_07866
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Brief History of Mass
Willenbrock, Scott
High Energy Physics - Phenomenology
High Energy Physics - Experiment
It has been known since the 1950's that an unstable particle is associated with a complex pole in the propagator. This had to be rediscovered twice: in the early 1970's in the context of hadronic resonances, and in the early 1990's in the context of the $Z$ boson. The physical mass of the particle is the real part of the pole in the complex energy plane. In hadronic physics, this replaced the ``Breit-Wigner mass,'' which was found to depend on the parameterization of the ``energy-dependent width.'' In $Z$ physics, it replaced the ``on-shell'' mass, which was found to be gauge dependent. Although the mass defined from the complex pole position has been widely discussed in the literature, it has not yet made its way into quantum field theory textbooks.
title A Brief History of Mass
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
url https://arxiv.org/abs/2503.07866