https://doi.org/10.1140/epjc/s10052-021-09008-9
Regular Article - Theoretical Physics
Spectral properties of local gauge invariant composite operators in the SU(2) Yang–Mills–Higgs model
1
Department of Physics, KU Leuven Campus Kortrijk–Kulak, Etienne Sabbelaan 53 bus 7657, 8500, Kortrijk, Belgium
2
Department of Physics and Astronomy, Ghent University, Krijgslaan 281-S9, 9000, Ghent, Belgium
3
Departamento de Física Teórica, Instituto de Física, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier 524, Maracanã, 20550-013, Rio de Janeiro, Brazil
Received:
9
December
2020
Accepted:
23
February
2021
Published online:
9
March
2021
The spectral properties of a set of local gauge (BRST) invariant composite operators are investigated in the SU(2) Yang–Mills–Higgs model with a single Higgs field in the fundamental representation, quantized in the ’t Hooft 
-gauge. These operators can be thought of as a BRST invariant version of the elementary fields of the theory, the Higgs and gauge fields, with which they share a gauge independent pole mass. The two-point correlation functions of both BRST invariant composite operators and elementary fields, as well as their spectral functions, are investigated at one-loop order. It is shown that the spectral functions of the elementary fields suffer from a strong unphysical dependence from the gauge parameter 
, and can even exhibit positivity violating behaviour. In contrast, the BRST invariant local operators exhibit a well defined positive spectral density.
© The Author(s) 2021
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