Effects of custodial symmetry breaking in the Georgi-Machacek model at high energies

Effects of custodial symmetry breaking in the Georgi-Machacek model at high energies The model proposed by Georgi and Machacek enables the Higgs sector to involve isospin triplet scalar fields while retaining a custodial SU(2)V symmetry in the potential and, thus, ensuring the electroweak ρ parameter to be one at tree level. This custodial symmetry, however, is explicitly broken by loop effects of the U(1)Y hypercharge gauge interaction. In order to make the model consistent at high energies, we construct the most general form of the Higgs potential without the custodial symmetry, and then we derive the one-loop β functions for all the model parameters. Assuming the δi quantities describing the custodial symmetry breaking to be zero at low energy, we find that |δi| are typically smaller than the magnitude of the U(1)Y gauge coupling and the other running parameters in the potential also at high energy without spoiling perturbativity and vacuum stability. We also clarify that the mass degeneracy among the SU(2)V 5-plet and 3-plet Higgs bosons is smoothly broken by ∼0.1% corrections. These results show that the amount of the custodial symmetry breaking is kept well under control up to energies close to the theory cutoff. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Physical Review D American Physical Society (APS)

Effects of custodial symmetry breaking in the Georgi-Machacek model at high energies

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Effects of custodial symmetry breaking in the Georgi-Machacek model at high energies

Abstract

The model proposed by Georgi and Machacek enables the Higgs sector to involve isospin triplet scalar fields while retaining a custodial SU(2)V symmetry in the potential and, thus, ensuring the electroweak ρ parameter to be one at tree level. This custodial symmetry, however, is explicitly broken by loop effects of the U(1)Y hypercharge gauge interaction. In order to make the model consistent at high energies, we construct the most general form of the Higgs potential without the custodial symmetry, and then we derive the one-loop β functions for all the model parameters. Assuming the δi quantities describing the custodial symmetry breaking to be zero at low energy, we find that |δi| are typically smaller than the magnitude of the U(1)Y gauge coupling and the other running parameters in the potential also at high energy without spoiling perturbativity and vacuum stability. We also clarify that the mass degeneracy among the SU(2)V 5-plet and 3-plet Higgs bosons is smoothly broken by ∼0.1% corrections. These results show that the amount of the custodial symmetry breaking is kept well under control up to energies close to the theory cutoff.
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Publisher
The American Physical Society
Copyright
Copyright © © 2017 American Physical Society
ISSN
1550-7998
eISSN
1550-2368
D.O.I.
10.1103/PhysRevD.96.015001
Publisher site
See Article on Publisher Site

Abstract

The model proposed by Georgi and Machacek enables the Higgs sector to involve isospin triplet scalar fields while retaining a custodial SU(2)V symmetry in the potential and, thus, ensuring the electroweak ρ parameter to be one at tree level. This custodial symmetry, however, is explicitly broken by loop effects of the U(1)Y hypercharge gauge interaction. In order to make the model consistent at high energies, we construct the most general form of the Higgs potential without the custodial symmetry, and then we derive the one-loop β functions for all the model parameters. Assuming the δi quantities describing the custodial symmetry breaking to be zero at low energy, we find that |δi| are typically smaller than the magnitude of the U(1)Y gauge coupling and the other running parameters in the potential also at high energy without spoiling perturbativity and vacuum stability. We also clarify that the mass degeneracy among the SU(2)V 5-plet and 3-plet Higgs bosons is smoothly broken by ∼0.1% corrections. These results show that the amount of the custodial symmetry breaking is kept well under control up to energies close to the theory cutoff.

Journal

Physical Review DAmerican Physical Society (APS)

Published: Jul 1, 2017

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