The Alternative Left-Right Scenario: Unitarity, Vacuum Stability and RG Evolution
Abstract
We study the theoretical constraints on the scalar sector of the Alternative Left-Right Model (ALRM), an E6-motivated extension of the Standard Model based on the gauge group SU(3)c ⊗ SU(2)L ⊗ SU(2)R' ⊗ U(1)B−L, supplemented by a global U(1)S symmetry. We derive the complete set of tree-level perturbative unitarity constraints on the model, resulting in 14 independent conditions on the quartic scalar couplings. When combined with the boundedness-from-below conditions and the requirement of positive-definite scalar mass-squared eigenvalues, these constraints are found to be complementary, with their simultaneous imposition yielding significantly more stringent restrictions on the parameter space than either set alone. We then perform a one loop renormalization group analysis, evolving the model parameters from the electroweak scale up to a high energy cut-off scale, and requiring that the vacuum stability, the unitarity, and the perturbativity conditions are preserved throughout. The renormalisation group evolution is found to restrict the allowed parameter space considerably beyond the tree-level bounds, with the constraints on the quartic couplings becoming more stringent as the cut off scale is raised. Consequently, the physical scalar masses in the model acquire upper bounds. For the right-hand symmetry breaking scale, vR = 10 TeV and requiring theoretical consistency up to 1016 GeV, we obtain mH1± ≲ 6.5 TeV, mH2± ≲ 1.5 TeV, and mH10 ≃ mA1 ≲ 1.3 TeV, with all bounds scaling with vR. These findings offer a predictive and falsifiable framework for searches of the extended Higgs sector of the ALRM at the current and future collider experiments.
Versions
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BibTeX
@misc{deka2026alternative,
title = {{The Alternative Left-Right Scenario: Unitarity, Vacuum Stability and RG Evolution}},
author = {Hrishikesh Deka and Avnish and Sumit K. Garg and Poulose Poulose},
howpublished = {arXiv},
year = {2026},
month = may,
doi = {10.48550/arxiv.2605.20794},
eprint = {2605.20794},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.20794},
}
RIS
TY - UNPB
TI - The Alternative Left-Right Scenario: Unitarity, Vacuum Stability and RG Evolution
AU - Hrishikesh Deka
AU - Avnish
AU - Sumit K. Garg
AU - Poulose Poulose
PY - 2026
DA - 2026/05/20
PB - arXiv
DO - 10.48550/arxiv.2605.20794
UR - https://arxiv.org/abs/2605.20794
AB - We study the theoretical constraints on the scalar sector of the Alternative Left-Right Model (ALRM), an E_6-motivated extension of the Standard Model based on the gauge group SU(3)_c ⊗ SU(2)_L ⊗ SU(2)_R' ⊗ U(1)_B−L, supplemented by a global U(1)_S symmetry. We derive the complete set of tree-level perturbative unitarity constraints on the model, resulting in 14 independent conditions on the quartic scalar couplings. When combined with the boundedness-from-below conditions and the requirement of positive-definite scalar mass-squared eigenvalues, these constraints are found to be complementary, with their simultaneous imposition yielding significantly more stringent restrictions on the parameter space than either set alone. We then perform a one loop renormalization group analysis, evolving the model parameters from the electroweak scale up to a high energy cut-off scale, and requiring that the vacuum stability, the unitarity, and the perturbativity conditions are preserved throughout. The renormalisation group evolution is found to restrict the allowed parameter space considerably beyond the tree-level bounds, with the constraints on the quartic couplings becoming more stringent as the cut off scale is raised. Consequently, the physical scalar masses in the model acquire upper bounds. For the right-hand symmetry breaking scale, v_R = 10 TeV and requiring theoretical consistency up to 10^16 GeV, we obtain m_H_1^± ≲ 6.5 TeV, m_H_2^± ≲ 1.5 TeV, and m_H_1^0 ≃ m_A_1 ≲ 1.3 TeV, with all bounds scaling with v_R. These findings offer a predictive and falsifiable framework for searches of the extended Higgs sector of the ALRM at the current and future collider experiments.
ER -