Constraining the gauge and scalar sectors of the doublet left-right symmetric model
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Springer
Received: January Revised: July Accepted: August Published: September
14, 14, 11, 11,
2020 2020 2020 2020
V´ eronique Bernard,a S´ ebastien Descotes-Genonb and Luiz Vale Silvac a
Groupe de Physique Th´eorique, Institut de Physique Nucl´eaire, UMR 8606, CNRS, Univ. Paris-Sud, Universit´e Paris-Saclay, 91405 Orsay Cedex, France b Laboratoire de Physique Th´eorique, UMR 8627, CNRS, Univ. Paris-Sud, Universit´e Paris-Saclay, 91405 Orsay Cedex, France c IFIC, Universitat de Val`encia - CSIC, Parc Cient´ıfic, Catedr´ atico Jos´e Beltr´ an 2, E-46980 Paterna, Spain
E-mail: [email protected], [email protected], [email protected] Abstract: We consider a left-right symmetric extension of the Standard Model where the spontaneous breakdown of the left-right symmetry is triggered by doublets. The electroweak ρ parameter is protected from large corrections in this Doublet Left-Right Model (DLRM), contrary to the triplet case. This allows in principle for more diverse patterns of symmetry breaking. We consider several constraints on the gauge and scalar sectors of DLRM: the unitarity of scattering processes involving gauge bosons with longitudinal polarisations, the radiative corrections to the muon ∆r parameter and the electroweak precision observables measured at the Z pole and at low energies. Combining these constraints within the frequentist CKMfitter approach, we see that the fit pushes the scale of left-right symmetry breaking up to a few TeV, while favouring an electroweak symmetry breaking triggered not only by the SU (2)L × SU (2)R bi-doublet, which is the case most commonly considered in the literature, but also by the SU (2)L doublet. Keywords: Beyond Standard Model, GUT ArXiv ePrint: 2001.00886
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP09(2020)088
JHEP09(2020)088
Constraining the gauge and scalar sectors of the doublet left-right symmetric model
Contents 1
2 The 2.1 2.2 2.3 2.4 2.5
2 2 3 6 9 9
doublet left-right model Gauge structure and symmetry breaking Spin-0 sector Spin-1 sector Spin-1/2 sector Parameters
3 Constraints from tree-level unitarity 3.1 Constraints from the scattering of light gauge bosons 3.2 Constraints from the scattering of heavy gauge bosons 3.3 Constraints from scatterings involving both light and heavy gauge bosons 3.4 Summary
10 11 12 14 17
4 ∆r and the mass of the W at one loop 4.1 Renormalisation 4.2 Computation of ∆r
18 18 22
5 Electroweak precision observables 5.1 Computation in left-right models 5.2 Parametrization of the observables
24 24 25
6 Global fits 6.1 Method 6.2 Results
27 27 28
7 Conclusions
38
A Corrections from DLRM to EW precision observables
41
B Scalar sector B.1 Scalar mass eigenstates B.2 Some useful relations
43 43 44
C Feynman rules C.1 Couplings to fermions C.2 Couplings to gauge bosons
45 45 45
D More on renormalisation
46
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JHEP09(2020)088
1 Introduction
1
Introduction
–1–
JHEP09(2020)088
Left-Right (LR) symmetric models constitute a category of extension
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