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DOI: 10.5445/IR/1000085354
Veröffentlicht am 16.08.2018

Unitarity constraints in triplet extensions beyond the large s limit

Krauss, Manuel E.; Staub, Florian

Abstract:
Triplet extensions are attractive alternatives to the standard model (SM) of particle physics. While models with only one triplet are highly constrained by electroweak precision observables, this is not necessarily the case once several triplets are present as in the Georgi-Machacek model. As in all other BSM models, the parameter space of triplet extensions is constrained by the condition that perturbative unitarity is not violated. For this purpose, limits on the eigenvalues of the scalar 2→2 scattering matrix are set. It is very common in the BSM literature that the scattering matrix is calculated under one crucial assumption: the scattering energy s is so large that only point interactions involving quartic couplings provide non-negligible contributions. However, it is not given that this approximation is always valid—in fact, diagrams involving propagators can play an important role. We discuss the examples of (i) the SM model extended by a real triplet, (ii) the Y=1 triplet extension of the SM, and (iii) the Georgi-Machacek model, how the tree-level unitarity constraints are affected once the large s approximation is given up. ... mehr


Zugehörige Institution(en) am KIT Institut für Theoretische Physik (ITP)
Institut für Kernphysik (IKP)
Publikationstyp Zeitschriftenaufsatz
Jahr 2018
Sprache Englisch
Identifikator ISSN: 2470-0010, 2470-0029
URN: urn:nbn:de:swb:90-853547
KITopen ID: 1000085354
HGF-Programm 51.03.06; LK 01
Erschienen in Physical review / D
Band 98
Heft 1
Seiten Article No. 015041
Bemerkung zur Veröffentlichung Gefördert durch SCOAP3
Vorab online veröffentlicht am 31.07.2018
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