SMEFT Constraints on Top Electroweak Couplings and a Composite Higgs Interpretation
Abstract
Recent LHC measurements of tWZ, tt̅ Z and single top production provide complementary probes of top quark electroweak interactions. We incorporate these measurements into a global Standard Model effective field theory analysis of 46 independent dimension-six Wilson coefficients at linear order. The updated fit remains compatible with the Standard Model at 95% CL, and favors negative values of CHq(−)≡ CHq(1)−CHq(3) and CHt, with central values suggestive of TeV scale new physics. We also present an effective composite Higgs model based on a two-site description that realizes this pattern of Wilson coefficients through partial compositeness. The model includes custodial symmetry and protection of the Zb̅L bL coupling. A fermion bitriplet generates the required left-handed shift, and an additional embedding of the right-handed top allows negative contributions to CHt from both fermion and spin-one exchange. Scanning four right-handed top embeddings, we find parameter regions within the 68% CL contour that are compatible with electroweak precision data, Higgs coupling measurements and applicable direct searches. The T parameter limits the negative fermionic contribution to CHt, favoring a spin-one contribution of comparable or greater magnitude. Larger SU(2)R representations extend the reach toward negative CHt, and also enhance four-quark interactions that increase the four-top cross section, in the direction favored by current measurements. The mechanism connects the preferred top electroweak shifts to complementary tests through single production of quarks with electric charge −4/3, modified Higgs couplings and four-top production.
Related
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BibTeX
@misc{rold2026smeft,
title = {{SMEFT Constraints on Top Electroweak Couplings and a Composite Higgs Interpretation}},
author = {Leandro Da Rold and Juan Fernandez},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.05500},
eprint = {2611.05500},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.05500},
}
RIS
TY - UNPB
TI - SMEFT Constraints on Top Electroweak Couplings and a Composite Higgs Interpretation
AU - Leandro Da Rold
AU - Juan Fernandez
PY - 2026
DA - 2026/11/03
PB - arXiv
DO - 10.48550/arxiv.2611.05500
UR - https://arxiv.org/abs/2611.05500
AB - Recent LHC measurements of tWZ, tt̅ Z and single top production provide complementary probes of top quark electroweak interactions. We incorporate these measurements into a global Standard Model effective field theory analysis of 46 independent dimension-six Wilson coefficients at linear order. The updated fit remains compatible with the Standard Model at 95% CL, and favors negative values of C_Hq^(−)≡ C_Hq^(1)−C_Hq^(3) and C_Ht, with central values suggestive of TeV scale new physics. We also present an effective composite Higgs model based on a two-site description that realizes this pattern of Wilson coefficients through partial compositeness. The model includes custodial symmetry and protection of the Zb̅_L b_L coupling. A fermion bitriplet generates the required left-handed shift, and an additional embedding of the right-handed top allows negative contributions to C_Ht from both fermion and spin-one exchange. Scanning four right-handed top embeddings, we find parameter regions within the 68% CL contour that are compatible with electroweak precision data, Higgs coupling measurements and applicable direct searches. The T parameter limits the negative fermionic contribution to C_Ht, favoring a spin-one contribution of comparable or greater magnitude. Larger SU(2)_R representations extend the reach toward negative C_Ht, and also enhance four-quark interactions that increase the four-top cross section, in the direction favored by current measurements. The mechanism connects the preferred top electroweak shifts to complementary tests through single production of quarks with electric charge −4/3, modified Higgs couplings and four-top production.
ER -