Light top partners and precision physics
By Christophe Grojean, O. Matsedonskyi, G. Panico. 2013
204 citations recorded by the source corpus.
A bstractWe analyze the corrections to the precision EW observables in minimal composite Higgs models by using a general effective parametrization that also includes the lightest fermionic resonances. A new, possibly large, logarithmically divergent contribution to $ \widehat{S} $ is identified, which comes purely from the strong dynamics. It can be interpreted as a running of $ \widehat{S} $ induced by the non-renormalizable Higgs interactions due to the non- linear σ-model structure. As expected, the corrections to the $ \widehat{T} $ parameter coming from fermion loops are finite and dominated by the contributions of the lightest composite states. The fit of the oblique parameters suggests a rather stringent lower bound on the σ-model scale f ≳ 750 GeV. The corrections to the Z$ \overline{b} $LbL vertex coming from the lowest-order operators in the effective Lagrangian are finite and somewhat correlated to the corrections to $ \widehat{T} $. Large additional contributions are generated by contact interactions with 4 composite fermions. In this case a logarithmic divergence can be generated and the correlation with $ \widehat{T} $ is removed. We also analyze the tree-level corrections to the top couplings, which are expected to be large due to the sizable degree of compositeness of the third generation quarks. We find that for a moderate amount of tuning the deviation in Vtb can be of order 5% while the distortion of the Z$ \overline{t} $LtL vertex can be 10%.
Subfields: Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/d3ca3e5c8b9a9e0c7c6d95d79b2c6d659bb1233b
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In Nuclear and High Energy Physics
Citations in the corpus
- The composite twin Higgs scenario (2015, methodology): “A quantitative compatibility with EWPT is actually possible in ordinary Composite Higgs models only relying on the radiative effects of somewhat light colored Top Partners [6, 7], whose presence is precisely what we want to avoid with our construction.”
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