The running coupling of the minimal sextet composite Higgs model

Fodor, Zoltan; Mondal, Santanu; Holland, Kieran; Nogradi, Daniel; Wong, Chik Him; Kuti, Julius

doi:10.1007/JHEP09(2015)039

Journal Article

FZJ-2015-07587

The running coupling of the minimal sextet composite Higgs model

Fodor, Z. (Corresponding author)FZJ* ; Holland, K. (Corresponding author) ; Kuti, J. (Corresponding author) ; Mondal, S. (Corresponding author) ; Nogradi, D. (Corresponding author) ; Wong, C. H. (Corresponding author)

2015
Springer Berlin

Journal of high energy physics 2015(9), 39 (2015) [10.1007/JHEP09(2015)039]

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Please use a persistent id in citations: http://hdl.handle.net/2128/9591 doi:10.1007/JHEP09(2015)039

Abstract: We compute the renormalized running coupling of SU(3) gauge theory coupled to Nf = 2 flavors of massless Dirac fermions in the 2-index-symmetric (sextet) representation. This model is of particular interest as a minimal realization of the strongly interacting composite Higgs scenario. A recently proposed finite volume gradient flow scheme is used. The calculations are performed at several lattice spacings with two different implementations of the gradient flow allowing for a controlled continuum extrapolation and particular attention is paid to estimating the systematic uncertainties. For small values of the renormalized coupling our results for the β-function agree with perturbation theory. For moderate couplings we observe a downward deviation relative to the 2-loop β-function but in the coupling range where the continuum extrapolation is fully under control we do not observe an infrared fixed point. The explored range includes the locations of the zero of the 3-loop and the 4-loop β-functions in the MS¯$$ \overline{\mathrm{MS}} $$ scheme. The absence of a non-trivial zero in the β-function in the explored range of the coupling is consistent with our earlier findings based on hadronic observables, the chiral condensate and the GMOR relation. The present work is the first to report continuum non-perturbative results for the sextet model.

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