This title appears in the Scientific Report : 2015 

The running coupling of the minimal sextet composite Higgs model
Fodor, Zoltan (Corresponding author)
Holland, Kieran (Corresponding author) / Kuti, Julius (Corresponding author) / Mondal, Santanu (Corresponding author) / Nogradi, Daniel (Corresponding author) / Wong, Chik Him (Corresponding author)
Jülich Supercomputing Center; JSC
Journal of high energy physics, 2015 (2015) 9, S. 39
Berlin Springer 2015
Journal Article
Computational Science and Mathematical Methods
Please use the identifier: in citations.
Please use the identifier: in citations.
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.