The running coupling of 8 flavors and 3 colors

Abstract

We compute the renormalized running coupling of SU(3) gauge theory coupled to N f = 8 flavors of massless fundamental Dirac fermions. The recently proposed finite volume gradient flow scheme is used. The calculations are performed at several lattice spacings allowing for a controlled continuum extrapolation. The results for the discrete β-function show that it is monotonic without any sign of a fixed point in the range of couplings we cover. As a cross check the continuum results are compared with the wellknown perturbative continuum β-function for small values of the renormalized coupling and perfect agreement is found.

Dilaton EFT framework for lattice data

“…Lattice simulations of strongly interacting gauge theories indicate that infrared conformal behavior sets in with a sufficiently large number of light fermions [1][2][3][4][5][6][7][8][9][10][11][12][13][14] . In addition, a remarkably light singlet scalar particle appears in the spectrum of recent simulations as this number is increased toward the critical value for the transition to conformal behavior (the "bottom of the conformal window") [15][16][17][18][19].…”

Running coupling of the sextet composite Higgs model

“…The bare mass is set to zero. The applicability of the rooting procedure in our finite volume setup at zero bare mass has been shown to hold in [21] to which we refer for more details.…”

Status of a minimal composite Higgs theory

“…For comparison, red color marks the step β -function of four massless fermion flavors in the fundamental representation from an earlier publication [43]. The new published result for the step β -function of eight massless fermion flavors in the fundamental representation is marked with green color in the plot [45]. The step β -function of the sextet model of this proposal is marked with blue color in the plot from a recent publication [46].…”