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arXiv · 1607.06121

Fate of the conformal fixed point with twelve massless fermions and SU(3) gauge group

Zoltan Fodor·Kieran Holland·Julius Kuti·Santanu Mondal·Daniel Nogradi·Chik Him Wong
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Abstract

We report new results on the conformal properties of an important strongly coupled gauge theory, a building block of composite Higgs models beyond the Standard Model. With twelve massless fermions in the fundamental representation of the SU(3) color gauge group, an infrared fixed point of the $\beta$-function was recently reported in the theory (Cheng:2014jba) with uncertainty in the location of the critical gauge coupling inside the narrow $[ 6.0<g_*^2<6.4]$ interval and widely accepted since as the strongest evidence for a conformal fixed point and scale invariance in the theory with model-building implications. Using the exact same renormalization scheme as the previous study, we show that no fixed point of the $\beta$-function exists in the reported interval. Our findings eliminate the only seemingly credible evidence for conformal fixed point and scale invariance in the $N_f=12$ model whose infrared properties remain unresolved. The implications of the recently completed 5-loop QCD beta function for arbitrary flavor number are discussed with respect to our work.

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Zoltan Fodor, Kieran Holland, Julius Kuti, Santanu Mondal, Daniel Nogradi, Chik Him Wong. 2016-07-20. Fate of the conformal fixed point with twelve massless fermions and SU(3) gauge group. https://doi.org/10.1103/physrevd.94.091501

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