Two-Color Gauge Theory with Novel Infrared Behavior

Abstract

Using lattice simulations, we study the infrared behavior of a particularly interesting SU(2) gauge theory, with six massless Dirac fermions in the fundamental representation. We compute the running gauge coupling derived nonperturbatively from the Schrödinger functional of the theory, finding no evidence for an infrared fixed point up through gauge couplings g(2) of order 20. This implies that the theory either is governed in the infrared by a fixed point of considerable strength, unseen so far in nonsupersymmetric gauge theories, or breaks its global chiral symmetries producing a large number of composite Nambu-Goldstone bosons relative to the number of underlying degrees of freedom. Thus either of these phases exhibits novel behavior.

Composite Goldstone dark matter: experimental predictions from the lattice

“…For example, there are extensions that show how a 125 GeV scalar can emerge [16]. The USQCD collaboration highlighted this lattice theory in a recent white paper [17] and studied the effects of additional fermions in [18]. Other groups have reported results at strong coupling [19], results with nonzero chemical potential [20][21][22][23][24], and results with chiral lattice fermions [25].…”

Lattice tests of beyond standard model dynamics

“…Their γ m for N f = 6 ranges from 0.1-0.25 over observed g 2 range, smaller than the one loop perturbative value. The largest statistics study to date of N f = 6 is the Schrödinger functional study of Appelquist et al (2014c). They found no evidence for an IRFP.…”

Slope of the beta function at the fixed point of SU(2) gauge theory with six or eight flavors

“…A much studied case is SU(2) gauge theory with fermions in the fundamental representation [4][5][6][7][8][9]. While the upper edge of the conformal window is robust, as the asymptotic freedom is lost at N f = 11, a consistent picture of the extent of the conformal window has only recently emerged: simulations of the 8 flavor theory have shown the existence of a fixed point [9] and similarly the 6 flavor case [10].…”