Universal Imprints of a Pseudo-Nambu-Goldstone Higgs Boson

A large class of models addressing the electroweak naturalness problem postulates the existence of new spontaneously broken global symmetries above the weak scale. The Higgs boson arises as a pseudo-Nambu-Goldstone boson (PNGB) whose interactions are nonlinear due to the presence of degenerate vacua. We argue that, once the normalization of the PNGB decay constant $f$ is determined, the Higgs nonlinear interactions in the gauge sector are universal in the infrared and independent of the symmetry breaking pattern $G/H$, even after integrating out heavy composite resonances. We propose a set of “universal relations” in Higgs couplings with electroweak gauge bosons and in triple gauge boson couplings, which are unique predictions of the universal nonlinearity. Experimental measurements of these relations would serve as the litmus test of a PNGB Higgs boson.