Restoring naturalness via conjugate fermions

We propose a novel mechanism for canceling the leading order contribution to the potential in composite Higgs scenarios. The mechanism relies on the splitting of a pseudoreal representation of the global symmetry into a complex representation and its conjugate of the unbroken group. We identify two cosets one of which includes a custodial symmetry. A numerical analysis is performed in a phenomenological three-site model and the resulting fine-tuning is analyzed. The canceling of the leading order potential results in a drastic reduction of the fine-tuning. For a symmetry breaking scale of the strong sector as high as <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi>f</a:mi><a:mo>=</a:mo><a:mn>1600</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>GeV</a:mi></a:mrow></a:math>, fine-tuning can be as good as 10% or even better. We discuss a possible interpretation in the 5D holographic dual. Unique signatures of the model include quarks with baryon number <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>B</c:mi><c:mo>=</c:mo><c:mn>2</c:mn><c:mo>/</c:mo><c:mn>3</c:mn></c:math> with highly distinctive decays which can be looked for at the LHC. Published by the American Physical Society 2024