We critically assess to what extent it makes sense to bound the Wilson coefficients of dimension-six operators. In the context of Higgs physics, we establish that a closely related observable, cH, is well defined and satisfies a two-sided bound. cH is derived from the low momentum expansion of the scattering amplitude, or the derivative of the amplitude at the origin with respect to the Mandelstam variable s, expressed as M(HiHi→HjHj)=cHs+O(gSM,s−2) where gSM represents all Standard Model couplings. This observable is and, as a result, not sign-definite. We also determine the conditions under which the bound on cH is equivalent to a bound on the dimension-six operator OH=∂|H|2∂|H|2.
Published by the American Physical Society
2024