Falsifying Models of New Physics Via WW Scattering

TL;DR

It is shown that the coefficients of operators in the electroweak chiral Lagrangian can be bounded if the underlying theory obeys the usual assumptions of Lorentz invariance, analyticity, unitarity, and crossing to arbitrarily short distances.

Abstract

We show that the coefficients of operators in the electroweak chiral Lagrangian can be bounded if the underlying theory obeys the usual assumptions of Lorentz invariance, analyticity, unitarity and crossing to arbitrarily short distances. Violations of these bounds can be explained by either the existence of new physics below the naive cut-off of the the effective theory, or by the breakdown of one of these assumptions in the short distance theory. As a corollary, if no light resonances are found, then a measured violation of the bound would falsify generic models of string theory.

Figures (2)

• Figure 1: Bounds on electroweak chiral parameters from $Z^0_LZ^0_L$ and $W_L^+Z_L^0$ scattering as a function of $s$ in the dispersion relation, Eq. \ref{['naivebound']}.
• Figure 2: Bounds on the coefficients of the electroweak chiral lagrangian, $\hat{\alpha}_4$ and $\hat{\alpha}_5$ renormalized at the scale $v$.