Model Independent Effective Dimension Six Operators And Scattering Unitarity

TL;DR

This paper investigates how dimension-six operators in effective field theory can cause unitarity violations in high-energy scattering processes at the LHC, setting bounds on Wilson coefficients based on these violations.

Contribution

It provides a model-independent analysis of unitarity bounds on Wilson coefficients of dimension-six operators in the Standard Model effective field theory.

Findings

Unitarity violation occurs at LHC energies for small Wilson coefficients.

Bounds on Wilson coefficients are derived from unitarity considerations in various scattering channels.

Unitarity constraints limit the size of new physics effects in effective field theories.

Abstract

The effective field theory containing higher dimensional operators violates the unitarity of the $2 \rightarrow 2$ scattering processes in the Standard Model. This unitarity violation depends on the values of the Wilson coefficients corresponding to a higher dimensional operator. We showed that even a small values of some of the Wilson coefficients lead to the unitarity violation at the LHC centre of mass energies. Considering the final states as the gauge bosons in the longitudinal mode, the scalars, and the $t\overline{t}$, we showed that the unitarity violation in $WW \rightarrow WW$, $WW \rightarrow ZZ$, and $ZZ \rightarrow hh$ scattering amplitudes sets bounds on the Wilson coefficients of the dimension six effective operators.