Constructing massive on-shell contact terms

Abstract

The purely on-shell approach to effective field theories requires the construction of independent contact terms. Employing the little-group-covariant massive-spinor formalism, we present the first systematic derivation of independent four-point contact terms involving massive scalars, spin-1/2 fermions, and vectors. Independent three-point amplitudes are also listed for massive particles up to spin-3. We make extensive use of the simple relations between massless and massive amplitudes in this formalism. Our general results are specialized to the (broken-phase) particle content of the electroweak sector of the standard model. The (anti)symmetrization among identical particles is then accounted for. This work opens the way for the on-shell computation of massive four-point amplitudes.

27 pages, 1 figure and 5 tables; v2: vvvs counting corrected

References in corpus (4)

• Operator bases, $S$-matrices, and their partition functions
• Helicity Selection Rules and Non-Interference for BSM Amplitudes
• On-shell constructibility of tree amplitudes in general field theories
• On-shell constructibility of Born amplitudes in spontaneously broken gauge theories

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