Top Quark Amplitudes with an Anomalous Magnetic Moment

TL;DR

This paper develops a method to compute complex top quark scattering amplitudes involving anomalous magnetic moments and multiple gauge bosons using BCFW recursion, addressing challenges from higher-dimension couplings.

Contribution

It introduces a novel approach employing an auxiliary scalar theory to facilitate amplitude calculations with anomalous magnetic moments in an effective field theory.

Findings

Method successfully computes amplitudes with multiple photons and gluons.

Addresses computational challenges from higher-dimension operators.

Provides a framework for future top quark magnetic moment measurements.

Abstract

The anomalous magnetic moment of the top quark may be measured during the first run of the LHC at 7 TeV. For these measurements, it will be useful to have available tree amplitudes with ttbar and arbitrarily many photons and gluons, including both QED and color anomalous magnetic moments. In this paper, we present a method for computing these amplitudes using the Britto-Cachazo-Feng-Witten (BCFW) recursion formula. Because we deal with an effective theory with higher-dimension couplings, there are roadblocks to a direct computation with the BCFW method. We evade these by using an auxiliary scalar theory to compute a subset of the amplitudes.