The MHV QCD Lagrangian

Abstract

We perform a canonical change of the field variables of light-cone gauge massless QCD to obtain a lagrangian whose terms are proportional up to polarisation factors to MHV amplitudes and continued off shell by the CSW prescription. We solve for this transformation as a series expansion to all orders in the new fields, and use this to prove that the resulting vertices are indeed MHV vertices as claimed. We also demonstrate how this works explicitly for the vertices with: two quarks and two gluons, four quarks, and a particular helicity configuration of two quarks and three gluons. Finally, we generalise the construction to massive QCD.

**Important New Material:** Proof that vertices are MHV amps off-shell, **Plus** results for all MHV verts with massive quarks. Clarifications made, esp. on the link between massless quark-gluon vertices and known results, and the choice of massive poln. spinors. Citations revised. 42 pages, 2 figures, 4 tables. (This version published in JHEP.)

Cited by in corpus (13)

• Loop amplitudes in gauge theories: modern analytic approaches
• On the Structure of Supersymmetric Sums in Multi-Loop Unitarity Cuts
• On-shell supersymmetry for massive multiplets
• Review of AdS/CFT Integrability, Chapter V.1: Scattering Amplitudes - a Brief Introduction
• Twistor-inspired construction of massive quark amplitudes
• Wilson lines in the MHV action
• The MHV Lagrangian for a spontaneously broken gauge theory
• Exploring straight infinite Wilson lines in the Self Dual and the MHV Lagrangians
• A new Wilson line-based action for gluodynamics
• One-Loop Effective Action Approach to Quantum MHV Theory
• Generating MHV super-vertices in light-cone gauge
• Wilson Lines and Boundary Operators of BCFW Shifts
• Holonomies of gauge fields in twistor space 6: incorporation of massive fermions