The MHV QCD Lagrangian
Abstract
We perform a canonical change of the field variables of lightcone 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.
 Publication:

Journal of High Energy Physics
 Pub Date:
 August 2008
 DOI:
 10.1088/11266708/2008/08/103
 arXiv:
 arXiv:0805.0239
 Bibcode:
 2008JHEP...08..103E
 Keywords:

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