MCgrid: projecting cross section calculations on grids

Abstract: MCgrid is a software package that provides access to the APPLgrid interpolation tool for Monte Carlo event generator codes, allowing for fast and flexible variations of scales, coupling parameters and PDFs in cutting edge leading and next-to-leading-order QCD calculations. This is achieved by providing additional tools to the Rivet analysis system for the construction of MCgrid enhanced Rivet analyses. The interface is based around a one-to-one correspondence between a Rivet histogram class and a wrapper for an APPLgrid interpolation grid. The Rivet system provides all of the analysis tools required to project a Monte Carlo weight upon an observable bin, and the MCgrid package provides the correct conversion of the event weight to an APPLgrid fill call. MCgrid has been tested and designed for use with the SHERPA event generator, however as with Rivet the package is suitable for use with any code which can produce events in the HepMC event record format.