Introduction

The AlpgenInterface is undergoing a complete restructuring, according to the new guidelines for GeneratorInterfaces. This page documents this restructuring

New Features

Validation

• What with using the SLHA mass line? Is this doing something bad?

• W + jets
  • Basic mother-daughter relations validation.
• Z + jets
• ttbar + jets
  • Basic mother daughter relations validation.
  • Why is it freezing? Why does it stop freezing when I use FourVectors instead of doing calculations manually.
  • Always bitten by FORTRAN/C-style array differences.

Issues

• The PYUPRE subroutine:

C...PYUPRE
C...Rearranges contents of the HEPEUP commonblock so that
C...mothers precede daughters and daughters of a decay are
C...listed consecutively.

• What is the "phantom event" at the beginning of ALPDBG?
• How to make sure the PDF sets are chosen consistently in ALPGEN and PYTHIA?

FORTRAN routines

Here we describe the FORTRAN routines responsible for the matching in standalone matching.

UPINIT routine

• I/O
• Call ALSHCD - returns "PYT"
• I/O
  • Read until "****"
  • Read IHRD
  • Read six masses (mc, mb, mt, mw, mz, mh)
  • Read key-value pairs (PARVAL[NTMP] array)
  • Read until "****"
  • Read xsec, xsec_error, number of unw events, luminosity
• Call AHSPAR to setup parameters - this sets EBEAM.
  • This sets every parameter except IHRD, the masses and the jet clustering parameters.
• PBEAM1=DBLE(EBEAM), PBEAM2=DBLE(EBEAM), IH1=1 --> these are tramp variables to set up HEPRUP later.
• Call PDFCONVH (what does it do?)
• Call ALSHCD
• Prepares INORAD
• Gets jet matching criteria
• Sets up the HEPRUP
• Calls ALSHIN (passes the six masses to PYTHIA)
• Sets LPRUP (originally it was 661, now it has a meaning).

• UPINIT.odg: UPINIT

UPVETO routine

-- ThiagoTomei - 12 Feb 2009