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Opened 10 years ago

Closed 9 years ago

Last modified 7 years ago

#669 closed task (fixed)

Spin-correlated Born matrix elements

Reported by: cweiss Owned by: cweiss
Priority: P4 Milestone: v2.6.0
Component: nlo Version: 2.2.2
Severity: minor Keywords:
Cc: cweiss

Description

For processes with final-state gluons or photons, subtraction terms require the use of a spin-correlated Born matrix element.

Change History (8)

comment:1 Changed 10 years ago by Juergen Reuter

This also true for Catani-Seymour. I didn't implement the gluon splittings here, so I didn't work on this, but was aware of that problem already in 2010.

comment:2 Changed 9 years ago by cweiss

Cc: cweiss added
Status: newassigned

comment:3 Changed 9 years ago by cweiss

Because the use of other programs than Omega for subtraction terms is now enabled, I will have a first look into this issue.

comment:4 Changed 9 years ago by Juergen Reuter

Why do we need two different methods for subtraction terms? For validation?

comment:5 in reply to:  4 Changed 9 years ago by cweiss

Replying to jr_reuter:

Why do we need two different methods for subtraction terms? For validation?

  1. There seems to be a problem with our internal computations of color-correlated Born matrix elements, they fail e.g. for e+ e- -> u u~ d d~.
  1. It's the easiest way to obtain the spin-correlated Born matrix elements, or is Omega able to do this?

To make this clear: In a calculation, only one method is used for subtraction. But we are now able to choose between Omega and Gosam via Sindarin, and we can think of other programs, too.

comment:6 Changed 9 years ago by Juergen Reuter

Resolution: fixed
Status: assignedclosed

This has been implemented now.

comment:7 Changed 7 years ago by Juergen Reuter

Milestone: v2.4.0v2.5.0

Milestone renamed

comment:8 Changed 7 years ago by Juergen Reuter

Milestone: v2.5.0v2.6.0

Milestone renamed

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