Handling negative events (*crucial* for running on NLO events)

[jalwall@…]

For events generated with aMC@NLO, it is crucial that the event weight (+/-) is kept through the process, since negative events can't be avoided. Where is the event weight stored in the Delphes root file?
If this is not correctly treated at present, it would be great if this could be fixed with high priority. With aMC@NLO public, Delphes has the chance to become the *only* detector simulator that can correctly handle this.

All the best,
Johan

[Pavel Demin]

Hi Johan,

Thanks for the suggestion!

Would be enough to store the event weight in the "Event" branch?

What output file format aMC@NLO normally uses?

Regards,

Pavel

[favereau]

Any news on this topic ?

[Pavel Demin]

I've modified STDHEP reader in Delphes 3.0 and in ExRootAnalysis to be able to read aMC@NLO files.

The weight is now stored in the Event brunch.

Johan, would it be enough to treat weighted events properly?

[Johan Alwall]

Hi Pavel,

Sorry, I didn't receive any emails regarding this ticket, so I didn't know that you had already implemented this! Thanks so much!

I'll try it out when I get a chance, I'm sure it should work now!

All the best,
Johan