Delphes root file size

[Amin Abou Ibrahim]

Dear Delphes team,

In the Delphes 3 manual, you mention that the branches "particle" and "tower" consume the most of the storage space. I have turned these off and indeed I got a smaller root file. But the file is still not small enough (it went from 1.5 GB to 300 MB) since I am producing a large number of SM backgrounds so that would require a lot of disk space. The snowmass group have used a way to reduce the size even more by using (among other things) the StatusPidFilter module which I don't have access to (not sure if it is compatible with the present version anyway). My question is: can one reduce the root file even further?
Converting to lhco is an option but not all data I need are available in the lhco version.

Thank you,
Amin

[Michele Selvaggi]

Hi Amin,

you can turn off whichever collection you are not using in the treewriter section of the card. It won't affect consistency of the collections.
In particular, if you did not already, you can switch off jet particle flow constituents.

​https://github.com/delphes/delphes/blob/master/cards/delphes_card_ATLAS.tcl#L748-L750

[Amin Abou Ibrahim]

Hi,

Yes I have already done that. I guess there is no way around getting files of large size.
One more thing: is there a Delphes manual that explains the meaning of the jet grooming parameters, like PtFracTrim and others that appear in the delphes card?

[Michele Selvaggi]

already looked here?

https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook/Modules#FastJetFinder

[Amin Abou Ibrahim]

Yes, but this doesn't explain everything. I was trying to figure out the effect of PtFracTrim, for example, and how is it different from parameterR.

[Michele Selvaggi]

this is the code that uses it:

​https://github.com/delphes/delphes/blob/master/modules/FastJetFinder.cc#L453

if you want detailed information I guess you have to look at the relevant fastjet documentation.

[Amin Abou Ibrahim]

Thank you. Will do.

Best,
Amin