cms-sw/cmssw — pull request #6822 by rovere (2014-12-08 11:08:59+00:00)
Title: Enable cluster splitting in jet core

This PR will enable cluster splitting by default in the reconstruction step of pp scenario only. It includes few improvements to the base code itself of the cluster splitter, plus all the mandatory changes in the various cf{g,f,i}. The cosmic and HI scenarios should not be affected at all.

Preliminary results are gathers here, thanks to Matti:
https://mkortela.web.cern.ch/mkortela/tracking/validation/CMSSW_7_4_0_pre1/index.html

We expect no changes for TTbar, an increase in efficiency for QCD samples (varies according to Pt) with a corresponding one in fake rate.

Effects on physics should be estimated by different groups: BTag reported their observations in a recent tracking POG Meeting: https://indico.cern.ch/event/337846/contribution/1/material/slides/0.pdf

We do expect another round of fine tuning on top of the current code that will come at some point next year.

To ease your review process, the reformatting of the C++ code has been included in a single, stand-alone commit.

Locally tested on the limited version of runTheMatrix w/o problems.

One final remark: I somewhat arbitrarily changed the input cluster for the AlceRecoLUMIpixel to the pre-splitted collection and I am not at all sure if this is the right decision to take or not: I leave it to the proper experts to comment on that.