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2. Introduction

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Sebastian Wuchterl edited this page Jun 7, 2023 · 1 revision

Overview

Introductory lecture

An introductory slides from 2020 will be given to present the basic concepts of the measurement. The lecture is an overview of the public measurement performed at 8 TeV. It is meant to be used for discussion and introduction to the Physics of the analysis. If the basis is understood, then you'll be much more focused on the steps that will be taken throughout the exercise.

Documentation

The Physics Analysis Summary: CMS TOP-15-002

Setting up the code

Follow the instructions below to setup the CMSSW area for the code. This needs to be done once at the beginning of the exercise.

In the installation instructions it is assumed that you are already registered to GitHub. If not create an account here. Also, please make sure that you have exported an ssh key to git so that you don't have troubles fetching the code from git. In case you need some instructions on how to do this please find them here.

After connecting to lxplus at CERN, create your working area in the /afs/cern.ch/work/YOURUSER area and find out what shell you are in with the following command:

echo $0

If you are using csh/tcsh:

source /cvmfs/cms.cern.ch/cmsset_default.csh setenv SCRAM_ARCH slc7_amd64_gcc700

If you are rather using bash/sh:

source /cvmfs/cms.cern.ch/cmsset_default.sh
export SCRAM_ARCH=slc7_amd64_gcc700

Then, whatever your shell:

mkdir CMSDAS2023_TopMass
cd CMSDAS2023_TopMass
cmsrel CMSSW_10_6_29
cd CMSSW_10_6_29/src
cmsenv
git clone https://github.com/CERN-CMS-DAS-2023/long-ex-top
scram b -j4
cd long-ex-top/

Coordinate to create a group fork of this repository and add fellow group members as collaborators so that your code updates can be tracked by everyone.

You will need to setup your runtime environment using cmsenv everytime you start working in your CMSSW project area.

Data and simulation used for analysis

Our exercise will be based on data and simulation samples which have been previously pre-selected.

  • Data samples

The data is analyzed from the /MuonEG/Run2016*-{23Sep2016,PromptReco}-v*/MINIAOD primary dataset. The total integrated luminosity corresponds to 35867 pb-1.

  • Simulation samples

Official simulation samples are used to compare with the data. The table below summarizes the name of the samples as well as the cross sections used as baseline for the normalization.

Process Sample cross section [pb]
top quark pair production /TT_TuneCUETP8M2T4_13TeV-powheg-pythia8/RunIISummer16MiniAODv2-PUMoriond17_80X_mcRun2_asymptotic_2016_TrancheIV_v6-v1/MINIAODSIM 831.76
single top production /ST_tW_antitop_5f_inclusiveDecays_13TeV-powheg-pythia8_TuneCUETP8M2T4/RunIISummer16MiniAODv2-PUMoriond17_80X_mcRun2_asymptotic_2016_TrancheIV_v6-v1/MINIAODSIM 35.85
single top production /ST_tW_top_5f_inclusiveDecays_13TeV-powheg-pythia8_TuneCUETP8M2T4/RunIISummer16MiniAODv2-PUMoriond17_80X_mcRun2_asymptotic_2016_TrancheIV_v6-v1/MINIAODSIM 35.85
diboson production /WWTo2L2Nu_13TeV-powheg/RunIISummer16MiniAODv2-PUMoriond17_80X_mcRun2_asymptotic_2016_TrancheIV_v6-v1/MINIAODSIM 12.2
W+jets production /WJetsToLNu_TuneCUETP8M1_13TeV-madgraphMLM-pythia8/RunIISummer16MiniAODv2-PUMoriond17_80X_mcRun2_asymptotic_2016_TrancheIV_v6-v1/MINIAODSIM 61526.7
Drell-Yan production /DYJetsToLL_M-50_TuneCUETP8M1_13TeV-madgraphMLM-pythia8/RunIISummer16MiniAODv2-PUMoriond17_80X_mcRun2_asymptotic_2016_TrancheIV_v6_ext1-v2/MINIAODSIM 5765.4

As you can see, the dataset name informs you not only about the physical process that has been simulated, but also about the tune (that can affect both underlying event and fragmentation modeling), the center-of-mass energy, the matrix element generator used for the hard process, and the tool used for parton shower and hadronization/fragmentation. It also contains specific details about the McM campaign, the CMSSW release used for simulation, together with the GlobalTag.

Question: Which matrix element generator has been used to simulate the top-pair process ? What about the parton shower/hadronization simulation ?

Trigger

Dilepton triggers have been required in selecting data and MC. The following triggers have been used Mu17_TrkIsoVVL_Ele12_CaloIdL_TrackIdL_IsoVL and Mu8_TrkIsoVVL_Ele17_CaloIdL_TrackIdL_IsoVL. A logical OR of the two trigger paths is applied.

Pre-selection

MiniAOD were skimmed to keep only events with an isolated electron and an isolated muon of opposite sign and p_T>20 GeV, whose combination has an invariant mass bigger than 12 GeV.

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