Higgs Self-Couplings at the HL-LHC

Introduction

Analysis Code

The HiggsSelfCouplings package contains classes to build objects, to apply selection cuts and to implement the smearing, efficiency and fake-rate functions defined in the TruthToRecoFunctions package to parameterise the detector performance under HL-LHC conditions.

You can browse the code in:

WebSVN: https://svnweb.cern.ch/cern/wsvn/atlas-cbarrera

or in:

Trac: https://svnweb.cern.ch/trac/atlas-cbarrera/browser

Instructions

To help setting-up athena, add the following line to your .bashrc file:

alias asetup17='source /data/atlas09/ferrando/atlas_soft/17.2.2/AtlasSetup/scripts/asetup.sh 17.2.2.2' 

Now exit the terminal and open a fresh window.

First you need to get the code from SVN:

export SVNUSR=svn+ssh://<cern_username>@svn.cern.ch/reps/atlas-cbarrera
svn co $SVNUSR/HiggsSelfCouplings/trunk HiggsSelfCouplings

The first time you use the package you need to run the script called setup_firsttime.sh, which sets up athena and updates the files inside RootCore so that they point to the correct directories:

cd HiggsSelfCouplings
source setup_firsttime.sh

This you need to do only once. Everytime you want to run the code, you just need to setup athena and RootCore by doing:

cd HiggsSelfCouplings
asetup17
source packages/RootCore/scripts/setup.sh

or, equivalently,

source setup.sh

To compile the code, just do:

make

This creates an executable file which you can run as:

./mainHHAnalysis <inputfiles.txt> <outputfile.root>

bbtautau Samples

Signal

/afs/phas.gla.ac.uk/data/atlas/hh01/lambda0/user.boehlerm.NTUP_TRUTH_lambda0_btau
/afs/phas.gla.ac.uk/data/atlas/hh01/lambda1/user.boehlerm.NTUP_TRUTH_lambda1_btau
/afs/phas.gla.ac.uk/data/atlas/hh01/lambda2/user.boehlerm.NTUP_TRUTH_lambda2_btau

Backgrounds

ttbar

/afs/phas.gla.ac.uk/data/atlas/hh01/ttbar/mc12_14TeV.105200.McAtNloJimmy_CT10_ttbar_LeptonFilter.merge.NTUP_TRUTH.e1323_p1087_tid00862321_00

The HiggsSelfCouplings package

Here you can find a brief description of what each class in the HiggsSelfCouplings package currently does.

• TruthAlgo: base class to initialise the configuration, tools and physics objects; the latter contains the information from the D3PD.
• TruthConfiguration: in this class all configurable variables are defined, such as cuts, whether or not to apply the smearing/efficiency functions, etc. It contains functions that test whether an object satisfies the quality requirements. Finally, it also dumps a table with the values of all the parameters when running the code.
• TruthD3PD: this class contains the list of all the variables in the D3PD.
• TruthObjects: in this class the vectors of 4-vectors of the selected objects are filled. It contains a separate function for each object type, as well as functions to calculate the sumEt and MET and a function that finds whether a jet fakes another object and returns the new jet and bjet vectors.
• TruthSelectBBTT: this class applies all the event requirements for the bbtautau channel using the selected object collections.
• TruthSmearing: this class contains all the necessary functions to smear the energy/momentum of the selected objects and functions to remove objects from their collections based on their reconstruction efficiencies.
• TruthTools: in this class a set of more general functions is defined, for example a function that calculates the dR separation between two 4-vectors or a function that calculates the mass of the tautau system based on the collinear approximation.
• TruthHistograms: this class is used to create and initialise histograms.
• mainHHAnalysis: main program. Here the input D3PDs are read and the analysis executed on an event-by-event basis.
• Makefile: self-explanatory.
• batch/: directory containing batch submission scripts as well as a script to merge the outputs.
• input/: directory containing a script to automatically generate the input files needed by the batch submission scripts.
• scripts/: directory containing scripts to dump the cutflow and to make plots.
• packages/RootCore: ATLAS package that allows the TruthToRecoFunctions package to be properly compiled and linked.
• packages/TruthToRecoFunctions: package containing all the smearing, efficiency and fake-rate functions.

ATLAS Talks

09.Sep.2013 - Higgs Prospects Approval Meeting: slides

22.Aug.2013 - Higgs Prospects Meeting: slides

08.Aug.2013 - Higgs Prospects Meeting: slides

First ATLAS Results

Performance PUB Note (ECFA): Performance assumptions based on full simulation for an upgraded ATLAS detector at a High-Luminosity LHC.

( Withdrawn ) HH PUB Note: Studies of the ATLAS potential for Higgs self-coupling measurements at a High Luminosity LHC.

Performance PUB Note (European Strategy): Performance assumptions for an upgraded ATLAS detector at a High-Luminosity LHC.

Phenomenology Papers

Barr, Dolan, Englert & Spannowsky paper ( MT2 ): Di-Higgs final states augMT2ed - selecting hh events at the high luminosity LHC.

Dolan, Englert & Spannowsky paper: Higgs self-coupling measurements at the LHC.

Baglio, Djouadi, Grober, Muhlleitner, Quevillon & Spira paper: The measurement of the Higgs self-coupling at the LHC: theoretical status.

Useful Links

HL-LHC cross-sections: HiggsEuropeanStrategy2012

HH ATLAS Twiki: HiggsSelfCouplingForHLLHC