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Low Mass Higgs -> gamma gamma

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*Responsible:* Camilo Carrillo

*Members:* Benoit Courbon, David Sabes, Giacomo Cacciapaglia, Aldo Deandrea, Nicolas Berger, Werner Porod, Ulrich Goerlach, Susan Gascon

Nom de FamillePrénomJour ArrivéeJour Départ


Information/How to install Delphes

How to run Delphes on an LHE file using Pythia for showering

Installation steps and commands (to perform as superuser on your machine):

  1. Download the latest Pythia8 from here

To intall HepMC

    tar -xvf HepMC-2.06.09.tar.gz
    cd HepMC-2.06.09/ 
    ./configure --with-gzip --enable-shared --with-momentum=GEV --with-length=CM
    make install

To install Pythia8

    tar -xvf pythia8209.tgz
    cd pythia8209
    ./configure --enable-shared --with-hepmc2=$complete path$/HepMC-2.06.09
    make install  

To install Delphes

    tar -xvf Delphes-3.2.0.tar.gz
    cd Delphes-3.2.0/
    ./configure --with-gzip --enable-shared --prefix=/home/miloc/delphes/pythia/
    export PYTHIA8=$complete path$/pythia8209
    export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$complete path$/pythia8209/lib 
    make HAS_PYTHIA8=true DelphesPythia8

Build your pythia card, this is an example for H→gg, note that the input lhe file is defined here

    Main:numberOfEvents = 100000
    Beams:frameType = 4
    Beams:LHEF = /home/miloc/lhe/h125SM.lhe
    25:onMode = off
    25:onIfMatch = 22 22

Finally to run Delphes, do

    ./DelphesPythia8 detectorcard.tcl output.root

For the detector card, you can use the one in Delphes-3.2.0/cards/
For the pythiasettings, there is a working example below (which you can just store in a text file)
(you will need to specify a .lhe file. You can find some in the following links)


Main:numberOfEvents = 1000
Beams:frameType = 4
Beams:LHEF = $complete path$/yourfile.lhe.gz.orig
To fix the decays of the Higgs, you have to add the following to the above pythia input card:
In case of H→gamma gamma
25:onMode = off
25:onIfMatch = 22 22
In case of H → ZZ → 4l
25:onMode = off
25:onIfMatch = 23 23
23:onMode = off
23:onIfAny = 11 13 15


First Meeting (Chat)Doodle:

NomPrénomFriday 11amFriday 14:30Friday 16:00Friday 18:00

Meeting 1: Friday 12th at 14:30

The first Meeting took place Friday 12 at 14:30 in the QCD room (main auditorium→left) marked as (Organisers)

We have 3 theoretical models (frameworks) where our final state is applicable:

Theory 1

Werner: in the NMSSM the lightest neutralinos/chargino can be mainly the MSSM higgsinos. In case of a large singlet-doublet couplings, one gets sizable cross section for pp → chi chi H_1. Here chi chi is the summation over all higgsinos which are mass degenerate within a few GeV.

The second interesting process ist pp → H_3 → H_1 H_1 where the H_3 is the heaviest neutral Higgs boson.

The third is pp → t t → W b H+ b where H+ decays into W H_1 and the later to gamma gamma.

Theory 2


Theory 3

Giacomo and Aldo

The model consists of a scalar which is pair produced by gauge interactions: qq → H' H', and VBF → H' H'. At low mass, the kinematically allowed decays are: W gamma (charged) and gamma gamma (neutral). We can start considering a triplet of SU(2)L, with production channels H'+ H'-, and H'+ H'0. We will create a MG file asap.

A sample model, with a singlet decaying in VV (but not gamma gamma): 1502.04718. More references to follow soon.


ATLAS: Nicolas

CMS: Camilo Benoit David

We are implementing a reliable model of CMS in DELPHES, the input of our software would be lhe files, the decay of the higgs can be done by us as well…. work is ongoing.

Meeting 2: Tuesday 16th at 10:00

The second Meeting takes place Tuesday 16th at 10:00 in the QCD room (main auditorium→left) marked as (Organisers)

Meeting 3: Wednesday 17th at 14:30

Preparation of the summary slides, based on your inputs in this twiki Presentation draft:

2015/groups/higgs/morehiggs/lowmassdiphoton.txt · Last modified: 2015/06/18 15:43 by camilo.carrillo