Generation of Radiative B-Decays

Decay Channels Bs Phi + Gamma Bd K* + Gamma

Gareth Brown, RAL PPD 5/10/06

Thanks to, Bill, John, Monica and Julie K at RAL, and also J.Catmore and M.Smizanska for their help

Decay Channels

Bs Phi +Gamma

PT cut on gamma of 4GeV PT cut on muon of 6GeV

Phi K+ + K-

Bd K* + Gamma

PT cut on gamma of 4GeV PT cut on muon of 6GeV

K* K+ + pi-

Generation Process

1. Set up to run Pythia B

2. cmt co Generators/PythiaB

3. Edit files uf_Bsphigamma.F, PythiaB.cxx, and user_finsel.F from src/

4. Recompile the code

5. Edit the Signal file (.py)

6. Run using Job Transforms on either Lxplus or Grid.

Setting up for Pythia B

Zsh Mkdir workdir cd workdir # create a requiremenst file that uses this workdir set CMTSITE CERN set SITEROOT /afs/cern.ch macro ATLAS_DIST_AREA ${SITEROOT}/atlas/software/dist macro ATLAS_TEST_AREA workdir use AtlasLogin AtlasLogin-* $(ATLAS_DIST_AREA) # set up the environment source /afs/cern.ch/sw/contrib/CMT/v1r18p20060301/mgr/setup.sh cmt config mkdir -p AtlasOffline-12.0.0/run source setup.sh -tag=12.0.0,opt source /afs/cern.ch/atlas/software/builds/AtlasOffline/12.0.0/AtlasOfflineRunTime/cmt/setup.sh cd AtlasOffline-12.0.0/run source /afs/cern.ch/atlas/software/releases/AtlasSimulation/2.0.0/AtlasSimulationRunTime/cmt/setup.sh cp /afs/cern.ch/atlas/software/releases/AtlasSimulation/2.0.0/Generators/PythiaB/share/* . get_files PDGTABLE get_files PDGTABLE.MeV athena PythiaB_Signal.py > log.txt

Editing files

In Generators/PythiaB/src/

uf_Bsphigamma.F

if(name_selv(I).eq.22.and. + name_father(I).eq.531.) then PT = SQRT(P(I,1)**2+P(I,2)**2) TH = ACOS(P(I,3)/SQRT(PT**2+P(I,3)**2)) ETA = -LOG(MAX(.0001,ABS(TAN(.5*TH)))) print *,'Ptgamma: ',PT,' eta: ',ETA if(PT.gt.4.and.abs(ETA).lt.2.5) then iret2=0. print *,'After cut Ptgamma: ',PT,' eta: ',ETA endif

PythiaB.cxx else if ( m_forceDecayChannel == "Bsphigamma" ) { idc = 6; }

user_finsel.F c 6: Bsphigamma (RAL) if ( iufdc .eq. 6) call uf_Bsphigamma(iret)

Recompiling the code in ../cmt

“cmt config” “gmake”

Edit the Signal file (.py)

PythiaB.PythiaCommand += ["pydat3 mdme 977 1 1", "pydat3 kfdp 977 1 333", "pydat3 kfdp 977 2 22" ]

PythiaB.ForceDecayChannel = "Bsphigamma"

Generated Events

Pt Distribution of gamma with a 4GeV cut

Data Sets

Generated data sets are:

/castor/cern.ch/user/s/scottw/gjab02/csc.018201.Bs_phi_Kplus_Kminus_gamma4.evgen._00001.pool.root /castor/cern.ch/user/s/scottw/gjab02/csc.018201.Bs_phi_Kplus_Kminus_gamma4.evgen._00002.pool.root /castor/cern.ch/user/s/scottw/gjab02/csc.018201.Bs_phi_Kplus_Kminus_gamma4.evgen._00003.pool.root /castor/cern.ch/user/s/scottw/gjab02/csc.018201.Bs_phi_Kplus_Kminus_gamma4.evgen._00004.pool.root /castor/cern.ch/user/s/scottw/gjab02/csc.018201.Bs_phi_Kplus_Kminus_gamma4.evgen._00005.pool.root /castor/cern.ch/user/s/scottw/gjab02/csc.018201.Bs_phi_Kplus_Kminus_gamma4.evgen._00006.pool.root /castor/cern.ch/user/s/scottw/gjab02/csc.018201.Bs_phi_Kplus_Kminus_gamma4.evgen._00007.pool.root /castor/cern.ch/user/s/scottw/gjab02/csc.018201.Bs_phi_Kplus_Kminus_gamma4.evgen._00008.pool.root /castor/cern.ch/user/s/scottw/gjab02/csc.018201.Bs_phi_Kplus_Kminus_gamma4.evgen._00009.pool.root

/castor/cern.ch/user/s/scottw/gjab02/csc.018201.Bs_phi_Kplus_Kminus_gamma4.evgen._00010.pool.root

Graphs showing the eta and phi difference between the daughter particles and the >4GeV Gamma

Graph showing the eta difference between daughter particles and gamma against the phi difference between daughter particles and gamma

Graph showing the eta difference between daughter particles and gamma against the eta difference between daughter particles and muon

Graph showing the eta difference between daughter particles and muon against the phi difference between daughter particles and muon

Graph showing the phi difference between daughter particles and gamma against the phi difference between daughter particles and muon

Summary

We can now generate any B-decay channel, adding cuts on kinematics quantities etc.

Currently Super symmetry isn’t involved in the generation process, and will need to be added.

We have generated10,000 events that are currently available in Castor, but still need to be simulated, digitized and reconstructed.