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Generation of Radiative B-Decays: Bs → φ + γ and Bd → K* + γ Processes

This document outlines the methods used to generate radiative B-decay channels, specifically focusing on the processes Bs → φ + γ and Bd → K* + γ. It details the setup and configuration for running Pythia B, including cuts on the transverse momentum of the gamma and muon particles. Edits made to the source files and steps for recompiling code are described. The report showcases 10,000 generated events, with emphasis on kinematic quantities and significance in particle physics research.

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Generation of Radiative B-Decays: Bs → φ + γ and Bd → K* + γ Processes

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  1. 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

  2. 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- Decay Channels

  3. Set up to run Pythia B cmt co Generators/PythiaB Edit files uf_Bsphigamma.F, PythiaB.cxx, and user_finsel.F from src/ Recompile the code Edit the Signal file (.py) Run using Job Transforms on either Lxplus or Grid. Generation Process

  4. 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

  5. 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

  6. PythiaB.cxx • else if ( m_forceDecayChannel == "Bsphigamma" ) { • idc = 6; } • user_finsel.F • c 6: Bsphigamma (RAL) • if ( iufdc .eq. 6) call uf_Bsphigamma(iret)

  7. 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"

  8. Generated Events Pt Distribution of gamma with a 4GeV cut

  9. 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

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

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

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

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

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

  15. 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.

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