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Hadron production in hard scattering

Hadron production in hard scattering. Event Generator. GEANT. JETSET:Single particle production in hard scattering. High probability to detect leading hadron in the forward detector. DIS: Q 2 >1GeV 2 W 2 >4 GeV 2 (10) y<0.85. LUND Fragmentation Functions. - Before. - After.

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Hadron production in hard scattering

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  1. Hadron production in hard scattering Event Generator GEANT

  2. JETSET:Single particle production in hard scattering High probability to detect leading hadron in the forward detector DIS: Q2>1GeV2 W2>4 GeV2 (10) y<0.85 LUND Fragmentation Functions - Before - After Target remnant quark The primary hadrons produced in string fragmentation come from the string as a whole, rather than from an individual parton.

  3. HERMES LUND Fragmentation Functions low PT high PT PDF side: gaussian <kT2>

  4. p+ p- p+ p- HERMES HERMES-MC Tune-2 Tune-3 JETSET-std Multiplicities PT K- K+ K+ K- z PT HERMES: Fragmentation and Multiplicities Tuning of JETSET FF parameters to multiplicities in acceptance MC: PYTHIA in combination with JETSET; PDF:CTEQ-6 DATA: unpolarised p-target Q2 > 1GeV2, W2>10 GeV2, z>0.2, 2<ph<15GeV z

  5. CLAS data vs LUND-MC CLAS data (4.3GeV) and LUND-MC comparison 0.5<z<0.8 LUND-MC tuned at higher energies Q2 > 1GeV2, W2>4 GeV2, z>0.5,y<0.85

  6. LUND event-II Particle number in the event charge and status Lund ID Parent and first daughter line numbers px py pz Momentum in GeV, Vx Vy Vz, Vertex in cm E m K*+ L K+ p p- g ep -> e’LK*+ -> e’p-pK+p0→2g

  7. Exclusive r+ at 6 GeV PYTIA-6 + 2p

  8. Exclusive production background from PYTHIA electron Pions from string (direct) present the lower limit for current fragmentation events p0 sample “clean” at large z (non-string pions are mainly from semi-inclusive r+, w) Filled (open) symbols represent pions from exclusive (all) vector mesons.

  9. 50o 13o GEANT simulation Maximum angle ~50o Minimum angle ~14o Angular acceptance for charged tracks for CLAS+IC configuration

  10. CLAS data GEANT+background Background studies for CLAS with IC Background accounting procedure tested with e1dvcs IC edge shielding target CLAS GEANT-MC + background consistent with data

  11. Acceptance moments from MC CLAS HERMES generated reconstructed Extract acceptance moments from MC

  12. 3 methods to analize the azimuthal moments I II fit III Different methods have different sensitivity to acceptance corrections

  13. LUND MC with Long. Pol. Target: SSA for p+ f distributions from MC vs 5.7 CLAS data. Fiducial cuts on e,p+ and smearing applied. CLAS-Data sinf and sin2f moments arising from the Collins effect added in MC using predictions from Efremov et al. Phys.Rev.D67:063511,2003 Simulated and reconstructed SSA moments consistent

  14. Summary Monte-Carlo generators have become an essential tool for feasibility studies, simulation of anticipated physics and background rates, acceptance and other corrections. Detailed simulation of processes of interest is crucial to keep under control systematic errors due to, both detector and physics background contributions LUND-MC combined with GEANT-simulation of detector response provide test of procedures for global analysis and extraction of physics observables.

  15. Support slides….

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