1. Muons from  /K CSC samples vs generator predictions: preliminary comparisons

2. Minimum bias 124k events simulated with PionDecayer Selected one light meson forced to decay Muon mother decay before calorimeter CSC Samples Single  p T vs  distribution extracted from min bias and J1-J8 di-jets PYTHIA generated sample –csc11.005001.pythia_minbias –csc11.005010.J1_pythia_jetjet –… –csc11.005017.J8_pythia_jetjet Get all pions coming from interaction point p T >2.5GeV |  |<2.7 Average  multiplicity per event = 0.38 1M events simulated with PionDecayer at various p T

3. Differential cross-sections typically used to compute rates for kaons,   , from generators: –PYTHIA 5.7 (JETSET 7.4) –DPMJET II.3 and II.4 from Oren Y. and Nisati L. Assumed cross-section from minimum bias only  =80 mbarn Old predictions

4. Decay weight for CSC samples Ratio of pT distribution for unweighted and weighted events Events reweighted for  probability of decaying into a  l maximum path m   mass p   momentum    life time c light speed

5. Cross-sections (  barn)   ot (    ) PYTHIA (*) DPMJET (*) Minimum bias (  only) Single  (all) (  only) (all) (  only) 3<p T <45 GeV 38.422.881.238.118.335.1 36.721.977.836.617.032.6 4<p T <45 GeV 10.35.9820.39.484.8011.0 9.855.7319.59.104.5010.2 5<p T <45 GeV 3.562.046.513.041.584.32 3.421.966.252.921.484.0 6<p T <45 GeV 1.480.832.591.210.631.96 1.420.792.491.160.601.81 (*) Oren Y. and Nisati L. |  |<2.7 |  |<2.4 DPMJET default for rates computation (more conservative)

6. p T and  projections DPMJET PYTHIA Single   pTpT Min bias In the following we will restrict to: 4000<p T <45000 MeV (min bias: p T <20000 MeV) |  |<2.4 4000<p T <45000 MeV |  |<2.4

7. PYTHIA / DPMJET all light hadrons PYTHIA  / DPMJET   pTpT  pTpT

8. PYTHIA  / single  DPMJET  / single   pTpT  pTpT

9. PYTHIA  / min bias,  only DPMJET  / min bias,  only  pTpT  pTpT

10. Conclusions There are differences between old predictions from PYTHIA and DPMJET (within a factor 1.5) New samples give cross-section predictions in agreement within a factor of 2 –We have good samples suitables for studying rejection of muons from light mesons