Muons from /K

CSC samples vs generator predictions: preliminary

comparisons

Minimum bias• 124k events

simulated with PionDecayer

• Selected one light meson forced to decay

• Muon mother decay before calorimeter

CSC SamplesSingle

• pT 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

• pT>2.5GeV

• ||<2.7

• Average multiplicity per event <n> = 0.38

• 1M events simulated with PionDecayer at various pT

• 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

∂∂

∂

Tp

2

Decay weight for CSC samples

Ratio of pT distribution for unweighted and

weighted events

Events reweighted for probability of

decaying into a

cp

m

τl

=w

l maximum pathm masspmomentumτ life timec light speed

Cross-sections (barn)

τot()PYTHIA(*) DPMJET (*)

Minimum bias ( only)

Single (all) ( only) (all) ( only)

3<pT<45 GeV

38.4 22.8 81.2 38.1 18.3 35.1

36.7 21.9 77.8 36.6 17.0 32.6

4<pT<45 GeV

10.3 5.98 20.3 9.48 4.80 11.0

9.85 5.73 19.5 9.10 4.50 10.2

5<pT<45 GeV

3.56 2.04 6.51 3.04 1.58 4.32

3.42 1.96 6.25 2.92 1.48 4.0

6<pT<45 GeV

1.48 0.83 2.59 1.21 0.63 1.96

1.42 0.79 2.49 1.16 0.60 1.81

(*) Oren Y. and Nisati L.||<2.7

||<2.4DPMJET default for rates computation (more conservative)

pT and projections

DPMJET

PYTHIA

Single

pT

Min bias

In the following we will restrict to:

4000<pT<45000 MeV(min bias: pT<20000 MeV)

||<2.4

4000<pT<45000 MeV

||<2.4

PYTHIA / DPMJET all light hadrons

PYTHIA / DPMJET

pT

pT

PYTHIA / single

DPMJET / single

pT

pT

PYTHIA / min bias, only

DPMJET / min bias, only

pT

pT

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