J/Psi in di-electron channel

Alla MaevskayaInstitute for Nuclear Research RAS, Moscow

CBM collaboration meeting11 March 2005 GSI Darmstadt

OutlookFor Au+Au 25AGeV collisions

J/Ψ momenta and rapidity spectra Background sources Simulation in different conditions:

pion suppression factors

applying different Pt cuts

applying different mass resolution For central and mbias collisions

For different beam energies

Conclusions

Alla Maevskaia INR RAS Moscow CBM collaboration meeting 11 March 2005

Au+Au 25AGeV:Transverce momenta and rapidity

distribution for J/Psi mesons.

Alla Maevskaia INR RAS Moscow CBM collaboration meeting 11 March 2005

Calculations was done by PLUTO for generation J/ψ kinematics and cbmroot version OCT04 for transport. J/ψ multiplicity was obtained according HSD predictions

all J/ψ accepted in detector with Pt >1GeV/c

Au+Au 25AGeV central:Tranverse momenta distribution for

e+e- from different background sources

Alla Maevskaia INR RAS Moscow CBM collaboration meeting 11 March 2005

open charm was calculated by V.Friese code by Goran; J/ψ momentum distribution - by PLUTO, multiplicity – by HSD

Background electrons from γ , π0, η & misidentified charged pions (suppression 10-4) were obtained from UrQMD generator + cbmroot vOCT04,STS + RICH +TRD in,field "FIELD.v04_pavel.map"

Au+Au 25AGeV central:invariant mass spectra

ψ

Alla Maevskaia INR RAS Moscow CBM collaboration meeting 11 March 2005

for 2x1010 events with cut Pt>1GeV and different pion suppression factors :

For pion suppression 10-4

and different Pt cuts

10-2; 10-3; 10-4 ; no pions

Au+Au 25AGeV centralInvariant mass spectra for different

mass resolution scenarioPt > 1GeV/c

Pt > 1.3 GeV/c

J/ψ mass resolution 30 MeV 90 MeV 150 MeV

Alla Maevskaia INR RAS Moscow CBM collaboration meeting 11 March 2005

Au+Au 25AGeV mbiasInvariant mass spectra for different

mass resolution scenarioPt > 1GeV/c

5% -150 MeV

Pt > 1.3 GeV

Alla Maevskaia INR RAS Moscow CBM collaboration meeting 11 March 2005

Pt cut Mass resolution S/B central S/B mbias1 GeV/c 30MeV 1 4.5

90MeV 0.46 0.8150MeV 0.28 0.67

1.3 GeV/c 30MeV 2.5 11.790MeV 1.26 5.5

150 MeV 0.67 3.2

Au+Au 25AGeV :Signal /Background ratio

dependance on mass resolution, Pt cuts and centrality

Alla Maevskaia INR RAS Moscow CBM collaboration meeting 11 March 2005

Pt cut S/B ε(J/ψ) S/B ε(J/ψ) S/B15AGeV 15AGeV 25AGeV25AGeV 35AGeV

1GeV/c 0.77 0.25 1 0.34 1.21.3 GeV/c 1.48 0.13 2.5 0.17 3.51.5GeV/c 3.24 0.027 3.36 0.04 6.6

Signal/Background and J/Psi efficiency for central Au+Au

collisions at 15, 25 and 35 AGeV

Alla Maevskaia INR RAS Moscow CBM collaboration meeting 11 March 2005

To be done :

“realistic” J/ψ generation using HSD and PYTHIA

Investigation of ψ' ??? Centrality dependence of the

statistical significance Normalisation of J/ψ cross

section ??? Using reconstructed tracks for

signal and background calculations