Feasibility of J/ψ studies by MPD detector Alla Maevskaya, Alexei Kurepin INR RAS Moscow NICA Roundtable Workshop 11 September 2009

2 Charm production at threshold [W. Cassing et al., Nucl. Phys. A 691 (2001) 753] HSD simulations CBM (NICA) will measure charm production at threshold → after primordial production, the survival and momentum of the charm quarks depends on the interactions with the dense and hot medium! → direct probe of the medium! charmonium in hot and dense matter? relation to deconfinement? relation to open charm? Claudia Höhne Quark Matter Conference India, February 2008

Generators Signal: J/ψ generated by HSD √s = 7 AGeV multiplicity 1.9  √s = 9 AGeV multiplicity 8  Background : 6400 central Au+Au events UrQMD √s = 7 AGeV & 9 AGeV Alla Maevskaya INR RAS NICA Roundtable Workshop 11 September 2009 Multiplicity of D 0, D +, D - and J/ψ predicted for central Au+Au collisions as function of beam energy by the HSD model [CBM TSR 2005 p371]

Simulation environment MpdRoot from end of May 2009 Set-up:ITTPCTOFECAL MC tracks in TPC acceptance with Y<1.2 Mass resolution assumed 1% Alla Maevskaya INR RAS NICA Roundtable Workshop 11 September 2009

J/ψ distributions for √s = 9 AGeV momentum transverse momentum rapidity Alla Maevskaya INR RAS NICA Roundtable Workshop 11 September 2009 HSD Registered in TPC

J/ψ distributions for √s = 7AGeV momentum transverse momentum momentum rapidity Alla Maevskaya INR RAS NICA Roundtable Workshop 11 September 2009 HSD Registered in TPC

Background sources 6400 UrQMD Au+Au central events √s =9AGeV J/ψ multiplicity ~8x10 -5 Alla Maevskaya INR RAS NICA Roundtable Workshop 11 September 2009 Momentum and transverse momentum of J/ψ different background sources: π°Dalitz decay; misidentified pions, protons and kaons

Invariant mass spectra J/ψ + combinatorial background for different pions, kaons and protons suppression factors Suppression S/B in 3σ Beam energy 7AGeV 9AGeV protons π & k 1000 protons π & k protons π & k J/ψ efficiency 55% 55% Alla Maevskaya INR RAS NICA Roundtable Workshop 11 September 2009 Superevent technique was used for invariant mass of background, so 196 J/ψ were added to corresponding (6400x6400) central events √s =9AGeV

Conclusions NICA will produce ~400 ( or up to 1000 if MPD efficiency wil be more than 10%) J/ψ per 10 weeks, so during long enough run period significant amount of particles could be collected and studies. J/ψ could be measured by MPD with existing set-up: TPC, TOF and ECAL together could provide background suppression as needed. Alla Maevskaya INR RAS NICA Roundtable Workshop 11 September 2009