Physics Priorities at NICA/MPD

1. Physics Priorities at NICA/MPD G. Musulmanbekov, K. Gudima, D.Dryablov, V.Geger, E.Litvinenko, V.Voronyuk, M.Kapishin, A.Zinchenko, V.Vasendina

2. What are we searching for? • Signatures of phase transition and/or mixed phase • QCD critical (triple)endpoint • Onset of chiral symmetry restoration at high ρB • The equation-of-state at high ρB

3. Observables • Signatures of phase transition and/or mixed phase • excitation function of particle yields and ratios (π, K, Λ, Σ, Ξ, Ω) • transverse mass spectra of kaon • particle correlations • QCD critical endpoint • excitation function of event-by-event fluctuations (multiplicities, K/π, transverse momenta, …) • Onset of chiral symmetry restoration at high ρB • in-medium modifications of hadrons (ρ, ω, φ → e+e-(μ+μ-)) • The equation-of-state at high ρB • collective flow of hadrons • particle production at threshold

4. What have been measured at AGS, SPS and BES RHIC ? • excitation function of particle yields and ratios (π, K, Λ, Σ, Ξ, Ω)? • transverse mass spectra of kaon • e-by-e fluctuations • femtoscopy correlations • dilepton spectra • azimuthal asymmetry of particle yield • flows of particles

5. Bulk properties : yield of particles, nch,, pt, mtdistributions, Event-by-eventfluctuations: particleratio, netbaryon (proton), pt Collective flows, Reaction Plane Femtoscopycorrelations Dileptonsyield Strange particle (mesons and hyperons) yield AzymuthalAsymmetries: CME, CVE Whatisplanedtomeasure Simulation of AuAueventsforcentral and semicentralcollisions√s = 4 – 11 GeV Models • Model generators: • UrQMD, HSD, PLUTO, FASTMC, LAQGSM, Glauber models

6. Particle Yield SPS AGS

7. UrQMD vs Exp. Data Model Adequacy

8. LAQGSM vs UrQMD Model Adequacy √s = 4.7 GeV

9. LAQGSM vs UrQMD Model Adequacy • • use existing generated events produced with QGSM at √s = 5 and 9 AGeV and with UrQMD at √s = 3, 5 and 9 AGeV to estimate model dependence, 5-7k events per sample • • QGSM and UrQMD generate very different particle and energy flow spectra in pseudo-rapidity range of extZDC • UrQMD failed to describe emission of nucleons and nuclear fragments in forward rapidities! • QGSM suits for this purpose.

10. MPD Reconstruction efficiency √s = 4 GeV

11. MPD Reconstruction efficiency Hyperon Study Hyperon Generator dN / dpt = pt · exp (-mt / T), where mt = √(M · M + pt · pt), M – hyperon mass, T ~ 200 MeV dN / dy = exp (-y2/ 2σ2y ), σ2y≈ 0.7 Track acceptance criterium: in TPC with |η| < 1.3 and Nhits ≥ 10 “Perfect particle ID

12. Hyperons Study: Λ Only TPC: Eff. ≈ 4.3% S / B (± 3σ) = 2434 / 443 ≈ 5.5 S / √(S+B) ≈45.4 TPC + ITS: Eff. ≈ 8.1% S / B (± 3σ) = 4310 / 468 ≈ 9.2 S / √(S+B) ≈62.4 Only TPC TPC + ITS

13. Hyperons Study Ξ- TPC + ITS: Eff. ≈ 3.8% S / B (± 3σ) = 245 / 18 ≈ 13.7 S / √(S+B) ≈15.1 Ω- TPC + ITS: Eff. ≈ 3.8% S / B (± 3σ) = 245 / 18 ≈ 13.7 S / √(S+B) ≈15.1

14. Estimated particle yields (central AuAu collisions at √s = 9 GeV, event rate 300 Hz)‏ • Charged hyperon study with MPD looks feasible • ITS significantly improves detector capabilities for such analysis

15. E-byE FluctuationsTheory predictions: enhancement of fluctuations near the Critical Point

16. K/pi ratio E-by-E fluctuationsndyn,K/p • TPC+TOF (GeV/c): • p : 0.2 < pT < 1.4 • K : 0.2 < pT < 1.4 • TPC+TOF includes statistical and systematic errors from electron contamination. • Pion contamination of kaons < 3% using TPC and TOF. • Difference between STAR and NA49 result below √sNN = 11.5 GeV. • (NA49 data from C. Alt et al. [NA49 Collab.], Phys. Rev. C 79, 044910 (2009) • Both models show little acceptance effects. • UrQMD predicts little energy dependence. • HSD predicts an energy dependence. Differences could be due to difference in acceptance and/or PID selections --- under discussion Additional check is needed! Quark Matter 2011 May 23, 2011

17. K/pi Ratio Fluctuations Observables at MPD dyn

18. Transverse Momentum Fluctuations Event mixing for the statistical background estimation: , where For the system of independently emitted particles fluctuation Фpt goes to zero. No evidence for enhancement of fluctuations!

19. Femtoscopy correlations of pions Reconstruction of Correlation functions in central AuAu collisions at √s = 9 GeV

20. Byellipticflow in TPC Resolution vs centrality at √s = 9 GeV Resolution vscollisionenergy Reaction Plane Resolution NICA/MPD results are comarable with STAR data

21. Event Plane Reconstruction at STAR with Directed Flow: n1 STAR Resolution • Event plane measurements at STAR: • TPC (|η| ≤ 1) • (3) BBC (3.8 ≤ |η| ≤ 5.2)

22. Withdirectflow in ExtZDC Resolution vs centrality at √s = 9 GeV Reaction Plane Resolution Extended ZDC detector (2.2<η<4.8) can measure RP with resolution of δφRP~22o-30o at medium b (4<b<10 fm for 9 GeV AuAu), which is much more better then TPCs at NICA and TPC and BBC at STAR can give!

23. Which measurements could be preferable in NICA energy region • Enhanced yield of positive and neutral kaons near threshold. • Enhanced yield of one, double and triple strange baryons near threshould. • Correlation of kaons with hyperons • Elliptic and direct flows of hyperons • Polarization of hyperons • Enhanced mass spectra of dileptons • Polarization of dileptons

24. Thank you for your attention!