Signatures of phase transitions in high energy collisions & NICA project

1. Thermal hadron production & phase diagram • Evidence for deconfinement at SPS, RHIC & LHC • Call for the new generation experiments - Fluctuation signature of the CEP • Femtoscopic signature of the QGP 1-st order PT • Project NICA - Conclusions Signatures of phase transitions in high energy collisions & NICA project Richard Lednicky New Trends , Alushta, Ukraine

2. March 2009

4. Exp.: Thermal f-o (T - μB): SPS SPS RHIC nantiparticle  nparticle RHIC

5. Thermal Model T  165 MeV B  0  nantiparticle  nparticle

6.  1st order PT crossover

7. & MPD @ NICA/JINR Lattice says: crossover at µ = 0 but CEP location is not clear CEP: T ~ 160-170 MeV, μB > 200 MeV

8. April, Critical opalescence Water liquid-gas CEP: 374 °C and 218 atm

9. QCD phase diagram Deconfined matter (high e,T,nB): e >1 GeV/fm3, T>150 MeV or nB>(3-5)n0 • Energy Range of NICA • The most intriguing and unexplored • region of the QCD phase diagram: • Highest net baryon density • Onset of deconfinement phase transition • Strong discovery potential: a) Critical End Point (CEP) b) Chiral Symmetry Restoration с) Hypothetic Quarkyonic phase • Complementary to the RHIC/BES, CERN, FAIR and Nuclotron-M experimental programs RHIC-BES NICA Nuclotron-M Comprehensive experimental program requires scan over the QCD phase diagram by varying collision parameters : system size, beam energyand collision centrality

10. Evidence for deconfinement at SPS - Strangeness enhancement & K/pi horn • Plateau in mT(pT2+m2)1/2 in the entire SPS energy range • J/ suppression • UrQMD: predicts too small tr. flow at top SPS energies •  too large femtoscopic radii & too large Rout /Rside NA49:anomalies in hadron production: “Horn” – sharp maximum in the K+/pi+ or strangeness-to-entropy ratio in the transition region “Step” - plateau in the excitation function of the apparent temperature or mt of hadrons NA50: anomalous J/y suppression in central A+A QGP HG Mixed phase Quarkonium suppression by color screening

11. KP’71-75: Correlation Femtoscopy momentum correlations of emitted particles are sensitive to space-time structure of the source due to QS & FSI Fermi’34 CF=1+(-1)Scos qx total pair spin exp(-ip1x1) p1 2 x1 ,nns,s x2 1/R0 1 p2 2R0 nnt,t x = x1-x2 q = p1-p2 |q| 0

12. BW: Retiere@LBL’05 , , Flow & Radii x-out, y-side, z-long pion 0.91c 0.73c ← Emission points at a given tr. velocity px = 0.15 GeV/c 0.3 GeV/c Rz22 (T/mt) Ry2 = y’2 Kaon Rx2= x’2-2vxx’t’+vx2t’2 t’2 (-)2 ()2 px = 0.53 GeV/c 1.07 GeV/c For a Gaussian tr. density profile: (r) ~ exp(-r2/2RG2) and a linear flow velocity profile: F (r) = 0r/ RG  Proton px = 1.01 GeV/c 2.02 GeV/c Ry2 = RG2 / [1+ 02 mt /T] Rz  = evolution time Rx = emission duration Rx , Ry  0= tr. flow velocity pt–spectra T= temperature

13. AGSSPSRHIC: radii Femto-puzzle I Contradiction with transport and simple hydro calcul. • Small space-time scales • their weak energy dep. • Rout/Rside ~ 1 • Basically solved due to the initial flow increasing with energy (likely related to the increase of the initial energy density and partonic energy fraction)

14. Elliptic flow v2vs energy  increasing fraction of the partonic matter & a saturation on the ideal liquid level at the top RHIC energy Hydro expansion transfers the initial spatial eccentricity  into elliptic flow v2   v2 v2/ε vs particle density in the transverse plane v2 for midrapidity 25% most central collisions AGS SPS IDEAL RHIC

15. Evidence for deconfinement at RHIC • Large elliptic flow: v2/ close to ideal liquid value at top RHIC energies • CQNS of v2 • CME (Chiral Magnetic Effect) • Jet quenching Strong high pT suppression in hadron production  highly opaque matter for colored probes (not for ’s) Constituent quark number scaling of elliptic flow  partonic collectivity in a relativistic quantum liquid sQGP matter at RHIC

16. News from BES @ RHIC: Quark Matter 2011  CQNS of v2 not valid below 39 GeV

17. News from BES @ RHIC: Quark Matter 2011 (LPV)

18. : Jet Quenching at RHIC

19. Evidence for deconfinement at LHC • Direct observation of jet quenching • Similar differential elliptic flow v2(pt) as at RHIC  close to ideal • liquid but increased /s at LHC compensating the increase of  and T • (from liquid to gas ?) • Femtoscopic correlations confirmed the multiplicity scaling of the • correlation volume  universal freeze-out density Universal freeze-out density First direct evidence of strong jet quenching observed in LHC HI collisions by ATLAS and CMS

20. Observed similar differential elliptic flow v2(pt) as at RHIC  increased /s at LHC compensating the increase of  and T : from liquid to gas ? Song, Bass, Heinz, arXiv:1103.2380 v2 in Hydro+UrQMD transport code /s = 0.16 at RHIC  0.20-0.24 at LHC Heinz, Shen, Song, arXiv:1108.5323 but: 0.16 at LHC Tomasik, Levai, arXiv:1104.3262 ~25% of v2 may come from hard partons  /s > 0.20-0.24 at LHC Xu, Ko, arXiv:1101.2231 v2 in AMPT multiphase transport model parton = 10 mb at RHIC  1.5 mb at LHC /s ~ (T2parton)-1 increased T at LHC more than compensated by decreased parton Bhatt, Mishra,Sreekanth, arXiv:1103.4333 /s  with T may lead to cavitation (gas bubbles)  hydro at LHC applic. up to 2 fm/c only ?

21. Dense matter (collective flows) also in pp collisions at LHC (for high Nch) ? • pt increases with nch and particle mass • BE CF vs nch and pt points to expansion at high nch • Ridge effect observed in angular correlations at high nch Ridge effect R(kt)  at large Nch  expansion

22. Color flux tubes  longitudinal translation invariance of transverse flows Origin of Ridge in Rel. HICs: Similar picture in HM pp: Increasing number of color flux tubes with multiplicity  similar energy densities at HM pp as in Rel. HICs  similar tr. Flows (Ridge)

23. Ridge in HM pp 7 TeV pt= 1-3 GeV/c K.Werner et al. arXiv:1011.0375 EPOS+hydro:  Ridge EPOS w/o hydro:  No Ridge

24. Lessons from the 1st generation HI experiments • Evidence for the onset of deconfinement @ low SPS energies √sNN ~ 7 GeV & sQGP matter @ RHIC • 2nd generation HI experiments (STAR, NA61, ALICE, • ATLAS, CMS) continue the exploration of the QCD • phase diagram But, a further research program in studying the QCD phase diagram with the existing detectors appears to have drawbacks due limitations either in accelerator parameters (energy range, luminosity) or by constrains in experimental setups (acceptance, event rates, etc..)

25. Motivation for the next generation of HI experiments 3rd generation experiment with dedicated detectors are required for more sensitive and detailed study

26. 2nd generation HI experiments STAR/PHENIX @ BNL/RHIC. Originally designed for higher energies (sNN > 20 GeV), low luminosity for LES program L<1026 cm-2s-1 for Au79+, too few energies. NA61 @ CERN/SPS. Fixed target, non-uniform acceptance, few energies (10,20,30,40,80,160A GeV), poor nomenclature of beam species ALICE, ATLAS, CMS @ CERN/LHCToo high energies (sNN > ~1TeV ), poor nomenclature of beam species 3rd generation HI experiments CBM @ FAIR/SIS-100/300 Fixed target, E/A=10-40 GeV, high luminosity, But, max. energies in 2018! MPD @ JINR/NICA.Collider, small enough energy steps in the range sNN = 4-11 GeV, a variety of colliding systems, L~1027 cm-2s-1 for Au79+ at 9 GeV.

27. Why the NICA and FAIR energy range is so important The energies of the NICA and FAIR sit right on top of the region where the baryon density at the freeze-out is expected to be thehighest. It will thus allow to analyze the highest baryonic density under laboratory conditions. Also, in this energy range the system occupies a maximal space-time volume in the mixed quark-hadron phase (the phase of coexistence of hadron and quark-qluon matter similar to the water-vapor coexistence-phase).

28. CP:  ______ _________ ___  

29. News from BES @ RHIC: Quark Matter 2011 s==0 for Gaussian distr.

30. News from BES @ RHIC: Quark Matter 2011 (contrary to fixed target NA49 data)

31. Cassing – Bratkovskaya: Parton-Hadron-String-Dynamics Perspectives at FAIR/NICA energies

32. CEP signals in multiplicity and pt fluctuations for ξ =3 and 6 fm assuming CEP at T=162 MeV µB=360 MeV & Gaussian fluctuation shape with the width of 10 MeV in T 30 MeV in µB ω= D(N)/‹N› pt = (D(∑pti)/‹N›)1/2-(D(pt))1/2 ξ =6 fm pt 10 MeV/c for ξ = 3 fm  2.5 MeV/c for NA49 acc.= 0.24 M. Stephanov .. ’99 B. Berdnikov .. ‘00 ξ <~3 fm due to finite fireball lifetime  pt< 0.5 MeV if max partonic energy fraction~20% asexpected in PHSD 3 fm

33. Rischke & Gyulassy, NPA 608, 479 (1996) With 1st order Phase transition Femtoscopic signature of QGP onset 3D 1-fluid Hydrodynamics Initial energy density 0 Long-standing signature of QGP onset: • increase in , ROUT/RSIDEdue to the Phase transition • hoped-for “turn on” as QGP threshold in 0is reached • decreases with decreasing Latent heat & increasing tr. Flow (high 0or initial tr. Flow)

34. Femto-puzzle II No signal of a bump in Rout near the QGP threshold (expected at AGS-SPS energies) !? – likely solved due to a decrease of partonic phase at these energies

35. NICA : Nuclotron-basedIonCollider fAcility Location : JINR, Dubna • New flagship project at JINR • Based on the technological • development of the Nuclotron facility • Optimal usage of the existing • infrastructure • Modern machine which incorporates • new technological concepts • First beams expected in 2016 • NICA advantages: • Energy range sNN = 4-11 GeV- highest baryon density • Rich nomenclature of beams : from p to Au • Highest luminosity : Au+Au up to 1027 3

36. Facility Scheme and Operation Scenario KRION-6T & HILac SPI & LU-20 (“Old” linac) 2.5 m 4.0 m Booster Synchrophasotron yoke Nuclotron Fixed target experiments MPD Spin Physics Detector (SPD) NICA Layout Bldg #1 Bldg #205 Collider C = 500 m

37. Booster magnet yoke manufactured Nuclotron-type SC magnets for Booster

38. The NICA design passed the stage of concept formulation and is presently under • detailed simulation of accelerator elements parameters, • development of working project, • manufacturing and construction of prototypes, • preparation of the project for state expertise • in accordance with regulations of Russian Federation. • The project realization plan foresees a staged construction and commissioning of accelerators forming the facility. The main goal is the facility commissioning in 2016. 38

39. NICA construction schedule

40. Conclusions • Some indications of deconfined partonic matter come from SPS, RHIC & LHC HIC at √sNN > 10 GeV (µB < 400 MeV); particularly, FO points (T, µB) calculated within Thermal Model seem to be close to QGPphase boundary for small µB< 400 MeV • Absence of fluctuation & femtoscopic signals of CEP and 1-st order PT at √sNN < 10 GeV is likely due to a dramatic decrease of partonic phase with decreasing energy • Search for the effects of QGP 1-st order PT (onset and CEP) can be successful only in dedicated high statistics and precise experiments like NICAand FAIR • NICA is under construction in JINR and its startup is supposed in 2016 Welcome

41. if added heavy resonances (motivated by e+e-) + 

42. News from BES @ RHIC: Quark Matter 2011

43. AGSSPSRHIC: radii Clear centrality & mt dependence Weak energy dependence STAR Au+Au at 200 AGeV 0-5% central Pb+Pb or Au+Au R ↑ with centrality &  with mt only Rlong slightly ↑ with energy Rside R/(1+mt F2/T)½  tr. collective flow velocity F Rlong (T/mt)½  Evolution (freeze-out) time

44. Femtoscopy of Pb+Pb at LHC arXiv:1012.4035 All radii increase with Nch from RHIC to LHC multiplicity scaling of the correlation volume  universal freeze-out density The LHC fireball: • hotter • lives longer & • expands to a larger size Freeze-out time f from Rlong=f(T/mt)1/2

45. FREEZE-OUT AND PHASE DIAGRAMS Critical end-point 1st order PT Ivanov, Russkikh,Toneev ’06 : At lower energies the system spents an essential time in the mixed phase Randrup, Cleymans ‘06 : NICA&FAIR sNN = 9 AGeV The freeze-out baryon density is maximal at sNN= (4+4) GeV covered by NICA and FAIR SNN = 4-11 GeV is a most promising energy region to search for mixed phase & critical end-point Besides NICA & FAIR also RHIC & SPS plan to partly cover this energy range

47. Fluctuation Observables, sdyn • NA49 uses the variable dyn s is the reduced width of K/p distribution Quark Matter 2011 May 23, 2011

48. Fluctuation Observables, ndyn • STAR uses a different fluctuation observable, ndyn. • Introduced to study net-charge fluctuations. • Measures deviation from Poisson behavior. • It has been demonstrated that,

49. EPOS+hydro: energy density & radial velocity @ s = 0, =1.3 fm/c HM pp 7 TeV • very fast expansion;  drops from ~50 to ~3 GeV/fm3 in 1.3 fm/c and radial velocity near boundary achieves 80% c  Similar collective expansion expected in HM pp & AA Energy density GeV/fm3 Radial velocity %c

50. First observation of new phenomenain p-p Observation of Long-Range Near-Side Angular Correlations in Proton-Proton Collisions at LHC CMS Collaboration, JHEP 9 (2010) 1 arXiv:1009.4122 Ridge Several papers on possible interpretations. New set of measurements to understand better the dynamics. It will be very interesting to compare the measurements in pp and heavy-ions modes.