PoS(EPS-HEP 2013)192 http://pos.sissa.it/ ∗ ´ nski (for the NA49 and NA61/SHINE Collaborations) [email protected] Speaker. The exploration of the QCDhadronic phase to diagram partonic particularly degrees thechallenging of search tasks for freedom in a and present phase possibly heavy-ionhadronic transition physics. a observables from in critical As central endpoint, observed Pb+Pb by istheir collisions the at energy one NA49 the dependence. of experiment, CERN the several SPS Thesecate show features most the qualitative are changes onset not in of observed a inexpected phase to elementary transition result in interactions in the and the SPS indi- increaseprovided energy that of range. the event-by-event The fluctuations freeze-out existence of of of the variousagram measured hadronic a and hadrons observables critical the occurs point evolution close of is to the its finalinformation hadron location about phase in the does the existence not phase and erase di- naturegained the from of fluctuations the a signals. studies phase of Further event-by-event transition fluctuations of inperformed final the state by hadron SPS NA61/SHINE, distributions energy and the range yields successor can ofboth be experiments the on NA49 event-by-event experiment. fluctuations of Experimental transverse-momentum,low multiplicity results mass as from well as pair and protonsystem number size. fluctuations are shown as a function of beam energy and ∗ Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. c

The European Physical Society Conference on18-24 High July Energy 2013 Physics -EPS-HEP2013 Stockholm, Sweden Institute of Physics, Jan Kochanowski University,E-mail: PL-25406 Kielce, Poland Maciej Rybczy Onset of deconfinement and search forpoint the of critical strongly interacting matter atenergies CERN SPS PoS(EPS-HEP 2013)192 shows an update of ] and data on central 1 5 spectra. T m (Color online) Inverse slope parameter of Figure 2: negative ] were released. Figure 6 ´ nski (for the NA49 and NA61/SHINE Collaborations) 2 ], thus locating the onset of deconfinement energy around 3 ] creation with data taking for central Pb+Pb collisions at 1 ] around 30A GeV and dedicated experiments, NA61/SHINE 4 Maciej Rybczy , 3 6 GeV). . 7 ≈ ] that the onset of deconfinement should to rapid changes of the energy de- 2 NN s √ (Color online) Mean pion multiplicity per Until recently the evidence of onset of deconfinement was based on the results of a single Several structures in excitation functions were expected within the SMES: a kink in the in- In 1999, the NA49 experiment at the CERN Super Synchrotron started a search for the Au+Au collisions from the RHIC BES program [ experiment. Recently new results on central Pb+Pb collisions at the LHC [ participant nucleon. 2.1 Verification of NA49 results and their interpretation by STAR and ALICE Figure 1: 30A GeV ( crease of the pion yield pertion participant as nucleon a (change consequence of of slope thestrangeness due activation to of to entropy partonic increased ratio, degrees entropy of produc- and(constant freedom), a temperature a step and sharp pressure in peak in the (horn) a+ inverse in mixed A slope the collisions phase). parameter by Such the of signatures NA49 transverse experiment were [ mass indeed spectra observed in A 40A GeV. Runs at 80A andwas 20A, motivated by 30A the GeV predictions followed of insions a 2000 (SMES) statistical and [ model 2002, of respectively. thependence This early of search several stage hadron of production nucleus-nucleus properties, all colli- jectured appearing features in were a observed common energy [ domain.at Con- the CERN SPS and theregion beam of energy the scan onset at of BNL deconfinement. RHIC, continue detailed studies in the energy 2. Onset of deconfinement onset of quark-gluon plasma (QGP) [ Onset of deconfinement and search 1. Introduction PoS(EPS-HEP 2013)192 , within its 1 . 3 ´ nski (for the NA49 and NA61/SHINE Collaborations) 3 Kaon to pion yield (near midrapidity). Maciej Rybczy Figure 3: shows the inverse slope parameter of negative kaon transverse mass spectra. The LHC yield (near midrapidity) is presented in Fig. 2 + π ] for details. / 7 + The mean pion multiplicity at LHC was estimated based on the ALICE measurement of charged particle multiplic- As seen, RHIC results confirm NA49 measurements at the onset of deconfinement. Moreover, Fluctuations and correlations may serve as a signature of the onset of deconfinement. Close to Figure K 1 ity, see [ point and the RHIC BES pointsThe confirm the step structure expected for the onset of deconfinement. LHC (ALICE) data demonstrate that the energyrapid dependence changes of hadron only production at properties low shows (17.3 SPS GeV) energies, and and the a current LHC smooth (2.76with evolution TeV) energies. is the All observed interpretation three between of structures the the confirm topenergy that NA49 results only SPS structures agree a as smooth due change to of onset QGP properties of with deconfinement. increasing Above energy is the expected. 3. onset New results on fluctuations the phase transition the equation ofof state changes fluctuations. rapidly which can Moreover, impactstrongly fluctuations the interacting energy and matter. dependence correlations This canfluctuations is help close in to analogy to the to locate critical critical the point. opalescence, critical For where strongly point we interacting expect of matter enlarged a maximum of fluctuations the kink plot, where BES points follow the line for A+A collisions and the LHC point Onset of deconfinement and search large uncertainty, does not contradict extrapolations from high SPS and RHIC energies. PoS(EPS-HEP 2013)192 ]. This 8 (with M ) ) and then , increases π M B ( field are also m µ 2 − F σ ] and . The close to the two pion 11 [ − π ] the critical fluctuations π + π m 10 m ´ nski (for the NA49 and NA61/SHINE Collaborations) may reach the two-pion threshold (2 4 field fluctuations are expected at the critical point c T − σ < T field. Since protons are easier to detect than neutrons the − particles produced in abundance at the critical point) [ σ ]. Furthermore, as pointed out in [ − Maciej Rybczy 9 σ in transverse momentum space are expected to follow a power-law pairs) with invariant mass just above 2 from intermittency analysis: (a) for protons in the 10% most central C+C, Si+Si 2 2 particles at − F Φ π ∆ σ + . space. Significant c π T T field fluctuations at the critical point. Local density fluctuations are expected p − σ 6 GeV). . Power law exponents 7 ≈ It was suggested that the analogue of critical opalescence may be detectable through inter- The NA49 experiment searched for an intermittency signal in transverse momentum space of NN s √ transferred to the baryon density [ being the bin size in eachtransverse transverse momentum momentum space space were direction) computed of for real di-pionwhere data and only and proton for statistical densities artificially in fluctuations produced mixed areof events present. mixed events) moments The combinatorial background subtracted (by use mittency analysis in reconstructed di- ( 3.1 Proton and pion intermittency signals critical point is the endpoint ofof a line the of chiral first order symmetry transitions whenbeyond associated a with the the critical temperature partial value T, restoration fordecay given into baryochemical two potential pions, thereforemass density incorporate fluctuations of di-pions with both in configuration and momentum space.the chiral In condensate a and finite-density the medium baryon there density. is Thus a the mixing critical between fluctuationsof of the the chiral condensate are alsoof directly the transferred protons to the with net theperspective proton isospin density of zero through detecting the the coupling QCDvery promising. critical point through fluctuations of the net proton density is analysis was performed for p+p, C+Cand Pb+Pb and (proton Si+Si intermittency) interactions both at (pion 158A intermittency) GeV. The and second C+C, factorial Si+Si moments Figure 4: (density fluctuations of zero mass Onset of deconfinement and search and Pb+Pb interactions at 158A158A GeV: GeV. (b) for di-pions in p+p, and the 10% most central C+C and Si+Siis interactions at expected when freeze-out happensthese near fluctuations the is critical that point. theshould A system be prerequisite has searched for first for the reached above appearance( the deconfinement. of onset Therefore of the deconfinement energy, critical found point by NA49 to be 30A GeV PoS(EPS-HEP 2013)192 , − pK the K Φ (3.1) (3.2) + pK + K and ), the scaled = distributions ). For p 5 x K , K d , π K / , − E π π between 7.3 and 8.7 + = p i + π 0. For ,( π Φ 2 i = = N i j π Φ at the top SPS energy indicates and . As a strongly intensive mea- i i 2 j N F 6 protons for systems freezing-out  N / ∆ 1 5 ) with the magnitude of fluctuations + − for combinations of two hadron types: i π = i j 1 independent of the number of wounded N i j 2 ω 2 h Σ i Φ = φ i / i √ production due to strangeness conservation. , was chosen. It is defined as: N fitted to )] j i  ω i i − 2 · j N i K Φ N h j i i − h ´ nski (for the NA49 and NA61/SHINE Collaborations) j and 5 2 i ih N i i N N and ih N h i + + i N = h N K i i − h h j is sensitive to the fluctuations of the number of wounded p ω for p+p interactions is not visible in Pb+Pb collisions. N i 3 (di-pions), and ω = K / N π 2 h i j Maciej Rybczy ( Φ ] was developed to extract second and third moments (pure and Φ 2 = ] suggests that the systematic and statistical errors are small enough 12 2 − φ i 13 ω i j does not allow to identify each particle uniquely as the d N h , with x 2 shows the energy dependence of d φ + ) / 6 j 2 E ω ]. M i . When no inter-particle correlations are present i 8 ( ] defined for two hadron types, were obtained for p+p interactions at 31, 40, 80 and 158 GeV/c. From the first is below 1, probably related to baryon number conservation. A comparison of N pK ¯ increase with increasing energy. There is a minimum for h ∼ shows that the power law exponent p 15 ω 2 , 4 i j + F = [ Φ is not only independent of the number of wounded nucleons or volume but also of their 14 p ∆ [ i j , and i j Σ i j = K Φ 1 for higher energies in agreement with predictions of the EPOS, HSD and UrQMD models. Φ p In order to compare results for p+p and central Pb+Pb collisions, the strongly intensive mea- Preliminary NA61/SHINE results on multiplicity fluctuations of All studied scaled variances increase with increasing collision energy (Figure The value of d Figure π , > p GeV. A similar but weaker effectUrQMD is models. visible in The Pb+Pb increase interactions. of It also appears in the EPOS and sure, fluctuations. Figure values of shows a clear difference between results for p+p, which increase with increasing energy, and for π and second corrected moments of the multiplicity distributions, sure and variance was computed. For Poisson multiplicity distributions for a sensitive search of the critical point in NA61/SHINE. where This may be caused by the correlation in mixed) of identified particleFirst multiplicity fluctuation distributions measurements corrected by for NA61 inPb+Pb this and p+p imperfect p+p reactions results identification. give at the the unique SPS opportunity energies. to compare nucleons. This may distortsions. the comparison of p+p data with results from nucleus+nucleusω colli- nucleons in the collisions. However, Onset of deconfinement and search behavior at critical point [ fluctuations approach in size thedifference may prediction be of due critical to freezing QCD out for at Si+Si a distance collisions. from3.2 the The critical Multiplicity remaining point. and transverse momentum fluctuations in Pb+Pb and p+p collisions overlap. The identity method [ For protons NA61/SHINE results on multiplicityexpected fluctuations at the (i.e. critical point [ PoS(EPS-HEP 2013)192 18 18 18 16 16 16 14 14 14 preliminary preliminary preliminary as a function of center- NN i j 12 12 12 s [GeV] Φ NN 10 10 s 10 Graph Graph Graph 8 8 8 NA61: p+p (NA61 acc) NA61: p+p (com acc) NA49: 3.5% Pb+Pb (NA49 acc) NA49: 3.5% Pb+Pb (com acc) EPOS: p+p (NA61 acc) UrQMD: p+p (NA61 acc) NA61: p+p acc) NA61: p+p (com NA49: 3.5% Pb+Pb (NA49 acc) NA49: 3.5% Pb+Pb (com acc) EPOS: p+p (NA61 acc) UrQMD: p+p (NA61 acc) NA49: 3.5% Pb+Pb (NA49 acc) NA49: 3.5% Pb+Pb (com acc) EPOS: p+p (NA61 acc) UrQMD: p+p (NA61 acc) NA61: p+p (NA61 acc) NA61: p+p (com acc) 6 6 6 (Color online) 0 0 0

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, , ω ω ω ω NN s from the RHIC Beam Energy Scan agreeLHC with data NA49 confirm measurements the on interpretation the of onset the of structures deconfinement. observed at low SPS energies as due to onset 4. Summary Figure 5: (upper panel), Pb+Pb which decrease√ with increasing energy. Both dependences cross zero at the same energy Onset of deconfinement and search (bottom panel) multiplicity distributions forlisions p+p as col- a functionNA61/SHINE of results center-of-mass are energy. shown bycompared The symbols to and EPOS, are HSD andlations UrQMD depicted by model lines. calcu- PoS(EPS-HEP 2013)192 , 291 , 149 44 761 , 129901 (2003)] 91 , 124024 (2011) ]. , 307 (2011) [arXiv:1006.1765 38 16 42 , 2705 (1999) [hep-ph/9803462]. , 547C (2009) [arXiv:0907.4101 [nucl-ex]]. 30 , 064907 (2010) [arXiv:0912.4198 [nucl-ex]]. 830 , 251 (1965). N. Itoh Prog. Theor. Phys. 81 1 , 014904 (2011) [arXiv:1101.4865 [nucl-th]]. , 044906 (2012) [arXiv:1204.6632 [nucl-th]]. , 024903 (2008) [arXiv:0710.0118 [nucl-ex]]. , 014001 (2011) [arXiv:1005.4814 [hep-ph]]. , 71 (1980). , 102003 (2003) [Erratum-ibid. , 67 (1975). J. C. Collins and M. J. Perry Phys. Rev. 84 86 77 74 61 ´ nski (for the NA49 and NA61/SHINE Collaborations) 91 7 , 124145 (2011) [arXiv:1106.6071 [nucl-ex]]. B 59 38 Acknowledgment Maciej Rybczy , 131 (1999) [nucl-th/9712050]. 8 , 124003 (2011) [arXiv:1106.5620 [hep-ex]]. 38 [NA49 Collaboration], Phys. Rev. C [NA49 Collaboration], Phys. Rev. C et al. , 1353 (1975). E. V. Shuryak Phys. Rep. et al. 34 [arXiv:1107.2345 [nucl-ex]]. [hep-ph]]. [hep-ph/0302002]. (2005) [hep-ph/0505185]. (1970). N. Cabibbo and G. ParisiLett. Phys. Lett. This research was supported by the National Science Center (NCN) under contracts DEC- [2] M. Gazdzicki and M. I. Gorenstein, Acta Phys. Polon. B [3] C. Alt [1] D. D. Ivanenko and D. F Kurdgelaidze Astrophysics [4] M. Gazdzicki, M. Gorenstein and P. Seyboth, Acta Phys. Polon. B [5] J. Schukraft, J. Phys. G [6] L. Kumar [STAR Collaboration], J. Phys. G [7] A. Rustamov, https://indico.cern.ch/conferenceDisplay.py?confId=144745 [8] N. G. Antoniou, Y. F. Contoyiannis, F. K. Diakonos and G. Mavromanolakis, Nucl.[9] Phys. A K. Fukushima and T. Hatsuda, Rept. Prog. Phys. [14] M. I. Gorenstein and M. Gazdzicki, Phys. Rev. C [13] K. Grebieszkow [NA49 Collaboration], Nucl. Phys. A [15] M. Gazdzicki, Eur. Phys. J. C [16] M. Gazdzicki [NA49 and NA61/SHINE Collaborations], J. Phys. G [12] A. Rustamov and M. I. Gorenstein, Phys. Rev. C 2011/03/B/ST2/02617 and DEC-2012/04/M/ST2/00816. References [11] T. Anticic [10] Y. Hatta and M. A. Stephanov, Phys. Rev. Lett. Onset of deconfinement and search of deconfinement. Fora central maximum A+A in collisions Si+Si fluctuationsenergies. collisions of This at pion result is 158A and a strong GeV. protonbe motivation Thus densities for continued the future by tend experiments the critical and to ion in point program fact, of may the the NA49 be efforts NA61/SHINE will experiment accessible [ at SPS