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MULTIPLICITY FLUCTUATION AND CORRELATION AS A PROBE FOR QCD PHASE TRANSITION

MULTIPLICITY FLUCTUATION AND CORRELATION AS A PROBE FOR QCD PHASE TRANSITION. Bedanga Mohanty Variable Energy Cyclotron Centre, Calcutta. OUTLINE Motivation N g and N ch fluctuation results from SPS experiment Contribution to future experiments Theoretical work Outlook. MOTIVATION.

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MULTIPLICITY FLUCTUATION AND CORRELATION AS A PROBE FOR QCD PHASE TRANSITION

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  1. MULTIPLICITY FLUCTUATION AND CORRELATION AS A PROBE FOR QCD PHASE TRANSITION Bedanga Mohanty Variable Energy Cyclotron Centre, Calcutta • OUTLINE • Motivation • Ng and Nch fluctuation results from SPS experiment • Contribution to future experiments • Theoretical work • Outlook Bedanga Mohanty

  2. MOTIVATION Bedanga Mohanty

  3. IS IT EXPERIMENATLLY POSSIBLE TO STUDY QCD TRANSITIONS ? Lattice gauge theory – critical temperature for phase transition is around 150 MeV  corresponds to energy density of 2-3 GeV/fm3 Estimated that energy density achieved in central region of nucleus-nucleus collision can be as high as 10 GeV/fm3 QGP and a chiral symmetry restored matter can be created in Laboratory Bedanga Mohanty

  4. WHY STUDY THIS PHASE TRANSITION ? • Properties of QCD • Big Bang was long back • Neutron stars are far away • Nucleosynthesis • Color superconductivity • Thermodynamics of matter under extreme conditions • Phase transition tri-critical point • Dark Matter ?? Chiral symmetry restored Tri-critical point?? Bedanga Mohanty

  5. RELATIVISTIC HEAVY-ION COLLISIONS • QCD transitions • Deconfinement • Chiral symmetry restoration • At Tricritical point • Large e-by-e fluctuations • in observables NPA 663 (2000)183; Peter Braun-Munzinger PRL 81 (1998) 4816; Stephanov et al. Bedanga Mohanty

  6. EVENT-BY-EVENT FLUCTUATIONS Thermodynamic properties of matter : Total heat capacity PRL 75 (1995) 1044 L. Stodolsky PLB 430 (1998) 9 S. Mrowczynski Compressibility Study of thermodynamical quantities (or fluctuations in experimental observables) can shed light on possible existence of phase transition and its nature At tricritical point – singularities in thermodynamical observables – large e-by-e fluctuations in Expt. Obs. Bedanga Mohanty

  7. CHIRAL SYMMETRY RESTORATION • Through search for disoriented • chiral condensates • Study and detection of DCC : • Nature of chiral phase transition • Vacuum structure of strong interaction Look at Ng vs. Nch correlation Bedanga Mohanty

  8. FLUCTUATIONS IN HEAVY-ION COLLISIONS • Large number of particles in single event • Large acceptance detectors • Near Gaussian distributions • Fluctuation studied by width SPS -> RHIC -> LHC WA98 WA98 WA98 NA49 PRC 65 (2002) 054912 WA98 Collaboration PLB 459 (1999) 679 NA49 Collaboration Bedanga Mohanty

  9. UNDERSTANDING FLUCTUATIONS Bedanga Mohanty

  10. FLUCTUATION STUDY IN SPMD : 2.35 < h < 3.75 PMD : 2.9 < h < 4.2 Bedanga Mohanty

  11. CERN SPS : 158A GeV Pb+Pb Charged Particles Ch. particlesvs. Photons Photons Single event display Bedanga Mohanty

  12. MULTIPLICITY FLUCTUATIONS Ng and Nch fluctuations are studied by looking at the simple variable • Centrality and pseudo-rapidity acceptance dependence • Compare to participant model and VENUS Participant model: N : Particle Multiplicity Npart : No. of participants ni : No of particles produced by ith participant, accepted within the acceptance of detector Bedanga Mohanty

  13. CENTRALITY DEPENDENCE OF MULTIPLICITY FLUCTUATIONS Data agree fairly well with model calculations Ref : PRC 65 (2002) 054912 Bedanga Mohanty

  14. PSEUDO-RAPIDITY ACCEPTANCE DEPENDENCE OF MULTIPLICITY FLUCTUATIONS Data agree fairly well with model calculations based on binomial sampling Int. J. Mod. Phys. A 17 (2002) 675 Bedanga Mohanty

  15. Ngvs. Nch FLUCTUATIONS • Top 5% central events ONLY • Bins in f : 1,2, 4, 8, 16 • Discrete Wavelet Analysis • Correlation Analysis: Results from data compared to mixed events and simulation Bedanga Mohanty

  16. MIXED EVENTS Mixed events help in filtering out different contributions to fluctuations Bedanga Mohanty

  17. COMPARISON OF RMS WIDTH OF DATA, M1-MIXED EVENTS AND SIMULATION Mix hits in PMD and SPMD separately Maintain global correlation Data widths larger than M1-mixed • Presence of • localized fluctuations. • Possibilities in: • Ng • Nch • Correlated fluctuation Ref : PRC 64 (2001) 011901 (R) Bedanga Mohanty

  18. CORRELATED FLUCTUATIONS ? DATA AND M2-MIXED EVENTS Mix one event of PMD with Another event of SPMD Hits unaltered in an event Ng– Nch correlation maintained Data matches with M2-mixed Absence of Correlated fluctuations. Ref : PRC 64 (2001) 011901 (R) Bedanga Mohanty

  19. DO BOTH Ng and Nch CONTRIBUTE ? DATA AND M3-MIXED EVENTS Mix hits in one detector only Hits unaltered in other detector This case is in between M1 and M2 Maintain global correlation M3-mixed between Data & M1. • Presence of individual • Fluctuations in both : • Ng • Nch Ref : PRC 64 (2001) 011901 (R) Bedanga Mohanty

  20. CENTRALITY DEPENDENCE OF LOCALIZED CHARGE-NEUTRAL FLUCTUATIONS Total localized fluctuations in photon and charged particle decreases with decrease in centrality Not detectable Ref : nucl-ex/0206017 Phys. Rev. C (in press) Bedanga Mohanty

  21. UPPER LIMIT ON DCC PRODUCTION AT SPS Based on a simple model of DCC Differences between data and M2 (event mixing) assumed solely due to DCC Helps theorists develop models of DCC Ref : nucl-ex/0206017 Phys. Rev. C (in press) Bedanga Mohanty

  22. HIGHLIGHTS OF ANALYSIS • Multiplicity fluctuation studies – first time studied at these energies – considered as “archival work” by community Ref : PRC 65 (2002) 054912 • First study of localized iso-spin fluctuations (DCC-type) at SPS energies Ref : PRC 64 (2001) 011901 (R) • These studies have enhanced the physics capability of PMD • The analysis will form the basis for any future work in this field at RHIC and LHC Ref : nucl-ex/0206017 (PRC in press) • Invited talk at the prestigious Quark Matter Conference 2002, France on the entire analysis. -Talk to be published in Nucl. Phys. A (2003) Bedanga Mohanty

  23. CONTRIBUTION TO FUTURE EXPERIMENTS Indian group is putting up a photon multiplicity detector in STAR and ALICE experiments to look for fluctuations/correlations Analysis of test data formed the heart of the technical design report of PMD Detailed study of physics performance of PMD in STAR and ALICE .Formed a major part of the technical design report of PMD in ALICE NIM A 488 (2002) 131 ALICE and STAR Technical design report : Photon Multiplicity detector. CERN-LHC-99-32 Bedanga Mohanty

  24. SOME THEORETICAL WORK • Search for DCC in heavy-ion collisions : Possibilities and Limiations. This work is a compilation of all our experience in look for DCC for 4 dedicated years in WA98 experiment. Mohanty, Nayak, Mahapatra, Viyogi – nucl-ex/0211007 (IJMPA in press) • Evolution of fluctuation in relativistic heavy-ion collisions Mohanty, Alam, Nayak– nucl-th/0301086; Phys. Rev C 67 (2003) 024904 • Velocity of sound in high energy heavy-ion collisions Mohanty and Alam – nucl-th/0301086; Submitted to Phys. Rev C (2003) • Under standing of source features and dynamics through photon interferometry Alam, Mohanty, Roy, Sarkar and Sinha; Submitted to Phys. Rev C (2003) Bedanga Mohanty

  25. OUTLOOK • Study fluctuations using RHIC data to see if QCD transitions have occurred at RHIC • Wealth of data exists at RHIC. Will study other signatures of QCD transitions • Installation of PMD and data taking • Lots of work to do on simulation sector for ALICE PMD • This field is one of the frontier areas in High energy physics. There are lots of things still to understand hence lots of scope to contribute. Bedanga Mohanty

  26. SUMMARY • First study on the search of disoriented chiral condensates in ultra relativistic heavy ion collisions at SPS energies through the analysis of the photon to charge particle ratio was carried out. This will form the basis for future research in this field at higher energies (RHIC/LHC). Ref : PRC 64 (2001) 011901 (R) • Exhaustive and innovative work on the analysis of correlation and fluctuations in multiplicity, transverse energy for the system formed in nucleus-nucleus collisions at relativistic energies has been performed. This is considered as an archival work by the community Ref : PRC 65 (2002) 054912 • Developed different techniques to investigate the fluctuations in observables of nucleus-nucleus collisions. Discrete wavelet transformation was applied to these studies for the first time. Physical Review C 66 (2002) 044901 PLB 461 (1999) 142 • Played major role in various hardware and simulation studies of photon multiplicity detector development. NIM A 488 (2002) 131 Bedanga Mohanty

  27. SOME OF MY RECENT PUBLICATIONS Bedanga Mohanty

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