1. Current status of the long- range correlations analysis in Be+Be at 150 AGeV/c E. Andronov, A. Seryakov NA61/NA49 Collaboration meeting Dubna, 10/04/14

2. Layout Two stage scenario of particles production String fusion model Long range correlations Analysis technique Recent BeBe 150 AGeV/c results Plans 2

3. Two stage scenario of particles production 3 p-p case, low energy I stage: strings formation. [1]A.Capella, U.P.Sukhatme, C.I.Tan and J.Tran Thanh Van, Phys. Lett. B81 (1979) 6 8; Phys. Rep. 236 (1994) 225. [2]A.B.Kaidalov, Phys. Lett., 116B(1982)459

4. Two stage scenario of particles production 4 II stage: string decay. [1]A.Capella, U.P.Sukhatme, C.I.Tan and J.Tran Thanh Van, Phys. Lett. B81 (1979) 6 8; Phys. Rep. 236 (1994) 225. [2]A.B.Kaidalov, Phys. Lett., 116B(1982)459

5. Two stage scenario of particles production 5 p-p case, low energy [1]A.Capella, U.P.Sukhatme, C.I.Tan and J.Tran Thanh Van, Phys. Lett. B81 (1979) 6 8; Phys. Rep. 236 (1994) 225. [2]A.B.Kaidalov, Phys. Lett., 116B(1982)459 p-p case, high energy I stage: strings formation.

6. Two stage scenario of particles production 6 A-A case [1]A.Capella, U.P.Sukhatme, C.I.Tan and J.Tran Thanh Van, Phys. Lett. B81 (1979) 6 8; Phys. Rep. 236 (1994) 225. [2]A.B.Kaidalov, Phys. Lett., 116B(1982)459

7. String fusion model “In case of AA collisions with growing energy and atomic number the number of strings grows and one has also to take into account the string fusion.” 7 [1]M.A.Braun and C.Pajares, Phys. Rev. Lett. 85 (2000) 4864; [2]M.A.Braun and C.Pajares, Phys. Lett. B287 (1992) 154; Nucl. Phys. B390 (1993) 542, 549; [3]N.S.Amelin, M.A.Braun and C.Pajares, Phys. Lett. B306 (1993) 312; [4]M.A.Braun, C.Pajares and V.V.Vechernin, Low pT Distributions in the Central Region and the Fusion of Colour Strings, Internal Note/FMD ALICE-­‐INT-­‐2001-­‐16 String (r~0.2fm) Transverse plane

8. Each cluster in the overlaps of strings could be considered as a new string with new properties The color field of cluster is the vector sum of fields of strings Individual string colors may be oriented in an arbitrary manner, then Last formula could be modified for not fully overlapping strings but arbitrary overlapping 8 String fusion model

9. Definitions Multiplicity n Event mean transverse momentum String fusion model

10. Definitions Multiplicity n Event mean transverse momentum String fusion model Single string Color field Multiplicity Event mean transverse momentum

11. Definitions Multiplicity n Event mean transverse momentum String fusion model Single string Overlapping strings Color field Multiplicity Event mean transverse momentum

12. 12 I. Bautista, J. G. Milhano, C. Pajares and J. Dias de Deus, Phys. Lett. B715 (2012) 230 Low energy (SFM + wounded nucleon model) High energy (SFM + multiple scattering) String fusion model Comparison with data

13. 13 I. Bautista, J. G. Milhano, C. Pajares and J. Dias de Deus, Phys. Lett. B715 (2012) 230 Low energy (SFM + wounded nucleon model) High energy (SFM + multiple scattering) String fusion model Comparison with data PbPb/AuAu CuCu pp

14. Long-range correlations 14 Definitions

15. Long-range correlations 15 A.Capella et al., Phys.Rep. 236,225(1994) Definitions

16. Long-range correlations 16 Types of correlations

17. 17 Single string case

18. 18 In case of sufficiently large gap between windows one string produces particles in both windows independently! Single string case

19. 19 In case of sufficiently large gap between windows one string produces particles in both windows independently! Single string case Phys.Rev.D vol.13, num.11(1986)

20. 20 Long-range correlations Linear regression case R.E. Ansorge et al. (UA5 Collaboration). Z. Phys., C37- 191, (1988).

21. String fusion model 21 Decrease of mean multiplicity and increase of mean transverse momentum lead to negative p T -n correlations! Negative correlations Fixed number of strings case

22. 22

23. 23 Analysis technique Event cuts: 1.T2 2.WFA 1.5 μs 3.ZCharge (by Emil) 4.BPD 5.Fitted Vertex 6.Fit Quality 7.Number of good vertex track > 2 8.Z coordinate +/- 5cm Track cuts: 1.Vertex track status and has track 2.Impact parameter X < 4cm Y < 2cm 3.VTPC clusters > 14 or GapTPC > 4 4.All TPC clusters > 14 5.Pt < 1.5 GeV/c 6.P > 300 MeV/c 7.Acceptance map (new) Method (based on MC data from EOS): 1. Loop through all simulated primary tracks. 2. Fill 3D histogram of generated tracks with (φ sim, pT sim, η sim ) 3. Loop through all primary tracks from RecEvent passed track cuts 4. Fill 3D histogram of selected tracks (φ rec, pT rec, η rec ) 5. Calculate efficiency 3D histogram by dividing selected by generated. 6. Calculate acceptance map: For each (φ,pT, η) bin in efficiency histogram: if efficiency is < 0.9 or if there is < 20 tracks in generated, the bin is not accepted Still no MC corrections due to lxbatch quota!

24. 24 Long-range correlations Definitions: relative variables Exclude trivial dependences

25. 25 Results: BeBe 150 AGeV/c Data without acceptance cut Data with acceptance cut MC with acceptance

26. 26 Results: BeBe 150 AGeV/c Data without acceptance cut Data with acceptance cut MC with acceptance

27. 27 Results: BeBe 150 AGeV/c Data without acceptance cut Data with acceptance cut MC with acceptance

28. 28 Results: BeBe 150 AGeV/c Data without acceptance cut Data with acceptance cut MC with acceptance

29. 29Results Testing acceptance cut (changing binomization, critical efficiency, matching etc.) Comparison with generated MC data MC-based corrections Centrality analysis (with new centrality classes from E. Kaptur) Azimuthal analysis Systematics Plans

30. 30