1 / 14

Fluctuations in Pb+Pb Collisions at 2.76 TeV

This study investigates the fluctuations in Pb+Pb collisions at 2.76 TeV, exploring the effects of finite system size and changes in quark susceptibilities near the QCD critical point. Measurements of the K/p ratio and dynamical fluctuations are performed, providing insights into net charge fluctuations. The analysis is conducted using data samples from ALICE and STAR experiments.

lindseykim
Download Presentation

Fluctuations in Pb+Pb Collisions at 2.76 TeV

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. K/p Fluctuations at 2.76 TeV in Pb+Pb Collisions Zubayer Ahammed , VECC, Kolkata

  2. Introduction • Large fluctuation is expected • in a phase transition near • QCD critical point. • Finite system size effects • may influence fluctuation • measurements. • There may be change in • behavior of quark • susceptibilities in the • vicinity of the QCD critical point. • Aoki, Endrodi, Fodor, Katz • and Szabo, • Nature 443, 675-678(2006) M. Cheng et al., Phys. Rev. D 79 (2009) 074505

  3. K/p Fluctuations measurement • Measure the K/p ratio event-by-event. • K = K+ + K- • = p+ + p- • Produce histogram of the K/p ratio. • Extract the width of K/p histogram to get σreal • Do the same for mixed event to get σmixed

  4. K/p Fluctuations at SPS • Define the dynamical fluctuations in terms of σdyn • Divide by the mean and multiply by 100 • to get %

  5. Measure, ndyn Used in STAR Experiment(RHIC) ndyn introduced to study net charge fluctuations. (PRC 68, 044905 [2003]) ndyn,Kp is insensitive to efficiency. ndyn,Kp properly deals with small multiplicities.

  6. Excitation Function for ndyn,K/p NA49 sdyn,K/p converted to ndyn,K/p using s2dyn = ndyn. • TPC+TOF (GeV/c): • p : 0.2 < pT < 1.4 • K : 0.2 < pT < 1.4 STAR, QM’12 NA49, QM’12 New results Phys. Rev. Lett. 103 (2009) 92301

  7. Analysis in ALICE Data Sample: Period : LHC10h Run Number : All Runs in the Period Event Selection Cuts : Value Physics Selection : Min.bias, only collision candidates Primary vertex : >= 1 contributor (tracks/SPD) Centrality : V0(M) Z-vertex : (-10.0, 10.0) cm Data Type Analysed: AOD CF_PbPb train used Centrality bins: 0-5 %, 5-10%, 10-20%,20-30%, 30-40%, 40-50%, 50-60% 60-70%,70-80% Track Cuts: 0.3 < pT < 1.5 GeV/c - 0.8 < η < 0.8

  8. K,p identification TPC • Extract the number of K+ + K- and p+ + p- event-by-event using dE/dX curvature in the TPC • Select kaons and pions with 0.3 < pT < 0.6 GeV/c and |η| < 0.8 • kaons: Nσ,K < 2, Nσ,p > 2 • pions: Nσ,p < 2, Nσ,K > 2 • electrons: Nσ,e < 1 dE /dx electrons pT (GeV/c)

  9. Some QA Plots

  10. Results No Bin Width Correction Fit: a+b / (dN/dη)

  11. Centrality Dependence No Bin Width Correction Fit: a+b / (NPart)

  12. Scaled Fluctuation Strength

  13. Comparison with STAR 0-5% central events STAR dN / dη uncorrected (QM’2012)

  14. Summary and Future Outlook • Preliminary results for K/pi ratio fluctuation is presented • ndyn decreases towards higher centrality(1/N dependence) • which is expected. • Scaled ndyn shows increased trend. • Further checks, analysis, MC simulations ongoing.

More Related