Initial state fluctuations from SPS to LHC J. Milo evi University - PowerPoint PPT Presentation

Initial state fluctuations from SPS to LHC J. Milo š evi ć University of Belgrade and Vin č a Institute of Nuclear Sciences, Belgrade, Serbia 08.08.2016 Reimei 2016, Tokai, Japan 1

Outline v Azimuthal anisotropy ² conventional methods ² Initial-state fluctuations (ISF) and higher order Fourier harmonics v Triangular flow at SPS, RHIC and LHC energies v Collectivity over a wide p T range in PbPb collisions v Collectivity in small pPb and smallest pp collision systems ² ISF on sub-nucleonic level v Factorization breaking – mechanism – p T dependent event plane – η dependent event plane v Principal Component Analysis (PCA) – method v PCA method in flow physics – leading and sub-leading flow modes v The PCA analysis in pPb and PbPb collisions at the LHC energy v Conclusions 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 2 ¡

Anisotropy harmonics v n – conventional methods Scalar Product (SP) method Event Plane (EP) method event plane x-z p y | Δη | > 3 p x vn = cos n ( φ −Ψ n ) y z � Ideal circle-like geometry – v 2 x four-particle cumulant method two-particle correlation method Advantage wrt offline pPb 5.02 TeV CMS pPb s = 5.02 TeV, N 110 ≥ 0-3% centrality (b) NN trk 2-part.corr.: 1 < p < 3 GeV/c N>110 1<p T <3 GeV/c T removes two- and three- cos( n Δ φ ) φ 1.8 pair Δ particle non- d N η 1.7 2 flow correlation Δ d d 1.6 trig ridge 1 N u v n from even higher order cumulants: 4 4 v n {6}, v n {8}, …. 2 2 Δ 0 φ Lee-Yang zero method 0 η -2 Δ Collective -4 correlates all particles of interest PLB 718 (2013) 795 behavior? 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 3 ¡

Role of initial state fluctuations (ISF) on anisotropy Anisotropy harmonics Ultra-central collisions with order higher than 2 JHEP ¡1402 ¡(2014) ¡088 (arXiv:1312.1845) geometry – v 2 Phys.Rev. ¡C89 ¡(2014) ¡044906 ISF – v 3 Ψ 6 Ψ 5 (arXiv:1310.8651) Ψ 2 Ψ 3 Asymmetric (pPb) high- Phys.Le8. ¡B724 ¡(2013) ¡213 Ψ 4 -multiplicity collisions (arXiv:1305.0609) v 2 , v 3 , v 4 , v 5 and v 6 Pb using multiple methods p Simple, circle-like geometry does not describe the formed system precisely enough 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 4 ¡

Triangular flow – one of higher order Fourier harmonics B. ¡Alver ¡and ¡G. ¡Roland ¡ The triangular initial shape è triangular hydrodynamic flow PRC ¡81(2010) ¡054905 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 5 ¡

Triangular flow in PbAu at the top SPS energy TPC coils ≈ 30M PbAu collisions collected during 2000 data taking period σ / σ geo =<5.5%> o 15 =17.3 A GeV s NN voltage divider UV detector 2 1/r E-field o 8 W-shield HV cathode beam RICH 1 mirror 1 RICH 2 target mirror 2 TPC drift volume SDD1/SDD2 UV detector 1 TPC read-out chamber EP ¡method ¡is ¡used 0.21 < η < 0.86 in center-of-mass system accepted ¡to ¡ Nucl.Phys.A -1 0 1 2 3 4 5m 12 - π not corrected for HBT correlations 〉 )] 0.05 - π corrected for HBT correlations (b) 3 10 a ¡huge ¡HBT ¡effect ¡at ¡ Ψ 0.04 - (a) ¡low-­‑p T 8 3 Ψ ) T 0.03 cos[3( (p N track 6 3 ∑ w i ( p Ti )sin(3 φ i ) v 0.02 Ψ 3 = 1 i = 1 4 3arctan 〈 2 N track 0.01 ∑ w i ( p Ti )cos(3 φ i ) 1/ 2 〈 σ / σ 〉 = 5.5% geo i = 1 0 80 100 120 140 160 180 200 220 240 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 6 ¡ p (GeV/c) N track T

v 3 vs p T – comparison to other experiments v First p T dependent measurement of the triangular flow at the top SPS energy v Top RHIC and LHC energy gives very similar v 3 magnitudes v The v 3 at the top SPS energy is about half of those at top RHIC and LHC v Linear increase but with different slopes ² Note limited p T 0.07 ± ALICE PbPb s = 2.76 TeV, h range restricted NN ± PHENIX AuAu s = 200 GeV, h to the CERES NN 0.06 acceptance - CERES PbAu s = 17.3 GeV, π NN accepted ¡to ¡ Nucl.Phys.A ² ALICE uses 0.05 large | Δη | gaps ² Jet yield is for ) 0.04 T more than one (p order of 3 0.03 v magnitude smaller at SPS 0.02 ² No option to include | Δη | gap ALICE 0 < σ / σ < 10.0% 0.01 geo at CERES PHENIX 0 < / < 10.0% σ σ geo CERES / = 5.5% 〈 σ σ 〉 geo 0 PHENIX PRL 107 (2011) 252301 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 p (GeV/c) ALICE PLB 719 (2013) 18 T 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 7 ¡

Energy dependence v RHIC 19.6 GeV is quite close to the top SPS energy of 17.3 GeV v Comparison is done at very similar centralities (< σ / σ geo > ≈ 5%) v A rather good agreement with an AMPT prediction for the ratio of about 0.6 at 19.6 GeV RHIC energy same v 3 at the top RHIC and LHC 1 ² As a referent level Accepted ¡to ¡ Nucl.Phys.A (200 GeV) is taken v 3 value at 0.9 the top RHIC energy ² v 3 values 0.8 integrated over 3 0.3 < p T < 2.1 /v 0.7 GeV/c ! 3 v ± ALICE PbPb s = 2.76 TeV, h NN ± PHENIX AuAu s = 200 GeV, h NN 0.6 a good ± STAR AuAu s = 19.6 GeV, h PHENIX NN agreement - PRL 107 (2011) 252301 CERES PbAu s = 17.3 GeV, π NN ALICE PLB 719 (2013) 18 3 2 10 10 10 STAR s (GeV) PRL 116 (2016) 112302 NN 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 8 ¡

v 3 in comparison with v 2 v Elliptic flow reflects the initial anisotropy and thus depends strongly on centrality v Triangular flow comes from the ISF and weakly depends on centrality v The different centrality behavior between v 2 and v 3 v For very central collisions (< σ / σ geo > = 2.4%), v 3 becomes close to the v 2 n = 2 0.05 0.05 n = 2 n = 3 n = 3 ² Triangular flow is dominant 0.04 0.04 anisotropy for ultra-central ) T 0.03 0.03 (p accepted ¡to ¡ Nucl.Phys.A collisions at the LHC n v 0.02 0.02 energies - - π π 0.01 0.01 / = 2.4% 〈 σ σ 〉 〈 σ / σ 〉 = 9.8% geo geo 0 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 p (GeV/c) p (GeV/c) T T 〈 σ / σ 〉 = 2.4% geo 0.05 〈 σ / σ 〉 = 9.8% geo 0.04 ) T 0.03 (p 3 v 0.02 0.01 CMS 0 JHEP 1402 (2014) 088 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 p (GeV/c) 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 9 ¡ T

Comparision with hydro+UrQMD predictions v Relativistic hydrodynamics + transport models (hybrid models) ² vHLLE viscous hydrosolver + UrQMD hadron cascade ( I. Karpenko, P. Huovinen, H. Petersen and M. Bleicher PRC 91 (2015) 064901) v The model predictions for hadrons within 0.2 < p T <2.0 GeV/c and -1 < η < 1 v Cerentrality samples roughly correspond to the experimental ones ² Particlization at - CERES , / = 5.5% π 〈 σ σ 〉 constant energy geo 0.05 density 0.5 GeV fm 3 - hydro+UrQMD , 0 < < 7% π σ ² Kinetic and chemical accepted ¡to ¡ Nucl.Phys.A freeze-out are 0.04 dynamical ) T 0.03 (p 3 ² Model predictions in v 0.02 a very good agreement with the CERES results 0.01 ² A small disagreement 0 appears at low-p T 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 p (GeV/c) T 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 10 ¡

Collectivity over a wide p T range in PbPb 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 11 ¡

v n {SP} over a wide p T range 0 - 5% 5 - 10% 10 - 20% 20 - 30% 0.2 0.2 0.2 0.2 CMS ¡PAS ¡HIN-­‑15-­‑014 0.1 0.1 0.1 0.1 n v 0.0 0.0 0.0 0.0 20 40 60 80 20 40 60 80 20 40 60 80 20 40 60 80 30 - 40% 40 - 50% 50 - 60% CMS Preliminary 0.2 0.2 0.2 0.2 PbPb s = 5.02 TeV NN 0.1 0.1 0.1 0.1 n v {SP} v 2 v {SP} 3 0.0 0.0 0.0 0.0 up to 100 GeV/c 20 40 60 80 20 40 60 80 20 40 60 80 20 40 60 80 p (GeV/c) p (GeV/c) p (GeV/c) p (GeV/c) T T T T v low-p T - hydrodynamic flow (v 2 – geometry, v 3 – ISF on nucleonic level) v v 2 non-zero up to very high p T v high-p T - may reflect the path-length dependence of parton energy loss v v 2 is complementary to R AA measurements v v 3 mainly consistent with zero at high-p T 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 12 ¡

Collectivity over a wide p T range CMS Preliminary 5 - 10% 10 - 20% 20 - 30% 0.2 PbPb s = 5.02 TeV 0.2 0.2 NN 0.1 0.1 0.1 n v CMS ¡PAS ¡HIN-­‑15-­‑014 0.0 0.0 0.0 20 40 60 80 20 40 60 80 20 40 60 80 v {SP} 30 - 40% 40 - 50% 50 - 60% 2 v {4} 0.2 0.2 0.2 2 v {6} 2 v {8} 0.1 0.1 0.1 n 2 v 0.0 0.0 0.0 20 40 60 80 20 40 60 80 20 40 60 80 p (GeV/c) p (GeV/c) p (GeV/c) T T T v low-p T – ratio v 2 {2k}/v 2 {SP} ≈ 0.8 and v 2 {4} ≈ v 2 {6} ≈ v 2 {8} ç hydrodynamics v high-p T – SP and multi-particle correlation tend to converge to the same value v v 2 {4} ≈ v 2 {6} ≈ v 2 {8} ≠ 0 ç collectivity (likely to be related to jet quenching) 08.08.2016 ¡ Reimei ¡2016, ¡Tokai, ¡Japan ¡ 13 ¡