Flow in p-pb collisions at 5 TeV?

Transcription

1 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes - Flow in p-pb collisions at 5 TeV? K.W. in collaboration with B. Guiot, Iu. Karpenko, T. Pierog

2 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes - Ultimate goal? Determining properties of the quark gluon plasma (in high energy collisions) Which tool? Observables related to hydrodynamic flow Which systems? Heavy ions, but not only

3 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes - Signatures of flow?

4 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes - Ridges & flow harmonics Ridges appear in R = N trigg dn d φ η p.4. assoc T R.-. GeV/c p trigg T.-4. GeV/c due to initial azimuthal anisotropies (longitudinally invariant) η EPOS φ 4

5 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -4 Particle spectra affected by radial flow dn/d dy π K p Λ ppb 5TeV -5% 4 EPOS.76 string decay (dotted) hydro (solid) => mass effect

6 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -5 Recent LHC data

7 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -6 ppb at 5.TeV CMS arxiv:7.44 Strong variation of shape with multiplicity for kaon and even more for proton pt spectra (flow like)

8 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -7 ppb at 5.TeV ALICE Phys.Lett. B79 () 9, arxiv:. ridge & significant v as in in PbPb...

9 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -8 ppb at 5.TeV ALICE arxiv:7.7 v ALICE π K p 4 mass splitting of v!!! pt one of the highlights in heavy ion collisions...

10 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -9 ppb data, interpreted in terms of hydrodynamic flow

11 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes - EPOS, B. Guiot, Y. Karpenko, T. Pierog, K. Werner arxix:7.479,arxiv:., Initial conditions: Gribov-Regge multiple scattering approach, elementary object = Pomeron = parton ladder, using saturation scale Q s N part ŝ λ Core-corona approach to separate fluid and jet hadrons Viscous hydrodynamic expansion, η/s =.8 Statistical hadronization, final state hadronic cascade see also P. Bozek, W. Broniowski, arxiv:4.44 and A. Bzdak, B. Schenke, P. Tribedy, R. Venugopalan, arxiv:4.4

12 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes - EPOS IC: Marriage pqcd+grt+energy sharing (Drescher, Hladik, Ostapchenko, Pierog, and Werner, Phys. Rept. 5, ) σ tot = cut P uncut P A cut G uncut G B } {{ } dσ exclusive cut Pom : G = ŝ Im {FT {T }}(ŝ, b), T = iŝ σ hard(ŝ) exp(r hardt) Nonlinear effects considered via saturation scale Q s N part ŝ λ

13 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes - σ tot = A d b B j= i= d b A i dzi A ρ A ( (b A i ) + (zi A) ) d b B j dzj B ρ B ( (b B j ) + (zj B) ) AB ( mk... ( δ Σmk ) dx + k,µ dx k,µ m l m AB l AB k= µ= AB ( m k G(x + k,µ m k! l k!, x k,µ, s, b + b A π(k) b B τ(k) ) k= A i= l k λ= ( µ= G( x + k,λ, x k,λ, s, b + b A π(k) b B τ(k) ) ) π(k)=i x + k,µ, π(k)=i x + k,λ ) α B j= ( l k λ= τ(k)=j d x + k,λ d x k,λ x k,µ τ(k)=j ) { x k,λ ) α }

14 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes - The hydrodynamic equations (Israel-Stewart formulation) in arbitrary coordinate system (implemented/solved by Yuri Karpenko), always η/s =.8, ζ/s = ;ν T µν = ν T µν + Γ µ νλ T νλ + Γ ν νλt µλ = γ ( t + v i i )π µν = πµν π µν NS + I π µν τ π γ ( t + v i i ) Π = Π Π NS τ Π + I Π T µν = ǫu µ u ν (p + Π) µν + π µν, ;ν denotes a covariant derivative, µν = g µν u µ u ν is the projector orthogonal to u µ, π µν and Π are the shear stress tensor and bulk pressure, respectively. π µν NS = η( µλ ;λ u ν + νλ ;λ u µ ) η µν ;λ u λ Π NS = ζ ;λ u λ I µν π = 4 πµν ;γ u γ [u ν π µβ + u µ π νβ ]u λ ;λ u β I Π = 4 Π ;γu γ

15 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -4 EPOS: Pomeron => parton ladder => flux tube (kinky string) y (fm) String segments with high pt escape => corona, the others form the core = initial condition for hydro ppb 5TeV 8 Pomerons depending on the local string density η = x (fm) dn/d dy pions x protons corona ppb 5TeV -4% core EPOS pt

16 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -5 We will compare EPOS with ppb data and also with EPOS LHC LHC tune of EPOS.99, : same GR, but uses parameterized flow T. Pierog et al, arxiv:6.54 AMPT Parton + hadron cascade Z.-W. Lin, C. M. Ko, B.-A. Li, B. Zhang and S. Pal, Phys. Rev. C 7, 649 (5). QGSJET GR approach, No flow S. Ostapchenko, Phys. Rev. D74 (6) 46

17 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -6 dn/d (normalized) dn/d (normalized) π QGSJETII-4 CMS.5.5 π EPOS LHC CMS.5.5 dn/d (normalized) dn/d (normalized) π AMPT CMS.5.5 π EPOS.76 CMS.5.5 Little change with <N_tracks> for pions CMS 4 multiplicity classes: <N_tracks> : 8, 84, 6, 5 (in η <.4)

18 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -7 dn/d (normalized) dn/d (normalized) K QGSJETII-4 CMS.5.5 K EPOS LHC CMS.5.5 dn/d (normalized) dn/d (normalized) K AMPT CMS.5.5 K EPOS.76 CMS.5.5 Kaon spectra change with <N_tracks> in EPOS: more and more flow contribution

19 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -8 dn/d (normalized) p QGSJETII-4 CMS.5.5 dn/d (normalized) p AMPT CMS.5.5 dn/d (normalized) p EPOS LHC CMS.5.5 dn/d (normalized) p EPOS.76 CMS.5.5 Strong variation of proton spectra => flow helps

20 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -9 ALICE arxiv: Two multiplicity classes: -5%, 6-8% (in.8 < η lab < 5.) Useful : ratios (Λ/K) ratio. Λ / Ks ppb 5.TeV data ALICE % 6-8% Significant variation of lambda/k like in PbPb

21 ratio ratio Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes Λ / Ks ppb 5.TeV data ALICE QGSJETII Λ / Ks ppb 5.TeV data ALICE EPOS LHC -5% 6-8% ratio ratio Λ / Ks ppb 5.TeV data ALICE AMPT -5% 6-8% Λ / Ks ppb 5.TeV data ALICE EPOS.76-5% 6-8% again, flow already needed for low multiplicity (even in pp!) => flow peak

22 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes - Ridges in pa ALICE, arxiv:., arxiv:7.7 p assoc T.-. GeV/c p trigg T.-4. GeV/c R.4... ALICE η EPOS φ 4

23 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes - Central - peripheral (to get rid of jets) assoc p T.-. GeV/c p trigg T.-4. GeV/c R η φ 4 ALICE EPOS.74

24 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes - Identified particle v v ALICE π K p 4 pt mass splitting, as in PbPb!!!

25 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -4 ppb in EPOS Pomerons (number and positions) characterize geometry (P. number multiplicity) random azimuthal asymmetry => asymmetric flow seen at higher pt for heavier ptls Robust results y (fm) ppb 5TeV 8 Pomerons η = x (fm)

26 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -5 v for π, K, p clearly differ v EPOS.74 π K p ALICE π K p mass splitting, due to flow

27 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -6 Summary Analyzing pt-spectra, ratios, and dihadrons correlations for identified hadrons: ppb looks very much like a hydrodynamically expanding system (more clean than PbPb, where hydro and minijets heavily interact, as well as the final hadrons among themselves) v EPOS.74 π K p ALICE π K p.5.5.5

28 Rencontres de Moriond QCD 4 Klaus Werner Subatech, Nantes -7 ALICE arxiv:.77