Recent flow results at RHIC

Transcription

1 Recent flow results at RHIC Hiroshi Masui / University of sukuba Flow and heavy flavour worksho in high energy heavy ion collisions: GRN worksho, Inchon, Feb./24-26, 215 H. Masui / Univ. of sukuba 1 /3

2 Outline Multi-strange hadrons Mass ordering violation at RHIC Beam Energy Scan Identified hadron v2 Blast wave model fit to v2 Direct hoton v n & blast wave fit Summary H. Masui / Univ. of sukuba 2 /3

3 Reminder dn d / 1+2 1X n=1 v n cos (n[ n]) v n = hcos (n[ n])i v n (hydrodynamical) flow vn is the azimuthal anisotroy of articles in momentum sace Crucial to understand the non-flow background momentum conservation (on v1), resonance decay, jet, Multi-article correlation (cumulant), and/or large raidity ga are tyical methods to avoid non-flow Most of non-flow is 2-article correlation, short-range correlation in (seudo)raidity H. Masui / Univ. of sukuba 3 /3

4 Multi-strange hadrons H. Masui / Univ. of sukuba 4 /3

5 Multi-strange hadrons SAR White aer: Nucl. Phys. A757 (25) Multi-strange hadrons (φ, Ω) freeze-out early Ideal hydrodynamical model with hadron cascade shows mass ordering violation between and φ v2() < v2(φ) in low radial flow at late stage + less hadronic cross section for φ, Ω H. Masui / Univ. of sukuba 5 /3

6 Multi-strange hadrons. Hirano et al: PRC77, 4499 (28) at chemical freeze-out hydro. + hadron cascade hydro. only.25.2 π φ.25.2 π φ.25.2 π, hydro φ, hydro, hydro (a).5 (b).5 (c) (GeV/c) (GeV/c) (GeV/c) Multi-strange hadrons (φ, Ω) freeze-out early Ideal hydrodynamical model with hadron cascade shows mass ordering violation between and φ v2() < v2(φ) in low radial flow at late stage + less hadronic cross section for φ, Ω H. Masui / Univ. of sukuba 6 /3

7 Particle identification PC OF π K! + oological reconstruction of Ξ and Ω Combinatorial background is estimated by rotational background from the same event H. Masui / Univ. of sukuba 7 /3

8 Mass ordering of v2() SAR, QM212 Event lane with ga Δη =.1 (φ) > v2() at low he effect is stronger in central qualitatively consistent with the rediction from hydro. + hadron cascade model H. Masui / Univ. of sukuba 8 /3

9 Recent udate of hydro. model Results - dn/2 d dy(c 2 /GeV 2 ) dn/2 d dy(c 2 /GeV 2 ) (b) (b) hybrid SAR hybrid SAR < (GeV/c) < (GeV/c) distributions dn/2 d dy(c 2 /GeV 2 ) dn/2 d dy(c 2 /GeV 2 ) (a) (c) hybrid SAR < (GeV/c) hybrid SAR < (GeV/c) hybrid -5% hybrid 1-4% hybrid 4-8% SAR -5% SAR 1-4% SAR 4-8% < (a).1 < (GeV/c) hybrid -1% hybrid -8% SAR -1% SAR -8% (GeV/c) S. akeuchi, AHIC 214 (d) Initial geometry fluctuation (MC Glauber), Lattice EoS Reasonable agreement with the data 9 H. Masui / Univ. of sukuba /3

10 Effect of hadronic rescattering < > (fluid) /< > (final) K dn d / ex e = m f m e hybrid m scaling (a) m (GeV/c 2 ) M!! (fluid) /(final) K hybrid (b) m (GeV/c 2 ) S. akeuchi, AHIC 214 Less rescattering effect on multi-strange hadrons Mean for multi-strange hadrons deviate from m scaling v2 almost unchanged between fluid and final stages H. Masui / Univ. of sukuba 1 /3

11 v2(φ) vs v2().14 without rescatterings.14 with rescatterings S. akeuchi, AHIC (a).2 (b) (GeV/c) (GeV/c) Comare below ~1 GeV/c in v2(π) > v2() v2(φ) without rescattering v2(π) > v2(φ) > v2() with rescattering Confirmed violation of mass ordering ~2% effect around.5 GeV/c in minimum bias events H. Masui / Univ. of sukuba 11 /3

12 2 GeV is secial? (a) GeV 11.5 GeV Au+Au, -8% 19.6 GeV η-sub EP SAR: PRC88, 1492 (213) GeV 39 GeV 62.4 GeV (GeV/c) () > v2(φ) in GeV Hadronic hase become dominant? emerature deendent η/s? H. Masui / Univ. of sukuba 12 /3

13 v2 in RHIC Beam Energy Scan H. Masui / Univ. of sukuba 13 /3

14 RHIC Beam Energy Scan htt:// critical oint? First order hase transition? Cross-over transition at µ B= from 1st rincile Lattice QCD calculations If hase transition is 1st order at high baryon density, the end oint is QCD critical oint Beam energy scan reach high baryon density Goals of BES at RHIC: Search for turn-off QGP signals Search for signals of 1st order hase transition Search for signals of QCD critical oint H. Masui / Univ. of sukuba 14 /3

15 Number of Constituent Quark scaling PHENIX: PRL98, (27).3 (a) π + +π - (PHENIX) + - K +K (PHENIX) K (SAR) S + (PHENIX) Λ+Λ (SAR) + Ξ - +Ξ (SAR) (b).1 (a) π + +π - (PHENIX) + - K +K (PHENIX) K (SAR) S + (PHENIX) Λ+Λ (SAR) + Ξ - +Ξ (SAR) (b).2 RHIC Energies /n q (GeV/c) KE (GeV) /n q (GeV/c) KE /n q (GeV) Aarent scaling by KE = m - m Meson and baryon branches NCQ scaling of hadronization by arton coalescence Originally redicted in intermediate Scaling works well down to low KE at RHIC H. Masui / Univ. of sukuba 15 /3

16 ffiffiffiffiffiffiffiffi NCQ scaling of v2 ffiffiffiffiffiffiffiffi ¼ SAR: PRL11, (213) GeV (a) 62.4 GeV (b) Au+Au, %-8% 11.5 GeV (c) Λ + Ξ + Ω - π - K K φ s 62.4 GeV (d) η-sub EP.1 Λ - Ξ - Ω + π + K K φ s (B)-fit m -m (GeV/c ) (color online). he uer anels deict the ellitic flow as a function of reduced transverse mass (m m ) for art and (b), and wo antiarticles, branches, (c) and (d), mesons in % 8% central & baryons ffiffiffiffiffiffiffiffi Au þ Au collisions in (m-m) at s NN ¼ 11:5at and62.4 GeV. GeV Simultaneous fi mesons excet the ions are shown as the dashed lines. he difference of the baryon and the meson fits are shown in the l els. Antiarticles already scaled before dividing by n q at 11.5 GeV NCQ scaling doesn t hold for antiarticles φ meson could be deviated at 11.5 GeV (statistics is limited) H. Masui / Univ. of sukuba 16 /3

17 Particles vs antiarticles (a) (X) 2 (X)-v (b) (X) 2 (X)-v.6 Au+Au, -8% η-sub EP (GeV) s NN.6 Au+Au, -8% η-sub EP - + Ξ -Ξ.4 - Λ- + Λ - K -K π + -π Ξ -Ξ -Λ - + K -K π + -π - Λ (GeV) µ B SAR: PRC88, 1492 (213) Quantify the difference of between articles and antiarticles NCQ scaling does not hold between articles and antiarticles Scaling seems to work searately Difference of increase with decreasing beam energy, in articular for baryons Difference of is linear as a function of µb related to baryon stoing? H. Masui / Univ. of sukuba 17 /3

18 Blast wave model R 2 d s cos (2 s )I 2 [ t ( s )]K 1 [ t( s )][1 + 2s 2 cos (2 s )] ( )= R 2 d s I [ t ( s )]K 1 [ t( s )][1 + 2s 2 cos (2 s )] t ( s )= sinh ( s), t( s )= m cosh ( s), ( s )= + a cos 2 s, = tanh ( ) Assumtions boost invariant longitudinal exansion system exands with common transverse velocity β freeze-out at constant temerature Mass deendence only aears in β t via m Fit articles and antiarticles searately in < 1.2 GeV/c Simultaneous fit for measured articles (or antiarticles) with 3 arameters (s2, ρ, ρa) is fixed to 12 MeV since ublished sectra is not available H. Masui / Univ. of sukuba 18 /3

19 Blast wave fit to v2() = X. Sun, H. Masui, A. M. Poskanzer, A. Schmah PRC91, 2493 (215) (a) GeV Au+Au %-8% 11.5 GeV π+ Λ Ks φ (b) GeV Au+Au %-8% 11.5 GeV π - Λ Ks φ GeV 27 GeV GeV 27 GeV GeV 62.4 GeV 39 GeV 62.4 GeV GeV 276 GeV Pb+Pb %-6% +Λ Λ +± π ± K.1 2 GeV 276 GeV Pb+Pb %-6% Λ+Λ +± π K ± (GeV/c) (GeV/c) Excluded ions from the fit for RHIC data (huge feed down) Clear mass ordering in blast wave fit 19 H. Masui / Univ. of sukuba /3

20 2 Why does blast ( )= wave = R 2 work? (a) GeV Au+Au %-8% 19.6 GeV 39 GeV 2 GeV 11.5 GeV t ( s )= π + Λ Ks φ 27 GeV 62.4 GeV 276 GeV Pb+Pb %-6% d s cos (2 s )I 2 [ t ( s )]K 1 [ t( s )][1 + 2s 2 c +Λ Λ +± π ± K d s I [ t ( s )]K 1 [ t( s )][1 + 2s 2 cos (2 sinh ( s), t( s )= m cosh ( s), ( s )= + a cos 2 s, = tanh ( ) For the same β heavier articles have larger - K1(βt) ~ ex(-βt) For a given, v2 is more out-of-lane extended for heavier articles - because articles around inlane ushes to higher lighter articles have larger v (GeV/c) H. Masui / Univ. of sukuba 2 /3

21 Feed down on ions =? (a) GeV Au+Au %-8% 19.6 GeV 11.5 GeV π+ Λ Ks φ 27 GeV ions data > blast wave in GeV feed down? Use MC simulation to evaluate feed down GeV 62.4 GeV - due to lack of sectra, resonance measurements BLAS WAVE FIS O ELLIPIC FLOW DAA A... s lar de GeV GeV Pb+Pb %-6%.5 1 (GeV/c) +Λ Λ +± π ± K H. Masui / Univ. of sukuba 21 /3 FIG. 1. (Color online) Ellitic flow as a function of transverse (% 7.7 wh a an as da flo at ass

22 Large radial flow for antiarticles = (a) GeV Au+Au %-8% 11.5 GeV π+ Λ Ks φ (b) GeV Au+Au %-8% 11.5 GeV π - Λ Ks φ GeV 27 GeV GeV 27 GeV GeV 62.4 GeV 39 GeV 62.4 GeV GeV 276 GeV Pb+Pb %-6% +Λ Λ +± π ± K.1 2 GeV 276 GeV Pb+Pb %-6% Λ+Λ +± π K ± (GeV/c) (GeV/c) Large sread of for antiarticles at lower energies Fit is better for antiarticles in terms of χ2 22 H. Masui / Univ. of sukuba /3

23 ransverse velocity.8 Pb+Pb %-6% anti-articles X. Sun, H. Masui, A. M. Poskanzer, A. Schmah PRC91, 2493 (215).6 Au+Au %-8% β.4 articles = 1 MeV = 12 MeV = 14 MeV s NN (GeV) 1 3 IG. 3. (Color online) he transverse exansion velocity Possible scenarios as a Different β for articles and antiarticles at lower energies Antiarticles roduced early large β since radial flow is cumulative Fraction of net-rotons (stoed rotons) increase, already significant at 62.4 GeV baryon stoing? H. Masui / Univ. of sukuba 23 /3

24 ransverse velocity.8 anti-articles Pb+Pb %-6%.6 Au+Au %-8% β.4 articles = 1 MeV = 12 MeV = 14 MeV s NN (GeV) 3 1 IG. 3. (Color online) he transverse exansion velocity Baryon stoing? as a v2 could be different for roduced and transorted quarks articles are contaminated by transorted u & d quarks Surface emission of antirotons due to the absortion effect is larger for lower energies (larger µb), smaller at higher energies H. Masui / Univ. of sukuba 24 /3

25 Direct hoton vn H. Masui / Univ. of sukuba 25 /3

26 Direct hoton uzzle PHENIX: arxiv: v1 PHENIX: PRL19, (212) d 2 N d dy [(GeV/c) 2 ] snn = 2GeV N coll -scaled fit fit Au+Au, min. bias PRL 14, (21) PRL 98, 122 (21) PRD 86, 728 (212) PRL 19, (212) PRL 14, (21) [GeV/c] (a) π (b) inc. γ RXN E.P. BBC E.P. ( η =1.~2.8) ( η =3.1~3.9) γ,inc - γ,inc γ,bg γ,bg (RXN).15 (BBC) [GeV/c] (c) dir. γ Enhancement of direct hoton sectra relative to + Inverse sloe ~24 MeV (-2%) for the excess of sectra Large for direct hoton at low comarable to the v2 for π Is direct hoton emitted early ( sectra) or late (v2)? H. Masui / Univ. of sukuba 26 /3

27 Several scenarios B C. Shen et al, PRC89, 4491 (214) Y Reaction lane Z X G. Basar et al, PRL19, 2233 (212), FIG. 2. (Color online) he inverse hoton sloe arameter eff = 1/sl equilibrium thermal emission rates (solid green lines) and from hydrodyn exerimental values (horizontal lines and error bands) for (a) Au + Au coll Strong magnetic field >, v3 ~ Radial flow effect >, v3 > Measurements of v 3 rovide additional constraints on direct hoton roduction mechanism exerimental values and error bands in anel (a) are from the PHENIX Collabor [7]. We note that the corresonding lot for Au + Au collisions at 2 4% ce in anel (a), in agreement with what the PHENIX Collaboration [6] found. Se differ slightly from what is used in the rest of this aer, due to the sensitivity of the hoton sectra to details of the rates that are not relevant for the study of effective temeratures. For the QGP contribution shown in Fig. 1, the H. Masui / Univ. of sukuba 27 /3 one init

28 Direct hoton v3 Comarison*of*γ dir. *v n *with*the*two*methods PHENIX: QM214 v2.3.2 g direct (calorimeter) g direct (conversions) Au+Au RXP(I+O) snn = 2GeV % 2-4% 4-6% v [GeV/c] Non-zero, ositive v 3 No strong centrality deendence, similar with hadron v 3 Strong magnetic field scenario cannot exlain the data 28 he)calorimeter)and)conversion)hoton)measurements)are)) consistent)within)systema9c)uncertainty.) γ dir. )v n )are)extended)to)lower),)by))the)conversion)hoton)analysis.) QM214*@*Darmstadt H. Masui / Univ. of sukuba /3

29 Blast-wave fit dy N/d 2 )d (1/2π dy N/d 2 )d (1/2π PIDed charged hadron sectra Centrality:-2% f =14.48±.57[MeV] ρ =.661±.4 π ± 1 ± K (GeV/c) Direct hoton sectra Calorimeter Conversion method f =14, ρ =.66 f =14, ρ = f =24, ρ = f =3, ρ = (GeV/c) PIDed charged hadron v 2 Fitting range Extraolation ρ =.21±.2 2 s 2 =.32± (GeV/c) Direct hoton v (GeV/c) v 3 v PIDed charged hadron v 3 ρ =.16±.1 3 s 3 =.6± (GeV/c) Direct hoton v 3 Sanshiro Mizuno, D-thesis (GeV/c) Blast wave fit to direct hoton sectra & vn sectra can be fitted with the same for hadrons Reasonable descrition for v2 & v3 H. Masui / Univ. of sukuba 29 /3

30 Summary Multi-strange hadron at 2 GeV shows mass ordering violation need quantitative comarison with the latest hydrodynamical models at RHIC BES (articles vs antiarticles) NCQ scaling break down between articles and antiarticles can be understood as different radial flow velocity (if mass ordering of v2 is only due to radial flow) Need more statistics, better model calculations Finite direct hoton v n at RHIC Naive strong magnetic field scenario cannot exlain the data Large vn, blast wave fit (if alicable) could suort that direct hotons are emitted from late stage H. Masui / Univ. of sukuba 3 /3