Proving Quark Gluon Plasma via Baryon Production at

Proving Quark Gluon Plasma via Baryon Production at RHIC Tatsuya Chujo University of Tsukuba Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Outline 1. 2. 3. 4. 5. 6. Introduction Overview of bulk properties at RHIC Systematic study of baryon enhancement What’s the origin of baryon enhancement? Exploring the QCD phase diagram at RHIC Summary 2 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

1. INTRODUCTION 3 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

p. T spectra at RHIC 2007. 0619 第８回 Seminar at Hiroshima Univ. (Nov. 30, 2008) 原子核実験特論（１） T. Chujo 4

RHIC data towards the precise measurements! Central Au+Au In p+p 5 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Why baryons? (mostly for protons and antiprotons in this talk) • Heavier mass than the light mesons, sensitive to the collective phenomena, such as a radial flow. • Sensitive to the baryo-chemical property of the matter. • Different number of constituent quarks from that for mesons, test of recombination models. 6 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

A lots of data and publications on baryons from RHIC experiments; 1 (spectra, yields, jet correlations) • BRAHMS – Nuclear Stopping in Au+Au Collisions at √s. NN = 200 Ge. V, PRL 93, 102301 (2004). • PHENIX – Scaling Properties of Proton and Antiproton Production in √s. NN = 200 Ge. V Au+Au Collisions, PRL 91, 172301 (2003). [TC] – Identified charged particle spectra and yields in Au+Au collisions at √s. NN=200 Ge. V, PRC 69, 034909 (2004). [TC] – Nuclear effects on hadron production in d + Au collisions at √s. NN = 200 Ge. V revealed by comparison with p + p data, PRC 74, 024904 (2006). [(TC)] – Jet structure of baryon excess in Au+Au collisions at √s. NN =200 Ge. V, PRC 71, 051902 (R) (2005). – Particle-Species Dependent Modification of Jet-Induced Correlations in Au+Au Collisions at √s. NN =200 Ge. V, PRL 101, 082301 (2008). – Correlated production of p and pbar in Au+ Au collisions at √s. NN = 200 Ge. V, PLB 649 (2007) 359 -369. – Au+Au 62. 4 Ge. V (preliminary) [TC], Cu+Cu 200 Ge. V (preliminary), to be published in early 2010 – Cu+Cu 22. 5, 62. 4 Ge. V (preliminary) [TC], p+p 62. 4 Ge. V (preliminary) [TC] – p+p 200 Ge. V (new data) 7 * note: not the complete list. Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

A lots of data and publications on baryons from RHIC experiments; 2 (spectra, yields, jet correlations) • PHOBOS – Identified hadron transverse momentum spectra in Au+Au collisions at √s. NN = 62. 4 Ge. V, PRC 75, 024910 (2007). • STAR – Identified Baryon and Meson Distributions at Large Transverse Momenta from Au+Au Collisions at √s. NN = 200 Ge. V, PRL 97, 152301 (2006). – Energy dependence of ±, p and p-bar transverse momentum spectra for Au+Au collisions at √s. NN = 62. 4 and 200 Ge. V, ar. Xiv: nucl-ex/0703040. – Identified hadron spectra at large transverse momentum in p + p and d + Au collisions at √s. NN = 200 Ge. V, PLB 637 (2006) 161 -169. – Systematic Measurements of Identified Particle Spectra in pp, d+Au and Au+Au Collisions from STAR, ar. Xiv: 0808. 2041. * note: not the complete list. 8 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

A recent STAR publication (systematic study of PID spectra in p+p (200 Ge. V), d+Au (200 Ge. V), Au+Au (62, 130, 200 Ge. V), ar. Xiv: 0808. 2041) • • ±, K±, p, pbar p. T spectra (low p. T region only, d. E/dx by TPC). A nice full paper (60 pages)! 9 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

2. BULK PROPERTIES AT RHIC 10 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

What are the bulk properties (EOS)? • • • • …. Energy density (e) Temperature (T): – critical temperature (Tc), initial temperature (Tini), chemical freeze-out temperature (Tch), kinetic freeze-out temperature (Tkin) Chemical potential ( ): – baryon chemical potential ( B), strangeness chemical potential ( s), strangeness suppression factor (gs) Collective flow velocity (< T>) Pressure gradient (DP), particle emission anisotropy (v 2) Particle multiplicity (d. N/dy, N) Transverse energy (d. ET/dy, ET) Transverse momentum distribution (Ed 3 N/dp 3) Particle abundance and ratio Average transverse momentum (<p. T>) HBT radii (Rout, Rside, Rlong, l) Velocity of sound (vs) Shear viscosity – entropy ratio (h/s) 11 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

What are the bulk properties (EOS)? • • • • …. Energy density (e) Temperature (T): – critical temperature (Tc), initial temperature (Tini), chemical freeze-out temperature (Tch), kinetic freeze-out temperature (Tkin) Chemical potential ( ): – baryon chemical potential ( B), strangeness chemical potential ( s), strangeness suppression factor (gs) Collective flow velocity (< T>) Pressure gradient (DP), particle emission anisotropy (v 2) Particle multiplicity (d. N/dy, N) Transverse energy (d. ET/dy, ET) Transverse momentum distribution (Ed 3 N/dp 3) Particle abundance and ratio Average transverse momentum (<p. T>) HBT radii (Rout, Rside, Rlong, l) • red: directly measured by p. T spectra Velocity of sound (vs) • pink: indirectly measured by p. T spectra Shear viscosity – entropy ratio (h/s) Q. How the bulk properties change as a function of 12 centrality, system and beam energy? Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Concentrate on mid-rapidty PHOBOS data Cu+Cu Preliminary 3 -6%, Npart = 100 Au+Au 35 -40%, Npart = 99 • Same number of participants, ~same number of charged particle density at RHIC. • Focus at the mid-rapidity to study the multiplicity scaling of bulk properties. 13 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

T 1/p. T d. N/dp. T purely thermal source explosive source light T, heavy p. T light heavy p. T • Au+Au central: 質量によって異なる p. T 分布 → <p. T>: < K < p 集団的膨張運動 (radial flow) を示唆 • 温度指標パラメータ T 0 + 集団運動をになうパラメータ T (ut)が必要 15 Seminar at Hiroshima Univ. (Nov. 30, 2008) 1/p. T d. N/dp. T 熱的分布と集団的膨張 T. Chujo

Semi-Inclusive soft particle spectra Au+Au 200 Ge. V central (b < 2. 6 fm) PHENIX: PRC 69, 034909 (2004) • <p. T>: < K < p Hydro QCD • consistent with radial flow picture. D. d'Enterria &D. Peressounko nucl-th/0503054 16 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo 2007. 0619 第８回

<p. T> vs. Nch STAR, ar. Xiv: 0808. 2041 ST: Transverse overlap area [fm 2] l <p. T> scales with √((d. N /dy)/S), p+p 200 Ge. V, Au+Au 62. 4, 130, 200 Ge. V data. l Suggests that the kinetic freeze-out properties in Au+Au collisions are energy independent. l CGC (gluon saturation): small x gluons overlap and recombine, reducing the total number of gluons and increasing their transverse energy. u Predicts a lower particle multiplicity and larger <p. T>. u In CGC, <p. T> scales with √((d. N /dy)/S). u Data is consistent with CGC picture. Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo 17

Antiparticle-to-Particle Ratios vs. Nch STAR, ar. Xiv: 0808. 2041 -/ +: Flat d. Nch/dy dependence, and unity for all systems. pbar/p: • A slight decrease with centrality (130, 200 Ge. V) • Considerable drop with centrality (62 Ge. V) indicating that larger baryon stopping in central collisions. 18 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

PHENIX 62. 4 Ge. V Au+Au Hum… pbar/p ratio: seems decreasing with Npart in PHENIX data too. DNP 2004 (TC) 19 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Chemical freeze-out hadron-chemistry: particle ratios chemical freeze-out properties STAR white paper Nucl. Phys A 757 (05) 102 • • short lived resonances Tch ≈ TC ≈ 165 ± 10 Me. V Chemical freeze-out ≈ hadronization. s ~ u, d Strangeness is chemically equilibrated at RHIC energies. 21 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo gs

Bulk properties vs. Nch (1) Tch, Tkin < T> STAR, ar. Xiv: 0808. 2041 Tch: constant with d. Nch/dy. close to the lattice QCD: Tc ~160 Me. V. universality at RHIC energies. Tkin: decreasing with d. Nch/dy. same trend for all systems at RHIC (with d. Nch/dy) indicating strong expansion and cooling? Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo < >: incleasing with d. Nch/dy, eventually saturate? 22

Bulk properties vs. Nch (2) m. B, s gs STAR, ar. Xiv: 0808. 2041 • B: finite value, weak centrality dependence (200 Ge. V Au+Au). • s: close to zero. Seminar at Hiroshima Univ. (Nov. 30, 2008) STAR, ar. Xiv: 0808. 2041 • gs: approaching to unity with d. Nch/dy. Strangeness production is strongly suppressed in p+p, d. Au, peripheral Au+Au. In central Au+Au, implying that strangeness is as equally equilibrated as light quarks. 23 T. Chujo

Bulk properties vs. Nch (3) HBT v 2/e PHENIX A. Enokizono 24 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Bulk properties vs. Nch (4) K-/ - STAR, ar. Xiv: 0808. 2041 25 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

“Only” Nch (or initial energy density) determines the bulk properties at RHIC? 26 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

3. SYSTEMATIC STUDY OF BARYON ENHANCEMENT

Baryon enhancement at RHIC PHENIX: PRL 91, 172301 (2003), PRC 69, 034909 (2004), PRC 74, 024904 (2006) In Au+Au s. NN = 200 Ge. V central collisions: • RCP (or RAA) • Pions: Strong suppression of yields above p. T ~ 2 Ge. V/c, due to jet quenching. • Protons: No suppression at intermediate p. T (2 -5 Ge. V/c). • p/ and pbar/ ratios • Factor ~3 more (anti) protons than pions at intermediate p. T (2 -5 Ge. V/c). • Strong centrality dependence. 28 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Systematic study of PID spectra: (Au+Au) Cu+Cu, p+p at s. NN = 22. 5, 62. 4, 200 Ge. V Au+Au, Cu+Cu, p+p @ 62. 4 Ge. V Cu+Cu, p+p (ISR) @ 22. 4 Ge. V (23 Ge. V in p+p) 29 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

s dep. of pbar/ - ratio (central) * No weak decay feed-down correction applied. p+p 62. 4 Ge. V, set the baseline for HI data. PHENIX data agrees with ISR data. 30 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

s dep. of pbar/ - ratio (central) Cu+Cu 22. 5 Ge. V, pbar/ ratio in central agrees with p+p. 31 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

s dep. of pbar/ - ratio (central) Cu+Cu 62. 4 Ge. V, pbar/ ratio larger than those in p+p and Cu+Cu 22. 5 Ge. V. 32 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

s dep. of pbar/ - ratio (central) Cu+Cu 200 Ge. V, similar to those in Cu+Cu 62. 4 Ge. V. 33 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

s dep. of pbar/ - ratio (central) Au+Au 62 Ge. V, pbar/ - is unchanged from Cu+Cu 200 Ge. V 34 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

s dep. of pbar/ - ratio (central) Au+Au 200 Ge. V, p-bar/ - is enhanced. 35 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

s dep. of pbar/ - ratio (peripheral) Peripheral collisions for all systems Seems to be conversing to the same line 36 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Comparison with SPS data T. Schuster, A. Laszlo (NA 49) nucl-ex/0606005 (Pb+Pb 17. 2 Ge. V) (Au+Au 200 Ge. V) Pb+Pb 17. 2 Ge. V (central) 0. 25 0 1. 0 p. T (Ge. V/c) 2. 0 3. 0 SPS Pb+Pb: consistent with Cu+Cu 22. 5 Ge. V pbar/. 37 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

pbar/ - ratio (central): summary • Increasing as a function of s. • Indicates the onset of baryon enhancement is in between 22 Ge. V and 62 Ge. V. * No weak decay feed-down correction applied. 38 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

0 p. T spectra in Cu+Cu and p+p at 22. 4, 62. 4, 200 Ge. V PHENIX: PRL 101, 162301 (2008) 39 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

0 RAA in Cu+Cu: energy dep. PHENIX: PRL 101, 162301 (2008) • Enhancement at 22 Ge. V. • Consistent with no energy loss model. Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo 40

RAA of antiprotons PRC 74, 024904 (2006), PHENIX Au+Au, d+Au 200 Ge. V JPS-DNP Hawaii 2009 (TC) Antiprotons: all looks similar, weaker √s. NN and system dependences. 41 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Comparison of RAA, pbar/p ratios (for central HI collisions) System Energy RAA of pions RAA of pbar suppression? around 1? pbar/pi ratio > Rp+p? Au+Au 200 Ge. V YES YES Au+Au 62. 4 Ge. V YES YES YES Cu+Cu 22. 4 Ge. V NO (enhanced, Cronin effect) YES NO (Ncoll scaling, Cronin effect? ) Pb+Pb (SPS) 17. 2 Ge. V NO - NO Qualitatively different at mid p. T between √s. NN = 22. 4 Ge. V and 62. 4 Ge. V for central HI collisions 42 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

4. WHAT’S THE ORIGIN OF BARYON ENHANCEMENT? 43 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Jet induced baryon enhancement? Away side Near side Away side two peaks (shoulder) 44 Seminar at Hiroshima Univ. (Nov. 30, 2008) Sonic shock wave? Baryon/Meson effect? T. Chujo

Jet-pair distribution for associated M/B PHENIX: PRL 101, 082301 (2008) • • Trigger particle: charged hadron (2. 5 <p. T, trig < 4. 0 Ge. V/c) Associate particle: meson or baryons (1. 0 – 2. 0 Ge. V/c). Near side: substantially weaker for associated baryons. Away side: similar for associated mesons and baryons. Same “Shoulder” structure appeared for both mesons and baryons. 45 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Conditional jet yields for M/B • PHENIX: PRL 101, 082301 (2008) Mesons: – Exponential decrease with increasing p. T, assoc. – Yield increase from peripheral to central, with different slope – Incompatible with in-vacuum fragmentation – Due to contribution from correlated soft partons, recombination, energy loss, etc… ? • Baryons: – Totally different from those for mesons. – Not exponential shape. – Yield (away) > Yield (near). – Might be due to the correlated soft parton recombination? 46 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Baryon/meson ratios associated with high p. T hadron trigger (2. 5 < p. T < 4 Ge. V/c) PHENIX: PRL 101, 082301 (2008) • Peripheral ratios ~ vacuum fragmentation • In-jet ratios ~ inclusive p/( +K) Away-side “shoulder” & baryon enhancement in single spectra might be same origin. • Recombination of correlated soft partons induced via strong parton medium interactions? • Need more high p data to conclude… T. Chujo. T Seminar at Hiroshima Univ. (Nov. 30, 2008) 47

Intermediate p. T ridge & Jet (near side only) (from SQM 08, O. Barannikova, STAR) p. Ttrig > 4. 0 Ge. V/c 2. 0 < p. TAssoc < p. Ttrig Au+Au 0 -10% 3 < pt, trig< 4 Ge. V/c p+p / ++ - STAR preliminary Au+Au: 2 < p. Ttrig < 3 Ge. V/c Cu+Cu: 3 < p. Ttrig < 6 Ge. V/c pt, assoc. > 2 Ge. V/c • p/ , L/K: Production mechanisms for jet and ridge are different. • Same origin for ridge (STAR) and away side shoulder (PHENIX)? Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Figure from “Future Science at the Relativistic heavy ion Collider (Aug. 25, 2006 version)”, by RHIC II Science Working Groups 5. EXPLORING THE QCD PHASE DIAGRAM AT RHIC 49 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Excitation functions of freeze-out properties STAR, ar. Xiv: 0808. 2041 Q: Freeze-out properties changes from AGS to SPS (e. g. √s. NN~10 Ge. V )? • μB: falls monotonically (log). • Tch: rapidly rises at SIS and AGS energy, saturates at SPS and RHIC energies (a unique Tch ~ Tc from lattice QCD). • Tkin: decoupled at √s. NN~10 Ge. V from Tch. Due to the strong collective flow, matter is cooled prolong period of chemical freeze-out and kinetic freeze-out. Seminar at Hiroshima Univ. (Nov. 30, 2008) • < T> : rapid increase from SIS to AGS, T. Chujoincreasing slowly from SPS to RHIC. 50

“hone” at SPS is true? STAR, ar. Xiv: 0808. 2041 l K−/π− ratio : steadily increases with √s. NN, while K+/π+ sharply increases at low energies. l A maximum K+/π+ value is reached at about √s. NN ≈ 10 Ge. V. l K+/K- vs sqrt(s): smooth decrease (log scale). l using the functional forms for K+/Kand K-/ -, then make the function for K+/ +. • Generates a maximum at 10 Ge. V (“horn”). . l More detail energy scan is needed. 51 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Another onset at RHIC PHENIX: PRL 101, 162301 (2008) Cu+Cu Emergence of opacity Approach to constant v 2 and hydrodynamic limit? Au+Au Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Onset of Quark Number Scaling? Where is the onset of quark number scaling? Relationship to quark DOF ? 53 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

p-bar/ - ratio vs. √s. NN • Increasing as a function of s. • Indicates the onset of baryon enhancement is in between 22 Ge. V and 62 Ge. V. * No weak decay feed-down correction applied. 54 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Search for QCD Critical Point (QCP) From C. Nonaka (JPS 2008 fall) Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Another interesting observable for QCD Critical Point (QCP) search ar. Xiv: 0803. 2449 v 4 M. Asakawa, S. A. Bass, B. Muller, C. Nonaka Slide from C. Nonaka (JPS 2008 fall) Proposed to look at pbar/p vs. p. T to find QCP. Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo 56

6. Summary • Baryons have a unique role to characterize the many bulk properties of matter, hadronization mechanism, and medium response. • Bulk properties at RHIC (at mid-rapidity) : governed by the charged particle multiplicity (~initial energy density) – Relevant to the CGC gluon saturation picture. • Systematic study of baryon enhancement: – qualitative difference between 22 Ge. V and 62. 4 Ge. V on the property of baryon enhancement (while freeze-out properties seems to be already changed at 10 Ge. V). – Jet correlation: indicating the jet induced baryon enhancement. • Towards the understanding of QCD phase diagram and QCP search. 57 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

Backup Slides 58 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo

0 RAA vs. s. NN D. d’Enterria, nucl-ex/0504001 Seminar at Hiroshima Univ. (Nov. 30, 2008) T. Chujo 59