Phase diagram Latice QCD QCD matter undergoes a

Phase diagram • Latice QCD: QCD matter undergoes a transition from a hadronic gas to a quark‐gluon plasma at a temperature Tc ~170 Me. V • At small net baryon density, the transition is a smooth cross‐over spanning a temperature range of 20‐ 30 Me. V • much reduced condensate of light quarks approximate restoration of chiral symmetry • screening of chromo‐electric force between heavy quarks absence of quark confinement Evgeny Kryshen Физика столкновений тяжелых ионов 2

HIC: physics motivation • • Evgeny Kryshen Goal: study nuclear matter at extreme conditions of temperature and density Heavy ion collisions studied since AGS, SPS & RHIC Produced QCD matter initially thought as weakly interacting gas of quarks and gluons but found as strongly interacting matter: – short mean free path – high collectivity and flows – large parton energy‐loss – almost perfect liquid ( /s ~ 1/4π) Физика столкновений тяжелых ионов 3

Global properties Lifetime (> 10 fm/c ~ 3 x 10 -23 с) Volume ≈ 2 x RHIC (≈ 300 fm 3) +40% x 2 RHIC Photon T = 304± 51 Me. V ~ 1. 4 x RHIC Energy density ~ 3 x RHIC ~ 10 Ge. V/fm 3 ? Evgeny Kryshen Физика столкновений тяжелых ионов 4

Hadrochemistry / thermal models • Hadron yields and ratios up to RHIC energies well-fitted by statistical model in terms of T, μB • Extracted (T, μB) in good agreement with transition curve in lattice QCD phase diagram • Confirmed/refined by RHIC data on beam energy scan. • At LHC, some tension with statistical description - Hadronic re-interactions? - Importance of charm contribution to strangeness production? Evgeny Kryshen Физика столкновений тяжелых ионов 5

RHIC energy scan and statistical model • Observation of a centrality dependence of the freeze‐out temperature vs. baryon chemical potential (beam energy) • Radial flow increase from most peripheral collisions at √s. NN = 7. 7 Ge. V to most central Au‐Au events at √s. NN = 200 Ge. V Evgeny Kryshen Физика столкновений тяжелых ионов 6

Strong suppression for hadrons • Stronger suppression at LHC Evgeny Kryshen Физика столкновений тяжелых ионов 7

3 regions in p. T Low: p. T < 3 -4 Ge. V/c • Bulk properties and collective radial flow Intermediate: 3 < p. T < 7 Ge. V/c • Test of valence quark scaling • Anomalous baryon enhancement and coalescence High: p. T > 7 Ge. V/c • Jet fragmentation, modification of fragmentation functions in medium ALICE, Phys. Lett. B 696, 30 (2011) Evgeny Kryshen Физика столкновений тяжелых ионов 9

Identified particles RAA • Strong suppression confirming previous measurements for non‐identified particles • For p. T below ~ 7 Ge. V/c: – RAA(p) < RAA(h±) – RAA(K) ≈ RAA(h±) – RAA(p) > RAA(h±) • At higher p. T: RAA are compatible medium does not significantly affect the fragmentation. Evgeny Kryshen Физика столкновений тяжелых ионов 11

Anisotropic flow Spatial asymmetry transforms into momentum space: Phys. Rev. Lett. 107, 032301 (2011) Evgeny Kryshen Физика столкновений тяжелых ионов 12

Hydrodynamics and flow • • • 3+1 dim hydro dynamics reproduces v 2, v 3, v 4, v 5 in p. T and centrality for matter with same dissipative property Most conservative bound: 0. 07 < /s < 0. 43 Models increasingly sensitive to initial conditions and their (quantum) fluctuations IP‐Sat. Glasma Schenke MC‐KLN MC‐Glauber Evgeny Kryshen Физика столкновений тяжелых ионов 13

Identified particle v 2 • • Mass ordering observed at low p. T for p, p, K±, K 0 s, L, f and (not shown) X, W �� -meson follows mass dependence at p. T < 3 Ge. V/c and “meson band” at higher p. T Overall qualitative agreement with viscous hydro calculations at low p. T Hadronic rescattering phase improves agreement Evgeny Kryshen Физика столкновений тяжелых ионов 14

NCQ scaling: RHIC PHENIX Phys. Rev. C 85 064914(2012) STAR, S. Shu at QM 2012 t ll a. . . e s e w rgie t i qu ene s d ol t low h g lin ties a a sc rali t Q NC y cen an Particles Evgeny Kryshen 0% e. V/c 1 n 0 t ~1 G i lds rt a o h a C s st I RH tion t a via g n de li : a n sc bi Q ity NC ntral ce Физика столкновений тяжелых ионов 15

NCQ scaling breaking: LHC • scaling off by 10‐ 20% at high p. T (where mass is negligible) • stronger radial flow or jet quenching/ rescattering, more important than coalescence ? Evgeny Kryshen Физика столкновений тяжелых ионов 16

Event Shape Engineering New tool towards better understanding of elliptic flow • At fixed centrality large flow fluctuations • v 2 splits by factor of two for semi‐central events (30– 50%) Evgeny Kryshen Физика столкновений тяжелых ионов 17

Hard probes

Three types of hard probes Evgeny Kryshen Физика столкновений тяжелых ионов 20

Electroweak probes PLB 710 (2012) 256 CMS-PAS HIN-12 -008 Z 0 m+m- W mn usingle muon recoil against missing p. T Ncoll scaling confirmed Evgeny Kryshen Физика столкновений тяжелых ионов ar. Xiv: 1205. 6334 Accepted by PLB 21

Suppression of charged particles Fully unfolded inclusive jet RAA pp 2. 76 Te. V reference Charged hadron RAA flat for p. T = 30 - 100 Ge. V Evgeny Kryshen Like for charged particles, high-p. T jet RAA flat at ≈ 0. 5 Физика столкновений тяжелых ионов 22

Jet quenching STAR preliminary ATLAS Evgeny Kryshen CMS Физика столкновений тяжелых ионов ALICE 23

Dijet asymmetry pp reference Small AJ Large AJ (Balanced jet) (Un‐alanced jet) • • • Parton energy loss is observed as a pronounced energy imbalance in central Pb. Pb collisions No apparent modification in the dijet Δφ distribution (Dijet pairs are still back‐to‐back in azimuthal angle) However information on initial jet momentum is missing + surface bias Evgeny Kryshen Физика столкновений тяжелых ионов 24

g+jet – “golden channel” Photon (191 Ge. V) Jet (98 Ge. V) Photon tag: • Identifies jet as u, d quark jet • Provides initial quark direction • Provides initial quark p. T Evgeny Kryshen Физика столкновений тяжелых ионов 25

g+jet: u, d quark energy loss nucl‐ex/1205. 0206 Jet-photon p. T balance drops by 14% Evgeny Kryshen 20% of photons lose jet partner Физика столкновений тяжелых ионов 26

D meson RAA JHEP 1209 (2012) 112 • D 0, D+ and D*+ RAA compatible within uncertainties. • Suppression up to a factor 5 at p. T~ 10 Ge. V/c. Evgeny Kryshen Физика столкновений тяжелых ионов 27

D meson RAA: comparison to charged pions Average D‐meson RAA: • – p. T < 8 Ge. V/c hint of slightly less suppression than for light hadrons • – p. T > 8 Ge. V/c both (all) very similar: no indication of colour charge dependence Evgeny Kryshen Физика столкновений тяжелых ионов 28

D meson v 2 Non‐zero D‐meson elliptic flow observed: • consistent among D‐meson species (D 0, D+, D*+) • comparable to v 2 of light hadrons Simultaneous description of RAA and v 2 – challenge for transport models Evgeny Kryshen Физика столкновений тяжелых ионов 29

Quarkonia

Screening and initial temperature • Different states have different binding energies Loosely bound states melt first! • Successive suppression of individual states provides a “thermometer” of the QGP Evgeny Kryshen Физика столкновений тяжелых ионов 31

Suppression or enhancement? • LHC energies : Enhancement via (re)generation of quarkonia, due to the large heavy‐quark multiplicity (A. Andronic et al. , PLB 571, 36 (2003)) Evgeny Kryshen Физика столкновений тяжелых ионов 32

SPS summary plot NA 50 (Pb‐Pb) and NA 60 (In‐In) results: In‐In 158 Ge. V (NA 60) Pb‐Pb 158 Ge. V (NA 50) Anomalous suppression for central Pb‐Pb collisions Agreement between Pb‐Pb and In ‐In in the common Npart region After correction for EKS 98 shadowing Pb‐Pb data not precise enough to clarify the details of the pattern! B. Alessandro et al. (NA 50), EPJC 39 (2005) 335 R. Arnaldi et al. (NA 60), Nucl. Phys. A (2009) 345 Anomalous suppression up to ~30%, compatible with (2 S) and c melting, i. e. with a sequential suppression scenario! Evgeny Kryshen Физика столкновений тяжелых ионов 33

RHIC results Comparison of RAA results obtained at different rapidities Mid‐rapidity Forward‐rapidity Stronger suppression at forward rapidities q Not expected if suppression increases with energy density (which should be larger at central rapidity) q Are we seeing a hint of (re)generation, since there are more pairs at y=0? q Or may other effects (e. g. cold nuclear matter effects) explain this feature ? Evgeny Kryshen Физика столкновений тяжелых ионов 34

RHIC vs SPS • Nice “universal” behavior • Maximum suppression ~40‐ 50%, still compatible with only (2 S) and c melting N. Brambilla et al. , EPJ C 71(2011) 1534 Evgeny Kryshen Физика столкновений тяжелых ионов 35

J/ suppression at LHC: RAA vs Npart q Comparison with PHENIX: stronger centrality dependence at lower energy q Systematically larger RAA values for central events in ALICE q Behaviour qualitatively expected in a (re)generation scenario Look at theoretical models Evgeny Kryshen Физика столкновений тяжелых ионов 36

RAA vs Npart in p. T bins recombination Compare RAA vs Npart for low‐p. T (0<p. T<2 Ge. V/c) and high‐p. T (5<p. T<8 Ge. V/c) J/ Different suppression pattern for low‐ and high‐p. T J/ Smaller RAA for high p. T J/ In the models, ~50% of low‐p. T J/ are produced via (re)combination, while at high p. T the contribution is negligible fair agreement from Npart~100 onwards Ø Need p. A for cold nuclear matter effects Ø Ø Evgeny Kryshen Физика столкновений тяжелых ионов 37

J/ v 2 The contribution of J/ from recombination should lead to a significant elliptic flow signal at LHC energy • STAR: v 2 compatible with zero everywhere • ALICE: hint for non‐zero v 2 • Significance up to 3. 5 • Qualitative agreement with transport models including regeneration Evgeny Kryshen Физика столкновений тяжелых ионов 38

Sequential suppression 2011 data ar. Xiv: 1208. 2826 Observation of sequential suppression of Y family Expected in terms of binding energy CMS-PAS HIN-12 -014, HIN-12 -007 Evgeny Kryshen Физика столкновений тяжелых ионов 39

p. A highlights

d. Nch/dη in p‐Pb collisions ar. Xiv: 1210. 3615 [nucl-ex] • • • p. A crucial to discriminate between initial (cold nuclear matter) effects and QGP dynamics p‐Pb at LHC → probe nuclear wave‐function at low x → nuclear gluon shadowing CGC: steeper ηlab dependence than the data HIJING (with shadowing) and DPMJET: describe the η‐shape rather well mid‐rapidity �Npart�normalized �d. Nch/dη�p‐Pb similar trend to pp Evgeny Kryshen Физика столкновений тяжелых ионов 41

Charged particle Rp. A • consistent with unity for p. T > 2 Ge. V/c • the strong suppression observed in Pb‐Pb is NOT an initial‐state but hot QCD matter effect ar. Xiv: 1210. 4520 [nucl-ex] Evgeny Kryshen Физика столкновений тяжелых ионов 42

Conclusions • Early to make conclusions… • Wealth of physics results from RHIC and first two LHC heavy‐ion runs: • bulk, soft probes: spectra and flow of identified particles, thermal photons • high‐p. T probes: jet fragmentation, particle‐type dependent correlations • heavy‐flavour physics: suppression and flow of D mesons, quarkonia • Entering the precision measurement era: • First studies of cold nuclear matter effects with p–Pb collisions, more next year Evgeny Kryshen Физика столкновений тяжелых ионов 43

A (valid) analogy

ALICE physics perspectives Status as of today Reachable for approved Reach with the upgrade Bulk production light flavours, v 2, HBT quantitative precision Intermediate pt v 2, correlations, baryon‐meson quantitative precision High‐pt – jets RAA, correlations, jet fragm. quantitative precision hint quantitative precision heavy‐flavour in jets PID fragmentation Heavy flavour D‐mesons, RAA hint quantitative precision D‐meson v 2 hint precision beauty, Ds hint quantitative precision hint Quantitative quantitative precision Precision hint quantitative precision charm baryons Charmonia J/ forward, RAA J/ v 2 ’, c Dileptons – g quantitative J/ central, U family hint virtual g hint quantitative r‐meson Heavy. Kryshen nuclei Evgeny hyper(anti)nuclei, H‐dibaryon LHC on the march hint precision quantitative precision 46

Example: Heavy‐flavour v 2 High rate, new ITS • • • No high rate, new ITS need >> 1 nb‐ 1 for precise measurement of charm and beauty v 2 systematic uncertainties and corrections mostly cancel in v 2 Other key measurements: Lb, Xc, B decays, virtual g, ’, c, tagged jets… Evgeny Kryshen LHC on the march 47