Experimental Summary פדריקו אנטינורי INFN

Experimental Summary פדריקו אנטינורי ) , INFN פדובה איטליה(

Prologue • it’s 2 am, I am fast asleep, it’s the middle of the night, after a tiring day • the phone rings… • “hrmpf? ” I say • “Helloooo Federicooooo, how are you? ” says a trumpeting voice at the other end of the line… • “gmrump”, say I, realising I am nine time zones off in Seattle and forgot to switch off my mobile phone… • “how about you giving the experimental summary at Hard Probes? ” says the happy man, whom I have in the meantime identified to be Itzhak • “harrrummpfff maybe lemmecheck” say I… • “great!” says happy Itzhak • so… here I am 2 פדריקו אנטינורי

Disclaimer • I have put together the talk at the conference – I know, the all say so, but this time (as you’ll see…) it’s true! • I have not tried to be ecumenical or politically correct • I have tried to honestly put together the main points that I, personally, will take away from this nice conference • but I still had to make hard choices, since there was too much interesting material… • given the available time, I have essentially just been able to assemble the talk using the original slides – but I will try to guide you through them – so: pay attention! 3 פדריקו אנטינורי

Contents • • 4 The LHC is here! Quarkonia The CGC? High p. T correlations Jets Energy loss Conclusions פדריקו אנטינורי

! The LHC is here פדריקו אנטינורי 5

• very good level of understanding of the apparatus 6 פדריקו אנטינורי

Kathrin Koch פדריקו אנטינורי 7

Illustration of vertexing performance Jiří Dolejší Vertex reconstruction efficiency as a function of nsel. BS. The coloured error bands show the total uncertainty, the black vertical lines the statistical uncertainty. Data: A zoomed-in view of the Y vs. X distribution of secondary reconstructed vertices due to hadronic interactions in minimum-bias events (after K 0 S, g , and L vetoes, and Z < 300 mm cut). 1 mm bins in X and Y. 8

• good level of understanding of the apparatus • immediately good agreement across experiments for the basic measurements, e. g. : 9 פדריקו אנטינורי

Momentum distribution 900 Ge. V p. T distribution Results: - Finally some (slight) difference ! - Spectrum seems to get harder towards midrapidity - MC’s have hard time to describe the full spectrum Comparison to MC’s versus √s Karel Šafařík

• more from the LHC maiden run later in the talk… 11 פדריקו אנטינורי

Pb-Pb run 2010 • expected luminosity ~ 2 orders of magnitude below nominal – 1027 cm-2 s-1 ~ 1025 cm-2 s-1 – ~ /10 from number of bunches – ~ /10 from increased beam size (lower energy, less focussing) 50 – 100 Hz min bias strategy: low bias trigger • expected data sample? – estimate: ~ 1 – 3 µb-1 • e. g. : 2 µb-1 = 1. 6 107 min bias events – for comparison: ALICE targets: • 0. 5 nb-1 for rare triggers • a few 107 central events for central physics 12 פדריקו אנטינורי

Physics reach? • global event properties – – multiplicity azimuthal asymmetry (v 2) Bose-Einstein correlations (HBT) bulk strangeness • with a p. T reach dependent on statistics… – particle correlations – nuclear modification factors – strange, identified particle spectra • a first glimpse of hard probes (depending on integrated lumi) – jets – J/ψ – heavy flavour • surprises? (always there so far at each new AA energy) 13 פדריקו אנטינורי

Quarkonia פדריקו אנטינורי 41

RAA ( ) in 200 Ge. V Au+Au Collisions q. Upsilon yield is obtained through a combined fit using the line shape from üthe simulated Upsilon and üThe calculated DY/bbar (PRD 82 (2010) 12004) Rosi Reed, Wei Xie (STAR) From 2007 Au+Au run: ü RAA (0 -60%)= 0. 78± 0. 32(stat) ± 0. 22(sys, DY+bb) ± 0. 09(sys, p+p lum) ü RAA (0 -10%)= 0. 63± 0. 44(stat) ± 0. 29(sys, DY+bb) ± 0. 07(sys, p+p lum) See R. Reed’s talk for Details 15

RCP vs. rapidity RCP has the advantage of cancelling most of the systematic uncertainties. However, it should not be mistaken for Rd. Au(central), as Rd. Au(periph) deviates significantly from unity (ie. p+p). Matthew Wysocki (PHENIX) 10/13/10 M. Wysocki - Hard Probes 2010 16

Fabio Maltoni פדריקו אנטינורי 71

The dimuon landscape in CMS R. Castello’s poster Ø Coverage down to low masses and low p. T possible thanks to the very loose muon trigger settings used for early data “Best Plot” Award Roberto Castello, Hermine Wöhri : CMS results in pp collisions Hermine K. Wöhri Hard Probes 2010 18

J/ + - : d J/ /dp. T Stat. errors only (ICHEP 2010) (stat errors only) Very good agreement with the LHCb result in the same rapidity range Roberta Arnaldi (ALICE) 19

Camilla Maiani פדריקו אנטינורי 02

J/ production cross section C. Lourenço’s talk Ø Prompt and non-prompt J/y fractions are separated by measuring the distance between the dimuon vertex and the IP Ø Surprising overlap between the LHC exp. s (and CDF) for the B hadron fraction 6 < p. T < 10 Ge. V/c |y| < 1. 4 prompt Surprise? Carlos Lourenço, Hermine Wöhri : CMS results in pp collisions Hermine K. Wöhri Hard Probes 2010 PAS BPH-10 -002 21

Carlos Lourenço (CMS) 22 פדריקו אנטינורי

High p. T correlations 23 פדריקו אנטינורי

Gunther Roland פדריקו אנטינורי 42

• so off goes the Mach Cone? • but wait a minute. . . hadn’t we decided that the structure on the away side was conical? (STAR three-particle correlations) PRL 102, 52302(2009) 25 פדריקו אנטינורי

and of course… LHC pp! 26 פדריקו אנטינורי

Gunther Roland + “S. Gennaro’s miracle” (A De Rújula) 27 פדריקו אנטינורי

Correlations: Outlook • LHC could not have started better – non-standard correlations already in pp! • we need to clarify if away-side correlations at RHIC are conical or not • + correlations with heavy quarks – extract/cross-check B cross section? – medium response to heavy partons? • + correlations with quarkonia – e. g. : extract/cross-check B J/Ψ? 28 פדריקו אנטינורי

Jets פדריקו אנטינורי 92

Yue Shi Lai (PHENIX) 30 פדריקו אנטינורי

dp. T systematics: summary Peter Jacobs (STAR) Centroid shift ~± 1 Ge. V Outliers from QPYTHIA: • 2 out of 30 jets • physics or modeling? • 30 different jets • each embedded in ~8 M different Background events Main result of this talk: Fluctuation distribution ~ universal within factor ~2 at dp. T=30 Ge. V HI Jets in implement in unfolding 31 To Hard Probes 2010 characterize distribution; STAR do: fully

~ 0. 5 ± 0. 1 @ 20 Ge. V in 10% Cu-Cu Yue Shi Lai 32 פדריקו אנטינורי

~ 0. 6 ± 0. 1 @ 20 Ge. V in 10% Au-Au Jörn Putschke 33 פדריקו אנטינורי

Yue Shi Lai פדריקו אנטינורי 43

Jörn Putschke 35 but what about the centrality dependence? פדריקו אנטינורי

פדריקו אנטינורי Jörn Putschke 63

Broadening of recoil jets p. T(trigger)> 20 Ge. V/c p. T(recoil)> 10 Ge. V/c p. T, cut=2 Ge. V/c for both trigger and recoil π Effect of v 2 under study. Broadening of the away-side for recoil jets with p. T, cut=2 Ge. V/c w. r. t p+p Elena Bruna, Yale University Elena Bruna 37

Softening of recoil jets: IAA p. T(trigger)> 20 Ge. V/c p. T(recoil)> 10 Ge. V/c p. T, cut=2 Ge. V/c for both trigger and recoil 4 3 2 π Jet-algorithm finds modified jets Significant enhancement at low p. T Elena Bruna, Yale University Elena Bruna 38

Direct Photon Tagged Jets to measure the awayside Fragmentation Function M. Connors ent m e anc nh E Megan Connors (PHENIX γ–jet) Flat IAA • Isolated p+p data agrees with the TASSO measurement of quark FF • IAA at low ξ is flat and <1 • But Au+Au shape is different at high ξ and hints at enhancement • This modified shape is well described by the MLLA prediction D(z) modified

Jets: the cynical outlook • as somebody was saying at the end of the jets round table: “quel bordel…” 40 פדריקו אנטינורי

LHC! Andreas Morsch 41 פדריקו אנטינורי

• but what Physics shall we find in the promised land above 100 Ge. V? • may the scenery out there turn out to be perturbatively “aseptic” ? • we better get geared to push down in jet energy as much as we can into the dirt again 42 פדריקו אנטינורי

Gregory Soyez פדריקו אנטינורי 34

Gregory Soyez פדריקו אנטינורי 44

Jet energy scale • Jet energy computed from calibrated topological clusters. • Calibration based on: – testbeam data – MC studies • In situ calibrations and cross-checks: – single hadrons E Ecalorimeter/ptracker – di-jets inter-calibration Attilio Andreazza • Currently jet energy scale known to 7% • Final aim is to achieve 1% 4 th International Conference on Hard and Electromagnetic Probes in HE Nuclear Collisions, Hard Probes 2010 - Eilat, 11 A. Andreazza – ATLAS p+p results 45

Esteban Fullana Torregrosa 46 פדריקו אנטינורי

V. Chiochia’s talk B-jet identification Ø Key observables like SV flight distance and associated mass match extremely well with MC prediction Ø First estimates of identification efficiency and mistag probability for light flavour jets obtained from data Hermine Wöhri Event with two reconstructed SVs : flight distances 6. 2 & 8. 6 mm associated masses 2. 9 & 3. 1 Ge. V Hard Probes 2010 Hermine K. Wöhri : CMS results in pp collisions PAS BTV-10 -001 47

Andreas Morsch פדריקו אנטינורי 84

Jets: the bright outlook • yes, jet physics in AA may look like a happy bazaar, so what? • is there THE ideal approach? – what if we had a robust prescription that would somehow “catch” the whole jet, and then let us could look inside the jet as a function of distance? • we enter the LHC era with a “positive plurality”… – look at jets from different angles compare the results – more “rigid”, cone-like approaches for RAA? – more “organic” approaches for softening, broadening studies? . . . provided the field does not come too religiously polarised • and of course, flavour will now enter the game – particle id – b tagging will surely be a lot of fun! 49 פדריקו אנטינורי

Energy loss פדריקו אנטינורי 05

The Brick Problem TECHQM: Theory-Experiment Collaboration on Hot Quark Matter https: //wiki. bnl. gov/TECHQM/index. php/Main_Page Gluon(s) Marco van Leeuwen Compare energy-loss in a well-defined model system: Fixed length L = 2, 5 fm Density T, q Quark, E = 10, 20 Ge. V Compare outgoing gluon, quark distributions Two types of comparison: - Same density - Same suppression and interpret/understand the differences 51

AMY, BDMPS, and ASW-MS “Best Formula” Single-gluon kernel from AMY Award Marco van Leeuwen based on scattering rate: Salgado, Wiedemann, PRD 68, 014008 BMPS-Z use harmonic oscillator: BDMPS-Z: Finite-L effects: Vacuum-medium interference + large-angle cut-off 52

Outgoing quark spectra Same temperature: T = 300 Me. V Marco van Leeuwen @Same T: suppression AMY > OE > ASW-MS Note importance of P 0 53

Conclusion Marco van Leeuwen • AMY gives most radiation – No L 2 effect at small L – No large-angle cut • Opacity expansions (GLV/ASW-SH) intermediate – Good at short lengths (L < 2 -3 fm) – Likely too much at large L • Multiple-soft scattering radiates least – Too much suppression at short L ? • Higher Twist more difficult to compare – Gives more radiation than GLV at single-gluon level Current calculations: Large uncertainties associated with large-angle radiation at low to moderate x We now know where the differences between formalisms come from ! Unfortunately: differences not dominated by physics, but by approximations 54

55 RAA & v 2 Parameter(s) tuned to match 0 -5% RAA. n n RAA and v 2 are anti-correlated. p. QCD based jet quenching models under-predicts the v 2. Xiaoyang Gong (PHENIX) WHDG

RAA(Df) vs Im 56 In many models, eloss scales as: radiative Xiaoyang Gong Better scaling with m=2, Ad. S/CFT JJ and R. Wei, PRC 82, 024902, 2010 Any model, with I 2 dependence, has to describe RAA & v 2 simultanously

What about heavy flavour? 57 פדריקו אנטינורי

STAR Solution üSignificantly Increase the S/B of this analysis (2008 -present) üCross check NPE measurements with early runs. Count STAR preliminary Beam pipe + SVT + SSD+ Dalitz Beam pipe + Dalitz TPC Inner Field cage Wei Xie R(cm) Yield of conversion electrons at different radial location 58

Comparison with the Published NPE Results STAR and PHENIX NPE result in 200 Ge. V p+p collisions üAre consistent within errors at pt > 2. 5 Ge. V/c STAR High p. T NPE results are consistent with FONLL in 200 Ge. V p+p collisions Wei Xie 59

STAR high p. T NPE Measurements in 200 Ge. V p+p collisions Wei Xie Measurement done using TPC+EMC using run 08 and run 05 data. üp. T>2. 5 Ge. V/c NPE measurement with dramatically different background agree with each very well • Combined using “Best Linear Unbiased Estimate”. χ2/ndf = 4. 81/7 = 0. 69 60

• the discrepancy on the NPE spectra seems to be understood • the discrepancy on the total cross section remains • STAR-PHENIX agreement was already better for NPE RAA • but disagreement with p. QCD quenching… 61 פדריקו אנטינורי

Quark Mass Corrections • All calculations assume MQ << p. T – Large corrections expected for observed NPE • NB: – Mbottom ~ 4. 75 Ge. V – 9 Ge. V e- from ~ 15 Ge. V b • c and b separation will help tremendously William Horiwitz Wicks et al. , NPA 784, 2007 3/18/2018 HP 2010 62

Compared to Data • String drag: qualitative agreement William Horiwitz WAH, Ph. D Thesis 3/18/2018 HP 2010 63

• more points for Ad. S/CFT? • astounding prediction for LHC… 64 פדריקו אנטינורי

LHC Rc. AA(p. T)/Rb. AA(p. T) Prediction (with speed limits) WAH, M. Gyulassy, PLB 666 (2008) William Horiwitz – T(t 0): “(”, corrections likely small for smaller momenta – Tc: “]”, corrections likely large for higher momenta Qualitatively, corrections to Ad. S/CFT result will drive double ratio to unity 3/18/2018 HP 2010 65

• more points for Ad. S/CFT? • astounding prediction for LHC… • Q: why does a rest mass in the Ge. V range still matter in the 100 Ge. V range? ? c/b separation at LHC + RHIC upgrades 66 פדריקו אנטינורי

Signals: D 0 K-p+ 108 events; 1 -12 Ge. V in 7 bins Andrea Dainese Hard Probes 2010, Eilat, Israel, 15. 10 Andrea Dainese 67

Charming and beautiful resonances in the CMS tracker Ø The CMS all-silicon tracker can accurately reconstruct multi-prong decays Bs → J/y f D* D* B- Hermine Wöhri Hard Probes 2010 Hermine K. Wöhri : CMS results in pp collisions PAS TRK-10 -002 DPS-2010/024 DPS-2010/033 68

Silvia Masciocchi 69 פדריקו אנטינורי

Diego Stocco פדריקו אנטינורי 07

Caveat • shadowing: the fly in the ointment? 71 פדריקו אנטינורי

III. Results from EPS 09 NLO 1. Modifications of NLO n. PDFs + uncertainties Largest uncertainties here Kari Eskola Central set Error sets initial scale Uncertainty band a larger scale small-x uncertainties shrink at larger scales 72 [JHEP 0904: 065, 2009, ar. Xiv: 0902. 4154 [hep-ph]]

Effect of shadowing on D 0 RAA? calculation by Andrea Dainese Pb-Pb 5. 5 Te. V Suppression extends up to ~12 Ge. V? Pb-Pb 2. 75 Te. V Suppression limited to 7 Ge. V. 10% enhancement above 10 Ge. V? NB: EPS 08 ~ at lower limit of EPS 09 gluon uncertainty band 73 פדריקו אנטינורי

Caveat • shadowing: the fly in the ointment? we will have to exercise some care below 7 Ge. V or so (until we have p. A) 74 פדריקו אנטינורי

… and more פדריקו אנטינורי 57

W boson measurements W e Attilio Andreazza ETmiss m. T W 4 th International Conference on Hard and Electromagnetic Probes in HE Nuclear Collisions, Hard Probes 2010 - Eilat, 11 A. Andreazza – ATLAS p+p results 76

Z boson measurement Z + - Z e+e. Attilio Andreazza 4 th International Conference on Hard and Electromagnetic Probes in HE Nuclear Collisions, Hard Probes 2010 - Eilat, 11 A. Andreazza – ATLAS p+p results 77

So, what will the LHC bring? • a host of new, abundant hard probes to study the system • we shall descend deeply into the wonders of low-x • we shall find that the Ad. S/CFT correspondence is more than just a computational coincidence • the wonderful world of deeply deconfined matter will open up to us revealing the existence of extra dimensions! 78 פדריקו אנטינורי

Just kidding… I apologise: I must have been temporarily in the bulk (out of my brane…) 79 פדריקו אנטינורי

What I really want to say is… the abundant hard probes at the LHC will help us: • understand the length dependence of energy loss • understand the energy dependence of energy loss • oh dammit… 80 פדריקו אנטינורי

What’s needed? n Establish length dependence of energy loss. Establish energy dependence of energy loss. Measure medium modification of angular and momentum distribution of radiated energy. Measure quark mass dependence of energy loss. n Many opportunities at RHIC and LHC: n n n Tagged jets (energy, flavor) ¨ Angle dependence ¨ System size dependence ¨ Fully reconstructed jets ¨ n Berndt Müller A world-class jet detector at RHIC is needed 81

My Warmest Thanks… • to the Organisers – for inviting me to give the Experimental Summary • to: Brian Cole, Megan Connors, Andrea Dainese, David d’Enterria, Barbara Jacak, Carlos Lourenço, José Guilherme Milhano, Gunther Roland, Karel Šafařík, Carlos Salgado, Thomas Ullrich, Urs Wiedemann – for material, suggestions, discussions, support • to the organisational staff – for providing me at superluminal speed with the slides of all the talks • to all the speakers whose file was named “HP 2010. ppt” – that really made it simple for me! 82 פדריקו אנטינורי