sPHENIX

sPHENIXThe Future Program of the PHENIX collaboration (central and forward rapidity)

Richard SetoHard ProbesMay 31, 20121

1sPHENIX and QCD2TMD Spin PDFsThe sQGP Color Glass CondensateTMD PDFs at low-xPolarized ppHeavy Ionsp(d)+AQCDSpin and theGround State of QCDsaturated stateof QCDExcited stateof QCDUnderstanding QCD means more than knowing the LagrangianIt means understanding how it manifests itself in different regimes.A+A and the sQGPOur understanding of the sQGP is limitedMechanism of phase transition, quasiparticlesTransport coefficientsJet medium interactionsOur understanding of the QGP would not be complete without a fundamental explanation for how the perfect fluid arises at strong coupling near TC from an asymptotically free theory of quarks and gluons.Jet observables at RHIC, enabled by the sPHENIX upgrade, are critical to providing this explanation by probing the QGP near TcWe have two handles: T and Q2Lever arm: LHC to RHIC to RHIC at lower energy (e.g. s=100, 62)Evolution of signals from RHIC to LHC is not trivial (e.g. J/ , hadron RAA)Geometric Control at RHIC (Corona) e.g. central Cu+Au3

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Temperature dependence of the sQGP?The weak coupling value for /s is > order of magnitude too largeYet we know at high T, the theory must be asymptotically free

additional Information: jetsLittle is known about what happens on a microscopic level.Strongly Coupled Scenario electric and magnetically charged quasiparticlesRHIC creates a system is close to TC Such information together with data fromthe LHC needed for clear understandingJet Quenching is a few times stronger near Tc Liao and Shuryak, PRL 102, 202302 (2009), PRC 75 054907

/s4 Would we be sensitive to the strength of the coupling S? ?E1 > 20 GeV

S=0.60.350.2vacuumDijet (E1-E2)/(E1+E2)

RHIC dijets very sensitive to effective couplingEmbed parton showers into partonic medium, where S can be variedChris Coleman-Smith (Duke)Incorporating strong coupling via AdS/CFT like path dependence gives better agreement

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PRL 105, 14230pQCD0B. Muller. Nucl.Phys., A855:7482, 2011, RHIC/AGS Users Meeting 2011This meeting

LHC Scenario

RHIC ScenarioT0=300 MeVParton ET = 30 GeVLHC ScenarioT0=390 MeVParton ET = 200 GeVQ2 Dependence: Heavy Quark Parton VirtualitypQCD

6This means that the very energetic parton hardly notices the medium for the first 3-4 fm of its path lengthQ2

Energy Loss Constrained by RHIC dataOver-prediction of quenching at LHC

7Q: Are RHIC and LHC the same of different?

Can we to measure jets?Rate together with the flexibility of RHIC will allow geometric control over measurements (A+A, A+B, p+A & p+p,), and allow us to vary T and Q2

Au+Au 10% Central105 Jets E>40 GeV (80% dijets)104 prompt photons E> 20 GeVJet Transverse Energy (GeV) raw measured with det resolution and underlying eventTruthMeasured and unfoldedUnfolding the Energy spectrum8w/stochastic coolingDetector conceptRequirementsJets (dijets): uniform, large solid angle coverage; reasonable jet resolution to 60 GeV; contain 97% of 50 GeV hadron+Jet: Good photon coverage/resolution Contain Cost: Compact, uniform electronicsChoices (Stage I a jet detector) || Segmentation =0.1x0.1Upgradeable 0 to 50 GeV (preshower)Resolve Upsilon states: high resolution trackingRetain capability to become an eRHIC detector (10x100 GeV2)Leave room in forward direction for CNM, spin studies

9The central barrel Detector : Stage I

EMCALTungsten-Fiber =0.02*0.02 ~17X010stage I 25K ChannelsHCALIron-Scintillator =0.1*0.15 (w/ EM=6 )

Solenoidal MagnetB=2T R=0.7m||