U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 0 Study of the Quark Gluon Plasma with Hadronic Jets What: the Quark Gluon Plasma Where: the Relativistic Heavy Ion Collider at BNL How: hadronic jets Summary Outlook: the Large Hadron Collider at CERN

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 1 Quark-Gluon Plasma (QGP) Lattice QCD - hadronic systems undergo a double phase transition at T C ~ MeV:  deconfined quark&gluon matter (QGP) – long range confining force screened  chiral symmetry restoration – quarks become massless q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 2 QCD Phase Diagram However, the QGP hadronizes very quickly: one can observe only signatures of its existence (jet quenching, J/  suppression, strangeness enhancement, large collective flow, thermal electromagnetic radiation, etc.) Baryonic Potential  B (MeV) AGS SIS SPS RHIC hadron gas neutron stars thermal freeze-out deconfinement chiral restauration nuclei Temperature (MeV) QGP (hot&baryon free)

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 3 The Relativistic Heavy Ion Collider (RHIC) at BNL PHENIX Runs (2000 – 2006): 200, 130, 62, 22 GeV 200, 62 GeV 200 GeV 200, 62, 22 GeV (polarized)

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 4 Hadronic Jets as Tools for QGP Study Observed via: - leading (high p T ) hadron spectra; - two-particle azimuthal correlations. Jet event in a hot QCD medium Bulk (soft) QCD particle production: - low-Q 2, long range strong processes, well described by hydro-/thermo-dynamical models; - ~90% of all final state particles are from vacuum ! Jet (hard) QCD particle production : - from partonic hard scattering (primarily gluons); - high-Q 2 processes with calculable cross section (  S (Q 2 )<<1) produced early (  <1fm); - interact strongly with the bulk QGP: loose energy (radiate gluons)  jet quenching and broadening

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 5 Hadronic Jet Suppression – Partonic Energy Loss Explained by (and only by) final state partonic energy loss models: dN gluon /dy ~ 1100 ε ~ 15 GeV/fm 3 (consistent with value from dN ch /dη meas.) Vitev & Gyulassy, PRL 89 (2002) nuclear modification factor

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 6 Why do I (we) believe that (a) QGP was formed at RHIC…  Dense: ε~15GeV/fm 3 (ε c ~1GeV/fm 3 ), dN g /dy~1100 – from nuclear modification factors and global measurements  Hot: T ave ~360MeV (T c ~160MeV) – from thermal photon spectra  Debye screening of J/ Ψ (suppression and recombination)  Strongly coupled: large collective flow coefficients (v 2 ) of all (light and heavy) mesons – quark number scaling  Thermal & chemical equilibrium: wide range of particle ratios are in agreement with statistical models Next phase: what kind of QGP? What are its properties?  Equation of state? Transition order?  Transport coefficients?  Speed of sound?

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 7 Back to (Di-)Jets: What happens with the dissipated energy? p-p d-Au PHENIX Preliminary  Hard partons loose energy. What happens to the lost energy?  Look at angular distributions of lower p T fragments…  Dijets in pp and dAu: near side (Δφ~0) from parton fragmentation; away side (Δφ~π) from fragmentation of opposite parton  Dijets in AuAu are expected to be strongly modified by the medium I. Vitev Phys.Lett. B630 (2005) 78

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 8 Di-Jet Shape Modification in Heavy Ion Collisions Displacement is dependent on collision centrality and independent on collision energy. IF it is indeed a Mach cone, D measures directly the speed of sound in the plasma! Away-side peak is displaced from Δφ = π: D D Mach shock wave: A supersonic parton will generate a conic shock wave at a Mach angle D = acos(c s ) Shuryak J.Phys. G31 (2005) L19 near away D D

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 9 Summary: Probing partonic state of dense matter RHIC has produced a dense, hot, strongly interacting, partonic state of matter at thermal and chemical equilibrium We now have started probing the properties of the matter – energy density  >15 GeV/fm 3 – gluon density dN g /dy > 1100 – initial state temperature T 0 ave = MeV More differential measurements, like angular particle correlations, are employed to gain deeper information about the properties of this state of matter

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 10 Outlook: RHIC II at BNL and LHC at CERN RHIC II: improved luminosity, new/upgraded detectors LANL is an important part of it: a large part of our team builds a new forward silicon vertex PHENIX detector; prototype funded through a LDRD-DR grant LHC at CERN (starts 2008): longer lived, hotter plasma LANL is also involved: a smaller part of our team is funded through a LDRD-ER grant to study the feasibility of using dileptons to tag the hadronic jets

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 11 Dilepton Tagged Jets with the CMS detector (LHC) We replace one jet in the di-jet with an electromagnetic probe (Z 0 /γ*  l + l - ), hence dilepton-tagged jet… Why? Electromagnetic probes don’t interact with the QCD medium  they measure the initial kinematics of the back-to-back jet. LDRD-ER team: Gerd J. Kunde (PI), Camelia Mironov, Maria Castro, P.C.

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 12

U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 13 Ratios of hadron yields consistent with system at chemical equilibrium Global fit to relative particle abundances with 4 parameters: chemical freezeout temperature (T chem ~ T crit baryon chemical potential for light & strange quarks (μ q, μ s ) strangeness saturation factor,  S (  S =1 is strangeness fully equilibriated) Kaneta, Xu nucl-th/ Braun-Munzinger, Redlich, Stachel nucl-th/