study of the quark gluon plasma with hadronic jets

U N C L A S S I F I E D


Slide 1

Operated by the Los Alamos National Security, LLC for the DOE/NNSA

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



Slide 2


Quark-Gluon Plasma (QGP)

Lattice QCD - hadronic systems undergo a double phase transition at TC~160 -170 MeV: deconfined quark&gluon matter (QGP) – long range confining force screened chiral symmetry restoration – quarks become massless

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Slide 3


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)0

200

250

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0 200 400 600 800 1000 1200

AGS

SIS

SPSRHIC

hadron gas neutron stars

thermal freeze-out

deconfinementchiral restauration

nucleiTem

per

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(M

eV)

QGP (hot&baryon free)QGP (hot&baryon free)



Slide 4


The Relativistic Heavy Ion Collider (RHIC) at BNL

PHENIX

Runs 1 - 6 (2000 – 2006): Au+Au @ 200, 130, 62, 22 GeV Cu+Cu @ 200, 62 GeV d+Au @ 200 GeV p+p @ 200, 62, 22 GeV (polarized)



Slide 5


Hadronic Jets as Tools for QGP Study

Observed via:- leading (high pT) hadron spectra;- two-particle azimuthal correlations.

Jet event in a hot QCD medium Bulk (soft) QCD particle production:

- low-Q2, 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-Q2 processes with calculable cross section (S(Q2)<<1) produced early (<1fm);- interact strongly with the bulk QGP: loose energy (radiate gluons) jet quenching and broadening



Slide 6


Hadronic Jet Suppression – Partonic Energy Loss

Explained by (and only

by) final state partonic

energy loss models:

dNgluon/dy ~ 1100

ε ~ 15 GeV/fm3

(consistent with value

from dNch/dη meas.)

Vitev & Gyulassy, PRL 89 (2002) 252301

ddpdT

ddpNdR

TNN

AA

TAA

AA /

/2

2

nuclear modification factor



Slide 7


Why do I (we) believe that (a) QGP was formed at RHIC…

Dense: ε~15GeV/fm3 (εc~1GeV/fm3), dNg/dy~1100 – from nuclear modification factors and global measurements

Hot: Tave~360MeV (Tc~160MeV) – from thermal photon spectra

Debye screening of J/Ψ (suppression and recombination)

Strongly coupled: large collective flow coefficients (v2) 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?



Slide 8


Back to (Di-)Jets: What happens with the dissipated energy?

p-pd-Au

PHENIX Preliminary

Hard partons loose energy. What happens to the lost energy? Look at angular distributions of lower pT 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



Slide 9


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(cs)

Shuryak J.Phys. G31 (2005) L19

near

away

D

Daway



Slide 10


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/fm3

– gluon density dNg/dy > 1100 – initial state temperature T0

ave = 300-400 MeV

• More differential measurements, like angular particle correlations, are employed to gain deeper information about the properties of this state of matter



Slide 11


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



Slide 12


Dilepton Tagged Jets with the CMS detector (LHC)

*/0Z

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We replace one jet in the di-jet withan electromagnetic probe (Z0/γ*l+l-),hence dilepton-tagged jet…

Why? Electromagnetic probes don’t interact with the QCD medium theymeasure the initial kinematics of theback-to-back jet.

LDRD-ER team: Gerd J. Kunde (PI), Camelia Mironov, Maria Castro, P.C.



Slide 13




Slide 14


Ratios of hadron yields consistent with system at chemical equilibrium

Global fit to relative particle abundances with 4 parameters:• chemical freezeout temperature (Tchem ~ Tcrit

• baryon chemical potential for light & strange quarks (μq, μs)• strangeness saturation factor, S (S =1 is strangeness fully equilibriated)

Kaneta, Xu nucl-th/0405068Braun-Munzinger, Redlich, Stachelnucl-th/0304013

study of the quark gluon plasma with hadronic jets

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