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R2D:R2D:New physics concepts for the New physics concepts for the

RHIC-II phaseRHIC-II phase

Rene BellwiedWayne State University

Workshop on RHIC-II physicsBrookhaven National Laboratory, Nov.19th-20th, 2004

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Expression of Interest -Expression of Interest -A Comprehensive New Detector at RHIC IIA Comprehensive New Detector at RHIC II

P. Steinberg, T. Ullrich (Brookhaven National Laboratory)

M. Calderon (Indiana University)

J. Rak (Iowa State University)

S. Margetis (Kent State University)

M.A. Lisa, D. Magestro (Ohio State University)

R. Lacey (State University of New York, Stony Brook)

G. Paic (UNAM Mexico)

T. Nayak (VECC Calcutta)

R. Bellwied, C. Pruneau, A. Rose, S. Voloshin (Wayne State University)

and

H. Caines, A. Chikanian, E. Finch, J.W. Harris, M.A.C. Lamont, C. Markert,

J. Sandweiss, N. Smirnov (Yale University)

& RHIC-II workshop ,Yale, April 16/17, 2004

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The Physics Pillars of R2DThe Physics Pillars of R2D What are the detailed properties of the sQGP and what

are the degrees of freedom at high densities ? What is the mechanism of hadronization and is chiral

symmetry restored in the deconfined medium ?

Is there another state (CGC) of matter at low x, what are its features, and how does it evolve into the QGP ?

What is the structure and dynamics inside the proton (parton spin, L) and what do we learn from parity violation and polarization measurements ?

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The Measurement Pillars of R2DThe Measurement Pillars of R2DParticle Identified Jet measurements

Measurement-jets & flavor tagged jets

Detailed onium measurements

Forward (low x) physics

Bulk observables in 4

High rate spin measurements

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Evolution of a strongly interacting systemEvolution of a strongly interacting system Measurements:

Initial conditions ( HBT, low-x physics)

Composition above Tc

(partons, di-quarks, pre-hadrons ?)Parton density

(jet tomography, flavor, intra-, inter-jet correlations)

Deconfinement Tc (Quarkonium melting)

Shuryak QM04 ?

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What are the initial conditions ? What are the initial conditions ? Color Glass Condensate (CGC): gluon saturation at low Q2.

Measure – Mid – forward rapidity

correlations (hep-ph/0403271)– Direct photons at forward

rapidities – HBT (coherence of sea-

quark source?)– Drell-Yan in forward region

(hep-ph/040321)– RpA, RAA of heavy mesons in

forward direction (hep-ph/0310358)

requires tracking, calorimetry and PID over large -range.

ln (

1/x)

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Bulk dynamics in 4Bulk dynamics in 4

change (, pT) vary (B ,T)

vary x

limiting fragmentation

forward HBT

increasing y

Need tracking& PID forward

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In and out of a sQGPIn and out of a sQGP

What are the degrees of freedom above TC ?

Is chiral symmetry restored above TC ?

How does hadronization and spontaneous breaking of chiral symmetry (SBCS) occur ?

Shuryak QM04 ?

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The sQGP degrees of freedom and The sQGP degrees of freedom and chiral symmetry restorationchiral symmetry restoration

C.Greiner (Jamaica 04): multi-gluon interactions (e.g.strong 2 to 3)Recombination models: constituent quark (dressed up valence

quarks)

C.Greiner (SQM04): high mass resonances near Tc (Hagedorn states)E.Shuryak (QM04): colored and colorless bound states above Tc

Measurements: High mass resonance shifts due to partonic bound states (Shuryak)

Resonances to prove SBCS– Is off mass shell resonance (e.g. shifting or broadening in mass) visible

in chiral partner pairs ( and a1) or ( and ) ?

Resonances in jets– Is the leading particle resonance different from the bulk matter

resonances (off shell vs on shell, same side vs away side, leading vs. next-to-leading)

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Hadronization and fragmentation Hadronization and fragmentation via particle identified jet physicsvia particle identified jet physics

pT

pQCDHydro

~ 2 GeV/c ~ 6 GeV/c

SoftSoft

Medium Medium modifiedmodifiedfragmentation fragmentation (jet quenching)(jet quenching)

0

pT independence of pbar/p ratio.

p/ and /K ratio increases with pT to > 1 at pT ~ 3-4 GeV/c in central collisions.

Suppression factors of p, different to that of , K0

s in the intermediate pT region.

Parton Parton recombinationrecombination

andandcoalescencecoalescence

Fragmentation Fragmentation

~ 30 GeV/c ?

LHC, RHIC-IISPS, RHIC-I

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00 in pp: well described by NLO in pp: well described by NLO

Ingredients (via KKP or Kretzer)– pQCD– Parton distribution functions– Fragmentation functions

p+p->0 + X

Hard

Scattering

Thermally-shaped Soft Production

hep-ex/0305013 S.S. Adler et al.

“Well Calibrated”

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Strange particles in ppStrange particles in pp

Specific NLO calculation describes K0 reasonably well, but is off for W.Vogelsang:maybeis too heavy, problems with heavy particles

B.Jaffe (PAC meeting): maybe we need to look at fragmentation again

RHIC-II will be the premier pp machine in the next decade because of its detector capabilities

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Do we understand fragmentationDo we understand fragmentationand its modification ?and its modification ?

statistical approach based on measured inclusive cross sections of baryons in e+e- annihilation:

alternate: de Florian et al., (1998) or J.J.Yang (2001,2002)

Induced Gluon Radiation ~collinear gluons in cone “Softened” fragmentation

in je

i j t

t

n e

: increases

z : decreases

chn

Modification according toGyulassy et al. (nucl-th/0302077)

Quite generic (universal) but attributable to radiative rather than collisional energy loss

2 GeV baryon in a 10 GeV jet

z z

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Yu.Dokshitzer

Different partons lose different Different partons lose different amounts of energyamounts of energy

Examples:1.) dead cone effect for heavy quarks:For heavy quarks in the vacuum and in the medium the radiation at small angles is suppressed (Dokshitzer & Kharzeev, PLB 519 (2001) 199)

2.) gluon vs. quark energy loss:Gluons should lose more energy and have higher particle multiplicities due to the color factor effect.

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Gluon jet selections at RHIC-IIGluon jet selections at RHIC-II

1.) Large rapidity interval correlations

(Mueller-Navelet Jets)

2.) Three jet events (?)

3.) PT-dependence of -jets (?)

low-x gluon

0.001< xg < 0.1

high-x valence quark

0.3 < xq< 0.7

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The goal of particle identified The goal of particle identified fragmentation in the mediumfragmentation in the medium

1.) we need to understand fragmentation (hadronization) in

pp collisions

2.) use the medium modified fragmentation functions in AA

collisions

3.) Different flavor contributions to D(z) at different z lose different z in the opaque

medium.

Measure fragmentation functions in pp & modifications in AA.

Study z = phadron/pjet and x dependence :

High pT identified particlesIntra- and inter-jet particle correlationsLarge acceptance for -tagged jets

Essential to understand hadronization

0.2 < z < 1 7 < p < 30 GeV/c 0.1 < x < 0.001 0 < < 3

pq,g > 10 GeV/call

106 particles in AA

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-charged hadron correlations in pp and AA-charged hadron correlations in pp and AA

0-5% 10-30%5-10%

30-50% 50-70%pp

Quark vs. gluon jet ?, baryon-meson effect ?flavor conservation ?No significant difference for different trigger particle species at intermediate trigger pt.But we are statistics limited, we need Anti-K to higher pt

Anticipated R2D rates:50,000 pairs > 4 GeV/c , 5,000 pp pairs > 10 GeV/c

STAR preliminary

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Asymmetry might develop as a function of Asymmetry might develop as a function of trigger pt (increased ‘jettiness’)trigger pt (increased ‘jettiness’)

(Same side – away side) two particle correlation strength incentral Au-Au Collisions at RHIC

Strange trigger, charged associated particles

(associated pt > 2 GeV/c)

trigger pt (GeV/c)STAR preliminary

STARpreliminary

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Requirements for a complete jet program Requirements for a complete jet program

Broadening in and pT in pp (+jet) and AA

Full coverage in tracking and pid and calorimetry

R2D rates per RHIC year: 40 GeV di-jets: 120kNChwith pt>5 GeV/c in -jets with E = 20 GeV :

19,000

Need hadronic calorimetry in order to apply isolation cuts for ’s

Glueck et al., PRL 73, 388

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Onium physics – the complete programOnium physics – the complete program – Melting of quarkonium states (Deconfinement TC)Tdiss(’) < Tdiss((3S)) < Tdiss(J/) Tdiss((2S)) < Tdiss((1S))

In order to resolve the question of melting of the states and its relevance to the sQGP we need to measure:

the J/ production mechanism (octet vs. singlet model)the effect of thermal recombination the effect of nuclear absorption the effect of co-mover absorptionthe feed-down from call states

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Why a more complete onium program ?Why a more complete onium program ? In pp: understand charm

production

(singlet vs octet model)

In pA nuclear absorption:

dependent on xF or x2 ?

In AA: co-mover absorption:Realistic cross sections ?

E866 J/ data Quark shadowing and final state absorption +

Gluon shadowing +

Anti-shadowing +

dE/dx

A. Capella, D. Sousa, nucl-th/0303055

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Requirements for a complete onium programRequirements for a complete onium program Full coverage high resolution forward calorimetry in order to

measure not only the J/ but also the c and the Y States

Full coverage (||< 3) calorimetry and muon absorbers give us up to 1,000,000 c, 10,000 Y(2s) and 10,000 Y(3s) per RHIC year. The J/ alone is not sufficient !

R2D

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Charm flow by STAR/PHENIXCharm flow by STAR/PHENIX

STAR data very preliminary

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How can something so heavy flow How can something so heavy flow with the light quarks ? with the light quarks ?

Either lots of interactions of the heavy quark with the rest of the partonic phase or the hadronicphase (thermalization ?)What are the degrees of freedom ? : dressed up constituent quarks, bare heavy quarks,

gluons, colorless bound states (glueballs ?).

Let’s measure v2 for D (through hadron channels),B-mesons (through J/channelsJ

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RHIC-II: the premier pp machine for RHIC-II: the premier pp machine for the next decadethe next decade

Attract new (and old) communities:RHIC SpinHigh energy hadron physics(Fermilab, Jlab, GSI)(proton driver at FNAL ?)

- quark models, lattice gauge tests- meson/baryon exotica- glueballs, multiquark states- diffractive physics, multi-pomeron

Contacts: M.Albrow, J.Appel (FNAL)E. Swanson (Pitt), T. Barnes (ORNL) Higher luminosity by varying quad position & superbunches

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Origin of Spin (of Proton)Origin of Spin (of Proton) Gluons

– -jet (provides x range) * – Heavy quarks (D, B) *– Heavy quarkonia (J/tag)– Large ET jets (ET ~ 40 - 50 GeV jets)

Sea-quarks– Anti-quarks (W production) *– Strange quark (Charm-tagged W production)

Orbital Angular Momentum? Polarization in AA?

* part of original RHIC Spin program

Transversity– Transversity dist. function of q andq– Sivers effect (di-jets, -jet) ST (P k) 0 – Quark mass dep. in QCD Lagrangian (B-jet)

Beyond the Standard Model– New Interactions & chirality (parity violating hard-

jet production)

p

p

sc

cg

We

D-jet

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RHIC-II: the premier pA machine for RHIC-II: the premier pA machine for the next decadethe next decade

Attract new communities:(in preparation for EIC)

eA community (Jlab, DESY)CGC theory

-wee partons, CGC-high parton density QCD-gluon production, spin structure

Contacts: A.Deshpande (SUNY)R.Milner (MIT), BNL- CGC folks

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Do we need RHIC-II in the LHC era ?Do we need RHIC-II in the LHC era ? Is the LHC viewing the sQGP through the distorted lens

of the Color Glass Condensate ? (M. Gyulassy)

Maybe the QGP degrees of freedom change from RHIC to LHC. Does the sQGP get weaker ? Are we in the sQGP sweet spot ?

The case needs to be made strongly by the theory community that is interested in RHIC-II.

The LHC detectors are not sufficient to characterize the sQGP.

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Requirements according to RHIC II Requirements according to RHIC II Physics PillarsPhysics Pillars

Detailed properties of sQGP

Quarkonium: EMC/HCal Resolution, Acceptance, Rates Jets: PID and tracking at high pT over full acceptance (-jet, jet-jet)

Mechanisms of hadronization PID at High pT, correlations, large acceptance, -tagged jets

Origin of Spin (of Proton) Large acceptance, jets, -jet, high pT identified particles, correlations

Low x physics (CGC QGP) High-pT identified particle yields to large Multi-particle correlations over small & large range

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Do we need a new RHIC-II detector ?Do we need a new RHIC-II detector ?Understanding QCD at high density requires

hermetic detectors with complete PID, HCal, EMCal, and tracking coverage.

The upgrades to the existing RHIC detectors do not fulfill the necessary detector requirements.

The LHC detectors do not cover all the requirements.

A new device is required in order to harvest the uniqueness of the RHIC-II physics program.