P-25 RHIC-SPIN research program Ming X. Liu, P-25

PDRC M.LIU 2/4/03 #1

P-25 RHIC-SPIN research programMing X. Liu, P-25

• RHIC Physics – Heavy Ion program - Mike’s talk– Nucleon Spin Structure (RHIC-SPIN)

• PHENIX-SPIN & LANL Involvement– Played a major role

• RHIC-SPIN physics and LANL focus – Gluon distribution– Sea quark distribution– New Physics

PDRC M.LIU 2/4/03 #2

Deep Inelastic Lepton Scattering (DIS)

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• Polarized DIS

– So far, source of all information on polarized parton structure of nucleon, mostly of quark polarization

– Polarized muon or electron beams with hadron targets

• Fixed target or collider mode• CERN,SLAC,DESY,JLab etc

– Only EM couple to quarks and anti-quarks

PDRC M.LIU 2/4/03 #3

• Proton Spin - a major puzzle from polarized DIS experiments

– Proton Spin Decomposition

• Origin of Proton Spin:

– gluon, sea quarks, orbital angular momentum ? – DIS can’t directly probe gluons and anti-quarks

• Need a new tool : RHIC-SPIN– a polarized proton collider– quark-gluon, quark-quark and gluon-gluon interactions– directly explore gluon and sea quark distributions

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RHIC-Spin PhysicsRHIC-Spin PhysicsNew Frontier of Nucleon Structure ResearchNew Frontier of Nucleon Structure Research

RHIC-Spin PhysicsRHIC-Spin PhysicsNew Frontier of Nucleon Structure ResearchNew Frontier of Nucleon Structure Research

Quarks only contribute ~30% of total proton spin !

PDRC M.LIU 2/4/03 #4

The ExperimentPHENIX=Pioneering High Energy Nuclear Interaction eXperiment

• Polarized Protons at RHIC – E_cm=50 - 500 GeV– Pol=70%– L=2x10^32 cm^-2sec^-1

• Particle Detectors– PHENIX et al

• Physics Studies– Nucleon Spin Structure

• Gluon distribution

• Quark distribution

– New Physics

PDRC M.LIU 2/4/03 #5

PHENIX in Today: ~450 scientists!

PDRC M.LIU 2/4/03 #6

BNL-RIKEN Agreement

• BNL-RIKEN Agreement on Spin Physics, 1995– With $20M from Japanese Lab, RHIC ventures into spin physics

– Large involvement from LANL group

• Half of the money that RIKEN brings to the collaboration will be used to build and install the Siberian snakes, spin rotators and other hardware needed to collide spin-polarized protons in RHIC.

• The other $10 million will add an additional detector system for PHENIX, one of the two large detectors now under construction for RHIC, which will allow this experiment to do spin physics.

PDRC M.LIU 2/4/03 #7

PHENIX with two muon arms

PDRC M.LIU 2/4/03 #8

Hadron Physics @LANL

• Nucleon structure– Understanding the structure of nucleon

in terms of quark and gluon constituents of QCD is one the outstanding fundamental questions in physics.

• LANL experience, expertise & interests

– FermiLab E772/789/866: dimuon exp.– Sea quark flavor asymmetry– Gluon shadowing– Drell-Yan, J/Psi – Heavy quarks etc

– Spin structure function– QCD dynamics– New physics

E772/E789/E866

RHIC

HISPIN

PDRC M.LIU 2/4/03 #9

PHENIX Muon Arms

• Muon Arms – Tracking+MuID– 1.2 < || < 2.4 =2– p 2GeV/c

• Physics– Drell-Yan– J/Psi– Heavy Quark– W±,Z0

• Critical for Spin Physics

PDRC M.LIU 2/4/03 #10

J/Psi Physics from the First Year p-p Data

QM2002

PDRC M.LIU 2/4/03 #11

Our Approach to Spin Puzzle

• Polarized hadron collider – RHIC-SPIN– Gluon polarization

• Jets - leading particles• Direct photon• Heavy quarks (LANL)

– Sea quark polarization• Drell-Yan (LANL)• W±, Z0 (LANL)

Gluons may play a significant role !

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PDRC M.LIU 2/4/03 #12

Polarized Interactions

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• Measures of Asymmetry

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PDRC M.LIU 2/4/03 #13

Heavy Quark Production and G

• Gluon-Gluon Fusion– dominant process at 200 GeV

• Experimental challenge:– Identify heavy quark events– Good beam polarization

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PDRC M.LIU 2/4/03 #14

Heavy Quark Measurement at PHENIX

• Open Charm/Bottom– high Pt single leptons– work in progress

• lepton charge correlation

• displaced vtx (svx upgrade)

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J. Moss, M.Brooks, Phenix Note 1997

PDRC M.LIU 2/4/03 #15

Flavor Asymmetry & Sea Quark Polarization

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• Nucleon is a complex system• Understand the dynamics

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PDRC M.LIU 2/4/03 #16

Quark and Anti-Quark Polarization

• Limits of DIS– Only couple quarks through – Can’t tell quark from anti-quark

• W± production in hadron collisons– (V-A) coupling – select helicity– Quark flavor selection– Quark and anti-quark separation

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PDRC M.LIU 2/4/03 #17

W± Measurement

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PDRC M.LIU 2/4/03 #18

Quark and Anti-Quark Polarization

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Experimental Sensitivity:

•Large parton level asymmetry

Bunce G. et al, hep-ph/0007218

PDRC M.LIU 2/4/03 #19

Searching for New Physics

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New parity violation in hadron interactions?

- unexplored at high energy- sensitive to new physics

many models of NEW PHYSICS predict PV,CPV

AL in contact interaction- Jet + X- high Pt heavy quark/muon- Drell-Yan

At low energy:

Bunce G. et al, hep-ph/0007218

PDRC M.LIU 2/4/03 #20

Summary

• Unique Opportunity

• Discovery Potential– New Physics @RHIC

• P-25/T8 collaboration

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