P-25 RHIC-SPIN Research Program Ming X. Liu, P-25

1
P-25 RHIC-SPIN Research ProgramMing X. Liu, P-25

• RHIC Physics
• Heavy Ion program - Mikes talk
• Nucleon spin structure (RHIC-SPIN)
• PHENIX-SPIN LANL Involvement
• A major role
• RHIC-SPIN physics and LANL focus
• Gluon distribution
• Sea quark distribution
• New physics

2
Deep Inelastic Lepton Scattering (DIS)

• 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 coupling to quarks and anti-quarks in
  inclusive DIS

3
RHIC-Spin Physics New Frontier of Nucleon
Structure Research

• Proton Spin - a major puzzle from polarized DIS
  experiments
• Proton Spin Decomposition
• Origin of Proton Spin
• gluon, sea quarks, orbital angular momentum ?
• Inclusive DIS cant directly probe gluons and
  anti-quarks
• Need new tools
• Leading order interactions of gluons and quarks,
  e.g. hadron colliders
• Reactions that distinguish quark from anti-quark
• Processes that can Identify quark flavors

Quarks only contribute 30 of total proton spin
!
Experimentally
4
The ExperimentPHENIXPioneering High Energy
Nuclear Interaction eXperiment

• Polarized Protons at RHIC
• E_cm50 - 500 GeV
• Pol70
• L2x1032 cm-2sec-1
• Particle Detectors
• PHENIX et al
• Physics
• Nucleon Spin Structure
• Gluon distribution
• Quark distribution
• New Physics

5
PHENIX is BIG 450 scientists!
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 that now under construction for RHIC,
  which will allow this experiment to do spin
  physics.

7
PHENIX with Two Muon Arms
8
Hadron Physics _at_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
HI
SPIN
9
PHENIX Muon Arms

• Muon Arms
• TrackingMuID
• 1.2 lt ? lt 2.4
• ??2?
• p ? 2GeV/c
• Physics
• Drell-Yan
• J/Psi
• Heavy Quark
• W,Z0
• Critical for Spin Physics

10
J/Psi Physics from the First Year p-p Data
11
Our Approach to Spin Puzzle

• RHIC-SPIN a polarized hadron collider
• Gluon polarization
• Jets - leading particles
• Direct photon
• Heavy quarks (LANL)
• Sea quark polarization
• Drell-Yan (LANL)
• W, Z0 (LANL)

Experimentally(indirect)
Gluons may play a significant role !
HERMES99
12
Polarized Interactions

• Measures of Asymmetry

13
Heavy Quark Production and ?G

• Gluon-Gluon Fusion
• dominant process at 200 GeV
• Experimental challenge
• Good beam polarization
• Identify heavy quark events

14
Heavy Quark Measurement at PHENIX

• Open Charm/Bottom
• high Pt single leptons
• work in progress
• lepton charge correlation
• displaced vtx (svx upgrade)

lepton
J. Moss, M.Brooks, Phenix Note 1997
Pt_jet
Jet
SVX Upgrade
VTX
b
_ b
IP
15
Flavor Asymmetry Sea Quark Polarization

• Nucleon is a complex system

LANL/E866
16
Quark and Anti-Quark Polarization

• Limits of DIS
• Only couple quarks through
• Cant tell quark from anti-quark
• W production in hadron collisions
• (V-A) coupling select helicity
• Tag quark flavors
• Separate quark from anti-quark

17
W Measurement

• Via high Pt muons

18
Quark and Anti-Quark Polarization
Bunce G. et al, hep-ph/0007218

• Experimental Sensitivity
• Large parton level asymmetry

19
Searching for New Physics

• 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

20
Summary

• Unique Opportunity
• directly probe
• Discovery Potential
• New Physics _at_RHIC
• P-25/T8 collaboration