p-25 rhic-spin research program ming x. liu, p-25
DESCRIPTION
P-25 RHIC-SPIN research program Ming 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. - PowerPoint PPT PresentationTRANSCRIPT
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)
),(
9
1),(
9
1),(
9
4
2
1),( 2222
1 QxssQxddQxuuQxg p
• 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
04.031.0
gqLG 2
1
2
1
Experimentally
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 !
17.0;03.018.041.0)(
)(
GxxG
xG
Experimentally(indirect)
HERMES’99
gqLG 2
1
2
1
PDRC M.LIU 2/4/03 #12
Polarized Interactions
)()()()(
)}()({)}()({)}()({)}()({
L
LL
A
A
• Measures of Asymmetry
)()()()(
)}()({)}()({)}()({)}()({
T
TT
A
A
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
aAQQgg
LL
XQQpp
LL xG
xG
xG
xGxx
)(
)(
)(
)(),(
2
2
1
121
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)
b cW-
-
s
W+
+
Jet
leptonPt_jet
VTX
IP
b_b
SVX Upgrade
J. Moss, M.Brooks, Phenix Note 1997
PDRC M.LIU 2/4/03 #15
Flavor Asymmetry & Sea Quark Polarization
)()(
)()(?
xdxu
xdxu
• Nucleon is a complex system• Understand the dynamics
LANL/E866
)()(
)()(?
xuxd
xuxd
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
2qe
PDRC M.LIU 2/4/03 #17
W± Measurement
sMxx W /21
W
• Via high Pt muons
s
Mxx
xs
E
W2
21
1*)cos1(
4
PDRC M.LIU 2/4/03 #18
Quark and Anti-Quark Polarization
211
1
211
1
)(
)(
)(
)(
xxifxd
xd
xxifxu
xu
AWL
Experimental Sensitivity:
•Large parton level asymmetry
Bunce G. et al, hep-ph/0007218
PDRC M.LIU 2/4/03 #19
Searching for New Physics
_d
u
+
2
2
2 WM
gG
)1()1(8 552
2
gLqqqq
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
...,,);(),(
)(
sdufxqxq
xG
ff
q
vu G
vd