Date post: | 18-Jan-2016 |
Category: |
Documents |
Upload: | nicholas-franklin |
View: | 232 times |
Download: | 0 times |
LANLLANL Nuclear Nuclear PhysicsPhysics
15/10/2006
Cold Nuclear Matter PhysicsCold Nuclear Matter Physics Mike Leitch
LANL Medium Energy Nuclear Physics
Cold Nuclear Matter (CNM) effects in Quarkonia Production• the underlying production physics• gluon saturation, energy loss, pT broadening• PHENIX dAu J/• implications for AA at RHICOpen charm & beauty with single muons• complementary to aboveFuture• dA at RHIC-II• pA at the LHC• dbar/ubar & quark energy loss at E906 & JPARC
LANLLANL Nuclear Nuclear PhysicsPhysics
25/10/2006
Understanding the underlying J/ψ production physics
Production of heavy vector mesons, J/, ’ and
Gluon fusion dominates • production: color singlet or octet cc: absolute cross section and polarization?
Hadronization time (important for pA nuclear effects)
Complications due to substantial feed-down from higher mass resonances, from ’, c (’ cleaner physics - harder experimentally)
χ,1,2 J/ ~30%
΄ J/ 5.5%
#J/ψ’s: ~400 (), ~100 (ee)
√s = 200 GeV
PRL 96, 012304 (2006)
Rapidity
LANLLANL Nuclear Nuclear PhysicsPhysics
35/10/2006
Gluon Shadowing and Saturation
Q = 2 GeV5 GeV
10 GeV
Leading twist gluon shadowing
phenomenological fit to DIS & Drell-Yan data,
and many other approaches
Amount of gluon shadowing differs by up to a factor of three between diff models!
Saturation or Color Glass Condensate (CGC)• At low-x there are so many gluons that 2 1 diagrams become important and deplete low-x region• Nuclear amplification: xAG(xA) = A1/3xpG(xp), i.e. gluon density is ~6x higher in Gold than the nucleon
high xlow x
LANLLANL Nuclear Nuclear PhysicsPhysics
45/10/2006
The J/ - a Cold Nuclear Matter (CNM) Puzzle
J/ suppression is a puzzle with possible contributions from shadowing & from:
Energy loss of incident gluon shifts effective xF and produces nuclear suppression which increases with xF
D
Dccmoversco-
Absorption (or dissociation) of into two D mesons by nucleus or co-movers (the latter most important in AA collisions where co-movers more copious)
cc
800 GeV p-A (FNAL)PRL 84, 3256 (2000); PRL 72, 2542 (1994)
HadronizedJ/ψ?
cc
open charm: no A-depat mid-rapidity
ANA
Absorption
shadowing,dE/dx, and/or intrinsic charm
What is the fundamental QCD description for gluon dE/dx?
LANLLANL Nuclear Nuclear PhysicsPhysics
55/10/2006
High x2
~ 0.09
Low x2
~ 0.003
Transverse Momentum Broadening for J/ψ’s
Upsilons
Drell-Yan
J/ & ’
PRL 96, 012304 (2006)
ANA
cc/J
gluon
Initial-state gluon multiple scattering causes pT broadening (or Cronin effect)
PHENIX 200 GeV results show pT broadening comparable to that at lower energy (s=39 GeV in E866/NuSea)
LANLLANL Nuclear Nuclear PhysicsPhysics
65/10/2006
something more, dE/dx?
&more?
= X1 – X2
19 GeV
39 GeV
200 GeVopen charm: no A-depat mid-rapidity
J/ for different s collisions
PHENIX J/ Nuclear Dependence from 200 GeV ppand dAu collisions – PRL 96, 012304 (2006)
Data favors weak shadowing & absorption• With limited statistics difficult to disentangle nuclear effects• Will need another dAu run! (more pp data also)
Klein,Vogt, PRL 91:142301,2003 Kopeliovich, NP A696:669,2001
Low x2 ~ 0.003(shadowing region)
ANA
Not universal vs x2 as expected for shadowing, but does scale with xF, why?• initial-state gluon energy loss?• Sudakov suppression (~energy conservation)?Analysis & paper writing led by MJL
LANLLANL Nuclear Nuclear PhysicsPhysics
75/10/2006
0 mb
3 mb
Low x2 ~ 0.003(shadowing region)
0 mb
3 mb
R. Vogt CNM calcs.
J/ suppression in AA collisions & CNM baseline
• AA suppression is somewhat stronger than CNM calculations predict• but really need more precise dAu constraint!
• CNM calculations with shadowing & absorption - Vogt & MJL• present dAu data probably only constrains absorption to: σABS ~ 0-3 mb
(CNM = Cold Nuclear Matter)
centralperiph.
LANLLANL Nuclear Nuclear PhysicsPhysics
85/10/2006
1st measurement of nuclear dependence in d+Au for forward prompt muons (charm & beauty) at RHIC
And also of light meson decays to muons
• Complementary to quarkonia studies• comparisons help isolate initial-state from final-state physics
• Suppression at large rapidity (small-x shadowing region) – see also physics discussion earlier
• gluon saturation?• leading twist shadowing?• coherence effects?• Sudakov suppression or limiting fragmentation• parton recombination?
• and enhancement at negative rapidity• will be greatly improved by FVTX upgrade
Heavy Quarks with Single Muons
lightmesons
open charm& beauty
led by Ming Liu, Anuj Purwar & Xiaorong Wang
LANLLANL Nuclear Nuclear PhysicsPhysics
95/10/2006
1st ’s at RHIC from ~3pb-1 collected during the 2005 run
• looking for larger signal in run6 & beyond
• also (mid-rapidity) ’s that decay into one muon in each muon arm
• and will extract reliable ’ signal in the high-mass tail of the J/ & on top of the substantial combinatoric background
• all of these will be substantially improved by the FVTX upgrade
Much More to Come!
Analysis done by MJL & Butsyk for QM05
LANLLANL Nuclear Nuclear PhysicsPhysics
105/10/2006
Cold Nuclear Matter at RHIC-II & the LHCRHIC-II – higher luminosity dA & pp program will enable studies of the most rare processes
• accurate J/, ’ & measurements - to solve the physics puzzle in quarkonia production & allow access to gluon saturation• explicit B J/ X and D,B μ measurements with detached vertices provided by the PHENIX Forward Vertex Detector (FVTX) upgrade - to explore saturation & complement the quarkonia measurements and help isolate the physics• also Drell-Yan, single charm pairs, dbar/ubar with W’s
RHIC-II spans the transition region in x for gluon saturation while measurements at the LHC will lie deep in that region
• the LHC pA program would be complementary to that at RHIC-II• but pA remains an upgrade at LHC, with the physics case largely undeveloped, and pA running not likely to occur until 2010 or laterSignal RHIC Exp.
(Au+Au)
RHIC I
(>2008)
RHIC II LHC
ALICE
J/ →e+e
J/ →
PHENIX 3,300
29,000
45,000
395,000
9,500
740,000
→ e+e-
→
STAR
PHENIX
830
80
11,200
1,040
2,600
8,400
MJL co-convenor of RHIC-II Forward/pA Science group
LANLLANL Nuclear Nuclear PhysicsPhysics
115/10/2006
LA-LP-98-56
dbar/ubar > 1 for x2 < 0.25• probably due to meson cloud of proton, i.e. quark counting (p → n + π+ → n + dbar-u)• does gluon splitting dominate at larger x2 and give dbar=ubar?• lower energy Drell-Yan D/H measurement needed to push to larger x2!• J/ studies could also access dbar/ubar
FNAL E906 (120 GeV) or JPARC (50 GeV)flavor asymmetry of the nucleon to larger x
LANLLANL Nuclear Nuclear PhysicsPhysics
125/10/2006
120 GeV
FNAL E906 (120 GeV) or JPARC (50 GeV)quark energy loss in nuclei
At 800 GeV, the nuclear dependence of Drell-Yan on nuclear targets could not unambiguously separate shadowing and dE/dx effects at low x
• E866 data are consistent with no energy loss (using EKS shadowing)• or Kopeliovich shadowing, Johnson et al. find 2.2 GeV/fm from the same data
• for 120 or 50 GeV p-A Drell-Yan x > 0.1 & only quark dE/dx remains (no shadowing)• also stronger, dE/dx ~ 1/s• and important for understanding of RHIC data
For Drell-Yan only initial state interactions are important—no final state strong interactions.
LANLLANL Nuclear Nuclear PhysicsPhysics
135/10/2006
Summary of LANL CNM Program
• Cold nuclear matter effects with quarkonia– gluon saturation, energy loss, ...– get new dA run for much higher accuracy ’ &
• Charm and beauty via single muons– complement quarkonia studies– also dbar/ubar via W+/W- at 500 GeV
• RHIC-II to enable rarest probes– Upsilon, Drell-Yan, B J/ X
• dbar/ubar & quark energy loss via Drell-Yan process– at E906/FNAL or JPARC
• Much of RHIC program strengthened by FVTX upgrade
• pA program at the LHC– LHC (in gluon saturation region)– RHIC-II (covers transition)
LANLLANL Nuclear Nuclear PhysicsPhysics
145/10/2006
Nucleon Sea Asymmetry & Parton Energy Loss at JPARC?(descendent of E866/NuSea at FNAL)
DRAFT Proposal