1. New cold nuclear matter constraints from J/ψ suppression in d+Au at PHENIX
L. A. Linden Levy
for the PHENIX collaboration
Department of Physics
390 UCB
University of Colorado
Boulder, CO

2. Why heavy quarkonia?
J/ψ was predicted as an excellent QCD thermometer.
Heavy quark anti-quark pairs allow potential models.
Different states have different binding energies (radii) as the pair is screened they dissociate. → Color Debye screening. (Matsui and Satz).
Corollary: The picture of sQGP has become even more complicated
Cold Nuclear Matter effects
Recombination of uncorrelated heavy flavor.
LQCD predictions of correlations T>TC.
Gluo-disassociation
Detailed balance of J/ψ depletion and restoration is necessary.
1.2 TC
A. Mocsy
9/22/2018
WWND, Jamaica

3. PHENIX Coordinate System
South Arm
Central Arm
North Arm Au d
200GeV d+Au collisions.
Di-Muons recorded via MuTr and MuID in N. & S. arm.
Di-Electrons from Central arm PC, DC, EMCal and RICH.
9/22/2018
WWND, Jamaica

4. Nuclear modification factor.
Suppression due to normal density nuclear matter in d+Au 200GeV (RHIC 2003)
Baseline p+p 200GeV data (RHIC 2005)
Forward
Mid
Backward d Au
Phys Rev C 77, Au d
9/22/2018
WWND, Jamaica

5. Quantitative comparison vs. centrality.
Ncoll dependence of the model from a Glauber inspired geometric model. (R. Vogt hep-ph )‏
Breakup cross section is a free param.
CEM model for x1,x2 (R. Vogt)
Woods-Saxon density profile for Au.
9/22/2018
WWND, Jamaica

6. More about fitting…. Type A: point to point uncorrelated (bars)
Phys Rev C 77,
Type A: point to point uncorrelated (bars)
Type B: point to point correlated (boxes)
Type C: global (relative)
PRC
9/22/2018
WWND, Jamaica

7. Breakup cross section NDSG σ = 0 mb σ = 4 mb EKS σ = 0 mb σ = 4 mb
2008 d+Au J/ψ results from PHENIX
Systematics cancel within a run.
~15X statistics of 2003 data set.
Expect a reduction in the Type A error of ~1/√2.
First look at shadowing predictions based on nPDF calculation (R. Vogt private communication).
Still interpreting the data: no sigma breakup best value yet.
Expect a a PRL publication in the near future.
NDSG
σ = 0 mb
σ = 4 mb
EKS
σ = 0 mb
σ = 4 mb
EPS08
σ = 0 mb
σ = 4 mb
Difficult to account for the forward rapidity with a breakup cross section ~0.
Or something completely different…
9/22/2018
WWND, Jamaica

8. √s=40GeV
Other physics at work?
Note: E866 has x2 range is ~ near the crossover from shadowing to anti-shadowing.
9/22/2018
WWND, Jamaica

9. Quantitative Extraction
@ Fixed y
RCP
Npart
9/22/2018
WWND, Jamaica

10. Rapidity dependence!
Extract best fit to RCP at a given rapidity versus centrality.
Based on predictions from R. Vogt.
Excellent agreement with E866 data versus yCM.
Parametrizes all the effect that shadowing is missing.
T. Frawley ETC, Trento
T. Frawley ECT, Trento
9/22/2018
WWND, Jamaica

11. Extrapolation for HI Corollaries:
A. Suppression of excited states assumed to be the same as J/ψ.
B. Only folded p+A not necessarily clear that CNM effects factorize in HI collisions
Extrapolation when σ(y) allowed (CEM - T. Frawley )
9/22/2018
WWND, Jamaica

12. A long d+Au run (with upgrades) to answer this quantitatively!
Resolves SPS ε question.(?)
9/22/2018
WWND, Jamaica

13. More than shadowing? Production Model? Color Glass Initial State?
CDF puzzle still not resolved!
Color Glass Initial State?
Initial State energy loss?
9/22/2018
WWND, Jamaica

14. Production model? Intrinsic 2 -> 1 RdAu
Softens the result
Does not completely describe forward suppression (shadowing model dependent)
What does this look like for CSM+IC? (arXiv: )
RdAu
Extrinsic 2 -> 2 & model dep.
Lansberg et al. arXiv:
9/22/2018
WWND, Jamaica

15. Coherent Multiple Scattering (CGC)?
Also calculate the backward rapidity? (anti-shadowing as conservation of momentum)
How is this valid for the low energy data at the SPS? “Due to slow energy dependence of Qs”
σpA=Aασpp
9/22/2018
WWND, Jamaica

16. “Guys this is important.”
We use 4 centrality bins, each corresponding to a range of impact parameters.
Therefore the curve and data on the previous slide are not exactly comparable.
One needs to convolute the impact parameter distribution with the theory.
This should reduce the amount of suppression.
We need to get together and make this plot.
“Guys this is important.”
-L. McLerran
9/22/2018
WWND, Jamaica

17. Energy Loss? Data from Drell-Yan at E772 and E866 at Fermilab
Energy loss calculated in target rest frame.
dE/dx = 2.73  0.37  0.5 GeV/fm (from hadronization)
dE/dx ~ 0.2 GeV/fm (from gluon radiation)
“This is the first observation of a non-zero energy loss effect in such experiments.”
Johnson, Kopeliovich, Potashnikova, E772 et al.
Phys. Rev.C 65, (2002) hep-ph/
Phys. Rev. Lett. 86, 4487 (2001) hep=ex/
9/22/2018
WWND, Jamaica

18. Why didn’t this catch on?
Is this the same as CGC?
(CATHIE-INT)
Backward shift in xF leads to a slope in rapidity
CEM with fixed fractional energy loss.
9/22/2018
WWND, Jamaica

19. A puzzle
Parametrized breakup cross section has a strong kinematic dependence on rapidity.
It contains some physics that we have missed with shadowing!
Possible Explanations
Production Mechanism?
“Intrinsic Charm?”– S.Brodsky hep-ph/
Gluon Saturation (CGC) ? Tuchin hep-ph/
Initial State energy loss?
Limiting Fragmentation?
Good News: There is more data coming RdAu(y;pT;b)
9/22/2018
WWND, Jamaica

20. Conclusions
Shadowing does not contain all the physics of d+Au collisions.
Cold nuclear matter effects predict the rapidity difference in HI collisions (still onset of suppression for central collisions)
Experiment:
Increase statistics, reduce systematic uncertainties in the measurements.
Make more measurements (i.e. χC in d+Au)
Theory:
Think about the missing physics.
9/22/2018
WWND, Jamaica

21. BACKUP