1. The Future of RHIC SQM2016
Berndt Mueller
July 1, 2016

2. A reporter calls
“I’ve been poking around the idea of a story about how studying quark-gluon plasmas
can help us figure out some of the big mysteries of matter – namely how gluons do their
binding to give nucleons their mass and other familiar properties. I think that could make
for a compelling story, so long as I can make the case that we really are learning some cool
and surprising things about how matter came to be (the transition from a quark-gluon broth
to hadrons) and, perhaps, why it doesn’t all fall apart.  
I’m particularly keen to get a grip on what we have already discovered by studying QGPs:
for instance, what have we learned about how quarks and gluons are bound by watching
QGPs as they cool? And what other important insights have come from studying QGP?
Right now I’m struggling to pin down the key insights.
I need to understand what we’re learning by creating QGPs and, say, watching them
cool to study confinement in reverse – that is, what we’re discovering about how gluons
bind quarks, and how that might help with the missing mass problem and/or other questions,
and how we plan to discover more in the future.“
Daniel Cossins (New Scientist Magazine) June 27,2016
We may not have the answers to his questions, but we have some cool answers to other questions. And we have a plan to discover more in the future….

3. 2015 Long Range Plan RECOMMENDATION I
The progress achieved under the guidance of the 2007 Long Range Plan has reinforced U.S. world leadership in nuclear science. The highest priority in this 2015 Plan is to capitalize on the investments made.
Complete and run CEBAF 12 GeV upgrade
Complete FRIB at MSU
Targeted program in neutrinos and fundamental symmetries
The upgraded RHIC facility provides unique capabilities that must be utilized to explore the properties and phases of quark and gluon matter in the high temperatures of the early universe and to explore the spin structure of the proton.

4. Completing the RHIC science mission
Explore and probe the microscopic structure of the liquid QGP using energetic (or massive) probes:
Heavy (c and b) quarks
Heavy quarkonia (charmonium and Upsilon)
Quark and gluon jets
Map and explore the QCD phase diagram
Use change of beam energy to vary (μB,T) location in phase diagram
Discover predicted topological transitions in the QCD vacuum
Isobar system (ΔZ=4) test to confirm Z2 magnetic field dependence of parity violating fluctuations in chirally symmetric QGP
Exploratory study of transverse spin dynamics in p+p
Insights will enable more reliable predictions for the EIC physics program

5. The RHIC Facility today
PHENIX
STAR

6. RHIC is versatile

7. Recent Results

8. Heavy Quark Transport in the QGP
Hadrons containing c quarks show signs of collective flow
Top: The picture shows that for the first time, we are able to directly reconstruct the
heavy-flavor D0 meson decay topology in heavy-ion collisions at very low momentum
with a new type of silicon vertex detector.
Heavy-Flavor is a sensitive probe of Quark-Gluon Plasma through Brownian motion-like
study.
Bottom: One of the amazing things about high-energy heavy-ion collisions is that in a volume about one-trillionth that of an atom, at a temperature of several trillion degrees, and existing for about a trillionth of a trillionth of a second we are creating a substance with material properties — like viscosity -- that we can actually measure. We're able to use hydrodynamic calculations -- 21st century versions of the ones you'd use to determine the flow of water around a ship -- to relate the pattern of where energy *is* at the beginning of a nucleus-nucleus collision to the pattern of where it is *going* at the end of the collision. The better a fluid is, the more “perfect" it is, the more faithfully it converts fine details of the initial energy density to fine modulations in the momenta of particles flying out of the collision. This gives us the best tool we have to give a quantitative answer to the question, "How perfect a fluid is the quark-gluon plasma?"
In the last couple of years, it has become clear that in certain circumstances the quark-gluon plasma can be created in even in very small collisions (like, for instance, protons hitting a gold nucleus). The fantastic thing about this is that it has provided us a way to manipulate the initial pattern of energy deposited in a “small smashing into big" collision. A proton (one nucleon), or a deuteron (two nucleons) or a helium-3 nucleus (three nucleons) hitting a gold nucleus can produce the distinctly different arrangements of initial "hot spots" as shown in the plot of the calculation by Bjoern Schenke I sent you. Seeing how those spots of initial energy are translated into modulations of particle momenta provides crucial insights into the physics at play during the collision. For instance, is there important physics *before* hydrodynamic behavior sets in? How much do strong correlations among gluons in the dense initial state contribute to what we see?
I changed the title of this slide from "RHIC Science Highlights" to "Hydrodynamics of the Perfect Fluid"
One of the ways we measure the properties of the fluid is by measuring its hydrodynamics. How do the particles that result from the collisions flow across the melted matter, the QGP, and emerge? We determine the hydrodynamics by using well- known ideas from thermal physics and statistical mechanics extrapolated to these conditions. 
(More graphically: One of the amazing things about high-energy heavy-ion collisions is that in a volume about one-trillionth that of an atom, at a temperature of several trillion degrees, and existing for about a trillionth of a trillionth of a second we are creating a substance with material properties — like viscosity -- that we can actually measure. We're able to use hydrodynamic calculations -- 21st century versions of the ones you'd use to determine the flow of water around a ship -- to relate the pattern of where energy *is* at the beginning of a nucleus-nucleus collision to the pattern of where it is *going* at the end of the collision. The better a fluid is, the more “perfect" it is, the more faithfully it converts fine details of the initial energy density to fine modulations in the momenta of particles flying out of the collision. This gives us the best tool we have to give a quantitative answer to the question, "How perfect a fluid is the quark-gluon plasma?")
In the upper left, we show the sensitivity of the upgraded PHENIX experiment to D0 mesons—one of the particles that results from the collisions. D0s consist of heavy quarks. The way they traverse the fluid, interacting with and being altered by it, offers a way to probe the fluid properties. The breakthrough here is a technical one— increasing our sensitivity to D0 mesons thereby permitting us to study their interactions with the heavy quarks, and make inferences about the fluid. These experiments are ongoing.
Correct, Strictly speaking, we are not measuring here the hydrodynamics of the fluid flow itself, but the transport properties relating to heavy quarks, like a fish swimming through water.
In the last couple of years, it has become clear that in certain circumstances the quark- gluon plasma can be created in even in very small collisions (like, for instance, protons hitting a gold nucleus). The fantastic thing about this is that it has provided us a way to manipulate the initial pattern of energy deposited in a “small smashing into big" collision. A proton (one nucleon), or a deuteron (two nucleons) or a helium-3 nucleus (three nucleons) hitting a gold nucleus can produce the distinctly different arrangements of initial "hot spots" as shown in the plot of the calculation by Bjoern Schenke I sent you. Seeing how those spots of initial energy are translated into modulations of particle momenta provides crucial insights into the physics at play during the collision. For instance, is there important physics *before* hydrodynamic behavior sets in? How much do strong correlations among gluons in the dense initial state contribute to what we see?
The figure on the lower right shows measurements of the Fourier components of the momenta that give a quantitative view of how the emerging particles are influenced by their interactions with the fluid.
The remarkable aspect here is that it seems to work perfectly for a very small projectile (3He) that produces a very small QGP droplet.
OK, enough preamble, here are some words. Let me know if they’re simple enough.
How the initial pattern of energy deposition in a nuclear collision turns into a final pattern of momentum tells us how "perfect" a fluid the quark-gluon plasma is. By studying collisions of one, or two, or three nucleons with a gold nucleus we can carry out a series of controlled experiments in which we deliberately vary the pattern of energy deposition. Calculations of those initial patterns are shown in the plot by Bjoern Schenke. The final week of the 2014 run was devoted to collisions of helium-3 nuclei with gold nuclei. We already have deuteron on gold data from 2008, and we’re currently taking proton on gold data right now. RHIC is the only accelerator with the versatility to do this complete systematic study. We perform a “Fourier transform" of the pattern of momentum coming out of the collision, and then we talk about the pattern in terms of "Fourier coefficients”. The coefficient "v2" tells you how elliptic the pattern is, "v3” tells how how triangular it is, and so on. The PHENIX plot shows experimentally obtained values of v2 and v3, plotted versus particle momentum, from the 2014 helium-3 on gold data. The curves represent various state-of-the-art calculations, each emphasizing different contributing physics. Not only is it impressive that all curves generally reproduce the data -- the similarities and differences between them provide key insights into the physics of the quark-gluon plasma.
Both b and c quarks are suppressed at large pT
Small heavy quark diffusion constant confirms strong coupling of QGP at different scale from hydrodynamics.

9. What is the smallest drop of QGP?
Data-Theory comparison confirms hydrodynamic collective flow
Initial
state
Final
state

10. Interaction between two antiprotons
Nature 527,
345 (2015)
We report two key parameters that characterize the corres-ponding strong interaction: the scattering length and the effective range of the interaction
By applying a technique similar to Hanbury-Brown and Twiss intensity interferometry, we show that the force between two antiprotons is attractive.

11. RHIC

12. Completing the RHIC science mission
Status: RHIC-II configuration is operational
RHIC reaches 44 times design luminosity
Plan:
2016: Completion of heavy flavor program
2017: Transverse spin physics in QCD
2018: Isobar system test of chiral symmetry
2018: Low energy e-cooling & iTPC upgrade
2019/20: High precision scan of the QCD phase diagram & search for critical point
2021: Install sPHENIX
2022-??: Probe structure of perfect liquid QGP with precision measurements of jet quenching and Upsilon suppression
LEReC
STAR HFT
The suite of upgrades of the RHIC accelerator and its detectors is now complete: The beam intensity of RHIC has been vastly increase thanks to 3-dimensional stochastic cooling, and the STAR and PHENIX detectors have been equipped with silicon vertex detectors that permit the identification of rapidly decaying heavy (charm and bottom) quarks. The integrated luminosity reach in this year’s RHIC run with gold beams exceeded that achieved in all 13 previous RHIC runs combined!
Our plan is now to complete the scientific mission of RHIC in 3 multi-year campaigns: In we will probe the properties of the strongly coupled QGP using heavy quarks, which are especially well suited to explore its interactions. After installing a new type of cooling more effective at low beam energies, using electrons as the cooling medium, in 2017, we will perform a high precision scan of the QCD phase diagram in One objective of this campaign is to find and locate a conjectured critical point in the phase diagram. We will then upgrade the PHENIX detector to a more powerful configuration, named superPHENIX, which will allow RHIC to perform precision measurements in of the interactions of quark jets and atoms of heavy quarks called quarkonia with the quark-gluon plasma. These probes will help us elucidate the internal structure of the quark-gluon plasma. We then plan to shut RHIC down and transition the RHIC complex to an electron-ion collider facility (eRHIC) to begin operations as early as 2025, budgets permitting.
For the next several years, however, RHIC will remain an extraordinarily productive, unique discovery facility producing approximately 30 PhDs per year and garnering more than 3,000 citations of its scientific publications.
sPHENIX
RHIC remains a unique discovery facility

13. Run-16 High luminosity 200 GeV Au+Au run (11 weeks)
Study heavy flavor flow, especially charmed baryons, parton energy loss in QGP, quarkonium studies (for NP milestone DM12)
PHENIX exceeded its luminosity goal
STAR reached its MB goal (2B events)
(in spite of 19-day interruption!)
d+Au beam energy scan (5 weeks)
Study beam energy dependence of small system collectivity and QGP properties
d+Au 200 GeV, 62.4 GeV, 39 GeV, 19.6 GeV completed
Statistics goals reached or exceeded (PHENIX and STAR)
1.8 nb-1 narrow vertex
15 weeks only pp

14. Run-17 Plan Run-18 Plan Strongly endorsed by 2016 RHIC PAC.
High luminosity 510 GeV transverse polarized p+p run (13 weeks)
Study scale evolution of the Sivers effect in W-boson production; possibly confirm sign change of the Sivers effect relative to DIS
Proof of Principle test of coherent electron cooling (1 week)
Run-18 Plan
Isobar system (96Ru - 96Zr) run (8 weeks)
Critical signature of Chiral Magnetic Effect
15 weeks only pp
Strongly endorsed by 2016 RHIC PAC.

15. W Sivers function (Run-17)
Phys. Rev. Lett. 116 (2016)

16. Probing Chiral Symmetry with Quantum Currents
The chiral anomaly of QCD creates differences in the number of left and right handed quarks.
In a chirally symmetric QGP, this imbalance can create charge separation along the magnetic field (chiral magnetic effect – just discovered in CM at BNL)
A similar mechanism in the electroweak theory is likely responsible for the matter/antimatter asymmetry of our universe
charge separation
observed at all but the lowest energy
B=1018 Gauss +
Something that ties together a wide range of topics in QCD: How do collective, many body phenomena arise from QCD. -
But models with magnetic field-independent flow backgrounds can also be tuned to reproduce the observed charge separation.

17. Probing Chiral Symmetry (Run-18)
Current understanding: backgrounds unrelated to the chiral magnetic effect may be able to explain the observed charge separation
Relative difference in charge separation (Ru vs Zr)
Something that ties together a wide range of topics in QCD: How do collective, many body phenomena arise from QCD.
Isobar collisions will tell us what fraction of the charge separation is due to CME to within +/- 6% of the observed signal

18. Beam Energy Scan II

19. STAR Upgrades for BES II
iTPC upgrade (2018) Replace inner TPC Sectors
Extend rapidity coverage
Better particle ID
Low pT coverage
Event Plane Detector (2018)
Improved Event Plane Resolution
Centrality definition
Improved trigger
Background rejection

20. Studying the Phases of QCD with RHIC
A unique RHIC capability -- a unique opportunity for U.S. science
Quark Gluon Plasma
Breaking of chiral symmetry in QCD generates most of the visible mass of the universe. Is chiral symmetry restored in these collisions?
At low density, the phase transition between QGP and hadrons is smooth. Is there a 1st order transition and a critical point at higher density?

21. Critical Behavior: Anomalies in the Pressure?
Maximum in lifetime?
Minimum in pressure?
Region of interest √sNN≲20 GeV, however, is complicated by a changing B/M ratio, baryon transport dynamics, longer nuclear crossing times, etc.
Requires concerted modeling effort: the work of the BESTheory topical collaboration is essential

22. Critical behavior
The moments of the distributions of conserved charges are related to susceptibilities and are sensitive to critical fluctuations
Higher moments like kurtosis*variance κσ2 change sign near the critical point
Non-monotonic trend observed in BES-I with limited statistical precision!

23. Mapping the QCD phase diagram in BES-II
Higher statistics
Low energy RHIC electron cooling upgrade
Larger acceptance

24. sPHENIX

25. The overarching scientific question:
How do asymptotically free quarks and gluons
create the near-perfect liquidity of the QGP? or
What degrees of freedom
not manifest in the QCD Lagrangian 
produce the near-perfect liquidity of the QGP?
The (experimental) answer:
Deploy probes with a resolution that reaches well below the thermal ~ 1 fm scale of the bulk:
Jets & b-quark (Upsilon) states

26. The RHIC Facility in 2022 s

27. Probing scales in the medium
How does the perfect fluidity of the QGP emerge from the asymptotically free theory of QCD?
Jets probe sub-thermal length scales
LHC
RHIC
Upsilon states probe thermal length scales

28. Complete calorimetric
Jets & Upsilon states
sPHENIX
capabilities
Complete calorimetric
jet spectroscopy
Completely resolved
Upsilon spectroscopy

29. RHIC & LHC complementarity

30. The Future of RHIC is Bright !
I hope you will be part of it.