Heavy Ion Collisions: The Big Picture, and the Big Questions

Heavy ion collisions quickly form a droplet of quark–gluon plasma (QGP) with a remarkably small viscosity. We give an accessible introduction to how to study this smallest and hottest droplet of liquid made on Earth and why it is so interesting. The physics of heavy ion collisions ranges from highly energetic quarks and gluons described by perturbative QCD to a bath of strongly interacting gluons at lower energy scales. These gluons quickly thermalize and form QGP, while the energetic partons traverse this plasma and end in a shower of particles called jets. Analyzing the final particles in various ways allows us to study the properties of QGP and the complex dynamics of multiscale processes in QCD that govern its formation and evolution, providing what is perhaps the simplest form of complex quantum matter that we know of. Much remains to be understood, and throughout the review big open questions are encountered.

Note:

49 pages, 9 figures. Invited review prepared for Annual Review of Nuclear and Particle Science 68 (2018)

quark-gluon plasma
heavy-ion collisions
relativistic hydrodynamics
jets
multiparticle production
quark–gluon plasma
heavy ion collisions
gluon: interaction
quark gluon: plasma
liquid: droplet

References(183)

Figures(9)

[1]

Quark-gluon plasma: From big bang to little bang

- Camb.Monogr.Part.Phys.Nucl.Phys.Cosmol. 23 (2005) 1-446,
- Cambridge, UK: Univ. Pr. (2005) 446 p,
- (Cambridge monographs on particle physics, nuclear physics and cosmology. 23)

[2]

Phenomenology of Ultra-Relativistic Heavy-Ion Collisions

Wojciech Florkowski
(
- Jan Kochanowski U. and
- Cracow, INP
)

- Singapore, Singapore: World Scientific (2010) 416 p

[3]

Quark-Gluon Plasma 5

Xin-Nian Wang
(
- CCNU, Wuhan, Inst. Part. Phys. and
- LBL, Berkeley
)
(ed.)

DOI:
- 10.1142/9533

[4]

Bulk Properties of Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV measured by ALICE

ALICE

Collaboration

•

Alberica Toia
(
- CERN
)

for the collaboration.

- J.Phys.G 38 (2011) 124007
•
e-Print:
- 1107.1973
•
DOI:
- 10.1088/0954-3899/38/12/124007

[5]

Collective flow and viscosity in relativistic heavy-ion collisions

Ulrich Heinz
(
- Ohio State U.
)
,
Raimond Snellings
(
- Utrecht U.
)

- Ann.Rev.Nucl.Part.Sci. 63 (2013) 123-151
•
e-Print:
- 1301.2826
•
DOI:
- 10.1146/annurev-nucl-102212-170540

[6]

Relativistic Fluid Dynamics In and Out of Equilibrium

Paul Romatschke
(
- Colorado U.
)
,
Ulrike Romatschke
(
- Colorado U. and
- NCAR, Boulder
)

•
e-Print:
- 1712.05815
•
DOI:
- 10.1017/9781108651998

[7]

Gravitational collisions and the quark-gluon plasma

Wilke van der Schee
(
- Utrecht U.
)

e-Print:
- 1407.1849

[8]

Y.-J. Lee
,
A.S. Yoon
,
W. Busza

- http://web.mit.edu/mithig/movies/LHCanmation.mov

[9]

Energy Deposition in High-energy Proton Nucleus Collisions

W. Busza
(
- MIT, LNS
)
,
R. Ledoux
(
- MIT, LNS
)

- Ann.Rev.Nucl.Part.Sci. 38 (1988) 119-159
•
DOI:
- 10.1146/annurev.ns.38.120188.001003

[10]

NUCLEAR STOPPING POWER

Wit Busza
(
- MIT, LNS
)
,
Alfred S. Goldhaber
(
- SUNY, Stony Brook
)

- Phys.Lett.B 139 (1984) 235,
- Phys. Lett. B144 (1984) 455. ( Phys. Lett. B139 (1984) 235)
•
DOI:
- 10.1016/0370-2693(84)91070-0

[11]

Chiral magnetic and vortical effects in high-energy nuclear collisions—A status report

D.E. Kharzeev
(
- Brookhaven and
- SUNY, Stony Brook and
- RIKEN BNL
)
,
J. Liao
(
- Indiana U. and
- Indiana U., CEEM and
- RIKEN BNL
)
,
S.A. Voloshin
(
- Wayne State U.
)
,
G. Wang
(
- UCLA
)

- Prog.Part.Nucl.Phys. 88 (2016) 1-28
•
e-Print:
- 1511.04050
•
DOI:
- 10.1016/j.ppnp.2016.01.001

[12]

The Physics of Ultraperipheral Collisions at the LHC

A.J. Baltz
(
- Brookhaven
)
,
G. Baur
(
- Julich, Forschungszentrum
)
,
D. d'Enterria
(
- CERN
)
,
L. Frankfurt
(
- Tel Aviv U.
)
,
F. Gelis
(
- Saclay, SPhT
)

et al.

- Phys.Rept. 458 (2008) 1-171
•
e-Print:
- 0706.3356
•
DOI:
- 10.1016/j.physrep.2007.12.001

[13]

Production of Meson Showers

W. Heisenberg
(
- Gottingen, Max Planck Inst.
)

- Nature 164 (1949) 65-66
•
DOI:
- 10.1038/164065c0

[14]

THEORY OF COSMIC RAY MESONS

- Phys.Rev. 64 (1943) 78-94,
- In *Peking Inst. Theor. Phys. Acad. Sin. ( Ed.): Selected Works Of Peng Huan-wu*, 112-128
•
DOI:
- 10.1103/PhysRev.64.78

[15]

E. Fermi

- Prog.Theor.Phys. 5 (1950) 570

[16]

On the multiparticle production in high-energy collisions

L.D. Landau

- Izv.Akad.Nauk Ser.Fiz. 17 (1953) 51-64

[17]

Very high-energy collisions of hadrons

Richard P. Feynman
(
- Caltech
)

- Phys.Rev.Lett. 23 (1969) 1415-1417,
•
DOI:
- 10.1103/PhysRevLett.23.1415

[18]

Full result for the QCD equation of state with 2+1 flavors

Szabocls Borsanyi
(
- Wuppertal U.
)
,
Zoltan Fodor
(
- Wuppertal U. and
- Julich, Forschungszentrum and
- Eotvos U.
)
,
Christian Hoelbling
(
- Wuppertal U.
)
,
Sandor D. Katz
(
- Eotvos U.
)
,
Stefan Krieg
(
- Wuppertal U. and
- Julich, Forschungszentrum
)

et al.

- Phys.Lett.B 730 (2014) 99-104
•
e-Print:
- 1309.5258
•
DOI:
- 10.1016/j.physletb.2014.01.007

[19]

Equation of state in ( 2+1 )-flavor QCD

HotQCD

Collaboration

•

A. Bazavov
(
- Iowa U.
)

et al.

- Phys.Rev.D 90 (2014) 094503
•
e-Print:
- 1407.6387
•
DOI:
- 10.1103/PhysRevD.90.094503

[20]

Gauge/String Duality, Hot QCD and Heavy Ion Collisions

Jorge Casalderrey-Solana
(
- CERN
)
,
Hong Liu
(
- MIT, LNS
)
,
David Mateos
(
- Barcelona U. and
- ICC, Barcelona U. and
- ICREA, Barcelona
)
,
Krishna Rajagopal
(
- MIT, LNS
)
,
Urs Achim Wiedemann
(
- CERN
)

- ,
- ,
- book:Gauge/String Duality, Hot QCD and Heavy Ion Collisions. Cambridge, UK: Cambridge University Press, 2014
•
e-Print:
- 1101.0618
•
DOI:
- 10.1017/9781009403504