Origins of collectivity in small systems

Abstract

We review recent developments in the theoretical description and understanding of multi-particle correlation measurements in collisions of small projectiles (p/d/${}^3$He) with heavy nuclei (Au, Pb) as well as proton+proton collisions. We focus on whether the physical processes responsible for the observed long range rapidity correlations and their azimuthal structure are the same in small systems as in heavy ion collisions. In the latter they are interpreted as generated by the initial spatial geometry being transformed into momentum correlations by strong final state interactions. However, explicit calculations show that also initial state momentum correlations are present and could contribute to observables in small systems. If strong final state interactions are present in small systems, recent developments show that results are sensitive to the shape of the proton and its fluctuations.

9 pages, 2 figures, Proceedings of the XXVIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2017) Chicago, February 6-11, 2017, references updated

References in corpus (30)

• The Color Glass Condensate
• Event-by-event gluon multiplicity, energy density and eccentricities at RHIC and LHC
• One fluid to rule them all: viscous hydrodynamic description of event-by-event central p+p, p+Pb and Pb+Pb collisions at $\sqrt{s}=5.02$ TeV
• Elliptic and triangular flow in p+Pb and peripheral Pb+Pb collisions from parton scatterings
• Imprints of fluctuating proton shapes on flow in proton-lead collisions at the LHC
• Explanation of systematics of CMS p+Pb high multiplicity di-hadron data at ${\sqrt{s}}_{\mathrm{NN}}=5.02$ TeV
• Eccentric protons? Sensitivity of flow to system size and shape in p+p, p+Pb and Pb+Pb collisions
• Revealing proton shape fluctuations with incoherent diffraction at high energy
• Angular Correlations in Gluon Production at High Energy
• Collectivity and electromagnetic radiation in small systems
• Mass ordering of spectra from fragmentation of saturated gluon states in high multiplicity proton-proton collisions
• High energy factorization in nucleus-nucleus collisions II - Multigluon correlations
• Do nuclear collisions create a locally equilibrated quark-gluon plasma?
• High energy factorization in nucleus-nucleus collisions III. Long range rapidity correlations
• Azimuthal asymmetries and the emergence of "collectivity" from multi-particle correlations in high-energy pA collisions
• Long-range azimuthal correlations in proton-proton and proton-nucleus collisions from the incoherent scattering of partons
• Two-particle correlations in high energy collisions and the gluon four-point function
• Initial state angular asymmetries in high energy p+A collisions: spontaneous breaking of rotational symmetry by a color electric field and C-odd fluctuations
• Azimuthal harmonics of color fields in a high energy nucleus
• Exploring correlations in the CGC wave function: odd azimuthal anisotropy
• Transverse momentum fluctuations in ultrarelativistic Pb+Pb and p+Pb collisions with wounded quarks
• Divergence of the Chapman-Enskog expansion in relativistic kinetic theory
• Collective effects in light-heavy ion collisions
• High order cumulants of the azimuthal anisotropy in the dilute-dense limit: Connected graphs
• Perturbative QCD and beyond: azimuthal angle correlations in deuteron-deuteron scattering from Bose-Einstein correlations
• Flow in small and large quark-gluon plasma droplets: the role of nucleon substructure
• CGC/saturation approach for high energy soft interactions: `soft' Pomeron structure and $v_n$ in hadron and nucleus collisions from Bose-Einstein correlation
• Hydrodynamic modeling of heavy-ion collisions
• Proton structure fluctuations: constraints from HERA and applications to p+A collisions
• PHENIX Overview

Cited by in corpus (21)

• The Large Hadron-Electron Collider at the HL-LHC
• Estimating initial state and quark-gluon plasma medium properties using a hybrid model with nucleon substructure calibrated to $p$-Pb and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV
• Predictions for Cold Nuclear Matter Effects in $p+$Pb Collisions at $\sqrt{s_{{}_{NN}}}=8.16$ TeV
• Bayesian parameter estimation for relativistic heavy-ion collisions
• Particle correlations from the initial state
• Multiparticle production in proton-nucleus collisions beyond eikonal accuracy
• Hot spots and gluon field fluctuations as causes of eccentricity in small systems
• Multi-particle production in proton-nucleus collisions in the Color Glass Condensate
• Influence of initial-state momentum anisotropy on the final-state collectivity in small collision systems
• Finite width effects on the azimuthal asymmetry in proton-nucleus collisions in the Color Glass Condensate
• Collectivity in large and small systems formed in ultrarelativistic collisions
• Initial conditions of bulk matter in ultrarelativistic nuclear collisions
• Quasi equilibrium state of expanding quantum fields and two-pion Bose-Einstein correlations in $pp$ collisions at the LHC
• A resummed method of moments for the relativistic hydrodynamic expansion
• Response relation in Pb-Pb and p-Pb collisions at 5.02 TeV
• Thermalization & hydrodynamics in Bjorken & Gubser flows
• Collective behavior in small systems
• The onset of fluid-dynamical behavior in relativistic kinetic theory
• Heavy flavour measurements with the ALICE experiment at the LHC
• Jet modifications in event-by-event hydrodynamically evolving media
• Event-shaped-dependent cumulants in p-Pb collisions at 5.02 TeV