Collectivity in Ultra-Peripheral Pb+Pb Collisions at the Large Hadron Collider

Abstract

We present the first full (3+1)D dynamical simulations of ultra-peripheral Pb+Pb collisions at the Large Hadron Collider. Extrapolating from p+Pb collisions, we explore whether a quasi-real photon γ * interacting with the lead nucleus in an ultra-peripheral collision can create a manybody system exhibiting fluid behavior. Assuming strong final-state interactions, we provide model results for charged hadron multiplicity, identified particle mean transverse momenta, and charged hadron anisotropic flow coefficients, and compare them with experimental data from the ALICE and ATLAS collaborations. The elliptic flow hierarchy between p+Pb and γ * +Pb collisions is dominated by the difference in longitudinal flow decorrelations and reproduces the experimental data well. We have demonstrated that our theoretical framework provides a quantitative tool to study particle production and collectivity for all system sizes, ranging from central heavy-ion collisions to small asymmetric collision systems at the Relativistic Heavy-Ion Collider and the Large Hadron Collider and even at the future Electron-Ion Collider.

Conservation Laws and Hydrodynamics

“…On the subject of nonolinear causality conditions, Plumberg [6] presented his and collaborators' work. On the development of hydro initial states, Shen [7] presented recent developments for ultra-peripheral collisions and Kanakubo [8] presented her recent work on the core-corona model. On applying hydrodynamics to systems near the QCD critical point, Pradeep [9], Wu [10], and Sogabe [11] presented their work in this conference.…”

CGC for ultra-peripheral Pb+Pb collisions at the Large Hadron Collider: a more realistic calculation

“…Within the Color Glass Condensate approach, the scattering and central rapidity particle production in photon-nucleus collisions pose yet another challenge (see ref. [16] for hydrodynamic approach to UPC). At the moment, the two -particle production was only studied in the forward, photon going direction [17], which is not appropriate to describe the central rapidity production for two reasons.…”