$p_T$-dependent multiplicity fluctuations from PCA and initial conditions

Fernando G. Gardim (1) , Frédérique Grassi , Pedro Ishida , Matthew Luzum , Jean-Yves Ollitrault (1)

1 IPHT - Institut de Physique Théorique - UMR CNRS 3681

We present a Principal Component Analysis for a hydrodynamic simulation and compare with CMS experimental data. While the results are reasonable for anisotropic flow, for multiplicity fluctuations they are qualitatively different. We argue that this is due to too large transverse momentum ( p T ) fluctuations and N − p T covariance in the simulation than seen experimentally. In turn this is related to too large initial size fluctuations.

Mots clés: Collective flow; Particle correlations and fluctuations; multiplicity: fluctuation; flow: anisotropy; principal component analysis; transverse momentum dependence; boundary condition; hydrodynamics; covariance; CMS

Domaines: Physique Nucléaire Théorique [nucl-th]

Fernando G. Gardim, Frédérique Grassi, Pedro Ishida, Matthew Luzum, Jean-Yves Ollitrault. $p_T$-dependent multiplicity fluctuations from PCA and initial conditions. 28th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions, Nov 2019, Wuhan, China. pp.121892, ⟨10.1016/j.nuclphysa.2020.121892⟩. ⟨hal-02491254⟩