Momentum-dependent flow fluctuations as a hydrodynamic response to initial geometry

Agradecimentos: This research was funded by FAPESP grants number 2016/13803-2 (D.D.C.), 2016/24029-6 (M.L.), 2017/05685-2 (all), 2018/01245-0 (T.N.dS.) and 2018/07833-1(M.H.). D.D.C., M.L., J.N., and J.T. thank CNPq for financial support. We also acknowledge computing time provided by the Research Computing Support Group at Rice University through agreement with the University of São Paulo Abstract: We propose a redefinition of the principal component analysis (PCA) of anisotropic flow that makes it more directly connected to fluctuations of the initial geometry of the system. Then, using state-of-the-art hydrodynamic simulations, we make an explicit connection between flow fluctuations and a cumulant expansion of the initial transverse geometry. In particular, we show that the second principal component of elliptic flow is generated by higher-order cumulants, and therefore probes smaller length scales of the initial state. With this information, it will be possible to put new constraints on properties of the early-time dynamics of a heavy-ion collision, including small-scale structure, as well as properties of the quark-gluon plasma FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ Fechado