Soft Physics of p+Pb and Pb+Pb Collisions from the ATLAS Experiment at the LHC

Physics of p+Pb and Pb+Pb collisions at the LHC covered with the ATLAS detector ranges from the studies of a relatively soft sector to the studies of the products of the hard scatterings. In the sector of low transverse momenta, the main areas of interest are the charged particle multiplicities and their scaling with the number of participating nucleons. Studied in details are also the collective phenomena arising from the initial collision shape and maintained by the hydrodynamical system evolution from the initial hard scattered quarks and gluons to the hadronized particles. Recent ATLAS results on the total charged particle multiplicities and spectra in p+Pb will be reviewed. The observation of the elliptic flow in the p+Pb will be also presented supplemented with the novel results on the flow coefficients fluctuations and their relation to the initial state of Pb+Pb collisions.