  Collective flow and femtoscopy in ultrarelativistic 3He-Au collisions are
investigated within the 3+1-dimensional (3+1D) viscous event-by-event
hydrodynamics. We evaluate elliptic and triangular flow coefficients as
functions of the transverse momentum. We find the typical long-range ridge
structures in the two-particle correlations in the relative azimuth and
pseudorapidity, in the pseudorapidity directions of both Au and 3He. We also
make predictions for the pionic interferometric radii, which decrease with the
transverse momentum of the pion pair. All features found hint on collectivity
of the dynamics of the system formed in 3He-Au collisions, with hydrodynamics
leading to quantitative agreement with the up-to-now released data.
