  Two-particle transverse momentum differential correlators, recently measured
in Pb--Pb collisions at energies available at the CERN Large Hadron Collider
(LHC), provide an additional tool to gain insights into particle production
mechanisms and infer transport properties, such as the ratio of shear viscosity
to entropy density, of the medium created in Pb-Pb collisions. The longitudinal
long-range correlations and the large azimuthal anisotropy measured at low
transverse momenta in small collision systems, namely pp and p-Pb, at LHC
energies resemble manifestations of collective behaviour. This suggests that
locally equilibrated matter may be produced in these small collision systems,
similar to what is observed in Pb-Pb collisions. In this work, the same
two-particle transverse momentum differential correlators are exploited in pp
and p-Pb collisions at $\sqrt{s} = 7$ TeV and $\sqrt{s_{\rm NN}} = 5.02$ TeV,
respectively, to seek evidence for viscous effects. Specifically, the strength
and shape of the correlators are studied as a function of the produced particle
multiplicity to identify evidence for longitudinal broadening that might reveal
the presence of viscous effects in these smaller systems. The measured
correlators and their evolution from pp and p--Pb to Pb--Pb collisions are
additionally compared to predictions from Monte Carlo event generators, and the
potential presence of viscous effects is discussed.
