  Correlations and fluctuations between produced particles in an
ultra-relativistic nuclear collision remain one of the successor to understand
the basics of the particle production mechanism. More differential tools like
Forward-Backward (FB) correlations between particles from two different
phase-space further strengthened our cognizance. We have studied the strength
of FB correlations in terms of charged particle multiplicity and summed
transverse momentum for proton-proton ($pp$) and proton-lead ($pPb$) collisions
at the centre-of-mass energies $\sqrt{s}$ = 13 TeV and $\sqrt{s_{\rm NN}}$ =
5.02 TeV respectively for the EPOS3 simulated events with hydrodynamical
evolution of produced particles. Furthermore, the correlation strengths are
separately obtained for the particles coming from the core and the corona. FB
correlation strengths are examined as a function of psedorapidity gap
($\eta_{gap}$), psedorapidity window-width ($\delta\eta$), centre-of-mass
energy ($\sqrt{s}$), minimum transverse momentum ($p_{Tmin}$) and different
multiplicity classes following standard kinematical cuts used by the ALICE and
the ATLAS experiments at the LHC for all three EPOS3 event samples. EPOS3 model
shows a similar trend of FB multiplicity and momentum correlation strengths for
both $pp$ \& $pPb$ systems, though the correlation strengths are found to be
larger for $pPb$ system than $pp$ system. Moreover, $\delta\eta$-weighted
average of FB correlation strengths as a function of different center-of-mass
energies for $pp$ collisions delineates a tendency of saturation at very high
energies.
