  The analysis of azimuthal correlations in multiparticle production can be
useful to uncover the existence of new physics beyond the Standard Model, e.g.,
Hidden Valley, in $e^+e^-$ annihilation at high energies. In this paper, based
on previous theoretical studies and using PYTHIA8 event generator, it is found
that both azimuthal and rapidity long-range correlations are enhanced due to
the presence of a new stage of matter on top of the QCD partonic cascade. Ridge
structures, similar to those observed at the LHC, show up providing a possible
signature of new physics at future $e^+e^-$ colliders.
