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We present a hypothesis that the anomaly in the folding angle distribution ofelectron-positron pairs, emitted in the decay of the excited levels of nucleus$^{8}$Be and $^{4}$He can be related to the cluster structure of the decayingstate. Furthermore, we present a hypothesis that the potentially observed bosonwith re st mass $m_{X}$=17 MeV can mediate the nucleon-nucleon interaction atthe low-energy regime of QCD, in particular in the weakly bound cluster statep+$^{7}$Li,$^{3}$H. We present a possible equations of state of symmetricnuclear matter corresponding to the vector meson mass $m_{v}$=17 MeV, obtainedusing relativistic mean field theory of nuclear force, QHD-I in particular,with physically relevant incompessibility K$_{0}$=240-260 MeV and the values ofcouplings $g_{v}$, $g_{s}$ lower than unity. Based on concepts of chiralsymmetry breaking, we show that reduction of the rest mass of pseudoscalarparticle from physical value $m_{\pi}$=135 MeV to $m_{X}$=17 MeV is equivalentto reduction of the quark mass from dynamical value around 310 MeV down tocurrent quark mass around 5 MeV ($\frac{m_{X}^2} {m_{q,curr}} \simeq\frac{m_{\pi}^2} {m_{q,dyn}}$). Corresponding version of Goldberger-Treimanrelation leads to the value of coupling close to the results from relativisticmean field theory of nuclear force. Both model approaches thus point towardsapparent restoration of chiral symmetry in nucleon-nucleon interaction at largedistances, possibly via bounce into false instanton vacuum. Observation ofboson with rest mass $m_{X}$=17 MeV in the decay of high lying excited statesof $^{8}$Be and $^{4}$He can possibly resolve one of the longest lasting openquestions in nuclear physics.

Anomaly in decay of 8Be and 4He -- can an observed light boson mediate low energy nucleon-nucleon interactions ?