  Beyond the standard model, a static potential between quark pairs is obtained
phenomenologically (QCD inspired), associated with the range of strong
interaction, when the virtual exchange gluon squared momentum transfer has a
periodicity for periodic boundary conditions of the quark-pair system enclosed
by a constant volume, in the lowest order of the effective perturbed QCD (in
which the gluon propagator is replaced by the effective gluon one). This
potential includes a periodicity dependent effect, characterized by a finite
face value of the periodicity $N$, in addition to the periodicity independent
potential (the Coulomb type plus linear one). That periodicity dependent
effect, dominant at short distance, is applied to an explanation of the top
quark mass $$m_t=8\pi m_\pi N^{{1/2}},$$ whose numerically calculated results
indicate approximately both upper and lower bounds of $m_t$
  $$177~\mbox{{GeV}} > m_t > 173 ~\mbox{{GeV}}$$ for the range of strong
interaction $L=1.40~fm~(=m_\pi^{-1})$.
