  How two-party entanglement (TPE) is distributed in the many-body systems?
This is a fundamental issue because the total TPE between one party with all
the other parties, $\mathcal{C}^N$, is upper bounded by the Coffman, Kundu and
Wootters (CKW) monogamy inequality, from which $\mathcal{C}^N \le \sqrt{N-1}$
can be proved by the geometric inequality. Here we explore the total
entanglement $\mathcal{C}^\infty$ and the associated total tangle $\tau^\infty$
in a $p$-wave free fermion model with long-range interaction, showing that
$\mathcal{C}^\infty \sim \mathcal{O}(1)$ and $\tau^\infty$ may become vanishing
small with the increasing of long-range interaction. However, we always find
$\mathcal{C}^\infty \sim 2\xi \tau^\infty$, where $\xi$ is the truncation
length of entanglement, beyond which the TPE is quickly vanished, hence
$\tau^\infty \sim 1/\xi$.
  This relation is a direct consequence of the exponential decay of the TPE
induced by the long-range interaction. These results unify the results in the
Lipkin-Meshkov-Glick (LMG) model and Dicke model and generalize the Koashi,
Buzek and Imono bound to the quantum many-body models, with much broader
applicability.
