(b)). This is too fast as compared with the lattice estimates [@Bazavov:2009] in 2+1 flavor QCD, but the difference can be ascribed to the simplifications introduced by the model under consideration (the essential difference is that the NJL model does not possess the quark-confinement property of QCD).

We can gain some understanding of the asymptotic behavior of $\nu (T)$ by considering eqs. (\[J0t\]) and (\[J-1\]). Firstly, it is easy to see that the integral $J_0(M^2,T,\mu )\to 0$ at $T\to\infty$. The reason for this is very simple and is contained in the integrand $(1-n_q-n_{\bar q})$ which vanishes at $T\to\infty$, as it explicitly follows from eqs. (\[n-occup\]). Secondly, eq. (\[J-1\]) contains $J_0$ as an integrand. Thus we conclude that $J_{-1}(M^2,T,\mu )\to 0$ at $T\to\infty$. Next, from the gap equation (\[gap-t\]) it follows that $h_f(T)\to 0$ at $T\to\infty$. Therefore $V(M_f,T,\mu )\sim C(T,\mu )$ at large $T$, i.e. we can say that the asymptotics is totally determined by the term $C(T,\mu )$, yielding $\nu(T\to
\infty )=31.5$, which is independent of any model parameters. This conclusion is attractive because it agrees with the general arguments of the previous paragraph. In fact, to many readers our conclusion that $\nu (T)$ has the correct asymptotics, may seem 