  We study the nucleon at finite temperature using Bethe-Salpeter equation
(BSE) where it is considered as a bound state of a scalar-diquark and a quark.
The interaction between the diquark and the quark is taken as an exchange
quark.The constituent quark and diquark substructures are considered momentum
and temperature dependent based on the lattice QCD and dynamical chiral
symmetry breaking (DCSB). The kernel interaction modification with temperature
is approximated using the mixed representation in the imaginary time formalism
and then we adopt an adiabatic (instantaneous) approximation after evaluating
the Matsubara frequencies sum. The results of BSE are compared with those for
MIT bag model. We argue the bag pressure is a temperature dependent and it
decreases smoothly with temperature to be consistent with the results for BSE.
Furthermore, the nucleon bound state obtained by BSE ceases to exist just below
the critical temperature and this indicates that the nucleon deconfines to its
constituent quarks at the critical temperature. The nucleon mass decreases with
temperature as $M_N(T)/M_N(0)\approx {\cal R}^{\delta}(T)$ where ${\cal
R}(T)=(1-b\frac{T^2}{T^2_c})^{1/2}$ and $\delta\approx 1$ and this suggests
$B(T)/B(0)={\cal R}^{4\delta}(T)$ for MIT bag.

Nuclear Theory