  In order to study the nuclear matter in the relativistic heavy ion collisions
and the compact stars, we need the hadronic density of states for the entire
($\mu_B-T$) phase transition diagram. We present a model for the continuous
high-lying mass (and volume) spectrum density of states that fits the Hagedorn
mass spectrum. This model explains the origin of the tri-critical point besides
various phenomena such as the quarkyonic matter and the quark-gluon liquid. The
Hagedorn mass spectrum is derived for the color-singlet quark-gluon bag with
various internal structures such as the unimodular unitary, orthogonal and
color-flavor locked symplectic symmetry groups. The continuous high-lying
hadronic mass spectrum is populated at first by the unitary Hagedorn states.
Then the spectrum turns to be dominated by the colorless orthogonal states as
the dilute system is heated up. Subsequently, the liquid/gas of orthogonal
Hagedorn states undergoes higher order deconfinement phase transition to
quark-gluon plasma. Under the deconfinement phase transition process, the
color-singlet states is broken badly to form the colored $SU(N_c)$ symmetry
group. On the other hand, when the hadronic matter is compressed to larger
$\mu_{B}$ and heated up, the colorless unitary states undergoes first order
phase transition to explosive quark-gluon plasma. The tri-critical point
emerges as a change in the characteristic behaviour of the matter and as an
intersection among various phases with different internal symmetries. When the
saturated hadronic matter is cooled down and compressed to higher density, it
turns to be dominated by the colorless symplectic states. This matter exhibits
the first order phase transition to quark-gluon plasma when it is heated up to
higher temperature. The role of chiral phase transition is also discussed.
