Primordial Black Holes and Cosmological Phase Transitions Report ...

PBHs and Cosmological Phase Transitions 82
cs 2
0.3
0.2
0.1
0
t1
t t
-6 -5.5 -5 -4.5 -4 -3.5
Log 10t1s
Figure 30: The sound speed c 2 s(t) for the QCD phase transition according to the
Lattice Fit with Tc = 170 MeV. During the coexistence phase, which occurs
between the instants t− =9.37×10 −5 s and t+ =1.08×10 −4 s the sound speed
drops to zero (dark gray zone). For t1 =5.1 × 10 −7 s the sound speed equals
95% of its ‘background’ value. The dashed line represents the ideal gas case for
which c 2 s =1/3.
cs 2
0.4
0.3
0.2
0.1
t
t1
t
-4.4 -4.2 -4 -3.8 -3.6
Log 10t1s
Figure 31: The sound speed c 2 s (t) for the QCD phase transition in the case
of a Crossover with a reference temperature Tc = 170 MeV and ∆T =0.1Tc.
The dashed lines represent, for reference, the location of the first–order phase
transition according to the Bag Model (t− =6.25 × 10 −5 s, t+ =1.08 × 10 −4 s).
Between the instants t1 ≈ 7.1 × 10 −5 s and t2 ≈ 1.96 × 10 −4 s the sound speed
stays below 95% of its ‘background’ value (c 2 s,0 =1/3).
t2