All Questions
Tagged with degrees-of-freedom cosmology
7 questions
1
vote
0
answers
326
views
Degrees of freedom in the early universe with MSSM?
As nicely summarized on P4 in On effective degrees of freedom in the early universe here; at high temperatures where all the particles of the Standard Model are present, we have 28 bosonic and 90 ...
- 1,496
1
vote
0
answers
146
views
graph relativistic degrees of freedom
I'm trying to graph the relativistic degrees of freedom, which should look like the figure
And I am trying to guide me with this Phys.SE answer: Number $g(T)$ of relativistic degrees of freedom as a ...
2
votes
1
answer
212
views
Hadron contribution to effective degrees of freedom in early Universe
In transition from quark-gluon plasma to hadron gas in the early Universe, the value of the effective degrees of freedom $g_{\star}$ decreases abruptly. This seems to me like a sort of decoupling: ...
- 1,154
2
votes
1
answer
2k
views
Degrees of freedom of neutrinos
In cosmology, in $g_{eff}$, the number of relativistic degrees of freedom, one finds that the contribution of neutrinos is 2 ($\frac{7}{8}\times 2$ more precisely) but what is due this 2 factor to ? ...
- 157
4
votes
1
answer
1k
views
Do photons have six degrees of freedom?
Calculations involving pressure and volume relationships of photon gas during the cosmologic expansion of the universe posit an adiabatic cooling process with a heat capacity ration of 4/3.
This ratio ...
- 545
14
votes
1
answer
10k
views
Number $g(T)$ of relativistic degrees of freedom as a function of temperature $T$
Let us consider the total number of relativistic degrees of freedom $g(T)$ for particle species in our universe:
$$g(T)=\left(\sum_Bg_B\right)+\frac{7}{8}\left(\sum_Fg_F\right)$$
Where the sums are ...
- 1,547
3
votes
2
answers
1k
views
Degrees of freedom in the early Universe
I am reading Dodelson's textbook on cosmology. On page 66 we find equation 3.26:
$$\rho = \frac{\pi^2}{30}T^4\biggl[\sum_{i=\text{bosons}}g_i+\frac{7}{8}\sum_{i=\text{fermions}}g_i\biggr]\equiv g_\...
- 2,134