# I Entropy production equation

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1. Nov 28, 2016

### shinobi20

From the paper, https://arxiv.org/abs/astro-ph/0305015, on page 3,
How did the author arrived with equation (10)? By using the radiation density and (8) defined in the previous paragraph,

$ρ_r = \frac{3}{4}Ts ~$ (radiation density) I think the author got it wrong ($ρ_r = \frac{4}{3}Ts ~$)
$T\dot s + 3HTs = Γ \dot φ ^2~$ (8)

We have, $~T \dot s = \frac{4}{3} \dot ρ_r ~$ and $~ \frac{4}{3} \dot ρ_r + 4Hρ_r = Γ \dot φ ^2~$

But why is that in the paper it is written as $~ \dot ρ_r + 4Hρ_r = Γ \dot φ ^2~$?

Also, how did the author get the radiation density $ρ_r = \frac{3}{4}Ts ~$ by saying that we set $~δm_T = 0~$ in (2)?

2. Dec 3, 2016

### Staff: Admin

Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.

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