MadDM

Incorrect relic abundance

Asked by Sanket Doshi

Hi Daniele,

In the context of the same model we've been considering in the bugs section, I am facing an issue with obtaining the right relic abundance.

The goal is to make the Omega*h^2 vs mDM/T plot and I am following the steps mentioned at the end below.

However, the values I get for Y (or Omega*h^2) are smaller than the right answer (obtained by solving Boltzmann equation in a script) by a factor of 4. Basically, if I multiply the MadDM answer by 4 I get the correct answer. 4 also happens to be the value of "g" for the DM in this model (it's a Dirac Fermion).

Can you tell me where I am going wrong?

Here are the steps I follow to obtain Y (or Omega*h^2) vs mDM/T plots:

1. Add a line "call odeint_check(1)" in the file maddm.f

2. Uncomment and copy: dxsav = 0.5d0
            kmax = 200
            kount = 0

   from the relic_coupled.f file

   also uncomment the "call odeint_check(1)" line

3. Uncomment "call odeint_check(1)" in the file relic_abundance.f

   and paste the 3 lines copied from above on top in the same file

   dxsav = 0.5d0
   kmax = 200
   kount = 0

4. The output folder of the project will have files "odeint_coupled_Yeq_chi1.txt" and "odeint_coupledchi1.txt"

   which have Y vs x values for equilibrium and after freezout respectively which we can convert to Omega*h^2

5. MadDM paper outlining this: 1308.4955v2

Please let me know,
Thanks

Question information

Language:
English Edit question
Status:
Expired
For:
MadDM Edit question
Assignee:
No assignee Edit question
Last query:
Last reply:
Revision history for this message
Daniele Massaro (dmassaro) said : 		#2

Hi Sanket,

sorry for the delay.
As far as I understand, your model relic density depends on both annihilation and coannihilation processes, right?
First of all, be aware that MadDM considers only 2 to 2 leading order processes for the computation of the relic density.
Next, I would like to know if there is a particular reason for you to set the argument of odeint_check to 1, meaning that you are enabling the computation with the full set of Boltzmann equations.
If there is no particular reason, I suggest first of all to try with odeint_check(0).

Let me know.
Cheers.
--
Daniele

Revision history for this message
Launchpad Janitor (janitor) said : 		#3

This question was expired because it remained in the 'Needs information' state without activity for the last 15 days.