alterbbn is hosted by Hepforge, IPPP Durham

Calculation of BBN abundances in alternative cosmologies

AlterBBN is a C program which computes the abundances of the elements predicted by Big-Bang nucleosynthesis (BBN). Different cosmological scenarios are implemented in AlterBBN, which can alter the BBN predictions. Also, AlterBBN is included in the SuperIso Relic package so that the alternative models can be tested using BBN constraints.

If you use AlterBBN to publish a paper, please cite:
A. Arbey, arXiv:1106.1363 [astro-ph.CO], Comput. Phys. Commun. 183 (2012) 1822
A. Arbey, J. Auffinger, K. P. Hickerson and E. S. Jenssen, arXiv:1806.11095 [astro-ph.CO]

For any comment, question or bug report please contact us.


NEW The latest version of the manual can be found here (18 July 2019).
The old version of the manual can be found here (20 June 2011).


Version 2.2 (18th July 2019)
  • Changed constraint routines.
  • Corrected equivalent neutrino density derivative for non-WIMP scenarios (thanks to F. Kahlhoefer and P. Stöcker).
  • Small improvements.

Version 2.1 (2nd May 2019)
  • Upgraded proton to neutron beta calculations.
  • Added a new executable for altering neutron beta rates, alter_neutron.
  • Repaired np beta code to correctly normalize to neutron lifetime.
  • Added Fermi functions to np beta rates.
  • Added Fierz interference term to np beta rates.
  • Improved neutrino decoupling.
  • Allowed scaling of samples used to compute np beta rates.
  • Precise calculation (failsafe=1) set as default.
  • New numerical integration methods added.
  • Interface with the REACLIB database added to expand the nuclear network.
  • Many improvements and small corrections.
  • Multiprocessors option for faster error calculation.

Version 2.0 (29 June 2018)
  • Extended nuclear network.
  • Several cases of WIMPs added.
  • Automatic error and correlation calculation added.
  • Scenario with decaying scalar field added.
  • Scenario with reheating added.
  • Multiprocessors option for faster error calculation.

Version 1.4 (28 June 2013)
  • Added calculation of the errors, inspired by astro-ph/9803177 (thanks to S. Sarkar).
  • Routine prototypes modified.
  • Neutrino degeneracy added.

Version 1.3 (4 March 2012)
  • Reaction rate moved to separate file bbnrate.c.
  • Evaluation of errors using low and high rates.
  • Several comments modified in the .c files (thanks to A. Mishra).

Version 1.2 (8 July 2011)
  • Improved p <-> n reaction rate.

Version 1.1 (20 June 2011)
  • Improved nuclear network.

Version 1.0 (7 June 2011)
  • First public release.