The neutrino - nucleon cross sections have been coded up and will be added to the VLE directory of GENIE soon (just need CVS permissions).
There are still some open issues. While waiting for responses on them, I thought it would be useful to show the current status. When the issues get resolved, I will plan to document the making of this class, in case it may be helpful to others.
Current cross section calculations:
or on log scale:
The IBD x-sec agrees very well with the table displayed in the paper:
However, this agreement is only achievable with:
- The proton anomalous magnetic moment being 1.793, as given in the paper. PDG (and GENIE) have k_p = 2.793. I have emailed Strumia regarding this issue, but so far haven't received a response. Update: After talking with the authors, the parameter used is the anomalous magnetic moment, which is k_p-1 for the proton (and k_n for the neutron).
- The minimum q^2, used for the integral to calculate the total cross section, is limited in GENIE to not be smaller than 10^-4. For the plots above, this limit had been changed to 10^-10.
The limit of q^2 >= 10^-4 (default in GENIE) can cause some trouble for very low energy neutrinos:
I've contacted Constantinos to talk about possible solutions.