Jberger7 new form factor

[jberger7]

Description

Please provide a detailed description of the changes this pull request introduces. If available, also link to a docdb link where the issue/change have been presented on/discussed.

The form factor initially implemented for Higgs Portal Scalar decays into pions in MeVPrtl was based off of an outdated, incorrect model. This request updates the form factor to conform to the numerical determination in arXiv:1909.11670v4 and references therein. A numerical fit was performed to determine the form factor based on the left panel of Fig. 1 in 1909.11670v4. This new form factor is left optional (on by default, but the old form factor can be recovered with an appropriate flag) for the purposes of reproducing existing simulated data.

• Have you added a label? (bug/enhancement/physics etc.)

This is pull request to add a new fix to the physics modeling of Higgs Portal Scalar decays in MeVPrtl.

• Have you assigned at least 1 reviewer?

gputnam and jamiecd have offered to act as reviewers for this request.

• Is this PR related to an open issue / project?

This request is related to an open issue in the physics modeling, but is not fixing any coding bugs.

• Does this PR affect CAF data format? If so, please assign a CAF maintainer as additional reviewer.

No effect.

• Does this PR require merging another PR in a different repository (such as sbnanobj/sbnobj etc.)? If so, please link it in the description.

No effect on other repositories.

• Are you submitting this PR on behalf of someone else who made the code changes? If so, please mention them in the description.

No. The changes were made by me.

[kjplows]

trigger build LArSoft/lar*@LARSOFT_SUITE_v10_14_02 SBNSoftware/sbncode@v10_14_02 SBNSoftware/sbn*@SBN_SUITE_v10_14_02

[FNALbuild]

✔️ CI build for LArSoft Succeeded on slf7 for c14:prof -- details available through the CI dashboard

[FNALbuild]

✔️ CI build for LArSoft Succeeded on slf7 for e26:prof -- details available through the CI dashboard

[FNALbuild]

❌ CI build for ICARUS Failed at phase build ICARUS on slf7 for c14:prof -- details available through the CI dashboard

🚨 For more details about the failed phase, check the build ICARUS phase logs

parent CI build details are available through the CI dashboard

[FNALbuild]

❌ CI build for SBND Failed at phase build SBND on slf7 for c14:prof -- details available through the CI dashboard

🚨 For more details about the failed phase, check the build SBND phase logs

parent CI build details are available through the CI dashboard

[FNALbuild]

❌ CI build for ICARUS Failed at phase ci_tests ICARUS on slf7 for e26:prof - ignored warnings for build -- details available through the CI dashboard

🚨 For more details about the failed phase, check the ci_tests ICARUS phase logs

parent CI build details are available through the CI dashboard

[FNALbuild]

⚠️ CI build for SBND Warning at phase ci_tests SBND on slf7 for e26:prof - ignored warnings for build -- details available through the CI dashboard

🚨 For more details about the warning phase, check the ci_tests SBND phase logs

parent CI build details are available through the CI dashboard