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GENIE-MC / Generator

The popular GENIE Generator product is used by nearly all accelerator neutrino experiments and it plays a key role in the exploitation of neutrino data. The Generator implements a modern software framework and it includes state-of-the-art physics modules. It captures the latest results of the GENIE global analysis of neutrino scattering data and includes several tunes that were produced using the proprietary Comparisons and Tuning products. The GENIE physics model is universal and comprehensive: It handles all neutrinos and targets, and all processes relevant from MeV to PeV energy scales. The Generator includes several tools (flux drivers, detector geometry navigators, specialized event generation apps, event reweighting engines) to simulate complex experimental setups in full detail and to support generator-related analysis tasks.
http://www.genie-mc.org
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Addition of new Vector Form Factors for RES #339

Closed jtenavidal closed 9 months ago

jtenavidal commented 10 months ago

The default GENIE for neutrinos is based on "miniBooNE approach". This approach was incorrect for electrons. The correct method for electrons is added - it is called Sarita-Schwinger. The dipole is also an option. The best agreement to data is shown by Sarita-Schwinger. DefaultMBFF.pdf DipoleFF.pdf SRFF.pdf

jtenavidal commented 10 months ago

The default parameterization for neutrinos is using the "MiniBooNE prenscription": https://arxiv.org/pdf/0909.3659.pdf

For electrons, we are for now using the Dipole prenscription.

I had a look at this paper: https://journals.aps.org/prd/pdf/10.1103/PhysRevD.77.053001 They suggest that the Rarita-Schwinger formalism for V+A form factors has better agreement with electron and neutrino data.

This prenscription is very similar to the current implementation for MiniBooNE. In fact, they should be exact, but they are not. (I believe the arxive had some errors..) The Rarita-Schwinger provides with specific form for EM or CC/NC, but this differentiation was not implemented. In addition, there's two results for the Axial part (Type I and Type II). Both are available on this new version.

Status: I am currently running splines for all cases to evaluate the impact on the electron side, and neutrino side.

jtenavidal commented 10 months ago

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jtenavidal commented 10 months ago

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jtenavidal commented 10 months ago

This file contains comparisons of EMRES predictions with data (no res-background or DIS is considered). It shows the predictions for 3 different form factor models: Rarita-Schwinger (R-W), Dipole, and the standard GENIE default ( referred to as MiniBooNE form factor in the code) comparisonRES.pdf

The MiniBooNE Form Factor was meant to be the same as Rarita-Schwinger , but the implementation was not correct. The R-S model is a correction of the previous model.

For now the changes do not affect the existing configurations in GENIE, as the MiniBooNE form factor is used. There's additional configurations that the user can use if desired.

For neutrinos, the changes are significant and including them would require a re-tune of the configuration: GVGANeutrinoParameterizations.pdf