A new Spectral Function model for several nuclei, including argon is added. The new model is consistent with NuWro's cascade model, double counting of FSI effects is avoided. Details are described in https://arxiv.org/pdf/2508.10101

Small fixes in MEC compared to 25.03

A new single pion production model, see [The Ghent Hybrid model in NuWro: a new neutrino single-pion production model in the GeV regime, Qiyu Yan et al , JHEP 12 (2024) 141; e-Print: 2405.05212 [hep-ph]]

A new MEC model, see [New multinucleon knockout model in the NuWro Monte Carlo generator,
Hemant Prasad et al, Phys.Rev.D 111 (2025) 3, 036032 • e-Print: 2411.11523 [hep-ph] based on theoretical paper Exclusive-final-state hadron observables from neutrino-nucleus multinucleon knockout,
J.E. Sobczyk, J. Nieves, F. Sánchez, Phys.Rev.C 102 (2020) 2, 024601 e-Print: 2002.08302 [nucl-th].

Also many minor improvements and bug fixing introduced over last cou[ple of years.

Few bugs were fixed.

• The cascade model for hyperon production in case of a hydrogen target works correctly now.

Few bugs were fixed.

• The cascade model (formation zone) for electron-induced exclusive nucleon knockout works correctly now.

Please note that some bugs were found in 21.09 and one should use patched version 21.09.2.

New interaction models:

• the phenomenological 2p2h model [T. Bonus et al., Phys.Rev. C 102 (2020) 015502],
• hyperon production and their FSI [C. Thorpe et al., arXiv:2010.12361],
• neutrino scattering off atomic electrons [D. Zhuridov et al., J.Phys. G 48 (2021) 055002],
• validated QE electron scattering.

Main programistic novelties:

• cmake support,
• support of atmospheric neutrino fluxes,
• more elastic input for detector geometries,
• bug fixes and optimization.

Few bugs were fixed.

• Detector simulations are now working properly.
• Usage with Root6 is now simplified.

The code is equivalent to NuWro 19.02.

The default NuWro parametrisation of the file data/params.txt is fixed to have the new cascade parameter kaskada_NN_corr = 1, which turns on the effective nucleon density corrections of arXiv:1902.05618.

Please note that some bugs were found in 19.02 and one should use patched version 19.02.2.

Major enhancement of the nucleon cascade model:

• Effective nucleon density taking into account nucleon-nucleon correlations, that completes an implementation of nuclear effects described in [V.R. Pandharipande, S. Pieper, Phys.Rev. C45 (1992) 791-798].
• Implementation of elastic nucleon-nucleon scattering angular coefficients from [J. Cugnon et al., Nucl.Instrum.Meth. B111 (1996) 215-220].
• New inelastic nucleon scattering cross sections and single pion production fractions done using the PDG data and fits by [J. Bystricky et al., J.Phys. France 48 (1987) 1901].
• In-medium inelastic nucleon scattering cross section corrections inspired by [D. Klakow et al., Phys.Rev. C48 (1993) 1982].

The detailed description of the physics behind the changes can be found in arXiv:1902.05618 (K. Niewczas, J. Sobczyk, Nuclear Transparency in Monte Carlo Neutrino Event Generators).

Note: the total cross sections output file has been recently tidied up what can make old, hardcoded, scripts panic; a recommended script [xSec.cc] for reading total cross sections is attached.

If debugging is the process of removing software bugs, then programming must be the process of putting them in.

Edsger Dijkstra

Few bugs fixed.