PoS(NuFact2019)050 One pion production in neutrino nucleon and neutrino nucleus interaction L. Alvarez-Ruso Instituto de Física Corpuscular (IFIC), Centro Mixto CSIC-Universidad de Valencia, Institutos de Investigación de Paterna, Apartado. 22085, 46071 Valencia, Spain E-mail: luis.alvarez@ific.uv.es E. Hernández ∗ Departamento de Física Fundamental e IFFyM, Universidad de Salamanca, 37008 Salamanca, Spain E-mail: gajatee@usal.es J. Nieves Instituto de Física Corpuscular (IFIC), Centro Mixto CSIC-Universidad de Valencia, Institutos de Investigación de Paterna, Apartado. 22085, 46071 Valencia, Spain E-mail: jmnieves@ific.uv.es J.E. Sobczyk Instituto de Física Corpuscular (IFIC), Centro Mixto CSIC-Universidad de Valencia, Institutos de Investigación de Paterna, Apartado. 22085, 46071 Valencia, Spain E-mail: Joanna.Sobczyk@ific.uv.es M.J. Vicente Vacas Departamento de Física Teórica and Instituto de Física Corpuscular (IFIC), Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigación de Paterna, 46071 Valencia, Spain E-mail: Manuel.J.Vicente@uv.es We very briefly describe the main ingredients, including the latest modifications, of the “HNV” model for one pion production in neutrino nucleon reactions. We present results for total cross sections as well as pion angular distributions with respect to the pion polar angles measured in the pion-nucleon center of mass. The latter show that the approximation of taking an isotropic distribution, as done in some Monte Carlo generators, is not supported by microscopic calcula- tions. With the corresponding medium effects taken into account, the model is applied to one pion production in nuclei for which we show some preliminary results. The 21st international workshop on neutrinos from accelerators (NuFact2019) August 26 - August 31, 2019 Daegu, Korea ∗ Speaker. c  Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). https://pos.sissa.it/