Neutrino interactions with pythia 8310

Never mind the branch name. This uses the latest pythia 8.310.

corsika/modules/pythia8/NeutrinoInteraction.hpp

+/*
+ * (c) Copyright 2024 CORSIKA Project, corsika-project@lists.kit.edu
+ *
+ * This software is distributed under the terms of the GNU General Public
+ * Licence version 3 (GPL Version 3). See file LICENSE for a full version of
+ * the license.
+ */
+
+#pragma once
+
+#include <tuple>
+#include <boost/filesystem/path.hpp>
+
+#include <corsika/framework/utility/CorsikaData.hpp>
+#include <corsika/framework/core/ParticleProperties.hpp>
+#include <corsika/framework/core/PhysicalUnits.hpp>
+#include <corsika/framework/random/RNGManager.hpp>
+#include <corsika/framework/process/InteractionProcess.hpp>
+#include <corsika/modules/pythia8/Pythia8.hpp>
+
+namespace corsika::pythia8 {
+
+  using HEPEnergyTypeSqr = decltype(1_GeV * 1_GeV);
+
+  class NeutrinoInteraction : public InteractionProcess<NeutrinoInteraction> {
+
+  public:
+    NeutrinoInteraction(bool const& handleNC = true, bool const& handleCC = true,
+                        bool const print_listing = false);
+    ~NeutrinoInteraction();
+    /**
+     * Returns inelastic (production) cross section.
+     *
+     * This cross section must correspond to the process described in doInteraction.
+     * Allowed targets are: nuclei or single nucleons (p,n,hydrogen).
+     *
+     * @param projectile is the Code of the projectile
+     * @param target is the Code of the target
+     * @param projectileP4 is the four momentum of the projectile
+     * @param targetP4 is the four momentum of the target
+     *
+     * @return inelastic cross section
+     */
+    /* NOTE: the cross section for neutrino interactions is fixed to an arbitrary small
+     * value. This is needed just so the interaction process is not skipped in the process
+     * loop when the interaction is forced. If needed the exact value could be made
+     * accessible. */
+    CrossSectionType getCrossSection(Code const projectile, Code const target,
+                                     FourMomentum const& projectileP4,
+                                     FourMomentum const& targetP4) const {
+      if (isValid(projectile, target, projectileP4, targetP4))
+        return cross_section_;
+      else
+        return CrossSectionType::zero();
+    };
+
+    bool isValid(Code const projectileId, [[maybe_unused]] Code const targetId,
+                 FourMomentum const& projectileP4, FourMomentum const& targetP4) const {
+      auto const S = (projectileP4 + targetP4).getNormSqr();
+      return is_neutrino(projectileId) &&
+             (is_nucleus(targetId) || targetId == Code::Proton ||
+              targetId == Code::Neutron) &&
+             S >= minQ2_;
+    };
+
+    /**
+     * In this function PYTHIA is called to produce one event. The
+     * event is copied (and boosted) into the shower lab frame.
+     */
+    template <typename TView>
+    void doInteraction(TView& output, Code const projectileId, Code const targetId,
+                       FourMomentum const& projectileP4, FourMomentum const& targetP4);
+
+  private:
+    CrossSectionType const cross_section_ = 4_nb;
+    int count_ = 0;
+    bool const print_listing_ = false;
+    bool const handle_nc_ = true;
+    bool const handle_cc_ = true;
+    HEPEnergyTypeSqr minQ2_ = 25_GeV * 1_GeV;
+    Pythia8::Pythia pythiaMain_;
+  };
+} // namespace corsika::pythia8
+
+#include <corsika/detail/modules/pythia8/NeutrinoInteraction.inl>
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