algorithms/reco/InclusiveKinematicsESigma.cc

0001 // SPDX-License-Identifier: LGPL-3.0-or-later
0002 // Copyright (C) 2022 Wouter Deconinck, Barak Schmookler
0003
0004 #include <Math/GenVector/LorentzVector.h>
0005 #include <Math/GenVector/PxPyPzE4D.h>
0006 #include <Math/Vector4Dfwd.h>
0007 #include <edm4eic/InclusiveKinematicsCollection.h>
0008 #include <edm4eic/ReconstructedParticleCollection.h>
0009 #include <edm4hep/MCParticleCollection.h>
0010 #include <edm4hep/Vector3f.h>
0011 #include <cmath>
0012 #include <tuple>
0013
0014 #include "Beam.h"
0015 #include "Boost.h"
0016 #include "InclusiveKinematicsESigma.h"
0017
0018 using ROOT::Math::PxPyPzEVector;
0019
0020 namespace eicrecon {
0021
0022 void InclusiveKinematicsESigma::init() {}
0023
0024 void InclusiveKinematicsESigma::process(const InclusiveKinematicsESigma::Input& input,
0025                                         const InclusiveKinematicsESigma::Output& output) const {
0026
0027   const auto [mc_beam_electrons, mc_beam_protons, escat, hfs] = input;
0028   auto [out_kinematics]                                       = output;
0029
0030   // Get first (should be only) beam electron
0031   if (mc_beam_electrons->empty()) {
0032     debug("No beam electron found");
0033     return;
0034   }
0035   const auto& ei_particle = (*mc_beam_electrons)[0];
0036   const PxPyPzEVector ei(round_beam_four_momentum(ei_particle.getMomentum(),
0037                                                   m_particleSvc.particle(ei_particle.getPDG()).mass,
0038                                                   electron_beam_pz_set, 0.0));
0039
0040   // Get first (should be only) beam proton
0041   if (mc_beam_protons->empty()) {
0042     debug("No beam hadron found");
0043     return;
0044   }
0045   const auto& pi_particle = (*mc_beam_protons)[0];
0046   const PxPyPzEVector pi(round_beam_four_momentum(pi_particle.getMomentum(),
0047                                                   m_particleSvc.particle(pi_particle.getPDG()).mass,
0048                                                   hadron_beam_pz_set, m_crossingAngle));
0049
0050   // Get boost to colinear frame
0051   auto boost = determine_boost(ei, pi);
0052
0053   // Get electron variables
0054   if (escat->empty()) {
0055     debug("No scattered electron found");
0056     return;
0057   }
0058   auto kf = escat->at(0);
0059   PxPyPzEVector e_lab(kf.getMomentum().x, kf.getMomentum().y, kf.getMomentum().z, kf.getEnergy());
0060   PxPyPzEVector e_boosted = apply_boost(boost, e_lab);
0061   auto pt_e               = e_boosted.Pt();
0062   auto sigma_e            = e_boosted.E() - e_boosted.Pz();
0063
0064   // Get hadronic final state variables
0065   if (hfs->empty()) {
0066     debug("No hadronic final state found");
0067     return;
0068   }
0069   auto sigma_h = hfs->at(0).getSigma();
0070
0071   if (sigma_h <= 0) {
0072     debug("No scattered electron found or sigma zero or negative");
0073     return;
0074   }
0075
0076   auto sigma_tot = sigma_e + sigma_h;
0077
0078   // Calculate kinematic variables
0079   const auto y_e  = 1. - sigma_e / (2. * ei.energy());
0080   const auto Q2_e = (pt_e * pt_e) / (1. - y_e);
0081
0082   const auto y_sig  = sigma_h / sigma_tot;
0083   const auto Q2_sig = (pt_e * pt_e) / (1. - y_sig);
0084   const auto x_sig  = Q2_sig / (4. * ei.energy() * pi.energy() * y_sig);
0085
0086   static const auto m_proton = m_particleSvc.particle(2212).mass;
0087   const auto Q2_esig         = Q2_e;
0088   const auto x_esig          = x_sig;
0089   const auto y_esig          = Q2_esig / (4. * ei.energy() * pi.energy() *
0090                                           x_esig); //equivalent to (2*ei.energy() / sigma_tot)*y_sig
0091   const auto nu_esig         = Q2_esig / (2. * m_proton * x_esig);
0092   const auto W_esig          = sqrt(m_proton * m_proton + 2 * m_proton * nu_esig - Q2_esig);
0093   auto kin                   = out_kinematics->create(x_esig, Q2_esig, W_esig, y_esig, nu_esig);
0094   kin.setScat(kf);
0095
0096   // Debugging output
0097   debug("x,Q2,W,y,nu = {},{},{},{},{}", kin.getX(), kin.getQ2(), kin.getW(), kin.getY(),
0098         kin.getNu());
0099 }
0100
0101 } // namespace eicrecon