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genie::BergerSehgalCOHPiPXSec2015 Class Reference

Computes the double differential cross section for CC & NC coherent pion production according to the Berger-Sehgal model. v(vbar)A->v(vbar)Api0, vA->l-Api+, vbarA->l+Api-. More...

#include <BergerSehgalCOHPiPXSec2015.h>

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Public Member Functions

 BergerSehgalCOHPiPXSec2015 ()
 
 BergerSehgalCOHPiPXSec2015 (string config)
 
virtual ~BergerSehgalCOHPiPXSec2015 ()
 
double XSec (const Interaction *i, KinePhaseSpace_t k) const
 Compute the cross section for the input interaction. More...
 
double Integral (const Interaction *i) const
 
bool ValidProcess (const Interaction *i) const
 Can this cross section algorithm handle the input process? More...
 
void Configure (const Registry &config)
 
void Configure (string config)
 
- Public Member Functions inherited from genie::XSecAlgorithmI
virtual ~XSecAlgorithmI ()
 
virtual bool ValidKinematics (const Interaction *i) const
 Is the input kinematical point a physically allowed one? More...
 
- Public Member Functions inherited from genie::Algorithm
virtual ~Algorithm ()
 
virtual void FindConfig (void)
 
virtual const RegistryGetConfig (void) const
 
RegistryGetOwnedConfig (void)
 
virtual const AlgIdId (void) const
 Get algorithm ID. More...
 
virtual AlgStatus_t GetStatus (void) const
 Get algorithm status. More...
 
virtual bool AllowReconfig (void) const
 
virtual AlgCmp_t Compare (const Algorithm *alg) const
 Compare with input algorithm. More...
 
virtual void SetId (const AlgId &id)
 Set algorithm ID. More...
 
virtual void SetId (string name, string config)
 
const AlgorithmSubAlg (const RgKey &registry_key) const
 
void AdoptConfig (void)
 
void AdoptSubstructure (void)
 
virtual void Print (ostream &stream) const
 Print algorithm info. More...
 

Private Member Functions

void LoadConfig (void)
 
double ExactKinematicTerm (const Interaction *i) const
 
double PionCOMAbsMomentum (const Interaction *i) const
 

Private Attributes

double fMa
 axial mass More...
 
double fRo
 nuclear size scale parameter More...
 
double fCos8c2
 cos^2(Cabibbo angle) More...
 
bool fRSPionXSec
 Use Rein-Sehgal "style" pion-nucleon xsecs. More...
 
const XSecIntegratorIfXSecIntegrator
 

Additional Inherited Members

- Static Public Member Functions inherited from genie::Algorithm
static string BuildParamVectKey (const std::string &comm_name, unsigned int i)
 
static string BuildParamVectSizeKey (const std::string &comm_name)
 
static string BuildParamMatKey (const std::string &comm_name, unsigned int i, unsigned int j)
 
static string BuildParamMatRowSizeKey (const std::string &comm_name)
 
static string BuildParamMatColSizeKey (const std::string &comm_name)
 
- Protected Member Functions inherited from genie::XSecAlgorithmI
 XSecAlgorithmI ()
 
 XSecAlgorithmI (string name)
 
 XSecAlgorithmI (string name, string config)
 
- Protected Member Functions inherited from genie::Algorithm
 Algorithm ()
 
 Algorithm (string name)
 
 Algorithm (string name, string config)
 
void Initialize (void)
 
void DeleteConfig (void)
 
void DeleteSubstructure (void)
 
RegistryExtractLocalConfig (const Registry &in) const
 
RegistryExtractLowerConfig (const Registry &in, const string &alg_key) const
 Split an incoming configuration Registry into a block valid for the sub-algo identified by alg_key. More...
 
template<class T >
bool GetParam (const RgKey &name, T &p, bool is_top_call=true) const
 
template<class T >
bool GetParamDef (const RgKey &name, T &p, const T &def) const
 
template<class T >
int GetParamVect (const std::string &comm_name, std::vector< T > &v, bool is_top_call=true) const
 Handle to load vectors of parameters. More...
 
int GetParamVectKeys (const std::string &comm_name, std::vector< RgKey > &k, bool is_top_call=true) const
 
template<class T >
int GetParamMat (const std::string &comm_name, TMatrixT< T > &mat, bool is_top_call=true) const
 Handle to load matrix of parameters. More...
 
template<class T >
int GetParamMatSym (const std::string &comm_name, TMatrixTSym< T > &mat, bool is_top_call=true) const
 
int GetParamMatKeys (const std::string &comm_name, std::vector< RgKey > &k, bool is_top_call=true) const
 
int AddTopRegistry (Registry *rp, bool owns=true)
 add registry with top priority, also update ownership More...
 
int AddLowRegistry (Registry *rp, bool owns=true)
 add registry with lowest priority, also update ownership More...
 
int MergeTopRegistry (const Registry &r)
 
int AddTopRegisties (const vector< Registry * > &rs, bool owns=false)
 Add registries with top priority, also udated Ownerships. More...
 
- Protected Attributes inherited from genie::Algorithm
bool fAllowReconfig
 
bool fOwnsSubstruc
 true if it owns its substructure (sub-algs,...) More...
 
AlgId fID
 algorithm name and configuration set More...
 
vector< Registry * > fConfVect
 
vector< bool > fOwnerships
 ownership for every registry in fConfVect More...
 
AlgStatus_t fStatus
 algorithm execution status More...
 
AlgMapfOwnedSubAlgMp
 local pool for owned sub-algs (taken out of the factory pool) More...
 

Detailed Description

Computes the double differential cross section for CC & NC coherent pion production according to the Berger-Sehgal model. v(vbar)A->v(vbar)Api0, vA->l-Api+, vbarA->l+Api-.

     The t-dependence of the triple differential cross (d^3xsec/dxdydt)
     is integrated out.

     Is a concrete implementation of the XSecAlgorithmI interface.
References:
PRD 79, 053003 (2009) by Berger and Sehgal
Author
G. Perdue, H. Gallagher, D. Cherdack
Created:
2014
License:
Copyright (c) 2003-2024, The GENIE Collaboration For the full text of the license visit http://copyright.genie-mc.org

Definition at line 35 of file BergerSehgalCOHPiPXSec2015.h.

Constructor & Destructor Documentation

BergerSehgalCOHPiPXSec2015::BergerSehgalCOHPiPXSec2015 ( )

Definition at line 30 of file BergerSehgalCOHPiPXSec2015.cxx.

30  :
31  XSecAlgorithmI("genie::BergerSehgalCOHPiPXSec2015")
32 {
33 
34 }
BergerSehgalCOHPiPXSec2015::BergerSehgalCOHPiPXSec2015 ( string  config)

Definition at line 36 of file BergerSehgalCOHPiPXSec2015.cxx.

36  :
37  XSecAlgorithmI("genie::BergerSehgalCOHPiPXSec2015", config)
38 {
39 
40 }
BergerSehgalCOHPiPXSec2015::~BergerSehgalCOHPiPXSec2015 ( )
virtual

Definition at line 42 of file BergerSehgalCOHPiPXSec2015.cxx.

43 {
44 
45 }

Member Function Documentation

void BergerSehgalCOHPiPXSec2015::Configure ( const Registry config)
virtual

Configure the algorithm with an external registry The registry is merged with the top level registry if it is owned, Otherwise a copy of it is added with the highest priority

Reimplemented from genie::Algorithm.

Definition at line 285 of file BergerSehgalCOHPiPXSec2015.cxx.

References genie::Algorithm::Configure(), and LoadConfig().

286 {
287  Algorithm::Configure(config);
288  this->LoadConfig();
289 }
virtual void Configure(const Registry &config)
Definition: Algorithm.cxx:62
void BergerSehgalCOHPiPXSec2015::Configure ( string  config)
virtual

Configure the algorithm from the AlgoConfigPool based on param_set string given in input An algorithm contains a vector of registries coming from different xml configuration files, which are loaded according a very precise prioriy This methods will load a number registries in order of priority: 1) "Tunable" parameter set from CommonParametes. This is loaded with the highest prioriry and it is designed to be used for tuning procedure Usage not expected from the user. 2) For every string defined in "CommonParame" the corresponding parameter set will be loaded from CommonParameter.xml 3) parameter set specified by the config string and defined in the xml file of the algorithm 4) if config is not "Default" also the Default parameter set from the same xml file will be loaded Effectively this avoids the repetion of a parameter when it is not changed in the requested configuration

Reimplemented from genie::Algorithm.

Definition at line 291 of file BergerSehgalCOHPiPXSec2015.cxx.

References genie::Algorithm::Configure(), and LoadConfig().

292 {
293  Algorithm::Configure(config);
294  this->LoadConfig();
295 }
virtual void Configure(const Registry &config)
Definition: Algorithm.cxx:62
double BergerSehgalCOHPiPXSec2015::ExactKinematicTerm ( const Interaction i) const
private

Definition at line 218 of file BergerSehgalCOHPiPXSec2015.cxx.

References genie::ProcessInfo::IsWeakCC(), genie::constants::kGF2, genie::constants::kPi0Mass, genie::constants::kPi2, genie::constants::kPionMass, genie::kRfLab, genie::InitialState::ProbeE(), genie::Interaction::ProcInfo(), genie::Kinematics::Q2(), genie::utils::kinematics::Q2(), and genie::Kinematics::y().

Referenced by XSec().

219 {
220  // This function is a bit inefficient but is being encapsulated as
221  // such in order to possibly migrate into a general kinematics check.
222  const Kinematics & kinematics = interaction -> Kine();
223  const InitialState & init_state = interaction -> InitState();
224 
225  bool pionIsCharged = interaction->ProcInfo().IsWeakCC();
226  double M_pi = pionIsCharged ? kPionMass : kPi0Mass;
227  double E = init_state.ProbeE(kRfLab); // nu E
228  double Q2 = kinematics.Q2();
229  double y = kinematics.y(); // inelasticity
230  double fp2 = (0.93 * M_pi)*(0.93 * M_pi);
231 
232  double term = ((kGF2 * fp2) / (4.0 * kPi2)) *
233  ((E * (1.0 - y)) / sqrt(y*E * y*E + Q2)) *
234  (1.0 - Q2 / (4.0 * E*E * (1.0 - y)));
235  return term;
236 }
double Q2(const Interaction *const i)
Definition: KineUtils.cxx:1077
Generated/set kinematical variables for an event.
Definition: Kinematics.h:39
double y(bool selected=false) const
Definition: Kinematics.cxx:112
double Q2(bool selected=false) const
Definition: Kinematics.cxx:125
double ProbeE(RefFrame_t rf) const
Initial State information.
Definition: InitialState.h:48
double BergerSehgalCOHPiPXSec2015::Integral ( const Interaction i) const
virtual

Integrate the model over the kinematic phase space available to the input interaction (kinematical cuts can be included)

Implements genie::XSecAlgorithmI.

Definition at line 260 of file BergerSehgalCOHPiPXSec2015.cxx.

References fXSecIntegrator, and genie::XSecIntegratorI::Integrate().

261 {
262  double xsec = fXSecIntegrator->Integrate(this,interaction);
263  return xsec;
264 }
virtual double Integrate(const XSecAlgorithmI *model, const Interaction *interaction) const =0
void BergerSehgalCOHPiPXSec2015::LoadConfig ( void  )
private

Definition at line 297 of file BergerSehgalCOHPiPXSec2015.cxx.

References fCos8c2, fMa, fRo, fRSPionXSec, fXSecIntegrator, genie::Algorithm::GetParam(), and genie::Algorithm::SubAlg().

Referenced by Configure().

298 {
299  GetParam( "COH-Ma",fMa ) ;
300  GetParam( "COH-Ro", fRo ) ;
301 
302  double thc ;
303  GetParam( "CabibboAngle", thc ) ;
304  fCos8c2 = TMath::Power(TMath::Cos(thc), 2);
305 
306  // fRSPionXSec => Do not use the pion-nucleus cross section from Table 1 in PRD 79, 053003
307  // Instead, use the Rein-Sehgal "style" pion-nucleon cross section and scale by A
308  // for all pion energies.
309  GetParam( "COH-UseRSPionXSec", fRSPionXSec ) ;
310 
311  //-- load the differential cross section integrator
313  dynamic_cast<const XSecIntegratorI *> (this->SubAlg("XSec-Integrator"));
314  assert(fXSecIntegrator);
315 }
Cross Section Integrator Interface.
bool fRSPionXSec
Use Rein-Sehgal &quot;style&quot; pion-nucleon xsecs.
double fRo
nuclear size scale parameter
bool GetParam(const RgKey &name, T &p, bool is_top_call=true) const
const Algorithm * SubAlg(const RgKey &registry_key) const
Definition: Algorithm.cxx:345
double BergerSehgalCOHPiPXSec2015::PionCOMAbsMomentum ( const Interaction i) const
private

Definition at line 238 of file BergerSehgalCOHPiPXSec2015.cxx.

References genie::ProcessInfo::IsWeakCC(), genie::constants::kPi0Mass, genie::constants::kPionMass, genie::kRfLab, genie::Target::Mass(), genie::InitialState::ProbeE(), genie::Interaction::ProcInfo(), genie::Kinematics::Q2(), genie::utils::kinematics::Q2(), genie::InitialState::Tgt(), and genie::Kinematics::y().

Referenced by XSec().

239 {
240  // This function is a bit inefficient but is being encapsulated as
241  // such in order to possibly migrate into a general kinematics check.
242  const Kinematics & kinematics = interaction -> Kine();
243  const InitialState & init_state = interaction -> InitState();
244 
245  bool pionIsCharged = interaction->ProcInfo().IsWeakCC();
246  double M_pi = pionIsCharged ? kPionMass : kPi0Mass;
247  double E = init_state.ProbeE(kRfLab); // nu E
248  double Q2 = kinematics.Q2();
249  double y = kinematics.y(); // inelasticity
250  double MT = init_state.Tgt().Mass();
251 
252  double W2 = MT*MT - Q2 + 2.0 * y * E * MT;
253  double arg = (2.0*MT*(y*E - M_pi) - Q2 - M_pi*M_pi)*(2.0*MT*(y*E + M_pi) - Q2 - M_pi*M_pi);
254  if (arg < 0) return arg;
255  double ppistar = TMath::Sqrt(arg) / 2.0 / TMath::Sqrt(W2);
256 
257  return ppistar;
258 }
double Q2(const Interaction *const i)
Definition: KineUtils.cxx:1077
Generated/set kinematical variables for an event.
Definition: Kinematics.h:39
double Mass(void) const
Definition: Target.cxx:224
double y(bool selected=false) const
Definition: Kinematics.cxx:112
double Q2(bool selected=false) const
Definition: Kinematics.cxx:125
const Target & Tgt(void) const
Definition: InitialState.h:66
double ProbeE(RefFrame_t rf) const
Initial State information.
Definition: InitialState.h:48
bool BergerSehgalCOHPiPXSec2015::ValidProcess ( const Interaction i) const
virtual

Can this cross section algorithm handle the input process?

Implements genie::XSecAlgorithmI.

Definition at line 266 of file BergerSehgalCOHPiPXSec2015.cxx.

References genie::Target::A(), genie::Target::HitNucIsSet(), genie::Interaction::InitState(), genie::pdg::IsAntiNeutrino(), genie::ProcessInfo::IsCoherentProduction(), genie::pdg::IsNeutrino(), genie::ProcessInfo::IsWeak(), genie::kISkipProcessChk, genie::InitialState::ProbePdg(), genie::Interaction::ProcInfo(), and genie::InitialState::Tgt().

Referenced by XSec().

267 {
268  if(interaction->TestBit(kISkipProcessChk)) return true;
269 
270  const InitialState & init_state = interaction->InitState();
271  const ProcessInfo & proc_info = interaction->ProcInfo();
272  const Target & target = init_state.Tgt();
273 
274  int nu = init_state.ProbePdg();
275 
276  if (!proc_info.IsCoherentProduction()) return false;
277  if (!proc_info.IsWeak()) return false;
278  if (target.HitNucIsSet()) return false;
279  if (!(target.A()>1)) return false;
280  if (!pdg::IsNeutrino(nu) && !pdg::IsAntiNeutrino(nu)) return false;
281 
282  return true;
283 }
bool IsWeak(void) const
bool IsNeutrino(int pdgc)
Definition: PDGUtils.cxx:110
int A(void) const
Definition: Target.h:70
bool IsCoherentProduction(void) const
A class encapsulating an enumeration of interaction types (EM, Weak-CC, Weak-NC) and scattering types...
Definition: ProcessInfo.h:46
bool IsAntiNeutrino(int pdgc)
Definition: PDGUtils.cxx:118
A Neutrino Interaction Target. Is a transparent encapsulation of quite different physical systems suc...
Definition: Target.h:40
int ProbePdg(void) const
Definition: InitialState.h:64
bool HitNucIsSet(void) const
Definition: Target.cxx:283
const Target & Tgt(void) const
Definition: InitialState.h:66
const UInt_t kISkipProcessChk
if set, skip process validity checks
Definition: Interaction.h:47
Initial State information.
Definition: InitialState.h:48
double BergerSehgalCOHPiPXSec2015::XSec ( const Interaction i,
KinePhaseSpace_t  k 
) const
virtual

Compute the cross section for the input interaction.

Implements genie::XSecAlgorithmI.

Definition at line 47 of file BergerSehgalCOHPiPXSec2015.cxx.

References genie::Target::A(), genie::units::A, genie::units::b, e, ExactKinematicTerm(), fCos8c2, genie::units::fermi, fMa, fRo, fRSPionXSec, genie::Interaction::FSPrimLepton(), genie::ProcessInfo::IsWeakCC(), genie::utils::mec::J(), genie::utils::kinematics::Jacobian(), genie::constants::kPi, genie::constants::kPi0Mass, genie::constants::kPionMass, genie::constants::kPionMass2, genie::kPSQ2yfE, genie::kRfLab, LOG, genie::Target::Mass(), genie::units::mb, pDEBUG, pERROR, pINFO, PionCOMAbsMomentum(), genie::utils::hadxs::berger::PionNucleonXSec(), genie::utils::hadxs::berger::PionNucleusXSec(), genie::InitialState::ProbeE(), genie::Interaction::ProcInfo(), genie::Kinematics::Q2(), genie::utils::kinematics::Q2(), genie::InitialState::Tgt(), genie::XSecAlgorithmI::ValidKinematics(), ValidProcess(), genie::Kinematics::x(), and genie::Kinematics::y().

49 {
50  // Here we are following PRD 79, 053003 (2009) by Berger and Sehgal
51  // This method computes the differential cross section represented
52  // in Eq.'s 6 (CC) and 7 (NC) from that paper.
53 
54  if(! this -> ValidProcess (interaction) ) return 0.;
55  if(! this -> ValidKinematics (interaction) ) return 0.;
56 
57  const Kinematics & kinematics = interaction -> Kine();
58  const InitialState & init_state = interaction -> InitState();
59 
60  bool pionIsCharged = interaction->ProcInfo().IsWeakCC();
61  double xsec = 0.0;
62 
63  double E = init_state.ProbeE(kRfLab); // nu E
64  double Q2 = kinematics.Q2();
65  double y = kinematics.y(); // inelasticity
66  double x = kinematics.x();
67  assert(E > 0.);
68  assert(y > 0.);
69  assert(y < 1.);
70  double ppistar = PionCOMAbsMomentum(interaction); // |Center of Mass Momentum|
71  if (ppistar <= 0.0) {
72  LOG("BergerSehgalCohPi", pDEBUG) << "Pion COM momentum negative for Q2 = " << Q2 <<
73  " x = " << x << " y = " << y;
74  return 0.0;
75  }
76  double front = ExactKinematicTerm(interaction);
77  if (front <= 0.0) {
78  LOG("BergerSehgalCohPi", pDEBUG) << "Exact kin. form = " << front <<
79  " E = " << E << " Q2 = " << Q2 << " y = " << y << " x = " << x;
80  return 0.0;
81  }
82 
83  double A = (double) init_state.Tgt().A(); // mass number
84  double A2 = TMath::Power(A, 2.);
85  double A_3 = TMath::Power(A, 1./3.);
86  double M = init_state.Tgt().Mass();
87  double M_pi = pionIsCharged ? kPionMass : kPi0Mass;
88  double Epi = y*E; // ~pion energy
89  double ma2 = TMath::Power(fMa, 2); // "axial mass" squared
90  double Ga = ma2 / (ma2 + Q2);
91  double Ga2 = TMath::Power(Ga, 2.); // propagator term
92  double Ro2 = TMath::Power(fRo * units::fermi, 2.);
93 
94  // the xsec is d^3xsec/dQ^2dydt but the only t-dependent factor
95  // is an exp(-bt) so it can be integrated analyticaly
96  double Epi2 = TMath::Power(Epi, 2.);
97  double R = fRo * A_3 * units::fermi; // nuclear radius
98  double R2 = TMath::Power(R, 2.);
99  double b = 0.33333 * R2;
100  double MxEpi = M * x / Epi;
101  double mEpi2 = (M_pi * M_pi) / Epi2;
102  double tA = 1. + MxEpi - 0.5 * mEpi2;
103  double tB = TMath::Sqrt(1.0 + 2 * MxEpi) * TMath::Sqrt(1.0 - mEpi2);
104  double tmin = 2 * Epi2 * (tA - tB);
105  double tmax = 2 * Epi2 * (tA + tB);
106  if (tmin < 1.0e-8) {
107  tmin = 1.0e-8;
108  }
109 
110  /* const KPhaseSpace & kphase = interaction->PhaseSpace(); */
111  /* Range1D_t tl = kphase.TLim(); // TESTING! */
112 
113  double sigtot_pin = utils::hadxs::berger::PionNucleonXSec(Epi, /* get_total = */ true, pionIsCharged);
114  double sigel_pin = utils::hadxs::berger::PionNucleonXSec(Epi, /* get_total = */ false, pionIsCharged);
115  double siginel_pin = sigtot_pin - sigel_pin;
116 
117  // fabs (F_{abs}) describes the average attenuation of a pion emerging
118  // from a sphere of nuclear matter with radius = R_0 A^{1/3}. it is
119  // Eq. 13 in Berger-Sehgal PRD 79, 053003
120  double fabs_input = (9.0 * A_3) / (16.0 * kPi * Ro2);
121  double fabs = TMath::Exp( -1.0 * fabs_input * siginel_pin);
122 
123  // my old hackery to get things to work, A. Mislivec provided a better alt.
124  // double factor = 0.1; // to go from 10^-37 cm^2 -> 10^-38 cm^2
125  // double RS_factor = (units::mb*A2*fabs)/(16.0*kPi) * (sigtot_pin*sigtot_pin);
126 
127  // A_RS for BS version of RS, and/or Tpi>1.0
128  double RS_factor = (A2 * fabs) / (16.0 * kPi) * (sigtot_pin * sigtot_pin);
129 
130  // get the pion-nucleus cross section on carbon, fold it into differential cross section
131  double tpi = (E * y) - M_pi - ((Q2 + M_pi * M_pi) / (2 * M));
132  double tpilow = 0.0;
133  double siglow = 0.0;
134  double tpihigh = 0.0;
135  double sighigh = 0.0;
136  double dsigdzfit = 0.0;
137  double dsigdtfit = 0.0;
138  int xsec_stat = 0;
139  double dsig = 0.0;
140  double tstep = 100;
141  double logt_step = TMath::Abs(log(tmax) - log(tmin)) / tstep;
142  double logt = log(tmin) - logt_step/2.0;
143  double t_itt = TMath::Exp(logt);
144  double t_width = 0.0;
145 
146  for (double t_step = 0; t_step<tstep; t_step++) {
147 
148  logt = logt + logt_step;
149  t_itt = TMath::Exp(logt);
150  t_width = t_itt*logt_step;
151 
152  if (tpi <= 1.0 && fRSPionXSec == false) {
153  xsec_stat = utils::hadxs::berger::PionNucleusXSec(tpi, ppistar, t_itt, A, tpilow, siglow, tpihigh, sighigh);
154  if(xsec_stat){
155  LOG("BergerSehgalCohPi", pERROR) << "Call to PionNucleusXSec code failed - return xsec of 0.0";
156  return 0.0;
157  }
158  dsigdzfit = siglow + (sighigh - siglow) * (tpi - tpilow) / (tpihigh - tpilow);
159  dsigdtfit = dsigdzfit / (2.0 * ppistar * ppistar);
160  // we are handed a cross section in mb, need to convert it to GeV^{-2}
161  dsig += 1.0 * front * Ga2 * t_width * dsigdtfit * units::mb;
162  }
163  else {
164  dsig += /*factor **/ front * Ga2 * t_width * RS_factor * exp(-1.0*b*t_itt);
165  }
166 
167  }
168  xsec = dsig;
169 
170  // Correction for finite final state lepton mass.
171  // Lepton mass modification is part of Berger-Sehgal and is not optional.
172  if (pionIsCharged) {
173  double C = 1.;
174  // First, we need to remove the leading G_{A}^2 which is required for NC.
175  xsec /= Ga2;
176  // Next, \cos^2 \theta_{Cabibbo} appears in the CC xsec, but not the NC.
177  xsec *= fCos8c2;
178  double ml = interaction->FSPrimLepton()->Mass();
179  double ml2 = TMath::Power(ml,2);
180  double Q2min = ml2 * y/(1-y);
181  if(Q2 > Q2min) {
182  double C1 = TMath::Power(Ga - 0.5 * Q2min / (Q2 + kPionMass2), 2);
183  double C2 = 0.25 * y * Q2min * (Q2 - Q2min) /
184  TMath::Power(Q2 + kPionMass2, 2);
185  C = C1 + C2;
186  } else {
187  C = 0.;
188  }
189  xsec *= (2. * C); // *2 is for CC vs NC in BS
190  }
191 
192 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
193  LOG("BergerSehgalCohPi", pDEBUG)
194  << "\n momentum transfer .............. Q2 = " << Q2
195  << "\n mass number .................... A = " << A
196  << "\n pion energy .................... Epi = " << Epi
197  << "\n propagator term ................ Ga2 = " << Ga2
198  << "\n total pi+N cross section ....... sigT = " << sigtot_pin
199  << "\n inelastic pi+N cross section ... sigI = " << siginel_pin
200  << "\n nuclear size scale ............. Ro = " << fRo
201  << "\n pion absorption factor ......... Fabs = " << fabs
202  << "\n t integration range ............ [" << tmin << "," << tmax << "]"
203  LOG("BergerSehgalCohPi", pINFO)
204  << "d2xsec/dQ2dy[COHPi] (Q2= " << Q2 << ", y="
205  << y << ", E=" << E << ") = "<< xsec;
206 #endif
207 
208  //----- The algorithm computes d^2xsec/dQ2dy
209  // Check whether variable tranformation is needed? May be working with logs.
210  // kPSlogQ2logyfE is possible - all others will not succeed
211  if(kps != kPSQ2yfE) {
212  double J = utils::kinematics::Jacobian(interaction,kPSQ2yfE, kps);
213  xsec *= J;
214  }
215  return xsec;
216 }
double J(double q0, double q3, double Enu, double ml)
Definition: MECUtils.cxx:147
#define pERROR
Definition: Messenger.h:59
bool fRSPionXSec
Use Rein-Sehgal &quot;style&quot; pion-nucleon xsecs.
double Q2(const Interaction *const i)
Definition: KineUtils.cxx:1077
int A(void) const
Definition: Target.h:70
Generated/set kinematical variables for an event.
Definition: Kinematics.h:39
double PionNucleonXSec(double Epion, bool get_total, bool isChargedPion=true)
Definition: HadXSUtils.cxx:96
double fRo
nuclear size scale parameter
double x(bool selected=false) const
Definition: Kinematics.cxx:99
double Mass(void) const
Definition: Target.cxx:224
double PionCOMAbsMomentum(const Interaction *i) const
double y(bool selected=false) const
Definition: Kinematics.cxx:112
static constexpr double b
Definition: Units.h:78
virtual bool ValidKinematics(const Interaction *i) const
Is the input kinematical point a physically allowed one?
const double e
#define LOG(stream, priority)
A macro that returns the requested log4cpp::Category appending a string (using the FILE...
Definition: Messenger.h:96
static constexpr double A
Definition: Units.h:74
static constexpr double mb
Definition: Units.h:79
#define pINFO
Definition: Messenger.h:62
double ExactKinematicTerm(const Interaction *i) const
bool ValidProcess(const Interaction *i) const
Can this cross section algorithm handle the input process?
double Jacobian(const Interaction *const i, KinePhaseSpace_t f, KinePhaseSpace_t t)
Definition: KineUtils.cxx:130
static constexpr double fermi
Definition: Units.h:55
double Q2(bool selected=false) const
Definition: Kinematics.cxx:125
const Target & Tgt(void) const
Definition: InitialState.h:66
double ProbeE(RefFrame_t rf) const
Initial State information.
Definition: InitialState.h:48
#define pDEBUG
Definition: Messenger.h:63
int PionNucleusXSec(double tpi, double ppistar, double t_new, double A, double &tpilow, double &siglow, double &tpihigh, double &sighigh)
Definition: HadXSUtils.cxx:205

Member Data Documentation

double genie::BergerSehgalCOHPiPXSec2015::fCos8c2
private

cos^2(Cabibbo angle)

Definition at line 61 of file BergerSehgalCOHPiPXSec2015.h.

Referenced by LoadConfig(), and XSec().

double genie::BergerSehgalCOHPiPXSec2015::fMa
private

axial mass

Definition at line 59 of file BergerSehgalCOHPiPXSec2015.h.

Referenced by LoadConfig(), and XSec().

double genie::BergerSehgalCOHPiPXSec2015::fRo
private

nuclear size scale parameter

Definition at line 60 of file BergerSehgalCOHPiPXSec2015.h.

Referenced by LoadConfig(), and XSec().

bool genie::BergerSehgalCOHPiPXSec2015::fRSPionXSec
private

Use Rein-Sehgal "style" pion-nucleon xsecs.

Definition at line 62 of file BergerSehgalCOHPiPXSec2015.h.

Referenced by LoadConfig(), and XSec().

const XSecIntegratorI* genie::BergerSehgalCOHPiPXSec2015::fXSecIntegrator
private

Definition at line 64 of file BergerSehgalCOHPiPXSec2015.h.

Referenced by Integral(), and LoadConfig().


The documentation for this class was generated from the following files: