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genie::ReinSehgalCOHPiPXSec Class Reference

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

#include <ReinSehgalCOHPiPXSec.h>

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Public Member Functions

 ReinSehgalCOHPiPXSec ()
 
 ReinSehgalCOHPiPXSec (string config)
 
virtual ~ReinSehgalCOHPiPXSec ()
 
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)
 

Private Attributes

double fMa
 axial mass More...
 
double fReIm
 Re/Im {forward pion scattering amplitude}. More...
 
double fRo
 nuclear size scale parameter More...
 
bool fModPCAC
 use modified PCAC (including f/s lepton mass) 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 Rein-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 analytically integrated out.

      Is a concrete implementation of the XSecAlgorithmI interface.
References:
D.Rein and L.M.Sehgal, Coherent pi0 production in neutrino reactions, Nucl.Phys.B223:29-144 (1983)

D.Rein and L.M.Sehgal, PCAC and the Deficit of Forward Muons in pi+ Production by Neutrinos, hep-ph/0606185

Author
Costas Andreopoulos <c.andreopoulos cern.ch> University of Liverpool
Created:
March 11, 2005
License:
Copyright (c) 2003-2024, The GENIE Collaboration For the full text of the license visit http://copyright.genie-mc.org

Definition at line 40 of file ReinSehgalCOHPiPXSec.h.

Constructor & Destructor Documentation

ReinSehgalCOHPiPXSec::ReinSehgalCOHPiPXSec ( )

Definition at line 31 of file ReinSehgalCOHPiPXSec.cxx.

31  :
32 XSecAlgorithmI("genie::ReinSehgalCOHPiPXSec")
33 {
34 
35 }
ReinSehgalCOHPiPXSec::ReinSehgalCOHPiPXSec ( string  config)

Definition at line 37 of file ReinSehgalCOHPiPXSec.cxx.

37  :
38 XSecAlgorithmI("genie::ReinSehgalCOHPiPXSec", config)
39 {
40 
41 }
ReinSehgalCOHPiPXSec::~ReinSehgalCOHPiPXSec ( )
virtual

Definition at line 43 of file ReinSehgalCOHPiPXSec.cxx.

44 {
45 
46 }

Member Function Documentation

void ReinSehgalCOHPiPXSec::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 176 of file ReinSehgalCOHPiPXSec.cxx.

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

177 {
178  Algorithm::Configure(config);
179  this->LoadConfig();
180 }
virtual void Configure(const Registry &config)
Definition: Algorithm.cxx:62
void ReinSehgalCOHPiPXSec::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 182 of file ReinSehgalCOHPiPXSec.cxx.

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

183 {
184  Algorithm::Configure(config);
185  this->LoadConfig();
186 }
virtual void Configure(const Registry &config)
Definition: Algorithm.cxx:62
double ReinSehgalCOHPiPXSec::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 151 of file ReinSehgalCOHPiPXSec.cxx.

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

152 {
153  double xsec = fXSecIntegrator->Integrate(this,interaction);
154  return xsec;
155 }
const XSecIntegratorI * fXSecIntegrator
virtual double Integrate(const XSecAlgorithmI *model, const Interaction *interaction) const =0
void ReinSehgalCOHPiPXSec::LoadConfig ( void  )
private

Definition at line 188 of file ReinSehgalCOHPiPXSec.cxx.

References fMa, fModPCAC, fReIm, fRo, fXSecIntegrator, genie::Algorithm::GetParam(), and genie::Algorithm::SubAlg().

Referenced by Configure().

189 {
190 
191  GetParam( "COH-Ma", fMa ) ;
192  GetParam( "COH-Ro", fRo ) ;
193  GetParam( "COH-ReImAmpl", fReIm ) ;
194  GetParam( "COH-UseModifiedPCAC", fModPCAC ) ;
195 
196  //-- load the differential cross section integrator
198  dynamic_cast<const XSecIntegratorI *> (this->SubAlg("XSec-Integrator"));
199  assert(fXSecIntegrator);
200 }
Cross Section Integrator Interface.
bool fModPCAC
use modified PCAC (including f/s lepton mass)
double fReIm
Re/Im {forward pion scattering amplitude}.
const XSecIntegratorI * fXSecIntegrator
bool GetParam(const RgKey &name, T &p, bool is_top_call=true) const
double fRo
nuclear size scale parameter
const Algorithm * SubAlg(const RgKey &registry_key) const
Definition: Algorithm.cxx:345
bool ReinSehgalCOHPiPXSec::ValidProcess ( const Interaction i) const
virtual

Can this cross section algorithm handle the input process?

Implements genie::XSecAlgorithmI.

Definition at line 157 of file ReinSehgalCOHPiPXSec.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().

158 {
159  if(interaction->TestBit(kISkipProcessChk)) return true;
160 
161  const InitialState & init_state = interaction->InitState();
162  const ProcessInfo & proc_info = interaction->ProcInfo();
163  const Target & target = init_state.Tgt();
164 
165  int nu = init_state.ProbePdg();
166 
167  if (!proc_info.IsCoherentProduction()) return false;
168  if (!proc_info.IsWeak()) return false;
169  if (target.HitNucIsSet()) return false;
170  if (!(target.A()>1)) return false;
171  if (!pdg::IsNeutrino(nu) && !pdg::IsAntiNeutrino(nu)) return false;
172 
173  return true;
174 }
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 ReinSehgalCOHPiPXSec::XSec ( const Interaction i,
KinePhaseSpace_t  k 
) const
virtual

Compute the cross section for the input interaction.

Implements genie::XSecAlgorithmI.

Definition at line 48 of file ReinSehgalCOHPiPXSec.cxx.

References genie::Target::A(), genie::units::A, genie::units::b, genie::units::fermi, fMa, fModPCAC, fReIm, fRo, genie::Interaction::FSPrimLepton(), genie::utils::hadxs::InelasticPionNucleonXSec(), genie::ProcessInfo::IsWeakCC(), genie::utils::mec::J(), genie::utils::kinematics::Jacobian(), genie::constants::kGF2, genie::constants::kNucleonMass, genie::constants::kPi, genie::constants::kPi3, genie::constants::kPionMass, genie::constants::kPionMass2, genie::kPSxyfE, genie::kRfLab, LOG, pDEBUG, pINFO, genie::InitialState::ProbeE(), genie::Interaction::ProcInfo(), genie::utils::kinematics::Q2(), genie::InitialState::Tgt(), genie::utils::hadxs::TotalPionNucleonXSec(), genie::XSecAlgorithmI::ValidKinematics(), ValidProcess(), genie::Kinematics::x(), and genie::Kinematics::y().

50 {
51  if(! this -> ValidProcess (interaction) ) return 0.;
52  if(! this -> ValidKinematics (interaction) ) return 0.;
53 
54  const Kinematics & kinematics = interaction -> Kine();
55  const InitialState & init_state = interaction -> InitState();
56 
57  //----- Compute the coherent NC pi0 production d2xsec/dxdy
58  // see page 34 in Nucl.Phys.B223:29-144 (1983)
59  double E = init_state.ProbeE(kRfLab); // neutrino energy
60  double x = kinematics.x(); // bjorken x
61  double y = kinematics.y(); // inelasticity y
62  double Q2 = 2.*x*y*kNucleonMass*E; // momentum transfer Q2>0
63  double A = (double) init_state.Tgt().A(); // mass number
64  double A2 = TMath::Power(A,2.);
65  double A_3 = TMath::Power(A,1./3.);
66  double Gf = kGF2 * kNucleonMass / (32 * kPi3);
67  double fp = 0.93 * kPionMass; // pion decay constant
68  double fp2 = TMath::Power(fp,2.);
69  double Epi = y*E; // pion energy
70  double ma2 = TMath::Power(fMa,2);
71  double propg = TMath::Power(ma2/(ma2+Q2),2.); // propagator term
72  double r2 = TMath::Power(fReIm,2.);
73  double sTot = utils::hadxs::TotalPionNucleonXSec(Epi); // tot. pi+N xsec
74  double sTot2 = TMath::Power(sTot,2.);
75  double sInel = utils::hadxs::InelasticPionNucleonXSec(Epi); // inel. pi+N xsec
76  double Ro2 = TMath::Power(fRo*units::fermi,2.);
77 
78  // effect of pion absorption in the nucleus
79  double Fabs = TMath::Exp( -9.*A_3*sInel / (16.*kPi*Ro2) );
80 
81  // the xsec in Nucl.Phys.B223:29-144 (1983) is d^3xsec/dxdydt but the only
82  // t-dependent factor is an exp(-bt) so it can be integrated analyticaly
83  double Epi2 = TMath::Power(Epi,2.);
84  double R = fRo * A_3 * units::fermi; // nuclear radius
85  double R2 = TMath::Power(R,2.);
86  double b = 0.33333 * R2;
87  double MxEpi = kNucleonMass*x/Epi;
88  double mEpi2 = kPionMass2/Epi2;
89  double tA = 1. + MxEpi - 0.5*mEpi2;
90  double tB = TMath::Sqrt(1. + 2*MxEpi) * TMath::Sqrt(1.-mEpi2);
91  double tmin = 2*Epi2 * (tA-tB);
92  double tmax = 2*Epi2 * (tA+tB);
93  double tint = (TMath::Exp(-b*tmin) - TMath::Exp(-b*tmax))/b; // t integral
94 
95  double xsec = Gf*fp2 * A2 * E*(1-y) * sTot2 * (1+r2)*propg * Fabs*tint;
96 
97 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
98  LOG("ReinSehgalCohPi", pDEBUG)
99  << "\n momentum transfer .............. Q2 = " << Q2
100  << "\n mass number .................... A = " << A
101  << "\n pion energy .................... Epi = " << Epi
102  << "\n propagator term ................ propg = " << propg
103  << "\n Re/Im of fwd pion scat. ampl. .. Re/Im = " << fReIm
104  << "\n total pi+N cross section ....... sigT = " << sTot
105  << "\n inelastic pi+N cross section ... sigI = " << sInel
106  << "\n nuclear size scale ............. Ro = " << fRo
107  << "\n pion absorption factor ......... Fabs = " << Fabs
108  << "\n t integration range ............ [" << tmin << "," << tmax << "]"
109  << "\n t integration factor ........... tint = " << tint;
110 #endif
111 
112  // compute the cross section for the CC case
113 
114  if(interaction->ProcInfo().IsWeakCC()) {
115  // Check whether a modification to Adler's PCAC theorem is applied for
116  // including the effect of the muon mass.
117  // See Rein and Sehgal, PCAC and the Deficit of Forward Muons in pi+
118  // Production by Neutrinos, hep-ph/0606185
119  double C = 1.;
120  if(fModPCAC) {
121  double ml = interaction->FSPrimLepton()->Mass();
122  double ml2 = TMath::Power(ml,2);
123  double Q2min = ml2 * y/(1-y);
124  if(Q2>Q2min) {
125  double C1 = TMath::Power(1-0.5*Q2min/(Q2+kPionMass2), 2);
126  double C2 = 0.25*y*Q2min*(Q2-Q2min)/ TMath::Power(Q2+kPionMass2,2);
127  C = C1+C2;
128  } else {
129  C = 0.;
130  }
131  }
132  xsec *= (2.*C);
133  }
134 
135 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
136  LOG("ReinSehgalCohPi", pINFO)
137  << "d2xsec/dxdy[COHPi] (x= " << x << ", y="
138  << y << ", E=" << E << ") = "<< xsec;
139 #endif
140 
141  //----- The algorithm computes d^2xsec/dxdy
142  // Check whether variable tranformation is needed
143  if(kps!=kPSxyfE) {
144  double J = utils::kinematics::Jacobian(interaction,kPSxyfE,kps);
145  xsec *= J;
146  }
147 
148  return xsec;
149 }
double J(double q0, double q3, double Enu, double ml)
Definition: MECUtils.cxx:147
static const double kNucleonMass
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 x(bool selected=false) const
Definition: Kinematics.cxx:99
bool ValidProcess(const Interaction *i) const
Can this cross section algorithm handle the input process?
bool fModPCAC
use modified PCAC (including f/s lepton mass)
double fReIm
Re/Im {forward pion scattering amplitude}.
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?
#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
#define pINFO
Definition: Messenger.h:62
double InelasticPionNucleonXSec(double Epion, bool isChargedPion=true)
Definition: HadXSUtils.cxx:20
double Jacobian(const Interaction *const i, KinePhaseSpace_t f, KinePhaseSpace_t t)
Definition: KineUtils.cxx:130
static constexpr double fermi
Definition: Units.h:55
const Target & Tgt(void) const
Definition: InitialState.h:66
double fRo
nuclear size scale parameter
double ProbeE(RefFrame_t rf) const
double TotalPionNucleonXSec(double Epion, bool isChargedPion=true)
Definition: HadXSUtils.cxx:51
Initial State information.
Definition: InitialState.h:48
#define pDEBUG
Definition: Messenger.h:63

Member Data Documentation

double genie::ReinSehgalCOHPiPXSec::fMa
private

axial mass

Definition at line 61 of file ReinSehgalCOHPiPXSec.h.

Referenced by LoadConfig(), and XSec().

bool genie::ReinSehgalCOHPiPXSec::fModPCAC
private

use modified PCAC (including f/s lepton mass)

Definition at line 64 of file ReinSehgalCOHPiPXSec.h.

Referenced by LoadConfig(), and XSec().

double genie::ReinSehgalCOHPiPXSec::fReIm
private

Re/Im {forward pion scattering amplitude}.

Definition at line 62 of file ReinSehgalCOHPiPXSec.h.

Referenced by LoadConfig(), and XSec().

double genie::ReinSehgalCOHPiPXSec::fRo
private

nuclear size scale parameter

Definition at line 63 of file ReinSehgalCOHPiPXSec.h.

Referenced by LoadConfig(), and XSec().

const XSecIntegratorI* genie::ReinSehgalCOHPiPXSec::fXSecIntegrator
private

Definition at line 66 of file ReinSehgalCOHPiPXSec.h.

Referenced by Integral(), and LoadConfig().


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