Merge pull request #19 from eic/WgA_limits_feature

Added Wgp limits features

README.md

@@ -58,6 +58,16 @@ ELECTRON_BEAM_GAMMA = (Electron Energy)/(0.000511 GeV)
 ELECTRON_BEAM_GAMMA = 9785 # 5GeV electrons from eRHIC
 ELECTRON_BEAM_GAMMA = 19569 #10GeV electrons from eRHIC
 ELECTRON_BEAM_GAMMA = 35225 #18GeV electrons from eRHIC
+```
+  * Note: The constraints on the center-of-mass energy of the vitrual photon and ion is set by:
+```
+W_GP_MAX = Max value of W_gp that user can set and wants to use (GeV)
+W_GP_MIN = Min value of W_gp that user can set and wants to use (GeV)
+```
+ * For example:
+ ```
+ W_GP_MAX = 30 # W_gp will have a maximum value of 30 GeV.
+ W_GP_MIN = 2 # W_gp will start to sample from the minimum value of 2 GeV. W_GP_MIN should not be greater than the center-of-mass energy of the electron and ion beams.
 ```
   * For exclusive backward (u-channel) production, use:
 ```

include/inputParameters.h

@@ -192,6 +192,8 @@ class inputParameters {
 	double       cmsMinPhotonEnergy       () const { return _cmsMinPhotonEnergy;          }  ///< returns maximum photon energy 
 	double       maxW                  () const { return _maxW.value();                   }  ///< returns maximum mass W of produced hadronic system [GeV/c^2]
 	double       minW                  () const { return _minW.value();                   }  ///< returns minimum mass W of produced hadronic system [GeV/c^2]
+	double       maxW_GP               () const { return _maxW_GP.value();                }  ///< returns maximum W of produced virtual photon and nucleon system [GeV/c^2]
+	double       minW_GP               () const { return _minW_GP.value();                }  ///< returns minimum W of produced virtual photon and nucleon system [GeV/c^2]
 	unsigned int nmbWBins              () const { return _nmbWBins.value();               }  ///< returns number of W bins in lookup table
 	double       maxRapidity           () const { return _maxRapidity.value();            }  ///< returns maximum absolute value of rapidity
 	unsigned int nmbRapidityBins       () const { return _nmbRapidityBins.value();        }  ///< returns number of rapidity bins in lookup table
@@ -236,7 +238,7 @@ class inputParameters {
 	starlightConstants::interactionTypeEnum interactionType      () const { return _interactionType; }  ///< returns interaction type
 	double protonEnergy                () const { return _protonEnergy.value(); }
 	double electronEnergy              () const { return _electronEnergy.value(); }
-        double inputBranchingRatio         () const { return _inputBranchingRatio; }
+	double inputBranchingRatio         () const { return _inputBranchingRatio; }
 	double targetRadius                () const { return _targetR; }
 
         void setBaseFileName          (std::string v )  {  _baseFileName = v;     }
@@ -249,6 +251,8 @@ class inputParameters {
 	//void setMaxPhotonEnergy       (double v)  {  _maxPhotonEnergy = v ;       }  ///< sets maximim photon energy
 	void setMaxW                  (double v)  {  _maxW = v;                   }  ///< sets maximum mass W of produced hadronic system [GeV/c^2]
 	void setMinW                  (double v)  {  _minW = v;                   }  ///< sets minimum mass W of produced hadronic system [GeV/c^2]
+	void setmaxW_GP                  (double v)  {  _maxW_GP = v;                   }  ///< sets maximum mass W of produced virtual photon and nucleon system [GeV/c^2]
+	void setminW_GP                  (double v)  {  _minW_GP = v;                   }  ///< sets minimum mass W of produced virtual photon and nucleon system [GeV/c^2]
 	void setNmbWBins              (unsigned int v)  {  _nmbWBins = v;         }  ///< sets number of W bins in lookup table
 	void setMaxRapidity           (double v)  {  _maxRapidity = v;            }  ///< sets maximum absolute value of rapidity
 	void setNmbRapidityBins       (unsigned int v)  {  _nmbRapidityBins = v;  }  ///< sets number of rapidity bins in lookup table
@@ -289,7 +293,6 @@ class inputParameters {
 
 	void setProtonEnergy        (double v)    { _protonEnergy = v;            }  ///< sets proton energy 
 	void setElectronEnergy      (double v)    { _electronEnergy = v;          }  ///< sets electron energy
-
 	template<typename T>
 	inline bool setParameter(std::string expression);
 
@@ -316,6 +319,8 @@ class inputParameters {
 	parameter<double, VALIDITY_CHECK>          _targetBeamLorentzGamma;       ///< Lorentz gamma factor of beam 2 in collider frame
 	parameter<double, VALIDITY_CHECK>          _maxW;                    ///< maximum mass W of produced hadronic system [GeV/c^2]
 	parameter<double, VALIDITY_CHECK>          _minW;                    ///< minimum mass W of produced hadronic system; if set to -1 default value is taken [GeV/c^2]
+	parameter<double, VALIDITY_CHECK>          _maxW_GP;                 ///< maximum mass W of produced virtual photon and nucleon system, has no maximum limit [GeV/c^2]
+	parameter<double, VALIDITY_CHECK>          _minW_GP;                 ///< minimum mass W of produced virtual photon and nucleon system, should be no greater than COM energy of source + traget or code will terminate [GeV/c^2]
 	parameter<unsigned int, VALIDITY_CHECK>    _nmbWBins;                ///< number of W bins in lookup table
 	parameter<double, VALIDITY_CHECK>          _maxRapidity;             ///< maximum absolute value of rapidity
 	parameter<unsigned int, VALIDITY_CHECK>    _nmbRapidityBins;         ///< number of rapidity bins in lookup table

include/photonNucleusCrossSection.h

@@ -39,7 +39,7 @@
 #include "beambeamsystem.h"
 #include "inputParameters.h"
 
-class photonNucleusCrossSection {
+class photonNucleusCrossSection{
 
 public:
 
@@ -135,6 +135,8 @@ class photonNucleusCrossSection {
 	double _maxPhotonEnergy;  ///< max photon energy in lab frame [GeV] (for vectormesons only)
 	double _cmsMinPhotonEnergy;
 	double _targetRadii;
+	double _maxW_GP;		  ///< max W_GP energy
+	double _minW_GP; 		  ///< min W_GP energy
 
 };
 

slight.in

@@ -14,6 +14,8 @@ TARGET_BEAM_GAMMA = 293.2 #275 GeV protons from eRHIC
 W_MAX = -1   #Max value of w from HERA
 W_MIN = -1    #Min value of w from HERA
 W_N_BINS = 50    #Bins i w
+W_GP_MAX = -1  #Max value of W_gp (virtual photon+nucleon COM energy)
+W_GP_MIN = -1  #Min value of W_gp
 EGA_N_BINS = 400
 CUT_PT = 0 #Cut in pT? 0 = (no, 1 = yes)
 PT_MIN = 1.0 #Minimum pT in GeV

src/inputParameters.cpp

@@ -58,6 +58,8 @@ inputParameters::inputParameters()
 	  _targetBeamLorentzGamma     ("TARGET_BEAM_GAMMA",0),
 	  _maxW                  ("W_MAX",0),
 	  _minW                  ("W_MIN",0),
+	  _maxW_GP           	 ("W_GP_MAX", 0,NOT_REQUIRED), 
+	  _minW_GP          	 ("W_GP_MIN", 0,NOT_REQUIRED), 
 	  _nmbWBins              ("W_N_BINS",0),
 	  _maxRapidity           ("RAP_MAX",9,NOT_REQUIRED),
 	  _nmbRapidityBins       ("RAP_N_BINS",100,NOT_REQUIRED),
@@ -110,7 +112,10 @@ inputParameters::inputParameters()
 
 	_ip.addParameter(_maxW);
 	_ip.addParameter(_minW);
-
+
+	_ip.addParameter(_maxW_GP);
+	_ip.addParameter(_minW_GP);
+
 	_ip.addParameter(_nmbWBins);
 
 	_ip.addParameter(_maxRapidity);
@@ -194,6 +199,8 @@ inputParameters::configureFromFile(const std::string &_configFileName)
 	double _totalEnergy_lab = 1.0*_electronEnergy_lab + _ionEnergy_lab;
 	double _totalPz_lab = _ionPz_lab + _electronPz_lab;
 	_rap_CM = (1.0/2.0)*log((_totalEnergy_lab + _totalPz_lab)/(_totalEnergy_lab - _totalPz_lab));
+	double _totalEnergy_COM;
+	_totalEnergy_COM = sqrt((_totalEnergy_lab) * (_totalEnergy_lab) - (_totalPz_lab) * (_totalPz_lab)); //This is Lorentz invariant.
 
 	_beamLorentzGamma = cosh(_rap_CM-rap2);
 	_targetLorentzGamma = cosh(rap1-rap2);
@@ -565,6 +572,26 @@ inputParameters::configureFromFile(const std::string &_configFileName)
 		return false;
 	}
 
+	if (_minW_GP.value() == -1)
+		_minW_GP = 0;
+	if (_maxW_GP.value() == -1)
+		_maxW_GP = 1e7;
+	if ( _maxW_GP.value() <= _minW_GP.value() ) {
+		printWarn << "maxW_GA must be greater than minW_GP" << endl;
+		printWarn <<"The value of minW_GP is " << _minW_GP << endl;
+		printWarn <<"The value of maxW_GP is " << _maxW_GP << endl;
+		return false;
+	}
+	if(_minW_GP.value() > _totalEnergy_COM) { 
+	/* If the minimum COM energy of gamma and nucleon is set by user 
+	to be greater than the total energy supply by electron and target, code will terminate. */
+  	printWarn << "ERROR: The current input minimum CoM energy (_minW_GP) is: "<< _minW_GP 
+  	<< " which is larger than the total center-of-mass energy of the electron-ion system: " 
+  	<<_totalEnergy_COM << endl;
+  	cout<<"Exiting now..." << endl;
+ 	return false;
+  	}
+
 	// Sanity check on Q2 range in case it is specified by user
 	if( _minGammaQ2.value() != 0 || _maxGammaQ2.value() != 0){
 	  if( _minGammaQ2.value() <0 || _maxGammaQ2.value() <=_minGammaQ2.value() )
@@ -647,6 +674,8 @@ inputParameters::write(ostream& out) const
 	    << "BEAM_GAMMA"    << beamLorentzGamma     () <<endl
 	    << "W_MAX"         << maxW                 () <<endl
 	    << "W_MIN"         << minW                 () <<endl
+	    << "W_GP_MAX"      << maxW_GP              () <<endl
+	    << "W_GP_MIN"      << minW_GP              () <<endl
 	    << "W_N_BINS"      << nmbWBins             () <<endl
 	    << "RAP_MAX"       << maxRapidity          () <<endl
 	    << "RAP_N_BINS"    << nmbRapidityBins      () <<endl

src/photonNucleusCrossSection.cpp

@@ -65,7 +65,9 @@ photonNucleusCrossSection::photonNucleusCrossSection(const inputParameters& inpu
 	  _maxQ2             (inputParametersInstance.maxGammaQ2()        ),
 	  _maxPhotonEnergy   (inputParametersInstance.cmsMaxPhotonEnergy()),
 	  _cmsMinPhotonEnergy(inputParametersInstance.cmsMinPhotonEnergy()),
-	  _targetRadii       (inputParametersInstance.targetRadius()      )
+	  _targetRadii       (inputParametersInstance.targetRadius()      ),
+	  _maxW_GP           (inputParametersInstance.maxW_GP()              ),
+	  _minW_GP           (inputParametersInstance.minW_GP()              )
 {
         // new options - impulse aproximation (per Joakim) and Quantum Glauber (per SK) SKQG
         _impulseSelected = inputParametersInstance.impulseVM();
@@ -909,7 +911,8 @@ photonNucleusCrossSection::sigmagp(const double Wgp)
 	// Function for the gamma-proton --> VectorMeson
 	// cross section. Wgp is the gamma-proton CM energy.
 	// Unit for cross section: fm**2
-
+	//If W_gp is not in the allowed region, i.e. W_GP_MIN < W_gp < W_GP_MAX, do not sample.
+  	if(Wgp < _minW_GP || Wgp > _maxW_GP) return 0;
 	double sigmagp_r=0.;
 
 	// Near the threshold CM energy (between WgpMin and WgpMax), 

utils/ConvertStarlightAsciiToTree.C

@@ -77,12 +77,13 @@ void ConvertStarlightAsciiToTree(const char* inFileName  = "slight.out",
 	std::map<string, int> set_up;
 	double photon_setup[5];
 	//
-	Float_t        q2, Egamma, vertex_t;
+	Float_t        q2, W, Egamma, vertex_t;
 	outTree->Branch("beam1","TLorentzVector", &beam1,            32000, -1);	
 	outTree->Branch("beam2","TLorentzVector", &beam2,            32000, -1);	
 	//
 	outTree->Branch("Egamma",         &Egamma, "Egamma/F");
 	outTree->Branch("Q2",         &q2, "q2/F");
+	outTree->Branch("W",          &W, "W/F");
 	outTree->Branch("t",         &vertex_t, "vertex_t/F");
 	outTree->Branch("Target","TLorentzVector", &target,            32000, -1);
 	outTree->Branch("source",    "TLorentzVector", &source,            32000, -1);
@@ -215,7 +216,11 @@ void ConvertStarlightAsciiToTree(const char* inFileName  = "slight.out",
 		*source = TLorentzVector(px, py, pz, E);
 
 		lineStream.clear();
-		//
+		// Four-momentum of the gamma-ion system started as four-momentum of the target.
+		double pxtot = tpx; 
+		double pytot = tpy;	
+		double pztot = tpz;	
+		double Etot = tE;
 		for (int i = 0; i < nmbTracks; ++i) {
 			// read tracks
 			int    particleCode;
@@ -228,13 +233,20 @@ void ConvertStarlightAsciiToTree(const char* inFileName  = "slight.out",
 			R__ASSERT(label == "TRACK:");
 			Double_t daughterMass = IDtoMass(particleCode);
 			if (daughterMass < 0) {break;}
+			/*Adding up the momenta and energies of every daughter particle produced to get the total four-momentum.*/
 			const double E = sqrt(  momentum[0] * momentum[0] + momentum[1] * momentum[1]
 			                      + momentum[2] * momentum[2] + daughterMass * daughterMass);
 			new ( (*daughterParticles)[i] ) TLorentzVector(momentum[0], momentum[1], momentum[2], E);
 			*parentParticle += *(static_cast<TLorentzVector*>(daughterParticles->At(i)));
-
+			// Distributing the components of the four-momentum of the system to 3d momentum vector and Energy.
+			pxtot += momentum[0];
+			pytot += momentum[1];
+			pztot += momentum[2];
+			Etot += E;
 			lineStream.clear();
 		}
+		W = sqrt(Etot * Etot - pxtot * pxtot - pytot * pytot - pztot * pztot); //Lorentz invariant.
+
 		daughterParticles->Compress();
 		outTree->Fill();
 	}