LHEReader Class Reference

Class to read LHE files and store the content in a MCParticle graph. More...

#include <LHEReader.h>

Collaboration diagram for LHEReader:

Public Member Functions
	BELLE2_DEFINE_EXCEPTION (LHECouldNotOpenFileError, "Could not open file %1% !")
	Exception is thrown if the LHE file could not be opened.
	BELLE2_DEFINE_EXCEPTION (LHEInvalidDaughterIndicesError, "Line %1%: Invalid daughter indices d1=%2%, d2=%3%, N=%4% (0<=d1<=d2<=N required)")
	Exception is thrown if the given indices of the daughters are not valid.
	BELLE2_DEFINE_EXCEPTION (LHEHeaderNotValidError, "Line %1%: Event header not understood: %2%")
	Exception is thrown if the header specifying the event header could not be parsed.
	BELLE2_DEFINE_EXCEPTION (LHEConvertFieldError, "Line %1%: Could not convert field %2%: %3%")
	Exception is thrown if a field in the LHE file could not be converted to a number.
	BELLE2_DEFINE_EXCEPTION (LHEParticleFormatError, "Line %1%: Particle format not understood, got %2% fields !")
	Exception is thrown if the format of a line of the LHE file could not be parsed.
	BELLE2_DEFINE_EXCEPTION (LHEEmptyEventError, "Line %1%: Number of particles in event is %2% ! (This could mean EOF is reached.) ")
	Exception is thrown if the number of particles for this event is 0 or less. More...
	LHEReader ()
	Constructor.
	~LHEReader ()
	Destructor.
void	open (const std::string &filename)
	Opens an ascii file and prepares it for reading. More...
void	closeCurrentInputFile ()
	Closes the current input file to allow opening the next one.
int	getEvent (MCParticleGraph &graph, double &weight)
	Reads the next event and stores the result in the given MCParticle graph. More...
bool	skipEvents (int n)
	Skips a given number of events. More...
void	setInitialIndex (int index)
	Set the maximum index of particles in each event that must be set as c_Initial (1-based). More...
void	setVirtualIndex (int index)
	Set the maximum index of particles in each event that must be set as c_IsVirtual (1-based). More...

Public Attributes
bool	m_wrongSignPz
	Bool to indicate that HER and LER were swapped.
TLorentzRotation	m_labboost
	Boost&rotation vector for boost from CM to LAB.
double	m_meanDecayLength = 0.
	Mean lifetime*c of displaced particle.
double	m_Rmin = 0.
	Minimum of vertex distance to IP.
double	m_Rmax = 0.
	Maximum of vertex distance to IP.
int	m_pdgDisplaced = 0
	PDG code of the displaced particle being studied.

Protected Types
typedef boost::tokenizer< boost::char_separator< char > >	tokenizer
	Just a typedef for simple use of the boost::tokenizer to split the lines.

Protected Member Functions
std::string	getLine ()
	Returns the current line from the LHE ascii file. More...
int	readEventHeader (double &eventWeight)
	Reads the event header from the hepevt file. More...
int	readParticle (MCParticleGraph::GraphParticle &particle)
	Reads the information for a single particle from the LHE file. More...

Protected Attributes
int	m_lineNr
	The current line number within the ascii file.
std::ifstream	m_input
	The input stream of the ascii file.
int	m_indexInitial
	Maximum index of particles in each event that must be set as c_Initial (1-based).
int	m_indexVirtual
	Maximum index of particles in each event that must be set as c_IsVirtual (1-based).

Static Protected Attributes
static const boost::char_separator< char >	sep
	The characters at which to split, defaults to ",; \t".

Detailed Description

Class to read LHE files and store the content in a MCParticle graph.

The class is very similar to the HepEvt Reader

The events are read sequentially with the option of skipping a certain number of events. Random access of events is not possible.

Definition at line 43 of file LHEReader.h.

Member Function Documentation

BELLE2_DEFINE_EXCEPTION()

BELLE2_DEFINE_EXCEPTION	(	LHEEmptyEventError	,
		"Line %1%: Number of particles in event is %2% ! (This could mean EOF is reached.) "
	)

Exception is thrown if the number of particles for this event is 0 or less.

getEvent()

int getEvent	(	MCParticleGraph &	graph,
		double &	weight
	)

Reads the next event and stores the result in the given MCParticle graph.

Parameters

graph	Reference to the graph which should be filled with the information from the LHE file.
weight	Reference to the event weight which can be filled from the file.

Returns

event numer if the event could be read and the number was provided in the file.

Definition at line 39 of file LHEReader.cc.

{
//   int eventID = -1;
//   int nparticles = readEventHeader(eventID, eventWeight);
  int nparticles = readEventHeader(eventWeight);
  if (nparticles <= 0) {
    throw (LHEEmptyEventError() << m_lineNr << nparticles);
  }
 
  int first = graph.size();
  //Make list of particles
  for (int i = 0; i < nparticles; i++) {
    graph.addParticle();
  }
 
  double r, x = 0, y = 0, z = 0, t = 0;
  //Read particles from file
  for (int i = 0; i < nparticles; ++i) {
    MCParticleGraph::GraphParticle& p = graph[first + i];
    int mother = readParticle(p);
 
    // add the mother
    if (mother > 0) {
      MCParticleGraph::GraphParticle* q = &graph[mother - 1];
      p.comesFrom(*q);
    }
 
    //move vertex position of selected particle and its daughters
    if (m_meanDecayLength > 0) {
      if (p.getPDG() == m_pdgDisplaced) {
        TF1 fr("fr", "exp(-x/[0])", 0, 1000000);
        TLorentzVector p4 = p.get4Vector();
        fr.SetRange(m_Rmin, m_Rmax);
        fr.SetParameter(0, m_meanDecayLength * p4.Gamma());
        r = fr.GetRandom();
        x = r * p4.Px() / p4.P();
        y = r * p4.Py() / p4.P();
        z = r * p4.Pz() / p4.P();
        p.setDecayVertex(TVector3(x, y, z));
        t = (r / Const::speedOfLight) * (p4.E() / p4.P());
        p.setDecayTime(t);
        p.setValidVertex(true);
      }
 
      if (mother > 0) {
        if (graph[mother - 1].getPDG() == m_pdgDisplaced) {
          p.setProductionVertex(TVector3(x, y, z));
          p.setProductionTime(t);
          p.setValidVertex(true);
        }
      }
    }
 
    // boost particles to lab frame: both momentum and vertex
    TLorentzVector p4 = p.get4Vector();
    TLorentzVector v4;
    if (m_wrongSignPz) // this means we have to mirror Pz
      p4.SetPz(-1.0 * p4.Pz());
    p4 = m_labboost * p4;
    p.set4Vector(p4);
    if (p.getPDG() == m_pdgDisplaced) {
      v4.SetXYZT(p.getDecayVertex().X(), p.getDecayVertex().Y(), p.getDecayVertex().Z(), Const::speedOfLight * p.getDecayTime());
      v4 = m_labboost * v4;
      p.setDecayVertex(v4.X(), v4.Y(), v4.Z());
      p.setDecayTime(v4.T() / Const::speedOfLight);
    } else if (mother > 0) {
      if (graph[mother - 1].getPDG() == m_pdgDisplaced) {
        v4.SetXYZT(p.getProductionVertex().X(), p.getProductionVertex().Y(), p.getProductionVertex().Z(),
                   Const::speedOfLight * p.getProductionTime());
        v4 = m_labboost * v4;
        p.setProductionVertex(v4.X(), v4.Y(), v4.Z());
        p.setProductionTime(v4.T() / Const::speedOfLight);
      }
    }
 
 
    // initial 2 (e+/e-), virtual 3 (Z/gamma*)
    // check if particle should be made virtual according to steering options:
    if (i < m_indexVirtual && i >= m_indexInitial)
      p.addStatus(MCParticle::c_IsVirtual);
 
    if (i < m_indexInitial)
      p.addStatus(MCParticle::c_Initial);
 
    if (m_indexVirtual < m_indexInitial) B2WARNING("IsVirtual particle requested but is overwritten by Initial");
 
  }
//   return eventID;
  return -1;
}

getLine()

std::string getLine ( )

protected

Returns the current line from the LHE ascii file.

• double eventWeight; /‍**< The event weight if provided in LHEfile else 1. *‍/ *‍/

  Returns

  The current line as a string.

Definition at line 149 of file LHEReader.cc.

open()

void open

(

const std::string &

filename

)

Opens an ascii file and prepares it for reading.

Parameters

filename

The filename of the LHE ascii file which should be read.

Definition at line 31 of file LHEReader.cc.

readEventHeader()

int readEventHeader ( double &  eventWeight )

protected

Reads the event header from the hepevt file.

Returns

The number of particles for the current event. @params: References to the eventID and the eventWeight which can both be read from the file.

Definition at line 168 of file LHEReader.cc.

readParticle()

int readParticle ( MCParticleGraph::GraphParticle &  particle )

protected

Reads the information for a single particle from the LHE file.

Parameters

particle

Reference to the particle which will be filled with the information from the LHE file.

Definition at line 215 of file LHEReader.cc.

setInitialIndex()

void setInitialIndex ( int  index )

inline

Set the maximum index of particles in each event that must be set as c_Initial (1-based).

Parameters

[in]

index

Maximum index for c_Initial.

Definition at line 106 of file LHEReader.h.

:

setVirtualIndex()

void setVirtualIndex ( int  index )

inline

Set the maximum index of particles in each event that must be set as c_IsVirtual (1-based).

Parameters

[in]

index

Maximum index for c_IsVirtual.

Definition at line 112 of file LHEReader.h.

skipEvents()

bool skipEvents

(

int

n

)

Skips a given number of events.

Parameters

n	The number of events which should be skipped.

Returns

True if the events could be skipped.

Definition at line 131 of file LHEReader.cc.

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

• generators/lhe/include/LHEReader.h
• generators/lhe/src/LHEReader.cc