Pythia7::String Class Reference

The String class describes the string of the Lund string fragmentation model. More...

#include <String.h>

List of all members.

Public Member Functions

void echo () const

Print function to be used for debugging.

Standard constructors and destructors.

String ()

Default constructor.

String (const String &)

Copy-constructor.

String (const PVector &)

Standard constructor.

~String ()

Destructor.

Access momenta and momentum fractions.

const LorentzMomentum & PtotRem () const

Returns the total remaining momentum of this String, currently available during fragmentation.

Energy2 Wrem2 () const

Returns the energy squared (Wrem2) of this String, currently available during fragmentation.

const LorentzMomentum & Pfwd (int fidx) const

Given a region index, fidx, return the forward longitudinal light-cone momentum.

const LorentzMomentum & Pbwd (int bidx) const

Given a region index, bidx, return the backward longitudinal light-cone momentum.

double Xremf (int fidx) const

Given a region index fidx, return the fraction of the longitudinal momentum available for fragmentation along the forward axis of this region.

double Xremb (int bidx) const

Given a region index bidx return the fraction of the longitudinal momentum available for fragmentation along the backward axis of this region.

const LorentzMomentum & Pplus (int j) const

Given the string region index j, return the light-cone momenta $p_{+j}$ .

const LorentzMomentum & Pminus (int k) const

Given the string region index k, return the light-cone momenta $p_{-k}$ .

double XplusRem (int j) const

Given the indicex j, return the remaining fraction of the light-cone momenta $p_{+j}$ in the corresponding region.

double XminusRem (int k) const

Given the indicex k, return the remaining fraction of the light-cone momenta $p_{-k}$ in the corresponding region.

Access <code>StringRegion</code>s.

int nPrimaryStringRegion () const

Return the number of string pieces in this String.

cStringRegionPtr getStringRegionPtr (int j, int k)

Given the indices j and k, return a pointer to the corresponding StringRegion.

cStringRegionPtr nextUp (cStringRegionPtr firstSR)

Given a pointer to a StringRegion (firstSR) return a pointer to its next nearest StringRegion in the up direction.

cStringRegionPtr nextDown (cStringRegionPtr firstSR)

Given a pointer to a StringRegion (firstSR) return a pointer to its next nearest StringRegion in the down direction.

cStringRegionPtr firstSR ()

Return pointer to the first (rightmost) StringRegion in the String plane representation.

cStringRegionPtr lastSR ()

Return pointer to the last (leftmost) StringRegion in the String plane representation.

Functions for updating the string (regions).

void reset ()

Compute thr string total momentum and initialize all Xrem(+,-)[i] to 1.

void updatePtotrem (const LorentzMomentum &HadronP)

Compute the remaining string total momentum, each time a new hadron of momentum HadronP is produced in the fragmentation process.

void updateXremf (int fidx, double xfnH)

Given a hadron produced with fraction xfnH of the forward momentum, compute the remaining fraction of the corresponding string regions with forward index fidx.

void updateXremb (int bidx, double xbnH)

Given a hadron produced with fraction xbnH of the backward momentum, compute the remaining fraction of the corresponding string regions with backward index bidx.

void setXplusRem (int jj, double newX)

Set the remaining forward fraction of regions with index jj to newX.

void setXminusRem (int kk, double newX)

Set the remaining backward fraction of regions with index kk to newX.

Private Types

typedef vector< double > xRemVec

Vector of remaining momentum fractions.

Private Member Functions

void InitXrem ()

Given the pointer to the first end-point computes the total momentum of this String.

void clearStringRegionMap ()

Delete all StringRegion objects and pointers of the StringRegionMap.

Private Attributes

LorentzMomentum Ptotrem

The Total momentum of the String.

MomentumVector pplus

Vector of the light-cone momenta $p_{+j}$ .

MomentumVector pminus

Vector of the light-cone momenta $p_{-k}$ .

xRemVec xPlusRem

Vector of the remaining positive light-cone fractions.

xRemVec xMinusRem

Vector of the remaining positive light-cone fractions.

StringRegionMap theStringRegionMap

The map of StringRegions.

int ns

Number of primary string regions in this String.

LorentzMomentum Ptot

The initial total momentum.

PVector partons

The initial, possibly pre-clustered particles.

Detailed Description

The String class describes the string of the Lund string fragmentation model.

implemented in the momentum (parameter) space representation.

The String describes both open of closed strings. Given one end point particle of the string, String(cPPtr) uses the colour-connection to build up the full string representation.

The string-regions are described by StringRegion objects. They are created dynamically when needed in the fragmentation process. by the getStringRegion() method. When created for the first time, a StringRegion is stored in a StringRegionMap according to the indices $(j,k)$ of the region light-cone momentum pair $(p_{+j} , p_{-k})$ available from the p_plus() and p_minus() functions.

Conventions for String construction:
The PDPtr sent to to the string constructor defines the rightmost endpoint of the string in the momentum space representation. Then Plus denotes the direction towards this rightmost end-point while Minus denotes the opposite direction.
String provides interfaces to access variables that depend on the orientation chosen to perform a step in the fragmentation procedure. If the step is taken from the right of the plane representation then a fwd (bwd) interface to such a variable returns its Plus (Minus) component, while if the step is taken from the left then a fwd (bwd) interface returns its Minus (Plus) component.

Warning : No consistency checks are made by the String. It is the responsibility of the client using the String class to send the correct end point to the string constructor.

See also:: StringRegion
Oriented

Definition at line 64 of file String.h.

Member Typedef Documentation

typedef vector<double> Pythia7::String::xRemVec [private]

Vector of remaining momentum fractions.

Definition at line 67 of file String.h.

Constructor & Destructor Documentation

Pythia7::String::String ( const PVector & )

Standard constructor.

Given the vector of particles of the string computes the light-cone-like momenta $(p_+,p_-)$ of all string pieces following the chain of the first end-point anti-colour neighbours. Also provide a cutoff in invariant mass squared below which two neighboring partons are clustered into one.

Member Function Documentation

void Pythia7::String::setXplusRem	(	int	jj,
		double	newX
	)			`[inline]`

Set the remaining forward fraction of regions with index jj to newX.

(Only used for closed string)

void Pythia7::String::setXminusRem	(	int	kk,
		double	newX
	)			`[inline]`

Set the remaining backward fraction of regions with index kk to newX.

(Only used for closed string)

void Pythia7::String::InitXrem ( ) [inline, private]

Given the pointer to the first end-point computes the total momentum of this String.

Initialize all Xrem(i) fractions to 1

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

String.h


Public Member Functions
void	echo () const
	Print function to be used for debugging.
Standard constructors and destructors.
	String ()
	Default constructor.
	String (const String &)
	Copy-constructor.
	String (const PVector &)
	Standard constructor.
	~String ()
	Destructor.
Access momenta and momentum fractions.
const LorentzMomentum &	PtotRem () const
	Returns the total remaining momentum of this String, currently available during fragmentation.
Energy2	Wrem2 () const
	Returns the energy squared (Wrem2) of this String, currently available during fragmentation.
const LorentzMomentum &	Pfwd (int fidx) const
	Given a region index, fidx, return the forward longitudinal light-cone momentum.
const LorentzMomentum &	Pbwd (int bidx) const
	Given a region index, bidx, return the backward longitudinal light-cone momentum.
double	Xremf (int fidx) const
	Given a region index fidx, return the fraction of the longitudinal momentum available for fragmentation along the forward axis of this region.
double	Xremb (int bidx) const
	Given a region index bidx return the fraction of the longitudinal momentum available for fragmentation along the backward axis of this region.
const LorentzMomentum &	Pplus (int j) const
	Given the string region index j, return the light-cone momenta $p_{+j}$ .
const LorentzMomentum &	Pminus (int k) const
	Given the string region index k, return the light-cone momenta $p_{-k}$ .
double	XplusRem (int j) const
	Given the indicex j, return the remaining fraction of the light-cone momenta $p_{+j}$ in the corresponding region.
double	XminusRem (int k) const
	Given the indicex k, return the remaining fraction of the light-cone momenta $p_{-k}$ in the corresponding region.
Access <code>StringRegion</code>s.
int	nPrimaryStringRegion () const
	Return the number of string pieces in this String.
cStringRegionPtr	getStringRegionPtr (int j, int k)
	Given the indices j and k, return a pointer to the corresponding StringRegion.
cStringRegionPtr	nextUp (cStringRegionPtr firstSR)
	Given a pointer to a StringRegion (firstSR) return a pointer to its next nearest StringRegion in the up direction.
cStringRegionPtr	nextDown (cStringRegionPtr firstSR)
	Given a pointer to a StringRegion (firstSR) return a pointer to its next nearest StringRegion in the down direction.
cStringRegionPtr	firstSR ()
	Return pointer to the first (rightmost) StringRegion in the String plane representation.
cStringRegionPtr	lastSR ()
	Return pointer to the last (leftmost) StringRegion in the String plane representation.
Functions for updating the string (regions).
void	reset ()
	Compute thr string total momentum and initialize all Xrem(+,-)[i] to 1.
void	updatePtotrem (const LorentzMomentum &HadronP)
	Compute the remaining string total momentum, each time a new hadron of momentum HadronP is produced in the fragmentation process.
void	updateXremf (int fidx, double xfnH)
	Given a hadron produced with fraction xfnH of the forward momentum, compute the remaining fraction of the corresponding string regions with forward index fidx.
void	updateXremb (int bidx, double xbnH)
	Given a hadron produced with fraction xbnH of the backward momentum, compute the remaining fraction of the corresponding string regions with backward index bidx.
void	setXplusRem (int jj, double newX)
	Set the remaining forward fraction of regions with index jj to newX.
void	setXminusRem (int kk, double newX)
	Set the remaining backward fraction of regions with index kk to newX.
Private Types
typedef vector< double >	xRemVec
	Vector of remaining momentum fractions.
Private Member Functions
void	InitXrem ()
	Given the pointer to the first end-point computes the total momentum of this String.
void	clearStringRegionMap ()
	Delete all StringRegion objects and pointers of the StringRegionMap.
Private Attributes
LorentzMomentum	Ptotrem
	The Total momentum of the String.
MomentumVector	pplus
	Vector of the light-cone momenta $p_{+j}$ .
MomentumVector	pminus
	Vector of the light-cone momenta $p_{-k}$ .
xRemVec	xPlusRem
	Vector of the remaining positive light-cone fractions.
xRemVec	xMinusRem
	Vector of the remaining positive light-cone fractions.
StringRegionMap	theStringRegionMap
	The map of `StringRegion`s.
int	ns
	Number of primary string regions in this String.
LorentzMomentum	Ptot
	The initial total momentum.
PVector	partons
	The initial, possibly pre-clustered particles.