SigmaProcess Class Reference

SigmaProcess is the base class for cross section calculations. More...

#include <SigmaProcess.h>

Inheritance diagram for SigmaProcess:

Public Member Functions
virtual	~SigmaProcess ()
	Destructor.
void	init (BeamParticle *beamAPtrIn, BeamParticle *beamBPtrIn, SLHAinterface *slhaInterfacePtrIn=0)
	Perform simple initialization and store pointers. More...
void	setLHAPtr (LHAupPtr lhaUpPtrIn)
	Store or replace Les Houches pointer.
void	updateBeamIDs ()
	Switch to new beam particle identities; for similar hadrons only.
virtual void	initProc ()
	Initialize process. Only used for some processes.
virtual bool	initFlux ()
	Set up allowed flux of incoming partons. Default is no flux. More...
virtual void	set1Kin (double, double, double)
virtual void	set2Kin (double, double, double, double, double, double, double, double)
virtual void	set2KinMPI (double, double, double, double, double, double, double, bool, double, double)
virtual void	set3Kin (double, double, double, Vec4, Vec4, Vec4, double, double, double, double, double, double)
virtual void	sigmaKin ()
	Calculate flavour-independent parts of cross section.
virtual double	sigmaHat ()
virtual double	sigmaHatWrap (int id1in=0, int id2in=0)
virtual double	sigmaPDF (bool initPS=false, bool samexGamma=false, bool useNewXvalues=false, double x1New=0., double x2New=0.)
void	pickInState (int id1in=0, int id2in=0)
	Select incoming parton channel and extract parton densities (resolved). More...
virtual void	setIdColAcol ()
	Select flavour, colour and anticolour.
virtual bool	final2KinMPI (int=0, int=0, Vec4=0., Vec4=0., double=0., double=0.)
	Perform kinematics for a Multiparton Interaction, in its rest frame.
virtual double	weightDecay (Event &, int, int)
virtual void	setScale ()
	Set scale, when that is missing for an external LHA process.
virtual string	name () const
	Process name and code, and the number of final-state particles.
virtual int	code () const
virtual int	nFinal () const
virtual string	inFlux () const
	Need to know which incoming partons to set up interaction for.
virtual bool	convert2mb () const
	Need to know whether to convert cross section answer from GeV^-2 to mb.
virtual bool	convertM2 () const
	For 2 -> 2 process optional conversion from |M|^2 to d(sigmaHat)/d(tHat).
virtual bool	isLHA () const
	Special treatment needed for Les Houches processes.
virtual bool	isNonDiff () const
	Special treatment needed for elastic and diffractive processes.
virtual bool	isResolved () const
virtual bool	isDiffA () const
virtual bool	isDiffB () const
virtual bool	isDiffC () const
virtual bool	isSUSY () const
	Special treatment needed for SUSY processes.
virtual bool	allowNegativeSigma () const
	Special treatment needed if negative cross sections allowed.
virtual int	id3Mass () const
virtual int	id4Mass () const
virtual int	id5Mass () const
virtual int	resonanceA () const
	Special treatment needed if process contains an s-channel resonance.
virtual int	resonanceB () const
virtual bool	isSChannel () const
	2 -> 2 and 2 -> 3 processes only through s-channel exchange.
virtual int	idSChannel () const
	NOAM: Insert an intermediate resonance in 2 -> 1 -> 2 (or 3) listings.
virtual bool	isQCD3body () const
	QCD 2 -> 3 processes need special phase space selection machinery.
virtual int	idTchan1 () const
	Special treatment in 2 -> 3 with two massive propagators.
virtual int	idTchan2 () const
virtual double	tChanFracPow1 () const
virtual double	tChanFracPow2 () const
virtual bool	useMirrorWeight () const
virtual int	gmZmode () const
	Special process-specific gamma*/Z0 choice if >=0 (e.g. f fbar -> H0 Z0).
bool	swappedTU () const
	Tell whether tHat and uHat are swapped (= same as swap 3 and 4).
int	id (int i) const
	Give back particle properties: flavours, colours, masses, or all.
int	col (int i) const
int	acol (int i) const
double	m (int i) const
Particle	getParton (int i) const
double	Q2Ren () const
double	alphaEMRen () const
double	alphaSRen () const
double	Q2Fac () const
double	pdf1 () const
double	pdf2 () const
double	thetaMPI () const
	Give back angles; relevant only for multipe-interactions processes.
double	phiMPI () const
double	sHBetaMPI () const
double	pT2MPI () const
double	pTMPIFin () const
void	saveKin ()
	Save and load kinematics for trial interactions.
void	loadKin ()
void	swapKin ()
virtual void	setIdInDiff (int, int)
	Set the incoming ids for diffraction.
Public Member Functions inherited from PhysicsBase
void	initInfoPtr (Info &infoPtrIn)
	This function is called from above for physics objects used in a run. More...
virtual	~PhysicsBase ()
	Empty virtual destructor.
bool	flag (string key) const
	Shorthand to read settings values.
int	mode (string key) const
double	parm (string key) const
string	word (string key) const
vector< bool >	fvec (string key) const
vector< int >	mvec (string key) const
vector< double >	pvec (string key) const
vector< string >	wvec (string key) const

Public Attributes
Z0 gamma *Z0 *	Usage: weightDecayFlav( process). */ virtual double weightDecayFlav( Event&) {return 1.

Protected Member Functions
	SigmaProcess ()
	Constructor.
void	addBeamA (int idIn)
void	addBeamB (int idIn)
int	sizeBeamA () const
int	sizeBeamB () const
void	addPair (int idAIn, int idBIn)
int	sizePair () const
virtual bool	setupForME ()
bool	setupForMEin ()
	Calculate incoming modified masses and four-vectors for matrix elements. More...
void	setId (int id1in=0, int id2in=0, int id3in=0, int id4in=0, int id5in=0)
	Set flavour, colour and anticolour.
void	setColAcol (int col1=0, int acol1=0, int col2=0, int acol2=0, int col3=0, int acol3=0, int col4=0, int acol4=0, int col5=0, int acol5=0)
void	swapColAcol ()
void	swapCol1234 ()
void	swapCol12 ()
void	swapCol34 ()
double	weightTopDecay (Event &process, int iResBeg, int iResEnd)
	Common code for top and Higgs secondary decay angular weights. More...
double	weightHiggsDecay (Event &process, int iResBeg, int iResEnd)
Protected Member Functions inherited from PhysicsBase
	PhysicsBase ()
	Default constructor.
virtual void	onInitInfoPtr ()
virtual void	onBeginEvent ()
	This function is called in the very beginning of each Pythia::next call.
virtual void	onEndEvent (Status)
virtual void	onStat ()
	This function is called from the Pythia::stat() call.
void	registerSubObject (PhysicsBase &pb)
	Register a sub object that should have its information in sync with this.

Protected Attributes
SusyLesHouches *	slhaPtr
	Pointer to an SLHA object.
LHAupPtr	lhaUpPtr
	Pointer to LHAup for generating external events.
bool	doVarE
	Initialization data, normally only set once.
int	nQuarkIn
int	renormScale1
int	renormScale2
int	renormScale3
int	renormScale3VV
int	factorScale1
int	factorScale2
int	factorScale3
int	factorScale3VV
double	Kfactor
double	mcME
double	mbME
double	mmuME
double	mtauME
double	renormMultFac
double	renormFixScale
double	factorMultFac
double	factorFixScale
int	higgsH1parity
	CP violation parameters for Higgs sector, normally only set once.
int	higgsH2parity
int	higgsA3parity
double	higgsH1eta
double	higgsH2eta
double	higgsA3eta
double	higgsH1phi
double	higgsH2phi
double	higgsA3phi
int	idA
	Information on incoming beams.
int	idB
double	mA
double	mB
bool	isLeptonA
bool	isLeptonB
bool	hasLeptonBeams
bool	beamA2gamma
bool	beamB2gamma
bool	hasGamma
vector< InBeam >	inBeamA
	Partons in beams, with PDF's.
vector< InBeam >	inBeamB
vector< InPair >	inPair
	Allowed colliding parton pairs, with pdf's.
double	mH
	Store common subprocess kinematics quantities.
double	sH
double	sH2
double	Q2RenSave
	Store Q2 renormalization and factorization scales, and related values.
double	alpEM
double	alpS
double	Q2FacSave
double	x1Save
double	x2Save
double	pdf1Save
double	pdf2Save
double	sigmaSumSave
int	id1
	Store flavour, colour, anticolour, mass, angles and the whole particle.
int	id2
int	id3
int	id4
int	id5
int	idSave [12]
int	colSave [12]
int	acolSave [12]
double	mSave [12]
double	cosTheta
double	sinTheta
double	phi
double	sHMass
double	sHBeta
double	pT2Mass
double	pTFin
Particle	parton [12]
Particle	partonT [12]
double	mSaveT [12]
double	pTFinT
double	cosThetaT
double	sinThetaT
double	phiT
double	mME [12]
Vec4	pME [12]
bool	swapTU
	Store whether tHat and uHat are swapped (= same as swap 3 and 4).
Protected Attributes inherited from PhysicsBase
Info *	infoPtr = {}
Settings *	settingsPtr = {}
	Pointer to the settings database.
ParticleData *	particleDataPtr = {}
	Pointer to the particle data table.
Logger *	loggerPtr = {}
	Pointer to logger.
HadronWidths *	hadronWidthsPtr = {}
	Pointer to the hadron widths data table.
Rndm *	rndmPtr = {}
	Pointer to the random number generator.
CoupSM *	coupSMPtr = {}
	Pointers to SM and SUSY couplings.
CoupSUSY *	coupSUSYPtr = {}
BeamSetup *	beamSetupPtr = {}
BeamParticle *	beamAPtr = {}
BeamParticle *	beamBPtr = {}
BeamParticle *	beamPomAPtr = {}
BeamParticle *	beamPomBPtr = {}
BeamParticle *	beamGamAPtr = {}
BeamParticle *	beamGamBPtr = {}
BeamParticle *	beamVMDAPtr = {}
BeamParticle *	beamVMDBPtr = {}
PartonSystems *	partonSystemsPtr = {}
	Pointer to information on subcollision parton locations.
SigmaTotal *	sigmaTotPtr = {}
	Pointers to the total/elastic/diffractive cross sections.
SigmaCombined *	sigmaCmbPtr = {}
set< PhysicsBase * >	subObjects
UserHooksPtr	userHooksPtr

Static Protected Attributes
static const double	CONVERT2MB = 0.389380
	Constants: could only be changed in the code itself. More...
static const double	MASSMARGIN = 0.1
	The sum of outgoing masses must not be too close to the cm energy.
static const double	COMPRELERR = 1e-10
static const int	NCOMPSTEP = 10

Additional Inherited Members
Public Types inherited from PhysicsBase
enum	Status {   INCOMPLETE = -1, COMPLETE = 0, CONSTRUCTOR_FAILED, INIT_FAILED,   LHEF_END, LOWENERGY_FAILED, PROCESSLEVEL_FAILED, PROCESSLEVEL_USERVETO,   MERGING_FAILED, PARTONLEVEL_FAILED, PARTONLEVEL_USERVETO, HADRONLEVEL_FAILED,   CHECK_FAILED, OTHER_UNPHYSICAL, HEAVYION_FAILED, HADRONLEVEL_USERVETO }
	Enumerate the different status codes the event generation can have.

Detailed Description

SigmaProcess is the base class for cross section calculations.

Member Function Documentation

virtual int id3Mass ( ) const

inlinevirtual

Flavours in 2 -> 2/3 processes where masses needed from beginning. (For a light quark masses will be used in the final kinematics, but not at the matrix-element level. For a gluon no masses at all.)

Reimplemented in Sigma2ggm2qqbar, Sigma2gmgm2ffbar, Sigma2fgm2Wf, Sigma2ffbar2Wgm, Sigma2qg2Wq, Sigma2qqbar2Wg, Sigma2fgm2gmZf, Sigma2ffbar2gmZgm, Sigma2qg2gmZq, Sigma2qqbar2gmZg, Sigma2qqbar2sleptonantislepton, Sigma2ffbar2HposHneg, Sigma2ffbar2WW, Sigma2ffbar2HchgH12, Sigma2ffbar2ZW, Sigma2ffbar2A3H12, Sigma2qqbar2chi0gluino, Sigma2ffbar2gmZgmZ, Sigma2qg2Hchgq, Sigma2qqbar2gluinogluino, Sigma2qqbar2Hglt, Sigma2ffbar2FfbarsW, Sigma2gg2gluinogluino, Sigma2ffbar2LEDUnparticlegamma, Sigma2qg2Hqlt, Sigma2ffbar2FFbarsgmZ, Sigma2qg2squarkgluino, Sigma2ffbar2LEDUnparticleZ, Sigma2gg2Hglt, Sigma2gg2squarkantisquark, Sigma2qqbar2LEDUnparticleg, Sigma2qg2Hq, Sigma2qqbar2QQbar3S11QQbar3S11, Sigma2qqbar2QQbar, Sigma2qg2LEDUnparticleq, Sigma2gg2QQbar3S11QQbar3S11, Sigma2gg2QQbar, Sigma3qqbar2HQQbar, Sigma2qqbar2squarkantisquark, Sigma2gg2LEDUnparticleg, Sigma3gg2HQQbar, Sigma2qq2squarksquark, Sigma2ffbar2TEVffbar, Sigma2gg2QQbarX8g, Sigma3ff2HfftWW, Sigma2qqbar2DY, Sigma2qq2QqtW, Sigma2qqbar2GravitonStarg, Sigma3ff2HfftZZ, Sigma2ffbar2HchgchgHchgchg, Sigma2qg2GravitonStarq, Sigma2gg2Sg2XXj, Sigma2qg2chi0squark, Sigma2ffbar2HW, Sigma2qqbar2lStarlStarBar, Sigma3ff2HchgchgfftWW, Sigma2gg2QQbar3PJ1g, Sigma2gg2GravitonStarg, Sigma2qqbar2lStarlbar, Sigma2ffbar2HZ, Sigma2qqbar2LQLQbar, Sigma2gg2QQbar3S11gm, Sigma2ffbar2ZpH, Sigma2qq2qStarq, Sigma2ffbar2fGfGbar, Sigma2gg2LQLQbar, Sigma2gg2QQbar3S11g, Sigma2qqbar2qGqGbar, Sigma2qqbar2chi0chi0, Sigma2qqbar2Zpg2XXj, Sigma2qg2LeptoQuarkl, and Sigma2gg2qGqGbar.

void init	(	BeamParticle *	beamAPtrIn,
		BeamParticle *	beamBPtrIn,
		SLHAinterface *	slhaInterfacePtrIn = 0
	)

Perform simple initialization and store pointers.

Beam pointers can differ from the main beam pointers in PhysicsBase.

Pointer to SLHA object allows semi-internal processes to access SLHA blocks via getEntry() methods, see arXiv:1109.5852

Read out some properties of beams to allow shorthand.

Photon sub-beams from leptons or hadrons.

K factor, multiplying resolved processes. (But not here for MPI.)

Allow variable energy, and optionally also variable beam kinds.

Maximum incoming quark flavour.

Medium heavy fermion masses set massless or not in ME expressions.

Renormalization scale choice.

Factorization scale choice.

CP violation parameters for the BSM Higgs sector.

If BSM not switched on then H1 should have SM properties.

bool initFlux ( )

virtual

Set up allowed flux of incoming partons. Default is no flux.

Set up allowed flux of incoming partons. addBeam: set up PDF's that need to be evaluated for the two beams. addPair: set up pairs of incoming partons from the two beams.

Reset arrays (in case of several init's in same run).

Read in process-specific channel information.

Case with g g incoming state.

Case with q g incoming state.

Case with q q', q qbar' or qbar qbar' incoming state.

Case with q qbar' incoming state.

Case with q qbar incoming state.

Case with f f', f fbar', fbar fbar' incoming state.

If beams are leptons then they are also the colliding partons unless lepton includes a photon beam.

First beam is lepton and second is hadron.

First beam is hadron and second is lepton.

Hadron beams gives quarks.

Case with f fbar' generic incoming state.

If beams are leptons then also colliding partons unless lepton includes a photon beam.

Hadron beams gives quarks.

Case with f fbar incoming state.

If beams are antiparticle pair and leptons then also colliding partons unless lepton includes a photon beam.

Else assume both to be hadrons, for better or worse.

Case with f fbar' charged(+-1) incoming state.

If beams are leptons then also colliding partons unless lepton includes a photon beam.

Hadron beams gives quarks.

Case with f gamma incoming state.

Fermion from incoming side A if no photon beam inside.

Fermion from incoming side B if no photon beam inside.

Photons in the beams.

Case with quark gamma incoming state.

Initialize initiators both ways if not photoproductions.

Photons in the beams.

Case with gamma quark incoming state. Need this when both resolved and unresolved photon beams.

Photon in the beam.

Case with gluon gamma incoming state.

If not photoproduction, initialize both ways. Otherwise keep track of initiator ordering to generate correct combinations (direct, resolved).

Case with gamma gluon incoming state. Need this when both resolved and unresolved photon beams.

Case with gamma gamma incoming state.

Unrecognized fluxType is bad sign. Else done.

Reimplemented in SigmaLHAProcess, and Sigma0Process.

void pickInState	(	int	id1in = 0,
		int	id2in = 0
	)

Select incoming parton channel and extract parton densities (resolved).

Multiparton interactions: partons already selected.

Pick channel. Extract channel flavours and pdf's.

double Q2Ren ( ) const

inline

Give back couplings and parton densities. Not all known for nondiffractive.

virtual void set1Kin ( double  , double  , double    )

inlinevirtual

Input and complement kinematics for resolved 2 -> 1 process. Usage: set1Kin( x1in, x2in, sHin).

Reimplemented in Sigma1Process.

virtual void set2Kin ( double  , double  , double  , double  , double  , double  , double  , double    )

inlinevirtual

Input and complement kinematics for resolved 2 -> 2 process. Usage: set2Kin( x1in, x2in, sHin, tHin, m3in, m4in, runBW3in, runBW4in).

Reimplemented in Sigma2Process.

virtual void set2KinMPI ( double  , double  , double  , double  , double  , double  , double  , bool  , double  , double    )

inlinevirtual

Ditto, but for Multiparton Interactions applications, so different input. Usage: set2KinMPI( x1in, x2in, sHin, tHin, uHin, alpSin, alpEMin, needMasses, m3in, m4in)

Reimplemented in Sigma2Process.

virtual void set3Kin ( double  , double  , double  , Vec4  , Vec4  , Vec4  , double  , double  , double  , double  , double  , double    )

inlinevirtual

Input and complement kinematics for resolved 2 -> 3 process. Usage: set3Kin( x1in, x2in, sHin, p3prel, p4prel, p5prel, m3in, m4in, m5in, runBW3in, runBW4in, runBW5in);

Reimplemented in Sigma3Process.

virtual bool setupForME ( )

inlineprotectedvirtual

Calculate and store all modified masses and four-vectors intended for matrix elements. Return false if failed.

Reimplemented in Sigma3Process, Sigma2Process, and Sigma1Process.

bool setupForMEin ( )

protected

Calculate incoming modified masses and four-vectors for matrix elements.

Initially assume it will work out to set up modified kinematics.

Correct incoming c, b, mu and tau to be massive or not.

If kinematically impossible return to massless case, but set error.

Do incoming two-body kinematics for massless or massive cases.

Done.

virtual double sigmaHat ( )

inlinevirtual

Evaluate sigma for unresolved, sigmaHat(sHat) for 2 -> 1 processes, d(sigmaHat)/d(tHat) for (resolved) 2 -> 2 processes, and |M|^2 for 2 -> 3 processes. Answer in "native" units, either mb or GeV^-2.

Reimplemented in Sigma2qgm2qgm, Sigma2qgm2qg, Sigma2ggm2qqbar, Sigma2gmgm2ffbar, Sigma2fgm2Wf, Sigma2ffbar2Wgm, Sigma2qg2Wq, Sigma2qqbar2Wg, Sigma2qqbar2LEDqqbarNew, Sigma2qqbar2LEDgg, Sigma2fgm2gmZf, Sigma2ffbar2gmZgm, Sigma2qq2LEDqq, Sigma2qg2gmZq, Sigma2qg2LEDqg, Sigma3qg2qqqbarSame, Sigma2qqbar2gmZg, Sigma3qqbar2qqbargSame, Sigma2gg2LEDqqbar, Sigma2qqbar2sleptonantislepton, Sigma2ffbar2HposHneg, Sigma2gg2LEDgg, Sigma3qq2qqgSame, Sigma2qqbar2chargluino, Sigma2ffbar2WW, Sigma2ffbar2HchgH12, Sigma2gg2LEDllbar, Sigma3qg2qqqbarDiff, Sigma2ffbar2ZW, Sigma2ffbar2A3H12, Sigma2qqbar2chi0gluino, Sigma2ffbar2LEDllbar, Sigma3qqbar2qqbargDiff, Sigma2ffbar2gmZgmZ, Sigma2qg2Hchgq, Sigma2gg2LEDgammagamma, Sigma1qq2antisquark, Sigma3qq2qqgDiff, Sigma1ffbar2Hchg, Sigma2qqbar2gluinogluino, Sigma2ffbar2LEDgammagamma, Sigma2qqbar2Hglt, Sigma2ffbar2FfbarsW, Sigma3qg2qgg, Sigma2gg2gluinogluino, Sigma2ffbar2LEDUnparticlegamma, Sigma3Process, Sigma2qg2Hqlt, Sigma2ffbar2FFbarsgmZ, Sigma2qg2squarkgluino, Sigma3qqbar2ggg, Sigma2ffbar2LEDUnparticleZ, Sigma2gg2Hglt, Sigma2Process, Sigma3gg2ggg, Sigma2ffbar2ffbarsW, Sigma2gg2squarkantisquark, Sigma2qqbar2LEDUnparticleg, Sigma2qqbar2QQbar3S11QQbar3S11, Sigma2qg2Hq, Sigma2qqbar2QQbar, Sigma1Process, Sigma2ffbar2ffbarsgmZ, Sigma2qg2LEDUnparticleq, Sigma2gg2QQbar3S11QQbar3S11, Sigma0Process, Sigma2gg2QQbar, Sigma3qqbar2HQQbar, Sigma2qqbar2squarkantisquark, Sigma2ffbar2ffbarsgm, Sigma2gg2LEDUnparticleg, Sigma2qqbar2qqbarNew, Sigma1ffbar2W, Sigma3gg2HQQbar, Sigma2QCffbar2llbar, Sigma2qq2squarksquark, Sigma2qqbar2gg, Sigma2ffbar2TEVffbar, Sigma1ffbar2gmZ, Sigma2gg2QQbarX8g, Sigma3ff2HfftWW, Sigma2qq2qq, Sigma2QCqqbar2qqbar, Sigma2qg2charsquark, Sigma2qqbar2DY, Sigma2qq2QqtW, Sigma2qg2qg, Sigma2qqbar2GravitonStarg, Sigma3ff2HfftZZ, Sigma2QCqq2qq, Sigma2ffbar2HchgchgHchgchg, Sigma2ff2fftW, Sigma2gg2qqbar, Sigma2qg2GravitonStarq, Sigma2qg2chi0squark, Sigma2gg2Sg2XXj, Sigma2ffbar2HW, Sigma2qqbar2lStarlStarBar, Sigma3ff2HchgchgfftWW, Sigma2ff2fftgmZ, Sigma2gg2gg, Sigma2gg2QQbar3PJ1g, Sigma2gg2GravitonStarg, Sigma1gg2S2XX, Sigma2qqbar2charchar, Sigma2qqbar2lStarlbar, Sigma2gg2gammagamma, Sigma1ffbar2Zv, Sigma2ffbar2HZ, Sigma1ffbar2Rhorizontal, Sigma0AB2AXB, Sigma2lgm2Hchgchgl, Sigma2qqbar2LQLQbar, Sigma2gg2QQbar3S11gm, Sigma2ffbar2ZpH, Sigma2qqbar2charchi0, Sigma0AB2XX, Sigma1qqbar2KKgluonStar, Sigma2ffbar2gammagamma, Sigma2qq2qStarq, Sigma2ffbar2fGfGbar, Sigma1ffbar2Wprime, Sigma1gmgm2H, Sigma1ll2Hchgchg, Sigma2gg2LQLQbar, Sigma2gg2QQbar3S11g, Sigma0AB2AX, Sigma2gg2ggamma, Sigma1ffbar2GravitonStar, Sigma1lgm2lStar, Sigma2qqbar2qGqGbar, Sigma0AB2XB, Sigma1gg2H, Sigma1ffbar2WRight, Sigma2qqbar2Zpg2XXj, Sigma2qg2LeptoQuarkl, Sigma2qqbar2chi0chi0, Sigma1ffbar2gmZZprime, Sigma2qqbar2ggamma, Sigma0AB2AB, Sigma2gg2qGqGbar, Sigma1ffbar2Zp2XX, Sigma1gg2GravitonStar, Sigma1ffbar2H, Sigma1qg2qStar, Sigma1ql2LeptoQuark, Sigma1ffbar2ZRight, Sigma2qg2qgamma, and Sigma0nonDiffractive.

virtual double sigmaHatWrap ( int  id1in = 0, int  id2in = 0  )

inlinevirtual

Wrapper to sigmaHat, to (a) store current incoming flavours and (b) convert from GeV^-2 to mb where required. For 2 -> 1/2 also (c) convert from from |M|^2 to d(sigmaHat)/d(tHat).

Reimplemented in Sigma2Process, and Sigma1Process.

double sigmaPDF ( bool  initPS = false, bool  samexGamma = false, bool  useNewXvalues = false, double  x1New = 0., double  x2New = 0.  )

virtual

Convolute above with parton flux and K factor. Sum over open channels. Possibly different PDF in initialization phase or no sampling for x_gamma (photons in leptons).

Convolute matrix-element expression(s) with parton flux and K factor. Possibly different PDFs for the phase-space initialization. Can also take new values for x's to correct for oversampling, as needed with external photon flux.

Evaluate and store the required parton densities.

Save the x_gamma values after PDFs are called if new value is sampled if using internal photon flux from leptons.

Loop over allowed incoming channels.

Evaluate hard-scattering cross section. Include K factor.

Multiply by respective parton densities.

Sum for all channels.

Done.

Reimplemented in SigmaLHAProcess, and Sigma0Process.

virtual double weightDecay ( Event &  , int  , int    )

inlinevirtual

Evaluate weight for decay angular configuration. Usage: weightDecay( process, iResBeg, iResEnd), where iResBeg <= i < iResEnd is range of sister partons to test decays of.

Reimplemented in Sigma2ffbarWggm, Sigma2ffbar2HposHneg, Sigma2ffbargmZggm, Sigma2ffbar2WW, Sigma2ffbar2HchgH12, Sigma2ffbar2ZW, Sigma2ffbar2A3H12, Sigma2ffbar2gmZgmZ, Sigma2qg2Hchgq, Sigma1ffbar2Hchg, SigmaLHAProcess, Sigma2qqbar2Hglt, Sigma2ffbar2FfbarsW, Sigma2qg2Hqlt, Sigma2ffbar2FFbarsgmZ, Sigma2gg2Hglt, Sigma2qg2Hq, Sigma2qqbar2QQbar, Sigma2gg2QQbar, Sigma3qqbar2HQQbar, Sigma1ffbar2W, Sigma3gg2HQQbar, Sigma2ffbar2TEVffbar, Sigma1ffbar2gmZ, Sigma3ff2HfftWW, Sigma2qq2QqtW, Sigma2qqbar2GravitonStarg, Sigma3ff2HfftZZ, Sigma2ffbar2HchgchgHchgchg, Sigma2qg2GravitonStarq, Sigma2ffbar2HW, Sigma2qqbar2lStarlStarBar, Sigma3ff2HchgchgfftWW, Sigma2gg2GravitonStarg, Sigma2qqbar2lStarlbar, Sigma1ffbar2Zv, Sigma2ffbar2HZ, Sigma2lgm2Hchgchgl, Sigma1qqbar2KKgluonStar, Sigma2qq2qStarq, Sigma1ffbar2Wprime, Sigma1gmgm2H, Sigma1ll2Hchgchg, Sigma1ffbar2GravitonStar, Sigma1lgm2lStar, Sigma1gg2H, Sigma1ffbar2WRight, Sigma1ffbar2gmZZprime, Sigma1gg2GravitonStar, Sigma1ffbar2H, Sigma1qg2qStar, Sigma1ffbar2ZRight, and Sigma2SUSY.

double weightHiggsDecay ( Event &  process, int  iResBeg, int  iResEnd  )

protected

Evaluate weight for Z0/W+- decay distributions in H -> Z0/W+ Z0/W- -> 4f and H -> gamma Z0 -> gamma f fbar.

If not pair Z0 Z0, W+ W- or gamma Z0 then return unit weight.

If mother is not Higgs then return unit weight.

H -> gamma Z0 -> gamma f fbar is 1 + cos^2(theta) in Z rest frame.

Parameters depend on Higgs type: H0(H_1), H^0(H_2) or A^0(H_3).

Option with isotropic decays (also for pseudoscalar fermion couplings).

Maximum and initial weight.

Find sign-matched order of Z0/W+- decay products.

Evaluate four-vector products and find masses..

For mixed CP states need epsilon product and gauge boson masses.

Z0 Z0 decay: vector and axial couplings of two fermion pairs.

Normal CP-even decay.

CP-odd decay (normal for A0(H_3)).

Mixed CP states.

W+ W- decay.

Normal CP-even decay.

CP-odd decay (normal for A0(H_3)).

Mixed CP states.

Done.

double weightTopDecay ( Event &  process, int  iResBeg, int  iResEnd  )

protected

Common code for top and Higgs secondary decay angular weights.

Evaluate weight for W decay distribution in t -> W b -> f fbar b.

If not pair W d/s/b and mother t then return unit weight.

Find sign-matched order of W decay products.

Weight and maximum weight.

Done.

Member Data Documentation

const double COMPRELERR = 1e-10

staticprotected

Parameters of momentum rescaling procedure: maximally allowed relative energy error and number of iterations.

const double CONVERT2MB = 0.389380

staticprotected

Constants: could only be changed in the code itself.

Conversion of GeV^{-2} to mb for cross section.

The SigmaProcess class. Base class for cross sections. Constants: could be changed here if desired, but normally should not. These are of technical nature, as described for each.

Particle partonT[12]

protected

Minimal set of saved kinematics for trial interactions when using the x-dependent matter profile of multiparton interactions.

Z0 gamma* Z0* Usage

Evaluate weight for simultaneous flavours (only gamma

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

• include/Pythia8/SigmaProcess.h
• src/SigmaProcess.cc