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Herwig++  2.7.0
Herwig::MEPP2Higgs Class Reference

The MEPP2Higgs class implements the matrix element for the process pp->Higgs with different Higgs shape prescriptions (see details in hep-ph/9505211) and the NLL corrected Higgs width (see details in the FORTRAN HERWIG manual). More...

#include <MEPP2Higgs.h>

Inheritance diagram for Herwig::MEPP2Higgs:

List of all members.

Public Member Functions

 MEPP2Higgs ()
 The default constructor.
virtual CrossSection dSigHatDR () const
 Return the matrix element for the kinematical configuation previously provided by the last call to setKinematics().
virtual void setKinematics ()
 Set the typed and momenta of the incoming and outgoing partons to be used in subsequent calls to me() and colourGeometries() according to the associated XComb object.
Member functions for the generation of hard QCD radiation
virtual POWHEGType hasPOWHEGCorrection ()
 Has a POWHEG style correction.
virtual bool hasMECorrection ()
 Has an old fashioned ME correction.
virtual void initializeMECorrection (ShowerTreePtr tree, double &initial, double &final)
 Initialize the ME correction.
virtual void applyHardMatrixElementCorrection (ShowerTreePtr)
 Apply the hard matrix element correction to a given hard process or decay.
virtual bool softMatrixElementVeto (ShowerProgenitorPtr initial, ShowerParticlePtr parent, Branching br)
 Apply the soft matrix element correction.
virtual HardTreePtr generateHardest (ShowerTreePtr)
 Apply the POWHEG style correction.
Virtual functions required by the MEBase class.
virtual unsigned int orderInAlphaS () const
 Return the order in $\alpha_S$ in which this matrix element is given.
virtual unsigned int orderInAlphaEW () const
 Return the order in $\alpha_{EW}$ in which this matrix element is given.
virtual double me2 () const
 The matrix element for the kinematical configuration previously provided by the last call to setKinematics(), suitably scaled by sHat() to give a dimension-less number.
virtual bool generateKinematics (const double *r)
 Generate internal degrees of freedom given nDim() uniform random numbers in the interval $ ]0,1[ $.
virtual Energy2 scale () const
 Return the scale associated with the last set phase space point.
virtual int nDim () const
 The number of internal degrees of freedom used in the matrix element.
virtual void getDiagrams () const
 Add all possible diagrams with the add() function.
virtual Selector< DiagramIndexdiagrams (const DiagramVector &dv) const
 Get diagram selector.
virtual Selector< const
ColourLines * > 
colourGeometries (tcDiagPtr diag) const
 Return a Selector with possible colour geometries for the selected diagram weighted by their relative probabilities.
virtual void constructVertex (tSubProPtr)
 Construct the vertex of spin correlations.
Functions used by the persistent I/O system.
void persistentOutput (PersistentOStream &os) const
 Function used to write out object persistently.
void persistentInput (PersistentIStream &is, int version)
 Function used to read in object persistently.

Static Public Member Functions

static void Init ()
 The standard Init function used to initialize the interfaces.

Protected Member Functions

tPDPtr quarkFlavour (tcPDFPtr pdf, Energy2 scale, double x, tcBeamPtr beam, double &pdfweight, bool anti)
 Method to extract the PDF weight for quark/antiquark initiated processes and select the quark flavour.
bool applyHard (ShowerParticleVector gluons, vector< tcBeamPtr > beams, PPtr higgs, unsigned int &iemit, unsigned int &itype, vector< Lorentz5Momentum > &pnew, pair< double, double > &xnew, tPDPtr &out)
 Return the momenta and type of hard matrix element correction.
bool getEvent (vector< Lorentz5Momentum > &pnew, int &emissiontype)
 generates the hardest emission (yj,p)
double getResult (int emis_type, Energy pt, double yj, tcPDPtr &outParton)
 Returns the matrix element for a given type of process, rapidity of the jet $y_j$ and transverse momentum $p_T$.
Clone Methods.
virtual IBPtr clone () const
 Make a simple clone of this object.
virtual IBPtr fullclone () const
 Make a clone of this object, possibly modifying the cloned object to make it sane.
Standard Interfaced functions.
virtual void doinit ()
 Initialize this object after the setup phase before saving an EventGenerator to disk.
virtual void dofinish ()
 Finalize this object.
Energy4 loME () const
 Members to calculate the real emission matrix elements.
Energy2 ggME (Energy2 s, Energy2 t, Energy2 u)
 The matrix element for $gg\to H g$.
Energy2 qgME (Energy2 s, Energy2 t, Energy2 u)
 The matrix element for $qg\to H q$.
Energy2 qbargME (Energy2 s, Energy2 t, Energy2 u)
 The matrix element for $qbarg\to H qbar$.
Complex B (Energy2 s, Energy2 mf2) const
 Members to calculate the functions for the loop diagrams.
complex< InvEnergy2 > C (Energy2 s, Energy2 mf2) const
 The $C(s)$ function of NBP339 (1990) 38-66.
complex< InvEnergy4 > D (Energy2 s, Energy2 t, Energy2 u, Energy2 mf2) const
 The $C(s)$ function of NBP339 (1990) 38-66.
Complex dIntegral (Energy2 a, Energy2 b, double y0) const
 The integral $\int\frac{dy}{y-y_0}\log(a-i\epsilon-b y(1-y))$ from NBP339 (1990) 38-66.
complex< Energy > me1 (Energy2 s, Energy2 t, Energy2 u, Energy2 mf2, unsigned int i, unsigned int j, unsigned int k, unsigned int i1, unsigned int j1, unsigned int k1) const
 The $M_{+++}$ matrix element of NBP339 (1990) 38-66.
complex< Energy > me2 (Energy2 s, Energy2 t, Energy2 u, Energy2 mf2) const
 The $M_{++-}$ matrix element of NBP339 (1990) 38-66.
Complex F (double x) const
 The $F(x)$ function for the leading-order result.

Private Member Functions

MEPP2Higgsoperator= (const MEPP2Higgs &)
 The assignment operator is private and must never be called.
double ggME (vector< VectorWaveFunction > g1, vector< VectorWaveFunction > g2, ScalarWaveFunction &, bool calc) const
 Members to return the matrix elements for the different subprocesses.
double qqME (vector< SpinorWaveFunction > &fin, vector< SpinorBarWaveFunction > &ain, ScalarWaveFunction &, bool calc) const
 Calculates the matrix element for the process q,qbar->h.

Private Attributes

unsigned int scaleopt_
 Selects a dynamic (sHat) or fixed factorization scale.
Energy mu_F_
 The value associated to the fixed factorization scale option.
unsigned int shapeOption_
 Defines the Higgs resonance shape.
unsigned int processOption_
 The processes to be included (GG->H and/or qq->H)
int minFlavour_
 Minimum flavour of incoming quarks.
int maxFlavour_
 Maximum flavour of incoming quarks.
ProductionMatrixElement me_
 Matrix element for spin correlations.
AbstractVVSVertexPtr HGGVertex_
 Pointer to the H-> 2 gluon vertex (used in gg->H)
AbstractFFSVertexPtr HFFVertex_
 Pointer to the fermion-fermion Higgs vertex (used in qq->H)
GenericMassGeneratorPtr hmass_
 The mass generator for the Higgs.
Energy mh_
 On-shell mass for the higgs.
Energy wh_
 On-shell width for the higgs.
ShowerAlphaPtr alpha_
 Pointer to the object calculating the strong coupling.
Energy2 mh2_
 Mass squared of Higgs.
double channelwgtA_
 Relative weight of the $qg$ to the $gg$ channel.
double channelwgtB_
 Relative weight for the $\bar{q}g$ to the $gg$ channel.
vector< double > channelWeights_
 Weights for the channels as a vector.
double ggPow_
 Power for the $\frac{{\rm d}\hat{s}}{\hat{s}^n}$ importance sampling of the $gg$ component.
double qgPow_
 Power for the $\frac{{\rm d}\hat{s}}{\hat{s}^n}$ importance sampling of the $qg$ and $\bar{q}g$ components.
double enhance_
 The enhancement factor for initial-state radiation.
unsigned int nover_
 Number of weights greater than 1.
unsigned int ntry_
 Number of attempts.
unsigned int ngen_
 Number which suceed.
double maxwgt_
 Maximum weight.
Energy minpT_
 The transverse momentum of the jet.
unsigned int minLoop_
 Stuff for the ME correction.
unsigned int maxLoop_
 Maximum flavour of quarks to include in the loops.
unsigned int massOption_
 Option for treatment of the fermion loops.
unsigned int mu_R_opt_
 Option for dynamic scale choice in alpha_S (0=mT,>0=pT)
unsigned int mu_F_opt_
 Option for dynamic scale choice in PDFs (0=mT,>0=pT)
Complex bi_ [5]
 Storage of the loop functions.
complex< InvEnergy2 > ci_ [8]
 C functions.
complex< InvEnergy4 > di_ [4]
 D functions.
double power_
 Constants for the sampling.
double pregg_
 The prefactor, $c$ for the $gg$ channel.
double preqg_
 The prefactor, $c$ for the $qg$ channel.
double pregqbar_
 The prefactor, $c$ for the $g\bar{q}$ channel.
vector< double > prefactor_
 The prefactors as a vector for easy use.
vector< tcBeamPtrbeams_
 Properties of the incoming particles.
vector< tcPDPtrpartons_
 Pointers to the ParticleDataObjects for the partons.
double yh_
 Properties of the boson and jets.
Energy mass_
 The mass of the Higgs boson.
double yj_
 the rapidity of the jet
Energy pt_
 The transverse momentum of the jet.
tcPDPtr out_
 The outgoing parton.

Static Private Attributes

static ClassDescription
< MEPP2Higgs
initMEPP2Higgs
 The static object used to initialize the description of this class.
static const complex< Energy2 > epsi_
 Small complex number to regularize some integrals.

Detailed Description

The MEPP2Higgs class implements the matrix element for the process pp->Higgs with different Higgs shape prescriptions (see details in hep-ph/9505211) and the NLL corrected Higgs width (see details in the FORTRAN HERWIG manual).

See also:
The interfaces defined for MEPP2Higgs.

Definition at line 38 of file MEPP2Higgs.h.


Member Function Documentation

bool Herwig::MEPP2Higgs::applyHard ( ShowerParticleVector  gluons,
vector< tcBeamPtr beams,
PPtr  higgs,
unsigned int &  iemit,
unsigned int &  itype,
vector< Lorentz5Momentum > &  pnew,
pair< double, double > &  xnew,
tPDPtr out 
) [protected]

Return the momenta and type of hard matrix element correction.

Parameters:
gluonsThe original incoming particles.
beamsThe BeamParticleData objects
higgsThe original outgoing higgs
iemitWhether the first (0) or second (1) particle emitted the radiation
itypeThe type of radiated particle (0 is gluon, 1 is quark and 2 is antiquark)
pnewThe momenta of the new particles
xnewThe new values of the momentuym fractions
outThe ParticleData object for the outgoing parton
Returns:
Whether or not the matrix element correction needs to be applied
Complex Herwig::MEPP2Higgs::B ( Energy2  s,
Energy2  mf2 
) const [protected]

Members to calculate the functions for the loop diagrams.

The $B(s)$ function of NBP339 (1990) 38-66

Parameters:
sThe scale
mf2The fermion mass squared.
complex<InvEnergy2> Herwig::MEPP2Higgs::C ( Energy2  s,
Energy2  mf2 
) const [protected]

The $C(s)$ function of NBP339 (1990) 38-66.

Parameters:
sThe scale
mf2The fermion mass squared.
virtual IBPtr Herwig::MEPP2Higgs::clone ( ) const [inline, protected, virtual]

Make a simple clone of this object.

Returns:
a pointer to the new object.

Implements ThePEG::InterfacedBase.

Reimplemented in Herwig::MEPP2HiggsPowheg.

Definition at line 217 of file MEPP2Higgs.h.

virtual Selector<const ColourLines *> Herwig::MEPP2Higgs::colourGeometries ( tcDiagPtr  diag) const [virtual]

Return a Selector with possible colour geometries for the selected diagram weighted by their relative probabilities.

Parameters:
diagthe diagram chosen.
Returns:
the possible colour geometries weighted by their relative probabilities.

Implements ThePEG::MEBase.

complex<InvEnergy4> Herwig::MEPP2Higgs::D ( Energy2  s,
Energy2  t,
Energy2  u,
Energy2  mf2 
) const [protected]

The $C(s)$ function of NBP339 (1990) 38-66.

Parameters:
sThe $s$ invariant
tThe $t$ invariant
uThe $u$ invariant
mf2The fermion mass squared
virtual Selector<DiagramIndex> Herwig::MEPP2Higgs::diagrams ( const DiagramVector dv) const [virtual]

Get diagram selector.

With the information previously supplied with the setKinematics method, a derived class may optionally override this method to weight the given diagrams with their (although certainly not physical) relative probabilities.

Parameters:
dvthe diagrams to be weighted.
Returns:
a Selector relating the given diagrams to their weights.

Reimplemented from ThePEG::MEBase.

Complex Herwig::MEPP2Higgs::dIntegral ( Energy2  a,
Energy2  b,
double  y0 
) const [protected]

The integral $\int\frac{dy}{y-y_0}\log(a-i\epsilon-b y(1-y))$ from NBP339 (1990) 38-66.

Parameters:
aThe parameter $a$.
bThe parameter $b$.
y0The parameter $y_0$.
virtual void Herwig::MEPP2Higgs::dofinish ( ) [protected, virtual]

Finalize this object.

Called in the run phase just after a run has ended. Used eg. to write out statistics.

Reimplemented from ThePEG::InterfacedBase.

virtual void Herwig::MEPP2Higgs::doinit ( ) [protected, virtual]

Initialize this object after the setup phase before saving an EventGenerator to disk.

Exceptions:
InitExceptionif object could not be initialized properly.

Reimplemented from ThePEG::InterfacedBase.

virtual CrossSection Herwig::MEPP2Higgs::dSigHatDR ( ) const [virtual]

Return the matrix element for the kinematical configuation previously provided by the last call to setKinematics().

Uses me().

Reimplemented from Herwig::HwMEBase.

virtual IBPtr Herwig::MEPP2Higgs::fullclone ( ) const [inline, protected, virtual]

Make a clone of this object, possibly modifying the cloned object to make it sane.

Returns:
a pointer to the new object.

Reimplemented from ThePEG::InterfacedBase.

Reimplemented in Herwig::MEPP2HiggsPowheg.

Definition at line 223 of file MEPP2Higgs.h.

virtual bool Herwig::MEPP2Higgs::generateKinematics ( const double *  r) [virtual]

Generate internal degrees of freedom given nDim() uniform random numbers in the interval $ ]0,1[ $.

To help the phase space generator, the dSigHatDR should be a smooth function of these numbers, although this is not strictly necessary.

Parameters:
ra pointer to the first of nDim() consecutive random numbers.
Returns:
true if the generation succeeded, otherwise false.

Reimplemented from Herwig::HwMEBase.

Reimplemented in Herwig::MEPP2HiggsPowheg.

bool Herwig::MEPP2Higgs::getEvent ( vector< Lorentz5Momentum > &  pnew,
int &  emissiontype 
) [protected]

generates the hardest emission (yj,p)

Parameters:
pnewThe momenta of the new particles
emissiontypeThe type of emission, as for getResult
Returns:
Whether not an emission was generated
double Herwig::MEPP2Higgs::getResult ( int  emis_type,
Energy  pt,
double  yj,
tcPDPtr outParton 
) [protected]

Returns the matrix element for a given type of process, rapidity of the jet $y_j$ and transverse momentum $p_T$.

Parameters:
emis_typethe type of emission, (0 is $gg\to h^0g$, 1 is $qg\to h^0q$ and 2 is $g\bar{q}\to h^0\bar{q}$)
ptThe transverse momentum of the jet
yjThe rapidity of the jet
outPartonthe outgoing parton
double Herwig::MEPP2Higgs::ggME ( vector< VectorWaveFunction g1,
vector< VectorWaveFunction g2,
ScalarWaveFunction ,
bool  calc 
) const [private]

Members to return the matrix elements for the different subprocesses.

Calculates the matrix element for the process g,g->h (via quark loops)

Parameters:
g1a vector of wave functions of the first incoming gluon
g2a vector of wave functions of the second incoming gluon
calcWhether or not to calculate the matrix element for spin correlations
Returns:
the amlitude value.
static void Herwig::MEPP2Higgs::Init ( ) [static]

The standard Init function used to initialize the interfaces.

Called exactly once for each class by the class description system before the main function starts or when this class is dynamically loaded.

Reimplemented from Herwig::HwMEBase.

Reimplemented in Herwig::MEPP2HiggsPowheg.

Energy4 Herwig::MEPP2Higgs::loME ( ) const [protected]

Members to calculate the real emission matrix elements.

The leading-order matrix element for $gg\to H$

complex<Energy> Herwig::MEPP2Higgs::me1 ( Energy2  s,
Energy2  t,
Energy2  u,
Energy2  mf2,
unsigned int  i,
unsigned int  j,
unsigned int  k,
unsigned int  i1,
unsigned int  j1,
unsigned int  k1 
) const [protected]

The $M_{+++}$ matrix element of NBP339 (1990) 38-66.

Parameters:
sThe $s$ invariant
tThe $t$ invariant
uThe $u$ invariant
mf2The fermion mass squared.
iWhich of the stored values to use for $D(u,t)$.
jWhich of the stored values to use for $D(u,s)$.
kWhich of the stored values to use for $D(s,t)$.
i1Which of the stored values to use for $C_1(s)$.
j1Which of the stored values to use for $C_1(t)$.
k1Which of the stored values to use for $C_1(u)$.
virtual double Herwig::MEPP2Higgs::me2 ( ) const [virtual]

The matrix element for the kinematical configuration previously provided by the last call to setKinematics(), suitably scaled by sHat() to give a dimension-less number.

Returns:
the matrix element scaled with sHat() to give a dimensionless number.

Implements ThePEG::MEBase.

Reimplemented in Herwig::MEPP2HiggsPowheg.

complex<Energy> Herwig::MEPP2Higgs::me2 ( Energy2  s,
Energy2  t,
Energy2  u,
Energy2  mf2 
) const [protected]

The $M_{++-}$ matrix element of NBP339 (1990) 38-66.

Parameters:
sThe $s$ invariant
tThe $t$ invariant
uThe $u$ invariant
mf2The fermion mass squared.
MEPP2Higgs& Herwig::MEPP2Higgs::operator= ( const MEPP2Higgs ) [private]

The assignment operator is private and must never be called.

In fact, it should not even be implemented.

void Herwig::MEPP2Higgs::persistentInput ( PersistentIStream is,
int  version 
)

Function used to read in object persistently.

Parameters:
isthe persistent input stream read from.
versionthe version number of the object when written.

Reimplemented from Herwig::HwMEBase.

Reimplemented in Herwig::MEPP2HiggsPowheg.

Function used to write out object persistently.

Parameters:
osthe persistent output stream written to.

Reimplemented from Herwig::HwMEBase.

Reimplemented in Herwig::MEPP2HiggsPowheg.

double Herwig::MEPP2Higgs::qqME ( vector< SpinorWaveFunction > &  fin,
vector< SpinorBarWaveFunction > &  ain,
ScalarWaveFunction ,
bool  calc 
) const [private]

Calculates the matrix element for the process q,qbar->h.

Parameters:
fina vector of quark spinors
aina vector of anti-quark spinors
calcWhether or not to calculate the matrix element for spin correlations
Returns:
the amlitude value.
virtual bool Herwig::MEPP2Higgs::softMatrixElementVeto ( ShowerProgenitorPtr  initial,
ShowerParticlePtr  parent,
Branching  br 
) [virtual]

Apply the soft matrix element correction.

Parameters:
initialThe particle from the hard process which started the shower
parentThe initial particle in the current branching
brThe branching struct
Returns:
If true the emission should be vetoed

Reimplemented from Herwig::HwMEBase.


Member Data Documentation

Properties of the incoming particles.

Pointers to the BeamParticleData objects

Definition at line 660 of file MEPP2Higgs.h.

Complex Herwig::MEPP2Higgs::bi_[5] [mutable, private]

Storage of the loop functions.

B functions

Definition at line 541 of file MEPP2Higgs.h.

The static object used to initialize the description of this class.

Indicates that this is a concrete class with persistent data.

Definition at line 392 of file MEPP2Higgs.h.

unsigned int Herwig::MEPP2Higgs::minLoop_ [private]

Stuff for the ME correction.

Parameters for the evaluation of the loops for the matrix elements Minimum flavour of quarks to include in the loops

Definition at line 504 of file MEPP2Higgs.h.

double Herwig::MEPP2Higgs::power_ [private]

Constants for the sampling.

The distribution is assumed to have the form $\frac{c}{{\rm GeV}}\times\left(\frac{{\rm GeV}}{p_T}\right)^n$ The power, $n$, for the sampling

Definition at line 625 of file MEPP2Higgs.h.

double Herwig::MEPP2Higgs::yh_ [private]

Properties of the boson and jets.

The rapidity of the Higgs boson

Definition at line 675 of file MEPP2Higgs.h.


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