\(\kt\)-factorised \(\ggff\) process#
The photon transverse momentum-dependant description of this process was previously developed in PPtoLL
, and described in [GdSFP+15].
It is defined as the pptoll
process in CepGen.
Process-specific options#
method
#
This integer allows to switch between the two matrix element definitions:
0
: on-shell amplitude,1
: off-shell amplitude.
mode
#
This enumeration allows to specify the kinematic regime to generate and the size of the phase space to perform the integration. It can take the following values:
ProcessMode.ElasticElastic := 1
: elastic emission of photons from the incoming protons (default value if unspecified),ProcessMode.ElasticInelastic := 2 / ProcessMode.InelasticElastic := 3
: elastic scattering of one photon and an inelastic/semi-exclusive emission of the other photon, resulting in the excitation/fragmentation of the outgoing proton state,ProcessMode.InelasticInelastic := 4
: both protons fragmented in the final state.
pair
#
This integer value allows the end-user to specify the PDG identifier of the fermion pair to be produced in the final state.
It can take the following values:
PDG.electron := 11
: \(e^+e^-\) pair productionPDG.muon := 13
: \(\mu^+\mu^-\) pair productionPDG.tau := 15
: \(\tau^+\tau^-\) pair productionPDG.down
,PDG.up
,PDG.strange
,PDG.charm
,PDG.bottom
,PDG.top
(or equivalently1-6
): quark pair production.
Full object reference#
-
class PPtoFF : public FactorisedProcess#
Compute the 2-to-4 matrix element for a CE \(\gamma\gamma\rightarrow f\bar f\) process.
Private Functions
-
inline virtual void prepareFactorisedPhaseSpace() override#
Prepare central part of the Jacobian after kinematics is set.
-
inline virtual double computeFactorisedMatrixElement() override#
Factorised matrix element (event weight)
-
double onShellME() const#
-
double offShellME() const#
Private Members
-
PPtoFF::OffShellParameters osp_#
-
double mf2_ = {0.}#
-
double qf2_ = {0.}#
-
std::function<double(double)> g_part1_ = {nullptr}#
-
std::function<double(double)> g_part2_ = {nullptr}#
Private Static Attributes
-
static constexpr double kFourPi = 4. * M_PI#
-
struct OffShellParameters : public SteeredObject<OffShellParameters>#
Parameters for the off-shell matrix element.
-
inline virtual void prepareFactorisedPhaseSpace() override#