Rambo Class Reference

Rambo flat phase-space generator. More...

#include <PhaseSpace.h>

Public Member Functions
	Rambo ()
	Deafult constructor.
	Rambo (Rndm *rndmPtrIn)
	Initializing constructor.
virtual	~Rambo ()
	Destructor.
void	initPtr (Rndm *rndmPtrIn)
	Initialize pointers.
double	genPoint (double eCM, int nOut, vector< Vec4 > &pOut)
	Rambo phase space generator. More...
double	genPoint (double eCM, vector< double > mIn, vector< Vec4 > &pOut)

Detailed Description

Rambo flat phase-space generator.

This is an implementation of the Rambo phase-space generator as presented in A New Monte Carlo Treatment Of Multiparticle Phase Space At High-Energies, R. Kleiss, W.J. Stirling, S.D. Ellis, CPC40 (1986) 359.

Member Function Documentation

double genPoint	(	double	eCM,
		int	nOut,
		vector< Vec4 > &	pOut
	)

Rambo phase space generator.

Rambo phase space generator. Generates nOut uniformly distributed massless 4-vectors with sqrt(s) = eCM. Output in pOut.

Massless flat phase space generator. Generate a random (uniformly distributed) massless PS point with nOut particles and total sqrt(s) = eCM.

Set size of output vector

Create momentum-sum four-vector

Generate nParticles independent massless 4-momenta with isotropic angles

Cos(theta), sin(theta), and phi

Norm

Add to vector and add to sum

Compute ECM and normalise to unity (with sign flip)

Transform momenta so add up to (eCM, 0, 0, 0)

The weight is always unity for the massless algorithm.

double genPoint	(	double	eCM,
		vector< double >	mIn,
		vector< Vec4 > &	pOut
	)

Massive generalisation, weights NOT 1 anymore - literal implementation of original RAMBO paper by Ellis, Kleiss and Stirling. Number of particles determined from size of mIn vector.

Massive flat phase space generator, generalised according to the original paper. The momenta are not distributed flat in phase space anymore, returns the weight of the phase space configutation.

Call the massless genPoint, initializing weight.

Set up the function determining the rescaling parameter xi.

If none of the reduced masses is > 1e-9, return.

Set up the mass and energy vectors.

Define the Xi function.

Rescale all the momenta.

Determine the quantities needed for the calculation of the weight.

There's a typo in eq. 4.11 of the Rambo paper by Kleiss, Stirling and Ellis, the Ecm below is not present there.

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

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