Detailed Description

The propagator as a function of the invariant-mass squared \(s\) for a two-body final state with relative orbital angular momentum \(l\) is given by

\[ \mathcal{A}(s) = \frac{ k(m,\Gamma_0) B_l(qr,0) }{ m^2 - s - i m \Gamma_{l}(s) }, \]

where the width \( \Gamma_{l}(s) \) is given by

\[ \Gamma_{l}(s) = \frac{\Gamma_0 q m_0}{q_0 \sqrt{s}} \left(\frac{q}{q_0}\right)^{2l} B_l( qr, q_0 r )^2, \]

where \(q\) is the linear momentum of either decay product in the rest frame of the parent, while \(q_0\) the same quantity evaluated at the resonance mass. The Blatt-Weisskopf functions, \(B_l(q,q_0)\) control the behaviour of functions at large momentum transfers. The width is normalised

such that \(\Gamma(m^2) = \Gamma_0 \). The parameters of the lineshape are tabulated below Parameter	User name	Description
\(m\)	particleName_mass	Breit-Wigner mass, defined as energy at which the self-energy of the resonance is

purely imaginary (defaults to value in PDG) \(\Gamma_0\) | particleName_width | Breit-Wigner width, defined as the width of resonance at the Breit-Wigner mass \(r\) | particleName_radius | Hadronic radius for Blatt-Weisskopf form-factor (defaults to 1.5GeV for light resonances, 3.5GeV for charm)

BL : Use Blatt-Weisskopf factors normalised at \( \sqrt{s}=m \) (by default, normalised at \(\sqrt{s}=0\))

Modulus and phase of the Relativistic Breit-Wigner propagator, for orbital momentum up-to four, using the mass and nominal

width of the rho meson."

Definition at line 128 of file Lineshapes.h.

Public Member Functions
	BW ()
AmpGen::Expression	get (const AmpGen::Expression &s, const AmpGen::Expression &s1, const AmpGen::Expression &s2, const std::string &particleName, const unsigned int &L, const std::string &lineshapeModifier, AmpGen::DebugSymbols *dbexpressions=0) const override
AmpGen::Expression	get (const AmpGen::Particle &p, const std::string &lineshapeModifier, AmpGen::DebugSymbols *dbexpressions=nullptr) const override
virtual Expression	get (const Expression &s, const Expression &s1, const Expression &s2, const std::string &particleName, const unsigned &L, const std::string &lineshapeModifier, DebugSymbols *dbexpressions=nullptr) const =0
Base *	create ()

Inheritance diagram for AmpGen::Lineshape::BW:

Constructor & Destructor Documentation

◆ BW()

AmpGen::Lineshape::BW::BW ( )

inline

Definition at line 128 of file Lineshapes.h.

Member Function Documentation

◆ create()

Base * AmpGen::Lineshape::Base::create ( )

inlineinherited

Definition at line 89 of file Lineshapes.h.

◆ get() [1/3]

virtual Expression AmpGen::Lineshape::Base::get	(	const Expression &	s,
		const Expression &	s1,
		const Expression &	s2,
		const std::string &	particleName,
		const unsigned &	L,
		const std::string &	lineshapeModifier,
		DebugSymbols *	dbexpressions = nullptr ) const

pure virtualinherited

◆ get() [2/3]

AmpGen::Expression AmpGen::Lineshape::BW::get	(	const AmpGen::Expression &	s,
		const AmpGen::Expression &	s1,
		const AmpGen::Expression &	s2,
		const std::string &	particleName,
		const unsigned int &	L,
		const std::string &	lineshapeModifier,
		AmpGen::DebugSymbols *	dbexpressions = 0 ) const

override

◆ get() [3/3]

AmpGen::Expression AmpGen::Lineshape::BW::get	(	const AmpGen::Particle &	p,
		const std::string &	lineshapeModifier,
		AmpGen::DebugSymbols *	dbexpressions = nullptr ) const

overridevirtual

Implements AmpGen::Lineshape::Base.

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

/github/workspace/AmpGen/Lineshapes.h