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Laura++  v2r0
A maximum likelihood fitting package for performing Dalitz-plot analysis.
LauBreitWignerRes.cc
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1 
2 // Copyright University of Warwick 2004 - 2013.
3 // Distributed under the Boost Software License, Version 1.0.
4 // (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
5 
6 // Authors:
7 // Thomas Latham
8 // John Back
9 // Paul Harrison
10 
15 //****************************************************************************
16 // Class for defining the Breit-Wigner resonance model
17 //****************************************************************************
18 
19 // --CLASS DESCRIPTION [MODEL] --
20 // Class for defining the Breit-Wigner resonance model
21 
22 #include "LauBreitWignerRes.hh"
23 
24 ClassImp(LauBreitWignerRes)
25 
26 
27 LauBreitWignerRes::LauBreitWignerRes(TString resName, Double_t resMass, Double_t resWidth, Int_t resSpin,
28  Int_t resCharge, Int_t resPairAmpInt, const LauDaughters* daughters) :
29  LauAbsResonance(resName, resMass, resWidth, resSpin, resCharge, resPairAmpInt, daughters)
30 {
31 }
32 
34 {
35 }
36 
38 {
39 }
40 
41 LauComplex LauBreitWignerRes::resAmp(Double_t mass, Double_t spinTerm)
42 {
43  // This function returns the complex dynamical amplitude for a Breit-Wigner resonance,
44  // given the invariant mass and cos(helicity) values.
45 
46  Double_t resMass = this->getMass();
47  Double_t deltaM = mass - resMass;
48 
49  Double_t resWidthO2 = 0.5 * this->getWidth();
50  Double_t resWidthO2Sq = resWidthO2*resWidthO2;
51 
52  LauComplex resAmplitude(deltaM, resWidthO2);
53 
54  resAmplitude.rescale(spinTerm/(deltaM*deltaM + resWidthO2Sq));
55 
56  return resAmplitude;
57 }
58 
virtual ~LauBreitWignerRes()
Destructor.
Double_t getMass() const
Get the mass of the resonance.
Class that defines the particular 3-body decay under study.
Definition: LauDaughters.hh:33
File containing declaration of LauBreitWignerRes class.
virtual void initialise()
Initialise the model.
Class for defining the simple Breit-Wigner resonance model.
Double_t getWidth() const
Get the width of the resonance.
Abstract class for defining type for resonance amplitude models (Breit-Wigner, Flatte etc...
void rescale(Double_t scaleVal)
Scale this by a factor.
Definition: LauComplex.hh:282
Class for defining a complex number.
Definition: LauComplex.hh:47
virtual LauComplex resAmp(Double_t mass, Double_t spinTerm)
Complex resonant amplitude.