AliPhysics  41af4b0 (41af4b0)
AliFlowLYZEventPlane.cxx
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15 
16 #define AliFlowAnalysisWithLYZEventPlane_cxx
17 
18 // AliFlowLYZEventPlane:
19 //
20 // Class to calculate the event plane and event weight from the LYZ method
21 // It needs input from the standard LYZ first and second run
22 // author: N. van der Kolk (kolk@nikhef.nl)
23 
24 #include "Riostream.h"
25 #include "TProfile.h"
26 #include "TFile.h"
27 #include "TComplex.h"
28 #include "TList.h"
29 
30 #include "AliFlowVector.h"
31 #include "AliFlowLYZConstants.h"
32 #include "AliFlowEventSimple.h"
33 #include "AliFlowLYZEventPlane.h"
34 
35 class AliFlowTrackSimple;
36 
37 using std::cout;
38 using std::endl;
39 ClassImp(AliFlowLYZEventPlane)
40 
41  //-----------------------------------------------------------------------
42 
44  fSecondRunList(0),
45  fWR(0),
46  fPsi(0),
47  fSecondReDtheta(0),
48  fSecondImDtheta(0),
49  fFirstr0theta(0)
50 {
51  // Constructor.
52 
53 }
54 //-----------------------------------------------------------------------
55 
56 
58 {
59  //destructor
60  delete fSecondRunList;
61 }
62 
63 
64 //-----------------------------------------------------------------------
66 {
67  //Declare histograms & get input files
68  cout<<"---Lee Yang Zeros Event Plane Method---"<<endl;
69 
70  //input histograms
71  if (fSecondRunList) {
72  fSecondReDtheta = (TProfile*)fSecondRunList->FindObject("Second_FlowPro_ReDtheta_LYZSUM");
73  fSecondImDtheta = (TProfile*)fSecondRunList->FindObject("Second_FlowPro_ImDtheta_LYZSUM");
74  fFirstr0theta = (TProfile*)fSecondRunList->FindObject("First_FlowPro_r0theta_LYZSUM");
75 
76  //warnings
77  if (!fSecondReDtheta) {cout<<"fSecondReDtheta is NULL!"<<endl; }
78  if (!fSecondImDtheta) {cout<<"fSecondImDtheta is NULL!"<<endl; }
79  if (!fFirstr0theta) {cout<<"fFirstr0theta is NULL!"<<endl; }
80  }
81 
82 
83 }
84 
85 //-----------------------------------------------------------------------
87 {
88  //declare variables
90  Double_t dCosTerm = 0;
91  Double_t dSinTerm = 0;
92  TComplex cDtheta;
93  TComplex cRatio;
94 
95  if (aQ.Mod()==0.) { cout<<"Q vector is NULL"<<endl; }
96  else {
97  for (Int_t theta=0;theta<iNtheta;theta++) {
98  Double_t dTheta = ((float)theta/iNtheta)*TMath::Pi()/2;
99  //Calculate Qtheta
100  Double_t dQtheta = aQ.X()*cos(2*dTheta)+aQ.Y()*sin(2*dTheta); //get Qtheta from Q vector
101 
102  //get R0
103  Double_t dR0 = fFirstr0theta->GetBinContent(theta+1);
104  //cerr<<"dR0 = "<<dR0<<endl;
105 
106  //get Dtheta
107  Double_t dReDtheta = fSecondReDtheta->GetBinContent(theta+1);
108  //cerr<<"dReDtheta = "<<dReDtheta<<endl;
109  Double_t dImDtheta = fSecondImDtheta->GetBinContent(theta+1);
110  //cerr<<"dImDtheta = "<<dImDtheta<<endl;
111  cDtheta(dReDtheta,dImDtheta);
112 
113  TComplex cExpo(0.,dR0*dQtheta); //Complex number: 0 +(i r0 Qtheta)
114  if (cDtheta.Rho()!=0.) { cRatio =(TComplex::Exp(cExpo))/cDtheta; } //(e^(i r0 Qtheta))/Dtheta
115  else { cRatio(0.,0.); }
116 
117  //sum over theta
118  dCosTerm += cRatio.Re() * TMath::Cos(2*dTheta); //Re{(e^(i r0 Qtheta))/Dtheta } cos(2 theta)
119  dSinTerm += cRatio.Re() * TMath::Sin(2*dTheta); //Re{(e^(i r0 Qtheta))/Dtheta } sin(2 theta)
120 
121  }//loop over theta
122 
123  //average over theta
124  dCosTerm /= iNtheta;
125  dSinTerm /= iNtheta;
126  //cerr<<"cosTerm & sinTerm are: "<<dCosTerm<<" & "<<dSinTerm<<endl;
127 
128  //calculate fWR
129  fWR = TMath::Sqrt(dCosTerm*dCosTerm + dSinTerm*dSinTerm);
130 
131  //calculate fRP
132  fPsi = 0.5*TMath::ATan2(dSinTerm,dCosTerm); //takes care of the signs correctly!
133  if (fPsi < 0.) { fPsi += TMath::Pi(); } //to shift distribution from (-pi/2 to pi/2) to (0 to pi)
134  }
135 
136 }
137 
double Double_t
Definition: External.C:58
Int_t GetNtheta() const
static AliFlowLYZConstants * GetMaster()
int Int_t
Definition: External.C:63
void CalculateRPandW(AliFlowVector aQ)