StRoot: StStrangeMuDstMaker/StDecayAngle.hh Source File

00001 /***********************************************************************
00002  *
00003  * $Id: StDecayAngle.hh,v 3.5 2002/04/30 16:02:47 genevb Exp $
00004  *
00005  * Author: Gene Van Buren, BNL, 26-Nov-2001
00006  *
00007  ***********************************************************************
00008  *
00009  * Description: class for returning decay angle characteristics
00010  *              Particle 1 is the parent of the decay
00011  *              Particle 2 is the daughter of interest of the decay
00012  *              px, py, pz, and m are their momemta and mass
00013  *
00014  ***********************************************************************
00015  *
00016  * $Log: StDecayAngle.hh,v $
00017  * Revision 3.5  2002/04/30 16:02:47  genevb
00018  * Common muDst, improved MC code, better kinks, StrangeCuts now a branch
00019  *
00020  * Revision 3.4  2002/02/10 15:29:09  genevb
00021  * Additional functions for momenta of decay daughters in CM frame
00022  *
00023  * Revision 3.3  2001/11/28 17:54:29  genevb
00024  * Some errors/omissions in last check-in
00025  *
00026  * Revision 3.2  2001/11/28 17:19:42  genevb
00027  * Some interface improvements to decay angle formulae
00028  *
00029  * Revision 3.1  2001/11/28 05:14:59  genevb
00030  * Additional decay angle functions
00031  *
00032  *
00033  ***********************************************************************/
00034 #ifndef StDecayAngle_hh
00035 #define StDecayAngle_hh
00036 #include "TLorentzVector.h"
00037 
00038 #define SHIFTED kTRUE
00039 #define UNSHIFTED kFALSE
00040 
00041 // Default beam axis is z-axis (for polarization calcs)
00042 static TVector3 StDecayAngleBeam(0.,0.,1.);
00043 static TLorentzVector StDecayAngleParent;
00044 static TLorentzVector StDecayAngleDaughter;
00045 static TLorentzVector StDecayAngleParentCopy;    // Use T (not M) to store
00046 static TLorentzVector StDecayAngleDaughterCopy;  //   value of m in Copy
00047 static Bool_t StDecayAngleShifted = UNSHIFTED; // Is daughter shifted?
00048 
00049 class StDecayAngle {
00050  public:
00051   StDecayAngle() {}
00052   virtual ~StDecayAngle() {}
00053   static Float_t decayTheta();
00054   static Float_t decayTheta(
00055     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00056     Float_t px2, Float_t py2, Float_t pz2, Float_t m2);
00057   static Float_t decayCosTheta();
00058   static Float_t decayCosTheta(
00059     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00060     Float_t px2, Float_t py2, Float_t pz2, Float_t m2);
00061 
00062   static Float_t decayThetaLab(
00063     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00064     Float_t px2, Float_t py2, Float_t pz2, Float_t m2);
00065   static Float_t decayCosThetaLab(
00066     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00067     Float_t px2, Float_t py2, Float_t pz2, Float_t m2);
00068 
00069   static Float_t polarityTheta();
00070   static Float_t polarityTheta(
00071     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00072     Float_t px2, Float_t py2, Float_t pz2, Float_t m2);
00073   static Float_t polarityCosTheta();
00074   static Float_t polarityCosTheta(
00075     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00076     Float_t px2, Float_t py2, Float_t pz2, Float_t m2);
00077 
00078   static TVector3 getShiftedDaughter(
00079     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00080     Float_t px2, Float_t py2, Float_t pz2, Float_t m2);
00081 
00082   static void setBeam(Float_t x, Float_t y, Float_t z);
00083   static void setParentDaughter(
00084     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00085     Float_t px2, Float_t py2, Float_t pz2, Float_t m2,
00086     Bool_t shift=UNSHIFTED);
00087   static void shiftToRest();
00088   static Bool_t different(TLorentzVector& v,
00089     Float_t px , Float_t py , Float_t pz , Float_t m );
00090 
00091 };
00092 
00093 
00094 inline void StDecayAngle::setBeam(Float_t x, Float_t y, Float_t z) {
00095   StDecayAngleBeam.SetXYZ(x,y,z);
00096 }
00097 
00098 inline Float_t StDecayAngle::decayTheta(
00099     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00100     Float_t px2, Float_t py2, Float_t pz2, Float_t m2) {
00101   setParentDaughter(px1,py1,pz1,m1,px2,py2,pz2,m2,SHIFTED);
00102   return decayTheta();
00103 }
00104 
00105 inline Float_t StDecayAngle::decayCosTheta(
00106     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00107     Float_t px2, Float_t py2, Float_t pz2, Float_t m2) {
00108   setParentDaughter(px1,py1,pz1,m1,px2,py2,pz2,m2,SHIFTED);
00109   return decayCosTheta();
00110 }
00111 
00112 inline Float_t StDecayAngle::decayThetaLab(
00113     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00114     Float_t px2, Float_t py2, Float_t pz2, Float_t m2) {
00115   setParentDaughter(px1,py1,pz1,m1,px2,py2,pz2,m2);
00116   return decayTheta();
00117 }
00118 
00119 inline Float_t StDecayAngle::decayCosThetaLab(
00120     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00121     Float_t px2, Float_t py2, Float_t pz2, Float_t m2) {
00122   setParentDaughter(px1,py1,pz1,m1,px2,py2,pz2,m2);
00123   return decayCosTheta();
00124 }
00125 
00126 inline Float_t StDecayAngle::polarityTheta(
00127     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00128     Float_t px2, Float_t py2, Float_t pz2, Float_t m2) {
00129   setParentDaughter(px1,py1,pz1,m1,px2,py2,pz2,m2,SHIFTED);
00130   return polarityTheta();
00131 }
00132 
00133 inline Float_t StDecayAngle::polarityCosTheta(
00134     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00135     Float_t px2, Float_t py2, Float_t pz2, Float_t m2) {
00136   setParentDaughter(px1,py1,pz1,m1,px2,py2,pz2,m2,SHIFTED);
00137   return polarityCosTheta();
00138 }
00139 
00140 inline void StDecayAngle::setParentDaughter(
00141     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00142     Float_t px2, Float_t py2, Float_t pz2, Float_t m2,
00143     Bool_t shift) {
00144   if (different(StDecayAngleParentCopy,px1,py1,pz1,m1)) {
00145     StDecayAngleParentCopy.SetXYZT(px1,py1,pz1,m1);
00146     StDecayAngleParent.SetXYZM(px1,py1,pz1,m1);
00147   }
00148   if (different(StDecayAngleDaughterCopy,px2,py2,pz2,m2)) {
00149     StDecayAngleDaughterCopy.SetXYZT(px2,py2,pz2,m2);
00150     StDecayAngleDaughter.SetXYZM(px2,py2,pz2,m2);
00151     StDecayAngleShifted = UNSHIFTED;
00152   } else if (StDecayAngleShifted && !shift) {
00153     StDecayAngleDaughter.SetXYZM(px2,py2,pz2,m2);
00154     StDecayAngleShifted = UNSHIFTED;
00155   }
00156   if (shift) shiftToRest();
00157 }
00158 
00159 inline void StDecayAngle::shiftToRest() {
00160   if (!StDecayAngleShifted) {
00161     StDecayAngleDaughter.Boost(-StDecayAngleParent.BoostVector());
00162     StDecayAngleShifted = SHIFTED;
00163   }
00164 }
00165 
00166 inline TVector3 StDecayAngle::getShiftedDaughter(
00167     Float_t px1, Float_t py1, Float_t pz1, Float_t m1,
00168     Float_t px2, Float_t py2, Float_t pz2, Float_t m2) {
00169   setParentDaughter(px1,py1,pz1,m1,px2,py2,pz2,m2,SHIFTED);
00170   return TVector3(StDecayAngleDaughter.Vect());
00171 }
00172 
00173 inline Float_t StDecayAngle::decayTheta() {
00174   return StDecayAngleDaughter.Vect().Angle(StDecayAngleParent.Vect());
00175 }
00176 
00177 inline Float_t StDecayAngle::decayCosTheta() {
00178   return TMath::Cos(decayTheta());
00179 }
00180 
00181 inline Float_t StDecayAngle::polarityTheta() {
00182   return StDecayAngleDaughter.Vect().Angle(
00183     StDecayAngleParent.Vect().Cross(StDecayAngleBeam));
00184 }
00185 
00186 inline Float_t StDecayAngle::polarityCosTheta() {
00187   return TMath::Cos(polarityTheta());
00188 }
00189 
00190 inline Bool_t StDecayAngle::different(TLorentzVector& v,
00191     Float_t px , Float_t py , Float_t pz , Float_t m ) {
00192   return ((px != v.X()) || (py != v.Y()) || (pz != v.Z()) || (m != v.T()));
00193 }
00194 
00195 #endif