ColinsSoperVariables.h File Reference

#include "TLorentzVector.h"
#include "TVector3.h"

Go to the source code of this file.

Macros
#define	CM_ENERGY   7000.0

Functions
void	calCSVariables (TLorentzVector mu, TLorentzVector mubar, double *res, bool swap)

Macro Definition Documentation

CM_ENERGY

#define CM_ENERGY   7000.0

Definition at line 1 of file ColinsSoperVariables.h.

Function Documentation

calCSVariables()

void calCSVariables	(	TLorentzVector	mu,
		TLorentzVector	mubar,
		double *	res,
		bool	swap
	)

Definition at line 7 of file ColinsSoperVariables.h.

                                                                                     {
  // convention. beam direction is on the positive Z direction.
  // beam contains quark flux.
  TLorentzVector Pbeam(0, 0, CM_ENERGY / 2.0, CM_ENERGY / 2.0);
  TLorentzVector Ptarget(0, 0, -CM_ENERGY / 2.0, CM_ENERGY / 2.0);
 
  TLorentzVector Q(mu + mubar);
  /************************************************************************
   *
   * 1) cos(theta) = 2 Q^-1 (Q^2+Qt^2)^-1 (mu^+ mubar^- - mu^- mubar^+)
   *
   *
   ************************************************************************/
  double muplus = 1.0 / sqrt(2.0) * (mu.E() + mu.Z());
  double muminus = 1.0 / sqrt(2.0) * (mu.E() - mu.Z());
 
  double mubarplus = 1.0 / sqrt(2.0) * (mubar.E() + mubar.Z());
  double mubarminus = 1.0 / sqrt(2.0) * (mubar.E() - mubar.Z());
 
  double costheta =
      2.0 / Q.Mag() / sqrt(pow(Q.Mag(), 2) + pow(Q.Pt(), 2)) * (muplus * mubarminus - muminus * mubarplus);
  if (swap)
    costheta = -costheta;
 
  /************************************************************************
   *
   * 2) sin2(theta) = Q^-2 Dt^2 - Q^-2 (Q^2 + Qt^2)^-1 * (Dt dot Qt)^2
   *
   ************************************************************************/
  TLorentzVector D(mu - mubar);
  double dt_qt = D.X() * Q.X() + D.Y() * Q.Y();
  double sin2theta =
      pow(D.Pt() / Q.Mag(), 2) - 1.0 / pow(Q.Mag(), 2) / (pow(Q.Mag(), 2) + pow(Q.Pt(), 2)) * pow(dt_qt, 2);
 
  /************************************************************************
   *
   * 3) tanphi = (Q^2 + Qt^2)^1/2 / Q (Dt dot R unit) /(Dt dot Qt unit)
   *
   ************************************************************************/
  // unit vector on R direction
  TVector3 R = Pbeam.Vect().Cross(Q.Vect());
  TVector3 Runit = R.Unit();
 
  // unit vector on Qt
  TVector3 Qt = Q.Vect();
  Qt.SetZ(0);
  TVector3 Qtunit = Qt.Unit();
 
  TVector3 Dt = D.Vect();
  Dt.SetZ(0);
  double tanphi = sqrt(pow(Q.Mag(), 2) + pow(Q.Pt(), 2)) / Q.Mag() * Dt.Dot(Runit) / Dt.Dot(Qtunit);
  if (swap)
    tanphi = -tanphi;
 
  res[0] = costheta;

References CM_ENERGY, amptDefaultParameters_cff::mu, RPCpg::mubar, BPhysicsValidation_cfi::muminus, BPhysicsValidation_cfi::muplus, funct::pow(), class-composition::Q, dttmaxenums::R, mathSSE::sqrt(), and edm::swap().

Referenced by ColinsSoperVariablesComputer::produce().