PCmsLabTransform.h

/**************************************************************************
 * BASF2 (Belle Analysis Framework 2)                                     *
 * Copyright(C) 2019 - Belle II Collaboration                             *
 *                                                                        *
 * Author: The Belle II Collaboration                                     *
 * Contributors: Marko Staric, Francesco Tenchini                         *
 *                                                                        *
 * This software is provided "as is" without any warranty.                *
 **************************************************************************/
 
#pragma once
 
#include <mdst/dbobjects/CollisionBoostVector.h>
#include <mdst/dbobjects/CollisionInvariantMass.h>
#include <framework/database/DBObjPtr.h>
 
#include <TLorentzRotation.h>
#include <TLorentzVector.h>
 
namespace Belle2 {
  class PCmsLabTransform {
 
  public:
 
    PCmsLabTransform();
 
    TVector3 getBoostVector() const
    {
      return m_boostVectorDB->getBoost();
    }
 
    double getCMSEnergy() const
    {
      return m_invariantMassDB->getMass();
    }
 
    TLorentzVector getBeamFourMomentum() const
    {
      return rotateCmsToLab() * TLorentzVector(0, 0, 0, getCMSEnergy());
    }
 
    const TLorentzRotation rotateLabToCms() const
    {
      TLorentzRotation rotation(-1.*getBoostVector());
      return rotation;
    }
 
    const TLorentzRotation rotateCmsToLab() const
    {
      return rotateLabToCms().Inverse();
    }
 
    static TLorentzVector labToCms(const TLorentzVector& vec);
 
    static TLorentzVector cmsToLab(const TLorentzVector& vec);
 
  private:
    const DBObjPtr<CollisionInvariantMass> m_invariantMassDB; 
    const DBObjPtr<CollisionBoostVector> m_boostVectorDB; 
  };
 
} // Belle2 namespace