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#ifndef DataFormats_PatCandidates_interface_ParametrizationHelper_h
#define DataFormats_PatCandidates_interface_ParametrizationHelper_h
#include "DataFormats/PatCandidates/interface/CandKinResolution.h"
#include <string>
namespace pat {
namespace helper {
namespace ParametrizationHelper {
/// Returns the number of free parameters in a parametrization (3 or 4)
inline uint32_t dimension(pat::CandKinResolution::Parametrization parametrization) {
return (static_cast<uint32_t>(parametrization) & 0x0F);
}
/// Convert a name into a parametrization code
pat::CandKinResolution::Parametrization fromString(const std::string &name);
/// Convert a number into a string
const char *name(pat::CandKinResolution::Parametrization param);
/// Given a choice of coordinate frame, a vector of coordinates and a reference 4-vector, produce a new 4 vector with the specified parameters.
/// The new 4-vector is not guaranteed to satisfy the constraints of these parametrization if the initial 4-vector does not satisfy them.
/// In the future this method will throw an exception if you go in an unphysical point of the coordinate system (e.g. E^2 < P^2)
math::PtEtaPhiMLorentzVector polarP4fromParameters(pat::CandKinResolution::Parametrization parametrization,
const AlgebraicVector4 ¶meters,
const math::PtEtaPhiMLorentzVector &initialP4);
/// Given a choice of coordinate frame, a vector of coordinates and a reference 4-vector, produce a new 4 vector with the specified parameters.
/// The new 4-vector is not guaranteed to satisfy the constraints of these parametrization if the initial 4-vector does not satisfy them.
/// In the future this method will throw an exception if you go in an unphysical point of the coordinate system (e.g. E^2 < P^2)
math::XYZTLorentzVector p4fromParameters(pat::CandKinResolution::Parametrization parametrization,
const AlgebraicVector4 ¶meters,
const math::XYZTLorentzVector &initialP4);
/// Returns a vector of coordinates values given a coordinate frame and a 4-vector.
AlgebraicVector4 parametersFromP4(pat::CandKinResolution::Parametrization parametrization,
const math::XYZTLorentzVector &p4);
/// Returns a vector of coordinates values given a coordinate frame and a 4-vector.
AlgebraicVector4 parametersFromP4(pat::CandKinResolution::Parametrization parametrization,
const math::PtEtaPhiMLorentzVector &p4);
/// Set the values of the parameters for a given 4-momentum
void setParametersFromP4(pat::CandKinResolution::Parametrization parametrization,
AlgebraicVector4 &pars,
const math::XYZTLorentzVector &p4);
/// Set the values of the parameters for a given 4-momentum
void setParametersFromP4(pat::CandKinResolution::Parametrization parametrization,
AlgebraicVector4 &pars,
const math::PtEtaPhiMLorentzVector &p4);
/// For internal use only, so we provide only the interface. Use the 'setParametersFromP4'.
template <typename T>
void setParametersFromAnyVector(pat::CandKinResolution::Parametrization parametrization,
AlgebraicVector4 &pars,
const T &p4);
/// Expresses the difference between two 4-momentum vectors as a shift in coordinates in a given frame.
/** Basically, if you do:
* <code>
* pars = parametersFromP4(param, simp4);
* diff = diffToParameters(param, simP4, recP4);
* </code>
* then up to roundoff errors
* <code>recP4 == p4fromParameters(param, pars+diff, simP4);</code>
*/
AlgebraicVector4 diffToParameters(pat::CandKinResolution::Parametrization parametrization,
const math::XYZTLorentzVector &p4ini,
const math::XYZTLorentzVector &p4fin);
/// Expresses the difference between two 4-momentum vectors as a shift in coordinates in a given frame.
/** Basically, if you do:
* <code>
* pars = parametersFromP4(param, simp4);
* diff = diffToParameters(param, simP4, recP4);
* </code>
* then up to roundoff errors
* <code>recP4 == p4fromParameters(param, pars+diff, simP4);</code>
*/
AlgebraicVector4 diffToParameters(pat::CandKinResolution::Parametrization parametrization,
const math::PtEtaPhiMLorentzVector &p4ini,
const math::PtEtaPhiMLorentzVector &p4fin);
/// Is this parametrization usable only with massless objects?
bool isAlwaysMassless(pat::CandKinResolution::Parametrization parametrization);
/// Is this parametrization usable only with massive objects?
bool isAlwaysMassive(pat::CandKinResolution::Parametrization parametrization);
/// If this parametrization has a mass constraint (including the 'isAlwaysMassless' case)
bool isMassConstrained(pat::CandKinResolution::Parametrization parametrization);
/// If this value of the parameters is meaningful in this parametrization.
/// It can be used e.g. when doing random smearing to check you're still within the physical region
/// This DOES check inequalities (e.g. E >= P, M >= 0, theta in [0,PI], ..)
/// This DOES NOT check strict equalities (e.g. M == 0)
/// This DOES NOT check that your parameters comply with your constraints (e.g. fixed mass constraint)
bool isPhysical(pat::CandKinResolution::Parametrization parametrization,
const AlgebraicVector4 &v4,
const math::PtEtaPhiMLorentzVector &initialP4);
} // namespace ParametrizationHelper
} // namespace helper
} // namespace pat
#endif
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