Interface
This section explains how an object can become a object with kinematic informations.
Definition
A type that adheres to the interface described in this section will be referred to as KinematicInterface-compliant. A package providing such a type will be called the provider.
Coordinate Systems
The provider must define a preferred coordinate system for its KinematicInterface-compliant type and provide accessors for the components of this system using standardized methods (outlined below). If the object natively supports multiple coordinate systems, the provider should choose the one in which component access is the most efficient as the preferred coordinate system. This system must be one of the supported options.
The LorentzVectorBase package supplements these component accessors to cover all supported coordinate systems. It uses the components of the preferred coordinate system to implement complementary accessors. Julia’s dispatch mechanism prioritizes the accessors provided by the object itself.
A KinematicInterface-compliant type can store additional data beyond the four-vector. For instance, a type representing an elementary particle may comply while containing more information than just the particle’s four-momentum.
Implementation
A type MyLorentzVector (which do not necessary need to be a vector) will comply with the KinematicInterface if it implements one of the following sets of methods:
Option 1: Position with Cartesian Coordinates
| Required Methods | Brief Description |
|---|---|
LorentzVectorBase.islorentzvector(::Type{MyLorentzVector}) | Declare that your type implements the interface |
LorentzVectorBase.coordinate_system(::Type{MyLorentzVector}) = LorentzVectorBase.XYZE | Declare the preferred coordinate system |
LorentzVectorBase.x(::MyLorentzVector) | X Cartesian coordinate |
LorentzVectorBase.y(::MyLorentzVector) | Y Cartesian coordinate |
LorentzVectorBase.z(::MyLorentzVector) | Z Cartesian coordinate |
LorentzVectorBase.t(::MyLorentzVector) | Time coordinate (t) |
Option 2: Four-Momentum with Cartesian Coordinates
| Required Methods | Brief Description |
|---|---|
LorentzVectorBase.islorentzvector(::Type{MyLorentzVector}) | Declare that your type implements the interface |
LorentzVectorBase.coordinate_system(::Type{MyLorentzVector}) = LorentzVectorBase.XYZE | Declare the preferred coordinate system |
LorentzVectorBase.px(::MyLorentzVector) | Momentum X-component |
LorentzVectorBase.py(::MyLorentzVector) | Momentum Y-component |
LorentzVectorBase.pz(::MyLorentzVector) | Momentum Z-component |
LorentzVectorBase.energy(::MyLorentzVector) | Energy |
Option 3: Four-Momentum with Cylindrical Coordinates
| Required Methods | Brief Description |
|---|---|
LorentzVectorBase.islorentzvector(::Type{MyLorentzVector}) | Declare that your type implements the interface |
LorentzVectorBase.coordinate_system(::Type{MyLorentzVector}) | Declare the preferred coordinate system, which must return PtEtaPhiM, PtEtaPhiE, PtYPhiM, or PtYPhiE (from LorentzVectorBase) |
LorentzVectorBase.pt(::MyLorentzVector) | Transverse momentum |
LorentzVectorBase.phi(::MyLorentzVector) | Azimuthal angle |
Additionally, you must implement one of the following:
| Required Method | Description |
|---|---|
LorentzVectorBase.eta(::MyLorentzVector) | Pseudorapidity |
LorentzVectorBase.rapidity(::MyLorentzVector) | Rapidity relative to the beam axis (z-axis) |
And one of:
| Required Method | Description |
|---|---|
LorentzVectorBase.energy(::MyLorentzVector) | Energy |
LorentzVectorBase.mass(::MyLorentzVector) | Invariant mass |
The methods returning the coordinates of the preferred system (as specified by coordinate_system()) must be implemented.
Optional Methods
| Optional Method | Description |
|---|---|
LorentzVectorBase.mass2(::MyLorentzVector) | Square of the mass |
LorentzVectorBase.rho2(::MyLorentzVector) | ρ² = |p|² (squared momentum magnitude) |
Additionally, any method from another option (i.e., a method from Option Y when methods from Option X are provided) may also be implemented.