class ThePEG::Direction< I >
Direction object can be used to specify that some following operations should be assumed to be performed with the z-direction of the momenta reversed.
As an example, if
Direction<0>::pos() is true, the method
Lorentz5Momentum::dirPlus() will return the positive, light-cone component, and
Lorentz5Momentum::dirMinus() the negative, while if
Direction<0>::pos() is false the behavior of the methods are reversed.
Direction is templated with an integer template argument (default = 0), and only one object per class can be instatiated at the time. Attempts to instatiate a second object of a
Direction class will result in an exception being thrown. To have several different directions classes with different template arguments must be instantiated.
Direction<0> is reserved for
Lorentz5Momentum. Attempts to use the static methods of a
Direction class when no object has been instatiated will result in an exception being thrown.
- See also
Definition at line 41 of file Direction.h.