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Herwig::ShowerAlpha Class Referenceabstract
This class is the abstract class from which all types of running couplings used in the Showering derive from. More...
Inheritance diagram for Herwig::ShowerAlpha:
This class is the abstract class from which all types of running couplings used in the Showering derive from.
The main purpose of this class, and the ones that derive from it, is to allow systematic uncertainties for the initial-state radiation and, independently, the final-state radiation effects, to be evaluated.
This is achieved by allowing a multiplicative factor, which is 1.0 for the "central value", for the scale argument, , of the running coupling. This factor, is given by the scaleFactor() member and the coupling returned by the value() member is such that
This scale factor is a parameter which is settable by the user, via the interface. Although, of course, it is not clear my how much we should scale in order to get a systematic error (but factors: 1/2 and 2 are quite common), this method provides a double side error, and it appears more sensible than the rough and one-sided evaluation obtained via turning off the I.S.R. and/or F.S.R. (possibilities which are, anyway, provided by Herwig).
Member Function Documentation
The standard Init function used to initialize the interfaces.
Called exactly once for each class by the class description system before the main function starts or when this class is dynamically loaded.
The assignment operator is private and must never be called.
In fact, it should not even be implemented.
Function used to read in object persistently.
Function used to write out object persistently.
It returns the factor that multiplies the scale argument, , of the running coupling.
This is supposed to be 1.0 in normal conditions (central values) whereas different values can be useful for systematics evaluation for Initial State radiation or Final State radiation effects.
The documentation for this class was generated from the following file:
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