Herwig 7.3.0
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This class is the abstract class from which all types of running couplings used in the Showering derive from. More...
#include <ShowerAlpha.h>
Public Member Functions | |
Standard constructors and destructors. | |
ShowerAlpha () | |
The default constructor. | |
virtual double | value (const Energy2 scale) const =0 |
Methods to return the coupling and the scaleFactor. | |
virtual double | overestimateValue () const =0 |
Virtual method, which should be overridden in a derived class to provide an overestimate approximation of the alpha value. | |
virtual double | ratio (const Energy2 scale, double factor=1.) const =0 |
Virtual method which returns the ratio of the running alpha value at the input scale to the overestimated value. | |
double | scaleFactor () const |
It returns the factor that multiplies the scale argument, \(\mu^2\), of the running coupling. | |
virtual double | showerValue (const Energy2 scale) const |
Virtual method that is supposed to return the running alpha value evaluated at the input scale. | |
virtual double | showerOverestimateValue () const |
Virtual method, which should be overridden in a derived class to provide an overestimate approximation of the alpha value. | |
virtual double | showerRatio (const Energy2 scale, double factor=1.) const |
Virtual method which returns the ratio of the running alpha value at the input scale to the overestimated value. | |
virtual void | initialize () |
Initialize this coupling. | |
Public Member Functions inherited from ThePEG::Interfaced | |
virtual bool | defaultInit () |
PPtr | getParticle (PID) const |
PDPtr | getParticleData (PID) const |
bool | used () const |
void | useMe () const |
tEGPtr | generator () const |
void | persistentOutput (PersistentOStream &os) const |
void | persistentInput (PersistentIStream &is, int version) |
PPtr | getParticle (PID) const |
PDPtr | getParticleData (PID) const |
bool | used () const |
void | useMe () const |
tEGPtr | generator () const |
Public Member Functions inherited from ThePEG::InterfacedBase | |
string | fullName () const |
string | name () const |
string | path () const |
string | comment () const |
void | setup (istream &is) |
void | update () |
void | init () |
virtual bool | preInitialize () const |
void | initrun () |
void | finish () |
void | touch () |
void | reset () |
void | clear () |
InitState | state () const |
bool | locked () const |
bool | touched () const |
virtual IBPtr | fullclone () const |
void | persistentOutput (PersistentOStream &os) const |
void | persistentInput (PersistentIStream &is, int version) |
virtual void | debugme () const |
void | update () |
void | init () |
virtual bool | preInitialize () const |
void | initrun () |
void | finish () |
void | touch () |
void | reset () |
void | clear () |
InitState | state () const |
bool | locked () const |
bool | touched () const |
virtual IBPtr | fullclone () const |
Public Member Functions inherited from ThePEG::Base | |
void | debug () const |
virtual void | debugme () const |
Public Member Functions inherited from ThePEG::Pointer::ReferenceCounted | |
CounterType | referenceCount () const |
Public Member Functions inherited from ThePEG::Named | |
Named (const string &newName=string()) | |
Named (const Named &)=default | |
const string & | name () const |
bool | operator== (const Named &other) const |
bool | operator< (const Named &other) const |
Functions used by the persistent I/O system. | |
double | _scaleFactor |
The scale factor. | |
void | persistentOutput (PersistentOStream &os) const |
Function used to write out object persistently. | |
void | persistentInput (PersistentIStream &is, int version) |
Function used to read in object persistently. | |
static void | Init () |
The standard Init function used to initialize the interfaces. | |
ShowerAlpha & | operator= (const ShowerAlpha &)=delete |
The assignment operator is private and must never be called. | |
Additional Inherited Members | |
Public Types inherited from ThePEG::InterfacedBase | |
enum | InitState |
Public Types inherited from ThePEG::Pointer::ReferenceCounted | |
typedef unsigned int | CounterType |
Static Public Member Functions inherited from ThePEG::Interfaced | |
static void | Init () |
Static Public Member Functions inherited from ThePEG::InterfacedBase | |
static void | Init () |
Static Public Member Functions inherited from ThePEG::Base | |
static void | Init () |
Public Attributes inherited from ThePEG::InterfacedBase | |
initializing | |
uninitialized | |
initialized | |
runready | |
Public Attributes inherited from ThePEG::Pointer::ReferenceCounted | |
const unsigned long | uniqueId |
Protected Member Functions inherited from ThePEG::Interfaced | |
void | reporeg (IBPtr object, string name) const |
bool | setDefaultReference (PtrT &ptr, string classname, string objectname) |
Interfaced (const string &newName) | |
Interfaced (const Interfaced &i) | |
void | setGenerator (tEGPtr generator) |
Protected Member Functions inherited from ThePEG::InterfacedBase | |
virtual void | readSetup (istream &is) |
virtual void | doupdate () |
virtual void | doinit () |
virtual void | doinitrun () |
virtual void | dofinish () |
virtual IVector | getReferences () |
virtual void | rebind (const TranslationMap &) |
virtual IBPtr | clone () const=0 |
InterfacedBase (string newName) | |
InterfacedBase (const InterfacedBase &i) | |
virtual void | readSetup (istream &is) |
virtual void | doupdate () |
virtual void | doinit () |
virtual void | doinitrun () |
virtual void | dofinish () |
virtual IVector | getReferences () |
virtual void | rebind (const TranslationMap &) |
Protected Member Functions inherited from ThePEG::Pointer::ReferenceCounted | |
ReferenceCounted (const ReferenceCounted &) | |
ReferenceCounted & | operator= (const ReferenceCounted &) |
Protected Member Functions inherited from ThePEG::Named | |
const Named & | operator= (const Named &other) |
const string & | name (const string &newName) |
Static Protected Member Functions inherited from ThePEG::Interfaced | |
static void | registerRepository (IBPtr) |
static void | registerRepository (IBPtr, string newName) |
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, \(\mu^2\), of the running coupling. This factor, \(f\) is given by the scaleFactor() member and the coupling returned by the value() member is such that
\[\alpha(\mu^2)\to \alpha(f\times\mu^2).\]
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 \(1\sigma\) 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).
Definition at line 49 of file ShowerAlpha.h.
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inline |
The default constructor.
Definition at line 58 of file ShowerAlpha.h.
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static |
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.
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inlinevirtual |
Initialize this coupling.
Reimplemented in Herwig::ShowerAlphaQCD.
Definition at line 131 of file ShowerAlpha.h.
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privatedelete |
The assignment operator is private and must never be called.
In fact, it should not even be implemented.
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pure virtual |
Virtual method, which should be overridden in a derived class to provide an overestimate approximation of the alpha value.
Implemented in Herwig::ShowerAlphaQCD, and Herwig::ShowerAlphaQED.
Referenced by showerOverestimateValue().
void Herwig::ShowerAlpha::persistentInput | ( | PersistentIStream & | is, |
int | version | ||
) |
Function used to read in object persistently.
is | the persistent input stream read from. |
version | the version number of the object when written. |
void Herwig::ShowerAlpha::persistentOutput | ( | PersistentOStream & | os | ) | const |
Function used to write out object persistently.
os | the persistent output stream written to. |
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pure virtual |
Virtual method which returns the ratio of the running alpha value at the input scale to the overestimated value.
scale | The scale |
Implemented in Herwig::ShowerAlphaQCD, and Herwig::ShowerAlphaQED.
Referenced by showerRatio().
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inline |
It returns the factor that multiplies the scale argument, \(\mu^2\), 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.
Definition at line 97 of file ShowerAlpha.h.
References _scaleFactor.
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inlinevirtual |
Virtual method, which should be overridden in a derived class to provide an overestimate approximation of the alpha value.
Definition at line 114 of file ShowerAlpha.h.
References overestimateValue().
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inlinevirtual |
Virtual method which returns the ratio of the running alpha value at the input scale to the overestimated value.
scale | The scale |
Definition at line 124 of file ShowerAlpha.h.
References ratio().
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inlinevirtual |
Virtual method that is supposed to return the running alpha value evaluated at the input scale.
scale | The scale |
Definition at line 105 of file ShowerAlpha.h.
References value().
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pure virtual |
Methods to return the coupling and the scaleFactor.
Pure virtual method that is supposed to return the running alpha value evaluated at the input scale.
scale | The scale |
Implemented in Herwig::ShowerAlphaQCD, and Herwig::ShowerAlphaQED.
Referenced by showerValue().
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private |