QCD Library
Public Member Functions | Static Public Attributes | List of all members
strong_coupling Class Reference

Implements the running and decoupling of the strong coupling constant. More...

Public Member Functions

 strong_coupling (reference_coupling alpha_s=reference_coupling{}, int order=max_running_order)
 
double operator() (double mu) const
 
int order () const
 
int nf () const
 
strong_coupling decouple_down (threshold thr) const
 Decouple down (remove) flavour in alpha_s. More...
 
strong_coupling remove (threshold thr) const
 Remove (decouple down) flavour in alpha_s. More...
 
strong_coupling decouple_up (threshold thr) const
 Decouple up (add) flavour in alpha_s. More...
 
strong_coupling add (threshold thr) const
 Add (decouple up) flavour in alpha_s. More...
 
strong_couplingerror (double err)
 Set error bounds for evolution. More...
 
strong_couplingabs_error (double abs_err)
 Set absolute error bound for evolution. More...
 
strong_couplingrel_error (double rel_err)
 Set relative error bound for evolution. More...
 

Static Public Attributes

static constexpr int max_running_order = 4
 Highest running order for the strong coupling.
 
static constexpr double default_error = 1e-6
 Default (relative and absolute) running error.
 

Detailed Description

Implements the running and decoupling of the strong coupling constant.

Constructor & Destructor Documentation

◆ strong_coupling()

strong_coupling ( reference_coupling  alpha_s = reference_coupling{},
int  order = max_running_order 
)
explicit

Construct a new strong coupling

Parameters
alpha_sReference value with the corresponding scale * and number of active flavours
orderRunning order between 0 and #max_order

Member Function Documentation

◆ operator()()

double operator() ( double  mu) const

Evolve the strong coupling to the given scale

Parameters
muTarget scale for the evolution
Returns
The value of the strong coupling

◆ order()

int order ( ) const

Get the current order for the evolution of the coupling

Returns
The running order

◆ nf()

int nf ( ) const

Get the number of active quark flavours

Returns
The number of flavours

◆ decouple_down()

strong_coupling decouple_down ( threshold  thr) const

Decouple down (remove) flavour in alpha_s.

Parameters
thrThe decoupling threshold
Returns
The strong coupling with nf - 1 active flavours

◆ remove()

strong_coupling remove ( threshold  thr) const

Remove (decouple down) flavour in alpha_s.

Parameters
thrThe decoupling threshold
Returns
The strong coupling with nf - 1 active flavours

◆ decouple_up()

strong_coupling decouple_up ( threshold  thr) const

Decouple up (add) flavour in alpha_s.

Parameters
thrThe decoupling threshold
Returns
The strong coupling with nf + 1 active flavours

◆ add()

strong_coupling add ( threshold  thr) const

Add (decouple up) flavour in alpha_s.

Parameters
thrThe decoupling threshold
Returns
The strong coupling with nf + 1 active flavours

◆ error()

strong_coupling& error ( double  err)

Set error bounds for evolution.

Parameters
errThe maximum absolute and relative error

◆ abs_error()

strong_coupling& abs_error ( double  abs_err)

Set absolute error bound for evolution.

Parameters
errThe maximum absolute error

◆ rel_error()

strong_coupling& rel_error ( double  rel_err)

Set relative error bound for evolution.

Parameters
errThe maximum relative error

The documentation for this class was generated from the following file: