QCDHelper Class Reference

Static utility class for QCD running and derived QCD block construction. More...

#include <QCDHelper.h>

Collaboration diagram for QCDHelper:

Static Public Member Functions
static void	Init ()
	Initializes the QCD dependent block.
static double	alpha_s (double mu, MassType mass_b_type=MassType::POLE, MassType mass_t_type=MassType::POLE)
	Computes the strong coupling constant α_s at scale μ.
static double	msbar_mass (int pdg_code, double mu, MassType mass_b_type=MassType::POLE, MassType mass_t_type=MassType::POLE)
	Computes the MS-bar running mass of a quark at scale μ.
static int	get_nf (double mu, MassType mass_b_type=MassType::POLE, MassType mass_t_type=MassType::POLE)
	Returns the number of active flavors n_f at scale μ.

Static Public Attributes
static QCDConstants	_static_constants {}
	Static storage for QCD constants.
static QCDConstants *	constants = &_static_constants
	Pointer to QCD constants (to conform with IQCDProvider interface).

Detailed Description

Static utility class for QCD running and derived QCD block construction.

QCDHelper:

• builds the "QCD" dependent block from SM inputs via Init(),
• provides α_s(μ) at arbitrary scales and for different mass schemes,
• provides running MS-bar masses for quarks,
• abstracts the matching across flavor thresholds (nf changes),
• exposes the internal QCDConstants via a static pointer.

It is intended as the low-level engine behind higher-level providers like QCDProvider.

Definition at line 88 of file QCDHelper.h.

Member Function Documentation

alpha_s()

double QCDHelper::alpha_s ( double  mu, MassType  mass_b_type = MassType::POLE, MassType  mass_t_type = MassType::POLE  )

static

Computes the strong coupling constant α_s at scale μ.

Uses the internally constructed QCD block (Λ_n) and the SM quark masses to determine the appropriate nf and perform matching across thresholds.

Parameters

mu	Renormalization scale μ.
mass_b_type	Mass scheme for bottom (pole or MS-bar) in thresholds.
mass_t_type	Mass scheme for top (pole or MS-bar) in thresholds.

Returns

α_s(μ).

Definition at line 52 of file QCDHelper.cpp.

get_nf()

int QCDHelper::get_nf ( double  mu, MassType  mass_b_type = MassType::POLE, MassType  mass_t_type = MassType::POLE  )

static

Returns the number of active flavors n_f at scale μ.

Uses ordered thresholds derived from the chosen mass schemes (m_b_type, m_t_type).

Parameters

mu	Renormalization scale.
mass_b_type	Bottom mass scheme.
mass_t_type	Top mass scheme.

Returns

Number of active flavors n_f.

Definition at line 166 of file QCDHelper.cpp.

Init()

void QCDHelper::Init ( )

static

Initializes the QCD dependent block.

Creates and registers a DependentBlock named "QCD" using DependentBlockManager, taking SM inputs (SMINPUTS, MASS) as sources. This block stores quantities such as:

• Λ_3, Λ_4, Λ_5, Λ_6,
• m_b in various schemes,
• m_t(m_t), etc.

Must be called once during the SM initialization sequence (see SMModelStrategy::postInitialization).

Definition at line 3 of file QCDHelper.cpp.

msbar_mass()

double QCDHelper::msbar_mass ( int  pdg_code, double  mu, MassType  mass_b_type = MassType::POLE, MassType  mass_t_type = MassType::POLE  )

static

Computes the MS-bar running mass of a quark at scale μ.

The starting point (initial mass and scale) is inferred from SM / QCD blocks, then the mass is evolved to μ using the appropriate nf and the R(α, nf) factor.

Parameters

pdg_code	PDG code of the quark (1..6).
mu	Target renormalization scale.
mass_b_type	Mass scheme for bottom thresholds.
mass_t_type	Mass scheme for top thresholds.

Returns

m_q(μ) in MS-bar scheme.

Definition at line 64 of file QCDHelper.cpp.

Member Data Documentation

_static_constants

QCDConstants QCDHelper::_static_constants {}

inlinestatic

Static storage for QCD constants.

Definition at line 130 of file QCDHelper.h.

constants

QCDConstants* QCDHelper::constants = &_static_constants

inlinestatic

Pointer to QCD constants (to conform with IQCDProvider interface).

Definition at line 132 of file QCDHelper.h.

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

• /home/runner/work/Hyperiso/Hyperiso/Hyperiso/Hyperiso/core/src/Core/infrastructure/QCDHelper.h
• /home/runner/work/Hyperiso/Hyperiso/Hyperiso/Hyperiso/core/src/Core/infrastructure/QCDHelper.cpp