### Abstract

_{s}is one of the fundamental parameters of the Standard Model (SM), setting the scale of the strength of the strong interaction theoretically described by Quantum Chromodynamics (QCD). Its measured (2014) value amounts to α

_{s}(m

^{2}

_{Z}) = 0.1185 ± 0.0006 at the reference Z pole mass scale. Given its current δα

_{s}(m

^{2}

_{Z})/α

_{s}(m

^{2}

_{Z}) ≈ 0.5% uncertainty—orders of magnitude larger than that of the gravitational (δG/G ≈ 10−5), Fermi (δGF/GF ≈ 10−8), and QED (δα/α ≈ 10−10)couplings—the strong coupling is the least precisely known of all fundamental constants in nature.Improving our knowledge of αs is a prerequisite to reduce the theoretical uncertainties in the calculations of all high-precision perturbative QCD (pQCD) processes whose cross sections or decayrates depend on higher-order powers of αs, as is the case for virtually all those measured at the LHC. In the Higgs sector, in particular, the uncertainty on α

_{s}is currently the second major contributor(after the bottom mass) to the parametric uncertainties of its dominant H →

*bb*partial decay.The same applies for the extraction of the charm Yukawa coupling via future H →

*cc¯*measurements

Original language | English |
---|---|

Title of host publication | High-Precision α_{s} Measurements from LHC to FCC-ee |

Editors | David d'Enterria, Peter Skands |

Place of Publication | Geneva Switzerland |

Publisher | CERN |

Pages | 3-4 |

Number of pages | 2 |

Publication status | Published - 16 Dec 2015 |

Event | High-Precision α_{s} Measurements from LHC to FCC-ee - CERN, Geneva, SwitzerlandDuration: 12 Oct 2015 → 13 Oct 2015 https://indico.cern.ch/event/392530/overview |

### Conference

Conference | High-Precision α_{s} Measurements from LHC to FCC-ee |
---|---|

Country | Switzerland |

City | Geneva |

Period | 12/10/15 → 13/10/15 |

Internet address |

### Cite this

*High-Precision α*(pp. 3-4). Geneva Switzerland: CERN.

_{s}Measurements from LHC to FCC-ee}

*High-Precision α*CERN, Geneva Switzerland, pp. 3-4, High-Precision α

_{s}Measurements from LHC to FCC-ee._{s}Measurements from LHC to FCC-ee, Geneva, Switzerland, 12/10/15.

**Introduction.** / d'Enterria, David; Skands, Peter Zeiler.

_{s}Measurements from LHC to FCC-ee. ed. / David d'Enterria; Peter Skands. Geneva Switzerland : CERN, 2015. p. 3-4.

Research output: Chapter in Book/Report/Conference proceeding › Foreword / Postscript › Other

TY - CHAP

T1 - Introduction

AU - d'Enterria, David

AU - Skands, Peter Zeiler

PY - 2015/12/16

Y1 - 2015/12/16

N2 - The strong coupling αs is one of the fundamental parameters of the Standard Model (SM), setting the scale of the strength of the strong interaction theoretically described by Quantum Chromodynamics (QCD). Its measured (2014) value amounts to αs(m2Z) = 0.1185 ± 0.0006 at the reference Z pole mass scale. Given its current δαs(m2Z)/αs(m2Z) ≈ 0.5% uncertainty—orders of magnitude larger than that of the gravitational (δG/G ≈ 10−5), Fermi (δGF/GF ≈ 10−8), and QED (δα/α ≈ 10−10)couplings—the strong coupling is the least precisely known of all fundamental constants in nature.Improving our knowledge of αs is a prerequisite to reduce the theoretical uncertainties in the calculations of all high-precision perturbative QCD (pQCD) processes whose cross sections or decayrates depend on higher-order powers of αs, as is the case for virtually all those measured at the LHC. In the Higgs sector, in particular, the uncertainty on αs is currently the second major contributor(after the bottom mass) to the parametric uncertainties of its dominant H → bb partial decay.The same applies for the extraction of the charm Yukawa coupling via future H → cc¯ measurements

AB - The strong coupling αs is one of the fundamental parameters of the Standard Model (SM), setting the scale of the strength of the strong interaction theoretically described by Quantum Chromodynamics (QCD). Its measured (2014) value amounts to αs(m2Z) = 0.1185 ± 0.0006 at the reference Z pole mass scale. Given its current δαs(m2Z)/αs(m2Z) ≈ 0.5% uncertainty—orders of magnitude larger than that of the gravitational (δG/G ≈ 10−5), Fermi (δGF/GF ≈ 10−8), and QED (δα/α ≈ 10−10)couplings—the strong coupling is the least precisely known of all fundamental constants in nature.Improving our knowledge of αs is a prerequisite to reduce the theoretical uncertainties in the calculations of all high-precision perturbative QCD (pQCD) processes whose cross sections or decayrates depend on higher-order powers of αs, as is the case for virtually all those measured at the LHC. In the Higgs sector, in particular, the uncertainty on αs is currently the second major contributor(after the bottom mass) to the parametric uncertainties of its dominant H → bb partial decay.The same applies for the extraction of the charm Yukawa coupling via future H → cc¯ measurements

UR - http://arxiv.org/pdf/1512.05194.pdf

M3 - Foreword / Postscript

SP - 3

EP - 4

BT - High-Precision αs Measurements from LHC to FCC-ee

A2 - d'Enterria, David

A2 - Skands, Peter

PB - CERN

CY - Geneva Switzerland

ER -

_{s}Measurements from LHC to FCC-ee. Geneva Switzerland: CERN. 2015. p. 3-4