Precision determination of the strong coupling constant within a global PDF analysis

Richard D. Ball; Stefano Carrazza; Luigi Del Debbio; Stefano Forte; Zahari Kassabov; Juan Rojo; Emma Slade; Maria Ubiali

doi:10.1140/epjc/s10052-018-5897-7

Precision determination of the strong coupling constant within a global PDF analysis

Richard D. Ball, Stefano Carrazza, Luigi Del Debbio, Stefano Forte^*, Zahari Kassabov, Juan Rojo, Emma Slade, Maria Ubiali

^*Corresponding author for this work

(Astro)-Particles Physics

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Abstract

We present a determination of the strong coupling constant α_s(m_Z) based on the NNPDF3.1 determination of parton distributions, which for the first time includes constraints from jet production, top-quark pair differential distributions, and the Zp_T distributions using exact NNLO theory. Our result is based on a novel extension of the NNPDF methodology – the correlated replica method – which allows for a simultaneous determination of α_s and the PDFs with all correlations between them fully taken into account. We study in detail all relevant sources of experimental, methodological and theoretical uncertainty. At NNLO we find α_s(m_Z) = 0.1185 ± 0. 0005 ^(exp)± 0. 0001 ^(meth), showing that methodological uncertainties are negligible. We conservatively estimate the theoretical uncertainty due to missing higher order QCD corrections (N³LO and beyond) from half the shift between the NLO and NNLO α_s values, finding Δαsth=0.0011.

Original language	English
Article number	408
Pages (from-to)	1-16
Number of pages	16
Journal	European Physical Journal C
Volume	78
Issue number	5
Early online date	24 May 2018
DOIs	https://doi.org/10.1140/epjc/s10052-018-5897-7
Publication status	Published - May 2018

Bibliographical note

NNPDF Collaboration

Funding

E. S. and J. R. are supported by an European Research Council Starting Grant “PDF4BSM”. J. R. is also supposed by the Netherlands Organization for Scientific Research (NWO). The work of Z.K. is supported by the European Research Council Consolidator Grant “NNLOforLHC2” and by the Executive Research Agency (REA) of the European Commission under the Grant Agreement PITN-GA-2012-316704 (HiggsTools). S. C. is supported by the HICCUP ERC Consolidator Grant (614577). S. C. and S. F. are supported by the European Research Council under the European Union’s Horizon 2020 research and innovation Programme (Grant agreement no 740006). R. D. B and L. D. D. are supported by UK STFC Grants ST/L000458/1 and ST/P0000630/1. Acknowledgements E. S. and J. R. are supported by an European Research Council Starting Grant “PDF4BSM”. J. R. is also supposed by the Netherlands Organization for Scientific Research (NWO). The work of Z.K. is supported by the European Research Council Consolidator Grant “NNLOforLHC2” and by the Executive Research Agency (REA) of the European Commission under the Grant Agreement PITN-GA-2012-316704 (HiggsTools). S. C. is supported by the HICCUP ERC Consolidator Grant (614577). S. C. and S. F. are supported by the European Research Council under the European Union’s Horizon 2020 research and innovation Programme (Grant agreement no 740006). R. D. B and L. D. D. are supported by UK STFC Grants ST/L000458/1 and ST/P0000630/1.

Funders	Funder number
HICCUP ERC
Horizon 2020 Framework Programme	683211
H2020 European Research Council
Seventh Framework Programme	316704, 740006
FP7 Ideas: European Research Council	614577
FP7 People: Marie-Curie Actions
Science and Technology Facilities Council	ST/P0000630/1, ST/L000458/1
European Commission	PITN-GA-2012-316704
European Research Council
Research Executive Agency
Nederlandse Organisatie voor Wetenschappelijk Onderzoek

Keywords

hep-ph
hep-ex

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1802.03398v1

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title = "Precision determination of the strong coupling constant within a global PDF analysis",

abstract = "We present a determination of the strong coupling constant αs(mZ) based on the NNPDF3.1 determination of parton distributions, which for the first time includes constraints from jet production, top-quark pair differential distributions, and the ZpT distributions using exact NNLO theory. Our result is based on a novel extension of the NNPDF methodology – the correlated replica method – which allows for a simultaneous determination of αs and the PDFs with all correlations between them fully taken into account. We study in detail all relevant sources of experimental, methodological and theoretical uncertainty. At NNLO we find αs(mZ) = 0.1185 ± 0. 0005 (exp)± 0. 0001 (meth), showing that methodological uncertainties are negligible. We conservatively estimate the theoretical uncertainty due to missing higher order QCD corrections (N3LO and beyond) from half the shift between the NLO and NNLO αs values, finding Δαsth=0.0011.",

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AU - Carrazza, Stefano

AU - Debbio, Luigi Del

AU - Forte, Stefano

AU - Kassabov, Zahari

AU - Rojo, Juan

AU - Slade, Emma

AU - Ubiali, Maria

N1 - NNPDF Collaboration

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N2 - We present a determination of the strong coupling constant αs(mZ) based on the NNPDF3.1 determination of parton distributions, which for the first time includes constraints from jet production, top-quark pair differential distributions, and the ZpT distributions using exact NNLO theory. Our result is based on a novel extension of the NNPDF methodology – the correlated replica method – which allows for a simultaneous determination of αs and the PDFs with all correlations between them fully taken into account. We study in detail all relevant sources of experimental, methodological and theoretical uncertainty. At NNLO we find αs(mZ) = 0.1185 ± 0. 0005 (exp)± 0. 0001 (meth), showing that methodological uncertainties are negligible. We conservatively estimate the theoretical uncertainty due to missing higher order QCD corrections (N3LO and beyond) from half the shift between the NLO and NNLO αs values, finding Δαsth=0.0011.

AB - We present a determination of the strong coupling constant αs(mZ) based on the NNPDF3.1 determination of parton distributions, which for the first time includes constraints from jet production, top-quark pair differential distributions, and the ZpT distributions using exact NNLO theory. Our result is based on a novel extension of the NNPDF methodology – the correlated replica method – which allows for a simultaneous determination of αs and the PDFs with all correlations between them fully taken into account. We study in detail all relevant sources of experimental, methodological and theoretical uncertainty. At NNLO we find αs(mZ) = 0.1185 ± 0. 0005 (exp)± 0. 0001 (meth), showing that methodological uncertainties are negligible. We conservatively estimate the theoretical uncertainty due to missing higher order QCD corrections (N3LO and beyond) from half the shift between the NLO and NNLO αs values, finding Δαsth=0.0011.

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Precision determination of the strong coupling constant within a global PDF analysis

Abstract

Bibliographical note

Funding

Keywords

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