Preprint/Report

PUBDB-2018-01255

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Impact of the heavy quark matching scales in PDF fits

Bertone, V. ; Britzger, D. ; Camarda, S. ; Cooper-Sarkar, A. ; Geiser, A. ; Giuli, F. ; Glazov, A. (Corresponding author)DESY* ; Godat, E. ; Kusina, A. ; Luszczak, A. ; Lyonnet, F. ; Olness, F. ; Placakyte, R. ; Radescu, V. ; Schienbein, I. ; Zenaiev, O. ; Team, T. x. D. (Collaboration Author)

2017

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Please use a persistent id in citations: doi:10.3204/PUBDB-2018-01255

Report No.: DESY-17-101; arXiv:1707.05343

Abstract: We investigate the impact of displaced heavy-quark matching scales in a global fit. The heavy-quark matching scale $\mu _{m}$ determines at which energy scale $\mu $ the QCD theory transitions from $N_{F}$ to $N_{F}+1$ in the variable flavor number scheme (VFNS) for the evolution of the parton distribution functions (PDFs) and strong coupling $\alpha _S(\mu )$ . We study the variation of the matching scales, and their impact on a global PDF fit of the combined HERA data. As the choice of the matching scale $\mu _{m}$ effectively is a choice of scheme, this represents a theoretical uncertainty, ideally, we would like to see minimal dependence on this parameter. For the transition across the charm quark (from $N_{F}=3$ to 4), we find a large $\mu _m=\mu _{c}$ dependence of the global fit $\chi ^2$ at NLO, but this is significantly reduced at NNLO. For the transition across the bottom quark (from $N_{F}=4$ to 5), we have a reduced $\mu _{m}=\mu _b$ dependence of the $\chi ^2$ at both NLO and NNLO as compared to the charm. This feature is now implemented in xFitter 2.0.0, an open source QCD fit framework.

Keyword(s): parton: distribution function ; scale ; quantum chromodynamics: perturbation theory ; higher-order: 1 ; higher-order: 2 ; DESY HERA Stor ; DGLAP equation ; strong coupling ; heavy quark ; charm ; bottom ; numerical calculations ; statistical analysis ; data analysis method

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Contributing Institute(s):

1. LHC/ATLAS Experiment (ATLAS)

Research Program(s):

1. 611 - Fundamental Particles and Forces (POF3-611) (POF3-611)

Experiment(s):

1. LHC: ATLAS

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Database coverage:
; ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; Nationallizenz ; Published ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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Linked articles:

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Report/Journal Article Bertone, V. ; Britzger, D.DESY* ; Camarda, S. ; Cooper-Sarkar, A. ; Geiser, A.DESY* ; Giuli, F. ; Glazov, A. (Corresponding author)DESY* ; Godat, E. ; Kusina, A. ; Luszczak, A.DESY* ; Lyonnet, F. ; Olness, F. (Corresponding author) ; Plačakytė, R.Extern* ; Radescu, V.Extern* ; Schienbein, I. ; Zenaiev, O.DESY*
Impact of the heavy-quark matching scales in PDF fits
The European physical journal / C 77(12), 837 (2017) [10.1140/epjc/s10052-017-5407-3]2017     Files  Fulltext by arXiv.org BibTeX | EndNote: XML, Text | RIS

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