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Title: Impact of the heavy-quark matching scales in PDF fits

Abstract

We investigate the impact of displaced heavy-quark matching scales in a global fit. The heavy-quark matching scale μm determines at which energy scale μ the QCD theory transitions from NF to NF + 1 in the variable flavor number scheme (VFNS) for the evolution of the parton distribution functions (PDFs) and strong coupling αS(μ).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 μm 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 NF = 3 to 4), we find a large μm = μc dependence of the global fit χ2 at NLO, but this is significantly reduced at NNLO. For the transition across the bottom quark (from NF = 4 to 5), we have a reduced μm = μb dependence of the χ2 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.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Southern Methodist Univ., Dallas, TX (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
The xFitter Developers’ Team
OSTI Identifier:
1411797
Alternate Identifier(s):
OSTI ID: 1510213
Grant/Contract Number:  
SC0010129
Resource Type:
Published Article
Journal Name:
European Physical Journal. C, Particles and Fields
Additional Journal Information:
Journal Name: European Physical Journal. C, Particles and Fields Journal Volume: 77 Journal Issue: 12; Journal ID: ISSN 1434-6044
Publisher:
Springer Science + Business Media
Country of Publication:
Germany
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

The xFitter Developers’ Team:, Bertone, V., Britzger, D., Camarda, S., Cooper-Sarkar, A., Geiser, A., Giuli, F., Glazov, A., Godat, E., Kusina, A., Luszczak, A., Lyonnet, F., Olness, F., Plačakytė, R., Radescu, V., Schienbein, I., and Zenaiev, O. Impact of the heavy-quark matching scales in PDF fits. Germany: N. p., 2017. Web. doi:10.1140/epjc/s10052-017-5407-3.
The xFitter Developers’ Team:, Bertone, V., Britzger, D., Camarda, S., Cooper-Sarkar, A., Geiser, A., Giuli, F., Glazov, A., Godat, E., Kusina, A., Luszczak, A., Lyonnet, F., Olness, F., Plačakytė, R., Radescu, V., Schienbein, I., & Zenaiev, O. Impact of the heavy-quark matching scales in PDF fits. Germany. doi:10.1140/epjc/s10052-017-5407-3.
The xFitter Developers’ Team:, Bertone, V., Britzger, D., Camarda, S., Cooper-Sarkar, A., Geiser, A., Giuli, F., Glazov, A., Godat, E., Kusina, A., Luszczak, A., Lyonnet, F., Olness, F., Plačakytė, R., Radescu, V., Schienbein, I., and Zenaiev, O. Thu . "Impact of the heavy-quark matching scales in PDF fits". Germany. doi:10.1140/epjc/s10052-017-5407-3.
@article{osti_1411797,
title = {Impact of the heavy-quark matching scales in PDF fits},
author = {The xFitter Developers’ Team: and Bertone, V. and Britzger, D. and Camarda, S. and Cooper-Sarkar, A. and Geiser, A. and Giuli, F. and Glazov, A. and Godat, E. and Kusina, A. and Luszczak, A. and Lyonnet, F. and Olness, F. and Plačakytė, R. and Radescu, V. and Schienbein, I. and Zenaiev, O.},
abstractNote = {We investigate the impact of displaced heavy-quark matching scales in a global fit. The heavy-quark matching scale μm determines at which energy scale μ the QCD theory transitions from NF to NF + 1 in the variable flavor number scheme (VFNS) for the evolution of the parton distribution functions (PDFs) and strong coupling αS(μ).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 μm 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 NF = 3 to 4), we find a large μm = μc dependence of the global fit χ2 at NLO, but this is significantly reduced at NNLO. For the transition across the bottom quark (from NF = 4 to 5), we have a reduced μm = μb dependence of the χ2 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.},
doi = {10.1140/epjc/s10052-017-5407-3},
journal = {European Physical Journal. C, Particles and Fields},
number = 12,
volume = 77,
place = {Germany},
year = {2017},
month = {12}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1140/epjc/s10052-017-5407-3

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Cited by: 3 works
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    Works referencing / citing this record:

    Impact of the heavy-quark matching scales in PDF fits
    text, January 2017


    Probing the strange content of the proton with charm production in charged current at LHeC
    journal, October 2019