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arXiv · 1709.08402

Impact of Charm H1-ZEUS Combined data and Determination of the Strong Coupling in Two Different Schemes

A. Vafaee·A. N. Khorramian
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Abstract

We study the impact of recent measurements of charm cross section H1-ZEUS combined data on simultaneous determination of parton distribution functions (PDFs) and the strong coupling, $α_s(M^2_Z)$, in two different schemes. We perform several fits based on Thorne-Roberts (RT) and Thorne-Roberts optimal (RTOPT) schemes at next-to-leading order (NLO). We show that adding charm cross section H1-ZEUS combined data reduces the uncertainty of the gluon distribution and improves the fit quality up to $\sim 0.4$~\% and $\sim 0.9$~\%~, without and with the charm contribution, from the RT scheme to the RTOPT scheme, respectively. We also emphasise the central role of the strong coupling, $α_s(M^2_Z)$, in revealing the impact of charm flavour contribution, when it is considered as an extra free parameter. We show that in going from the RT scheme to the RT OPT scheme, we get $\sim 0.9$~\% and $\sim 2.0$~\%~improvement in the value of $α_s(M^2_Z)$, without and with the charm flavour contribution respectively.

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A. Vafaee, A. N. Khorramian. 2017-09-25. Impact of Charm H1-ZEUS Combined data and Determination of the Strong Coupling in Two Different Schemes. https://doi.org/10.1088/1674-1137%2F41%2F11%2F113104

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