In this article, we present a Next-to-Leading Order (NLO) QCD analysis to study the role and influence of different schemes on simultaneous determination of the Parton Distribution Functions (PDFs) and strong coupling, α s (M 2 Z ). We perform our analysis based on three different data sets, HERA I and II combined data, H1-ZEUS charm combined data, and H1 and ZEUS beauty production cross sections data, in two different Thorne-Roberts (TR or RT) and Thorne-Roberts Optimal (RT OPT) schemes. We show in going from RT scheme to RT OPT scheme, in addition of reduction the uncertainty of some PDFs, specially for the gluon distribution, we get ∼ 0.4 % and ∼ 0.7 % improvement in the fit quality and ∼ 0.9 % and ∼ 1.6 % improvement for the strong coupling, α s (M 2 Z ), without and with heavy flavor contributions, respectively.
Because of color confinement hypothesis, which states that colored objects are always confined to color singlet states, there are several definitions for charm-quark mass, which one of the most popular definition is charm-quark pole mass m pole c . This Quantum Chromo Dynamics (QCD) analysis attempts to extract charm-quark pole mass from H1-ZEUS combined (H1Z), LHCb and H1Z+LHCb charm production cross section data and then investigate its pure impact on proton Parton Distribution Functions (PDFs). To reach this goal we makes several fits based on the very recently updated Fixed Flavor number scheme from Alekhin, Blumlein and Moch (FF ABM) at the Next-to-Leading Order (NLO). We show that the pure contribution of charm-quark pole mass in the improvement of the fit quality, when it is considered as an extra fit parameter in perturbative Quantum Chromo Dynamics (pQCD) level is ∼ 0 % , ∼ 25 % and ∼ 21 % corresponding to H1-ZEUS combined, LHCb and H1Z+LHCb charm production cross section data, respectively.
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