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$\bar{\rm MS}$ parton densities with NNLO heavy flavor matching conditions

A. Chuvakin·J. Smith
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Abstract

A study is made of charm and bottom flavor matching conditions on parton densities. Starting from an $\bar{\rm MS}$ three-flavor density set, where the scale $μ< m_c$, and using the recently derived two-loop matching conditions, we provide a new set of four-flavor parton densities where $ m_c \le μ< m_b$ and five-flavor densities where $μ\ge m_b$. The effect of the next-to-next-to-leading order matching conditions on the evolution equations is important for scales just above the transition regions. This includes the small $x$ and small $Q^2$ domain studied by the H1 and ZEUS experiments at HERA. At small $x$ the effects of the matching conditions never die away even for large $μ^2$.

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A. Chuvakin, J. Smith. 1999-11-30. $\bar{\rm MS}$ parton densities with NNLO heavy flavor matching conditions. https://arxiv.org/abs/hep-ph/9911504

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