MS parton densities with NNLO heavy flavor matching conditions

الأصل · EN

A study is made of charm and bottom flavor matching conditions on parton densities. Starting from an MS three-flavor density set, where the scale μ< mc, and using the recently derived two-loop matching conditions, we provide a new set of four-flavor parton densities where mc ≤ μ< mb and five-flavor densities where μ≥ mb. 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 Q² 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 μ².