The heavy quark-antiquark asymmetry in the variable flavor number scheme

Le résumé fourni par la source

The twist-2 heavy quark and antiquark distributions turn out to be different due to QCD corrections from three-loop onward. This is caused by terms containing the color factor $d_{abc} d^{abc}$ in the heavy flavor massive pure-singlet operator matrix elements (OMEs) $A^{\rm PS, s, (3)}_{Qq}$ for odd moments in the unpolarized case and for $\Delta A^{\rm PS, s,(3)}_{Qq}$ for even moments in the polarized case. Compared to the sum of the heavy quark and antiquark parton distributions their difference is small but non vanishing. We compute the corresponding three-loop heavy flavor distributions $(\Delta) f_Q(x,Q^2) - (\Delta) f_{\overline{Q}}(x,Q^2)$ in the variable flavor number scheme. The dependence on the factorization scale of the OMEs are ruled by the anomalous dimensions $\gamma^{\rm NS, s, (2)}_{qq}$ and $\Delta\gamma^{\rm NS, s, (2)}_{qq}$. The polarized calculations are performed in the Larin scheme.

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