Speaker
Description
We have calculated the $n_f^2$ and $n_f^3$ contributions to the flavour non-singlet structure functions $F_2$ and $F_L$ in inclusive deep-inelastic scattering at the fourth order in the strong coupling $\alpha_s$. The coefficient functions have been obtained by computing a very large number of Mellin-N moments using the method of differential equations, and then determining the analytic forms in N and Bjorken-x from these. Our new $n_f^2$ terms are numerically much larger than the $n_f^3$ leading large-nf parts which were already known; they agree with predictions of the threshold and high-energy resummations. Furthermore our calculation confirms the earlier determination of the four-loop $n_f^2$ part of the corresponding anomalous dimension. The next step is to obtain the expression for the $F_3$ structure function and therefore complete the unpolarized contributions for $n_f^2$ and $n_f^3$ at four-loop.
| Submitted on behalf of a Collaboration? | No |
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