Abstract
Abstract
We have calculated the $$ {n}_f^2 $$
n
f
2
and $$ {n}_f^3 $$
n
f
3
contributions to the flavour non-singlet structure functions F2 and FL in inclusive deep-inelastic scattering at the fourth order in the strong coupling αs. 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 $$ {n}_f^2 $$
n
f
2
terms are numerically much larger than the $$ {n}_f^3 $$
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 $$ {n}_f^2 $$
n
f
2
part of the corresponding anomalous dimension. Via the no-π2 theorem for Euclidean physical quantities, we predict the $$ {\zeta}_4{n}_f^3 $$
ζ
4
n
f
3
part of the fifth-order anomalous dimension for the evolution of non-singlet quark distributions.
Publisher
Springer Science and Business Media LLC
Subject
Nuclear and High Energy Physics
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