Next-to-next-to-leading order contributions to jet photoproduction and determination of ${\alpha }_s$

We present the first calculation of inclusive jet photoproduction with approximate next-to-next-to-leading-order contributions, obtained from a unified threshold resummation formalism. The leading coefficients for direct photoproduction are computed analytically. Together with the coefficients pertinent to parton-parton scattering, they are shown to agree with those appearing in our full next-to-leading-order calculations. For hadron-hadron scattering, numerical agreement is found with a previous calculation of jet production at the Tevatron. We show that the direct and resolved approximate next-to-next-to-leading-order contributions considerably improve the description of final ZEUS data on jet photoproduction and that the error on the determination of the strong coupling constant is significantly reduced.

Figure 1

Relative difference of D0 data, NLO, and aNNLO predictions with scales $\mu ,{\mu }_p=[0.5;2]\times E_T$ to the NLO prediction with scales $\mu ,{\mu }_p=0.5\times E_T$ as a function of jet transverse energy $E_T$.

Figure 2

Relative difference of ZEUS data, NLO, and aNNLO predictions with scales $\mu ,{\mu }_{\gamma },{\mu }_p=[0.5;2]\times E_T$ to the central NLO prediction with scales $\mu ,{\mu }_{\gamma },{\mu }_p=E_T$ as a function of jet transverse energy $E_T$.

Figure 3

Relative difference of ZEUS data, NLO, and aNNLO predictions with scales $\mu ,{\mu }_{\gamma },{\mu }_p=[0.5;2]\times E_T$ to the central NLO prediction with scales $\mu ,{\mu }_{\gamma },{\mu }_p=E_T$ as a function of jet rapidity $\eta$ for $E_T>17\mathrm{GeV}$.