Event generation at MEPS@NLO accuracy in neutral and charged current DIS at the EIC

Abstract

We present state-of-the-art hadron-level predictions for the deep-inelastic scat- tering process at next-to-leading-order precision for several multiplicities, con- sistently merged in one sample. For the first time at this level of accuracy, we consider both neutral and charged current deep-inelastic scattering at the Electron-Ion Collider, and present the first application of consistent next-to- leading-order merging to charged current deep-inelastic scattering in general. We critically examine inclusive predictions using multileg merging techniques, contrasting perturbative and nonperturbative uncertainties. Further, we study typical kinematic deep-inelastic scattering observables as well as jet measure- ments and 1-jettiness with realistic cuts implied by expected and past detector resolution. On the perturbative side, we see large corrections toward small vir- tualities and Bjorken-x, which can be captured by higher-multiplicity matrix elements and the merging procedure. Nonperturbative effects, while negligible in most jet observables, can reach similar size as the perturbative uncertainties around the peak of the 1-jettiness distributions especially at low values of $Q^2$ .

Figures (19)

• Figure 1: Sketch of an example Feynman diagram with three final-state partons in DIS. Depending on the hierarchy of the internal momenta, the event is clustered back to an underlying $2\to2$ core process. Only if $q^2 \gg k_1^2,\, k_2^2$ holds is the core process DIS-like.
• Figure 2: Differential distributions for $Q^2$ and $x$ at LO, MC@NLO, MEPS@LO and MEPS@NLO in inclusive CC DIS at the HERA. The lower panels show the ratio between data and the merged MEPS@LO and MEPS@NLO predictions, while we omit the ratio for the LO and MC@NLO simulations for clarity. The full (hatched) band corresponds to variations of $\mu_{\text{F}},\mu_{\text{R}}$ ($Q_{\mathrm{cut}}$). Experimental data points are from Ref. ZEUS:2008arl.
• Figure 3: Differential distributions for $\eta_{\mathrm{jet}}$ and $E_{T,\mathrm{jet}}$ at LO, MC@NLO, MEPS@LO and MEPS@NLO in inclusive CC DIS at the HERA. The lower panels show the ratio between data and the merged MEPS@LO and MEPS@NLO predictions, while we omit the ratio for the LO and MC@NLO simulations for clarity. The full (hatched) band corresponds to variations of $\mu_{\text{F}},\mu_{\text{R}}$ ($Q_{\mathrm{cut}}$). Experimental data points are from Ref. ZEUS:2008arl.
• Figure 4: Multijet distributions differential in the mass of the two (left) or three (right) leading jets at LO, MC@NLO, MEPS@LO and MEPS@NLO in inclusive CC DIS at the HERA. The lower panels show the ratio between data and the merged MEPS@LO and MEPS@NLO predictions, while we omit the ratio for the LO and MC@NLO simulations for clarity. The full (hatched) band corresponds to variations of $\mu_{\text{F}},\mu_{\text{R}}$ ($Q_{\mathrm{cut}}$). Experimental data points are from Ref. ZEUS:2008arl.
• Figure 5: Differential distributions for $Q^2$ (top left), $x$ (top right), $y$ (bottom left) and lepton transverse momentum $p_{\text{T}}^{\mathrm{lep}}\xspace$ (bottom right) in NC DIS at the EIC , comparing LO+PS, MC@NLO, MEPS@LO and MEPS@NLO predictions. The main panels show results with scale variation uncertainties for all but the LO+PS calculation. The first ratio panel displays the relative deviation from MEPS@NLO to highlight merging effects. The second ratio shows the relative scale uncertainties. The hatched band represents merging scale variation $Q_{\mathrm{cut}}$ in the MEPS@NLO sample.