Nuclear parton density functions from jet production in DIS at an EIC

We investigate the potential of inclusive-jet production in deep-inelastic scattering (DIS) at a future electron-ion collider (EIC) to improve our current knowledge of nuclear parton density functions (PDFs). We demonstrate that the kinematic reach is extended similarly to inclusive DIS, but that the uncertainty of the nuclear PDFs, in particular of the gluon density at low Bjorken-$x$, is considerably reduced, by up to an order of magnitude compared to the present situation. Using an approximate next-to-next-to-leading order (aNNLO) calculation implemented in the program JetViP, we also make predictions for three different EIC designs and for four different light and heavy nuclei.

Figure 1

Inclusive-jet production in electron–lead ion collisions at eRHIC and MEIC with electron beam energies of 12 to 21 GeV and ion beam energies per nucleon of 40 to 100 GeV. Shown are differential cross sections in the jet transverse momentum (top left), rapidity (top right), photon virtuality (bottom left) and Bjorken-$x$ of the parton in the nucleus (bottom right).

Figure 2

Inclusive-jet production in electron–lead ion collisions with beam energies of 16 and 100 GeV, respectively, at eRHIC. Shown are the K-factors (ratios) of NLO/LO (full black lines) and aNNLO/LO (dotted-dashed red lines) cross sections as a function of the jet transverse momentum (top left), rapidity (top right), photon virtuality (bottom left) and Bjorken-$x$ (bottom right). Error bars indicate the numerical integration accuracy.

Figure 3

Inclusive-jet production in electron-ion collisions with beam energies of 16 and 100 GeV, respectively, at eRHIC for different nuclei: Pb-208 (full black lines), Fe-56 (dashed blue lines), C-12 (dotted green lines), and He-4 (dotted-dashed red lines). Shown are the ratios of electron-ion over electron-proton cross sections as a function of the jet transverse momentum (top left), rapidity (top right), photon virtuality (bottom left) and Bjorken-$x$ (bottom right). Error bars indicate the expected experimental precision.

Figure 4

Inclusive-jet production in electron–lead ion collisions with beam energies of 16 and 100 GeV, respectively, at eRHIC. Shown is the ratio of electron–lead ion over electron-proton cross sections (full black lines) including the current nuclear PDF uncertainty from the nCTEQ15 fit to DIS and DY data only (red bands) as well as the relative gluon contribution to the total cross section (dashed blue lines) as a function of the jet transverse momentum (top left), rapidity (top right), photon virtuality (bottom left) and Bjorken-$x$ (bottom right). Error bars indicate the expected experimental precision.

Figure 5

Same as Fig. 4 for the nCTEQ15 fit including also inclusive pion data from D-Au collisions at BNL RHIC, and for the central EPPS16 fit (dotted green lines) to—in particular—dijet data from the LHC as well as the corresponding (green) error bands.