Nuclear structure functions at a future electron-ion collider

Abstract

The quantitative knowledge of heavy nuclei's partonic structure is currently limited to rather large values of momentum fraction x-robust experimental constraints below x ∼ 10 −2 at low resolution scale Q 2 are particularly scarce. This is in sharp contrast to the free proton's structure which has been probed in Deep Inelastic Scattering (DIS) measurements down to x ∼ 10 −5 at perturbative resolution scales. The construction of an electron-ion collider (EIC) with a possibility to operate with a wide variety of nuclei, will allow one to explore the low-x region in much greater detail. In the present paper we simulate the extraction of the nuclear structure functions from measurements of inclusive and charm reduced cross sections at an EIC. The potential constraints are studied by analyzing simulated data directly in a next-toleading order global fit of nuclear Parton Distribution Functions based on the recent EPPS16 analysis. A special emphasis is placed on studying the impact an EIC would have on extracting the nuclear gluon parton distribution function, the partonic component most prone to nonlinear effects at low Q 2 . In comparison to the current knowledge, we find that the gluon parton distribution function can be measured at an EIC with significantly reduced uncertainties.

Nuclear parton density functions from dijet photoproduction at the EIC

“…The impact of inclusive DIS has already been studied in 2012 in a White Paper [19], which was recently updated based on newer nPDFs. As shown there, an improvement of up to an order of magnitude in precision can be expected in inclusive DIS at low x [20]. In a recent publication, we studied the impact of inclusive jet production measurements in DIS, i.e., of photons with large virtuality Q 2 , at the EIC and reached similar conclusions [21] based on our previous theoretical calculations at NLO [3] and approximate next-to-next-to-leading order (aNNLO) [22].…”

Nuclear Parton Distributions at the future Electron-Ion Collider

“…In spite of some limitation, given by our current analysis not allowing for more flexible parametrizations of all the quark flavors simultaneously, our results indicate a significant reduction of the sea quark uncertainties [7].…”

“…In order to estimate the impact of an EIC on the current knowledge of nPDFs, we performed a novel global analysis [7] by adding all the simulated cross section measurements to the currently available experimental data. In this work, to obtain a reliable and less biased estimate of the data constraints, the stiffness of the EPPS16 functional form at small x was partly released by using a more flexible functional form for the gluons, called EPPS16*, and also described in Ref.…”

“…In this work, to obtain a reliable and less biased estimate of the data constraints, the stiffness of the EPPS16 functional form at small x was partly released by using a more flexible functional form for the gluons, called EPPS16*, and also described in Ref. [7].…”

Nuclear Parton Distribution Functions (nPDFs) and Their Uncertainties in the LHC Era

“…In the collinear factorized approach to perturbative QCD (pQCD), the structure and dynamics of nucleus are described by the nuclear parton distribution functions (nuclear PDFs) [1][2][3][4][5][6][7]. Analogously to the DIS data available for the free proton case, fixed-target ℓ+ DIS scattering has a huge potential to offer information on the nuclear PDFs.…”