A simple model for nuclear structure functions in the region of small x and small and moderate Q2 is presented. It is a parameter-free extension, in the Glauber-Gribov approach to nuclear collisions, ...of a saturation model for the nucleon. A reasonable agreement with experimental data on the ratios of nuclear structure functions is obtained. Nuclear effects in the longitudinal-to-transverse cross section ratios are found to be small. Predictions of the model for values of x smaller than those available to present experiments are given. The unintegrated gluon distribution and the behaviour of the saturation scale which result from this model are shown and discussed.
Electron-Ion Collider: The next QCD frontier Accardi, A; Albacete, J L; Anselmino, M ...
The European physical journal. A, Hadrons and nuclei,
09/2016, Volume:
52, Issue:
9
Journal Article
Peer reviewed
Open access
This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader ...nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics over the past decades and, in particular, the focused ten-week program on “Gluons and quark sea at high energies” at the Institute for Nuclear Theory in Fall 2010. It contains a brief description of a few golden physics measurements along with accelerator and detector concepts required to achieve them. It has been benefited profoundly from inputs by the users’ communities of BNL and JLab. This White Paper offers the promise to propel the QCD science program in the US, established with the CEBAF accelerator at JLab and the RHIC collider at BNL, to the next QCD frontier.
Novel considerations are presented on the physics, apparatus and accelerator designs for a future, luminous, energy frontier electron-hadron (
eh
) scattering experiment at the LHC in the thirties ...for which key physics topics and their relation to the hadron-hadron HL-LHC physics programme are discussed. Demands are derived set by these physics topics on the design of the LHeC detector, a corresponding update of which is described. Optimisations on the accelerator design, especially the interaction region (IR), are presented. Initial accelerator considerations indicate that a common IR is possible to be built which alternately could serve
eh
and
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collisions while other experiments would stay on
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in either condition. A forward-backward symmetrised option of the LHeC detector is sketched which would permit extending the LHeC physics programme to also include aspects of hadron-hadron physics. The vision of a joint
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and
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physics experiment is shown to open new prospects for solving fundamental problems of high energy heavy-ion physics including the partonic structure of nuclei and the emergence of hydrodynamics in quantum field theory while the genuine TeV scale DIS physics is of unprecedented rank.
The Future Circular Collider is a new proposed collider at CERN with centre-of-mass energies around 100 TeV in the pp mode. Ongoing studies aim at assessing its physics potential and technical ...feasibility. Here we focus on updates in physics opportunities accessible in pA and AA collisions not covered in previous Quark Matter contributions, including Quark-Gluon Plasma and gluon saturation studies, novel hard probes of QCD matter, and photon-induced collisions.
The unique physics opportunities accessible with nuclear collisions at the CERN Future Circular Collider (FCC) are summarized. Lead-lead (PbPb) and proton-lead (pPb) collisions at sNN=39 and 63 TeV ...respectively with Lint=33nb−1 and 8 pb−1 monthly integrated luminosities, will provide unprecedented experimental conditions to study quark-gluon matter at temperatures O(1 GeV). The following topics are succinctly discussed: (i) charm-quark densities thrice larger than at the LHC, leading to direct heavy-quark impact in the bulk QGP properties, (ii) quarkonia, including ϒ(1S), melting at temperatures up to five times above the QCD critical temperature, (iii) access to initial-state nuclear parton distributions (nPDF) at fractional momenta as low as x≈10−7, (iv) availability of about 5⋅105 top-quark pairs per run to study the high-x gluon nPDF and the energy loss properties of boosted colour-antennas, (v) study of possible Higgs boson suppression in the QGP, and (vi) high-luminosity γγ (ultraperipheral) collisions at c.m. energies up to 1 TeV.
Unintegrated gluon densities in nuclei, dipole-nucleus cross-sections and quark densities are numerically investigated in the high-color limit, with the scattering on a heavy nucleus exactly ...described by the sum of fan diagrams of BFKL pomerons. The initial condition for the evolution in rapidity is quickly forgotten, and the gluon density presents a “supersaturation” pattern, as previous studies indicated. Both dipole-nucleus cross-sections and quark densities present the expected saturation features. Identifying the position in transverse momentum l of the maximum of the gluon distribution with the saturation momentum \(Q_{\mathrm{s}}(y,b)\), at large rapidities all distributions depend on only one variable, \(l/Q_{\mathrm{s}}(y,b)\) or \(rQ_{\mathrm{s}}(y,b)\).
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