Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Nuclear beams in HERA

M. Arneodo, A. Bialas, M. W. Krasny, T. Sloan, M. Strikman

TL;DR

This paper argues that incorporating circulating nuclear beams at HERA would significantly extend the reach of QCD studies by exploiting electron–nucleus scattering to probe nonlinear small-$x$ dynamics, gluon shadowing, and diffractive phenomena. It outlines a comprehensive experimental program—shadowing with F2 ratios, gluon-density measurements via jet rates and scaling violations, inelastic $J/\psi$ production, diffraction, and parton propagation in nuclear matter—supported by feasibility estimates for existing detectors and realistic luminosities. The accompanying theoretical overview connects these measurements to coherence effects, color transparency, BFKL dynamics, and the interplay between diffraction and shadowing, with clear implications for heavy-ion physics at RHIC/LHC. Overall, the work positions $eA$ DIS at HERA as a powerful probe of high-density QCD and a bridge to understanding nuclear effects in future collider environments.

Abstract

A study has been made of the physics interest and feasibility of experiments with nuclear beams in HERA. It is shown that such experiments widen considerably the horizon for probing QCD compared to that from free nucleon targets. In addition there is some sensitivity to physics beyond the standard model. Hence the option to include circulating nuclear beams in HERA allows a wide range of physics processes to be studied and understood.

Nuclear beams in HERA

TL;DR

This paper argues that incorporating circulating nuclear beams at HERA would significantly extend the reach of QCD studies by exploiting electron–nucleus scattering to probe nonlinear small- dynamics, gluon shadowing, and diffractive phenomena. It outlines a comprehensive experimental program—shadowing with F2 ratios, gluon-density measurements via jet rates and scaling violations, inelastic production, diffraction, and parton propagation in nuclear matter—supported by feasibility estimates for existing detectors and realistic luminosities. The accompanying theoretical overview connects these measurements to coherence effects, color transparency, BFKL dynamics, and the interplay between diffraction and shadowing, with clear implications for heavy-ion physics at RHIC/LHC. Overall, the work positions DIS at HERA as a powerful probe of high-density QCD and a bridge to understanding nuclear effects in future collider environments.

Abstract

A study has been made of the physics interest and feasibility of experiments with nuclear beams in HERA. It is shown that such experiments widen considerably the horizon for probing QCD compared to that from free nucleon targets. In addition there is some sensitivity to physics beyond the standard model. Hence the option to include circulating nuclear beams in HERA allows a wide range of physics processes to be studied and understood.

Paper Structure

This paper contains 38 sections, 33 equations, 20 figures.

Table of Contents

  1. Introduction
  2. Experimental Overview
  3. Introduction
  4. Shadowing Measurements Using Nuclei in HERA
  5. The Accuracy of The Gluon Density Measurements Using Nuclei in HERA
  6. Introduction
  7. Determination of the Gluon Density in the Nucleus from the Jet Rates
  8. The Gluon Distribution in Nuclei from Scaling Violations
  9. Determination of the Gluon Density in the Nucleus from Inelastic $J/\psi$ production
  10. Diffraction from Nuclei in HERA
  11. Introduction
  12. Expected Accuracy of the Measurements of the Pomeron Structure
  13. Measurement of the $A$-dependence of the Fraction of Rapidity Gap Events
  14. Elastic Vector Meson Production
  15. Parton Propagation in Nuclei
  16. ...and 23 more sections

Figures (20)

  • Figure 1: The kinematic region covered by experiments at HERA compared to fixed target data (shaded region).
  • Figure 2: Partial compilation of results for $F_2^{A}/F_2^D$ (from nmc_li). Note that below $x \approx 0.01$, the average $Q^2$ value of the data is smaller than 2 GeV$^2$.
  • Figure 3: Ratio of the nucleon structure function in carbon to that in deuterium as a function of $x$. The NMC data nmc_li (open squares) are shown in comparison to data with the estimated statistical accuracy of an experiment of luminosity 1 pb$^{-1}$ per nucleon at HERA.
  • Figure 4: The slopes $d(F_2^A/F_2^D)/d \ln{Q^2}$ as function of $x$ showing the NMC data nmc_rean (open squares) and the statistical accuracy of an experiment with 1 pb$^{-1}$ per nucleon at HERA.
  • Figure 5: The processes giving rise to $2+1$ jet topology. P denotes here the projectile particle, a proton or a nucleus, $Q^2$ is the four-momentum transfer and $x$ is the Bjorken variable.
  • ...and 15 more figures