EIC

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EICBring the Glue to Light
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Gluons dominate QCD

• QCD is the fundamental theory that describes
  structure and interactions in nuclear matter.
• Without gluons there are no protons, no neutrons,
  and no atomic nuclei
• Facts
• The essential features of QCD (e.g. asymptotic
  freedom, chiral symmetry breaking, and color
  confinement) are all driven by the gluons!
• Unique aspect of QCD is the self interaction of
  the gluons
• 98 of mass of the visible universe arises from
  glue
• Half of the nucleon momentum is carried by gluons
• However, gluons are dark they do not interact
  directly with light
• ? high-energy collider!

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Exposing the high-energy (dark) side of the
nuclei
The High Energy View of Nuclear Matter The
visible Universe is generated by quarks, but
dominated by the dark glue!

• The Low Energy View of Nuclear Matter
• nucleus protons neutrons
• nucleon ? quark model
• quark model ? QCD

Remove factor 20
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Explore the new QCD frontier strong color
fields in nuclei  
Precisely image the sea-quarks and gluons
in the nucleon
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EIC science has evolved from new insights and
technical accomplishments over the last decade

• 1996 development of GPDs
• 1999 high-power energy recovery linac technology
  
• 2000 universal properties of strongly
  interacting glue
• 2000 emergence of transverse-spin phenomenon
• 2001 worlds first high energy polarized proton
  collider
• 2003 RHIC sees tantalizing hints of saturation
• 2006 electron cooling for high-energy beams

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EIC in Context
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Why HERA did not do EIC physics?

• eA physics
• Up to Ca beams considered
• Low luminosity (1000 compared to EIC)
• Would have needed 100M to upgrade the source
  to have more ions, but still the low luminosity
• Polarized e-p physics
• HERA-p ring is not planar
• No. of Siberian snake magnets required to
  polarize beam estimated to be 6-8 Not enough
  straight sections for Siberian snakes and not
  enough space in the tunnel for their cryogenics
• Technically difficult
• DESY was a HEP laboratory focused on the high
  energy frontier.

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Mapping and understanding the role of glue in the
nucleon

• The fundamental properties of the nucleon are
  dominated by gluons!
• Without the gluons, the nucleon mass would be
  just 10 MeV (98 of mass of the visible universe
  arises from glue)
• Half of the nucleon momentum is carried by
  gluons.
• We expect significant contribution to the proton
  spin from glue
• A full exploration of gluons in the nucleon
  gluon-tomography at EIC!
• Mapping out the gluon helicity contribution to
  the nucleon spin at the highest energy.
• Mapping out the space and momentum distributions
  of the gluons through novel hard exclusive
  processes.

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Draft Sidebar The Glue at the Heart of Matter

• Gluons are majority silent partners in ordinary
  matter
• A. Gluon self-interactions responsible for novel
  features of QCD B. Not apparent in
  quantum s, but dominate mass of visible
  universe C.
  Apparent untamed growth in gluon density at low
  x, high Q2 (HERA)
• Do gluons play an important role in proton spin?
• A. Missing spin problem
  
  B. Launch of RHIC spin program early
  constraints on gluon poln C. Direct
  sensitivity via photon-gluon fusion processes
  D. Ultimate determination
  by scaling violations in DIS _at_ EIC
• What QCD giveth, QCD taketh away
• A. Competition between gluon splitting and
  recombination ? saturation B. Do all protons and
  nuclei look the same when viewed at high energy?
  C. Search for universal saturated gluonic matter
  at EIC
• Gluons made manifest?
• A. Are there excited states of hadrons where
  gluons contribute directly to exotic quantum s?
  
  B.
  Photo-excitation as the way to excite gluonic
  vibrations C. GLUEx
  experiment at upgraded CEBAF