http://agenda.hep.wisc.edu/displayLevel.php?fid=3

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http//agenda.hep.wisc.edu/displayLevel.php?fid3
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exclusive (cont.)
Weiss

• ongoing work on role of excl. channels in SIDIS

• goals
• quantify uncert. for excl. meson electroprod.
• duality in SIDIS for z-gt1 ?

• tools
• factorization
• some model for GPDs

• limitations
• higher twist contr. ?
• frag. fcts. at low scales?
• (in particular, for strangeness
• production)

signs of duality
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M. Kopytin
DVCS Measurements at HERMES
Beam Charge Assymetry
Longitudinal Target Spin Assymetry
DsC cos(f) Re H
DsUL sin(f) Im H
Proton
Twist 3 ? Im(H3,H3)

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M. Kopytin
DVCS Measurements at HERMES
Beam Charge Assymetry
Longitudinal Target Spin Assymetry
DsC cos(f) Re H
DsUL sin(f) Im H
With increased statistic assymetries may
constrain GPD models
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A. Vandenbroucke
Exclusive Meson Production
Sensitive to E(x,x,t)
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Transversity
M.Diefenthaler
Statistical sample (not final) largely improved.
Clear evidence for both Collins and Sivers
asymmetry
Non vanish Lq
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Transversity
P.Pagano
No sizeable effect. Possible cancellations in
isoscalar target (6LiD) Expected 3statistic,
2006 runs on p target (NH3)
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SSA transversity (cont.)
Prokudin

• extraction of Sivers function

hep-ph/0501196
strategy (1) fix intr. trans. mom. from unpol.
data first
(2) estimate Sivers fct. from HERMES data
(3) check COMPASS data
consistent
HERMES
COMPASS
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Transversity
F.Videbaek
An (s - s-) / (s s-)

• p- lt 0 at 3 sigma, p gt0 at 1.5 sigma level.
  Sign consistent with lower energy results.
• An at negative xF for p and p- are consistent
  with 0 (as also found by STAR for p0)
• The protons are found to have AN 0

xF 0.17 - 0.32
p
xF lt0
BRAHMS preliminary
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Transversity Friends
H.Avakian

• SIDIS-SSA on L-polarised target
• Probes of Lq through quark transverse momentum
  distribution
• Access to new PDF not accessible in DIS

New inner calorimeter will open new avenue for
studies of SSA of exclusive and semi-inclusive
g, p0,h,r
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Transversity Friends
P.van der Nat
R.Joosten
p target
D target

• Asymmetry vs Minv, x, z consistent with 0 or
  small.
• More results expected with
• Improved statistic
• RICH information
• Runs using p-target (NH3)

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Transversity Friends
R.Seidl
All the previous Spin dependent Fragmentation
function analyses yields information on the
Collins and the Interference Fragmentation
function ! ?Always 2 unknown functions involved
which cannot be measured independently
2-h inclusive transverse momentum dependent
Xsection
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Transversity Friends
Milestone!
R.Seidl

• The double ratio method shows
• Significant non-zero asymmetries
• Rising behaviour vs. z
• First direct measurement of the Collins function

Only first steps, however Naïve LO analysis
shows significant Collins effect
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Future Transversity in DY
P.Lenisa
GSI
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SSA transversity (cont.)
Mukherjee

• new NLO results single-incl. hadrons

no improvement in scale dependence
GSI
interesting tool to learn about transversity no
other unknown (TMD) fcts. involved here!
at RHIC energies much improved scale dep. but
small asymmetries
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http//agenda.hep.wisc.edu/displayLevel.php?fid3
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Visualization of Sivers effect
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Summary
CEBAF operation _at_ 6 GeV has provided results with
unprecedented precision on structure functions
and form factors (including strangeness) Upcoming
years will highlight precision hypernuclear
studies, standard model tests and . . .

• The Upgrade to 12 GeV is essential to provide
  access
• to new kinematic regions and will
• determine with extreme precision the spin and
  flavour structure
• of the nucleon in the valence region
• provide a totally new and complete view of the
  nucleon structure
• access to
  quark angular momentum
• finally (after gt 30 years) determine the origin
  of the EMC effect
• test our understanding of quark confinement
• and much much more . . .

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Milestones and Timelines for 12 GeV

• 1994-2002 Development of Science Case and
  Exp.Equiment
• April 2002 Recommendation by NSAC Long Range
  Planning
• April 2004 DOE Approval of Mission Need (CD-0)
• 2004-2005 Development of Conceptual Design
  Report
• Oct 2004 GlueX Detector Review
• Jan 2005 Review of Spectrometer Options
• April 2005 DOE Science Review of the 12 GeV
  Upgrade
• (very positive
  response ! )
• Sept 2005 Critical Decision on Prel. Baseline
  Range (CD-1)
• 2007-2008 Engineering and Design
• 2008-2011 Construction
• 2012 Beam on Target