Forward Collisions and Spin Effects in Evaluating Amplitudes
N. Akchurin, Texas Tech University, USAN. Buttimore, Trinity College Dublin, Ireland A. Penzo, INFN & Dip di Fisica, Trieste, Italy
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Introduction• Proton proton collisions probe analyticity and spin
effects • A dispersion relation violation may suggest a new
mass scale • Hadronic spin effects appear in t = 0 fermion
fermion scattering • Seek the spin implications when evaluating
transition amplitudes • Study forward spin dependence for cross section
normalisation
September 30, 2010N. Buttimore, SPIN2010 Jülich
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Small Angle Collisions of Protons and Ions
The level of hadronic spin dependence is important in the context of
• Parton distribution functions and nucleon form factors
• Measuring the proton beam polarization at BNL RHIC, Makdisi, AIP Conf Proc 980
• Spin dependent couplings of the Pomeron, Trueman, Phys Rev D77
September 30, 2010N. Buttimore, SPIN2010 Jülich
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Analyzing Power in CNI Region
September 30, 2010N. Buttimore, SPIN2010 Jülich
• For the current analyses, we assume double-flip amplitude is zero• The Coulomb phase is 0.02• The rho parameter is 0.02
N. Buttimore, SPIN2010 Julich 5September 30, 2010
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Global Fit to Small –t Data
September 30, 2010N. Buttimore, SPIN2010 Jülich
E704 (p=200 GeV/c) RHIC (p=100 GeV/c)☐ RHIC (√s= 200 GeV)
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Phase Angle vs |r5|
September 30, 2010N. Buttimore, SPIN2010 Jülich
1s 3s2s
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Conclusions• When all available small –t data are analyzed, the
hadronic spin flip is small (value…)• The magnitude of |r5|= 0.059 ± 0.008 and the phase
angle q5= 94.1 ± 1.7 degrees• Only statistical experimental errors are considered in
this analysis. The systematic errors need to be included especially when they are comparable or larger
• pp data at 6.8 GeV suggest sizable hadronic spin flip…• pC data ….• ….
September 30, 2010N. Buttimore, SPIN2010 Jülich
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Overlay Alek6.8GeV (do we need this?) maybe save it as a back up
September 30, 2010N. Buttimore, SPIN2010 Julich
N. Buttimore, SPIN2010 Julich 10
pC Tojo Fit
September 30, 2010
N. Buttimore, SPIN2010 Julich 11
pC Tojo Contours (1, 2 and 3 sigma)
September 30, 2010
N. Buttimore, SPIN2010 Julich 12
pC Tojo Magnitude and Phase?
September 30, 2010
N. Buttimore, SPIN2010 Julich 13
pC Jinnouchi Fit
September 30, 2010
N. Buttimore, SPIN2010 Julich 14
pC Jinnouchi Contours (1, 2 and 3 sigma)
September 30, 2010
N. Buttimore, SPIN2010 Julich 15
pC Jinn Magnitude and Phase?
September 30, 2010
