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