Forward Collisions and Spin Effects in Evaluating Amplitudes N. Akchurin, Texas Tech University, USA N. Buttimore, Trinity College Dublin, Ireland A. Penzo, INFN & Dip di Fisica, Trieste, Italy

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 Jülich1

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 Jülich2

Analyzing Power in CNI Region September 30, 2010N. Buttimore, SPIN2010 Jülich3 For the current analyses, we assume double-flip amplitude is zero The Coulomb phase is 0.02 The rho parameter is 0.02

September 30, 2010N. Buttimore, SPIN2010 Julich4

Global Fit to Small –t Data September 30, 20105N. Buttimore, SPIN2010 Jülich E704 (p=200 GeV/c)  RHIC (p=100 GeV/c) ☐ RHIC (√s= 200 GeV)

Phase Angle vs |r 5 | September 30, 20106N. Buttimore, SPIN2010 Jülich 11 33 22

Conclusions When all available small –t data are analyzed, the hadronic spin flip is small (value…) The magnitude of |r 5 |= ± and the phase angle  5 = 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 Jülich7

Overlay Alek6.8GeV (do we need this?) maybe save it as a back up September 30, 20108N. Buttimore, SPIN2010 Julich