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

2. Introduction Polarized proton collisions probe dependence on spin Analyticity relates low and high energy helicity amplitudes Hadronic spin effects are enhanced by photon exchange interference Study forward spin dependence for cross section normalisation SPIN 2010 September 30 JülichN Buttimore / Akchurin1

3. Peripheral Proton and Ion Collisions Hadronic spin dependence is important for 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

4. Analyzing Power in CNI Region Interference value t c = 8  /  tot, hadronic slope B Bethe phase  ≈ 0.02, real-to-imaginary  ≈ 0.02 Proton mass m and anomalous moment  = 1.7928 September 30, 2010N. Buttimore, SPIN2010 Julich3 Analyses assume double-flip amplitude s are zero

5. Global Fit to Small –t Data September 30, 20104N. Buttimore, SPIN2010 Jülich E704 (p=200 GeV/c)  RHIC (p=100 GeV/c) ☐ RHIC (√s= 200 GeV)

6. Phase Angle vs |r 5 | September 30, 20105N. Buttimore, SPIN2010 Jülich 11 33 22

7. Conclusions When all available small –t data are analyzed, the hadronic spin flip is small (value…) The magnitude of |r 5 |= 0.059 ± 0.008 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… Systematic errors in pC data need study as the fourth quadrant spin-flip phase is very different from the second quadrant pp phase …. September 30, 2010N. Buttimore, SPIN2010 Jülich6

8. Overlay Alek6.8GeV (do we need this?) maybe save it as a back up September 30, 20107N. Buttimore, SPIN2010 Julich

9. pC Tojo Fit September 30, 2010N. Buttimore, SPIN2010 Julich8

10. pC Tojo Contours (1, 2 and 3 sigma) September 30, 2010N. Buttimore, SPIN2010 Julich9

11. pC Tojo Magnitude and Phase? September 30, 2010N. Buttimore, SPIN2010 Julich10

12. pC Jinnouchi Fit September 30, 2010N. Buttimore, SPIN2010 Julich11

13. pC Jinnouchi Contours (1, 2 and 3 sigma) September 30, 2010N. Buttimore, SPIN2010 Julich12

14. pC Jinn Magnitude and Phase? September 30, 2010N. Buttimore, SPIN2010 Julich13

15. Analyzing Power in CNI Region September 30, 2010N. Buttimore, SPIN2010 Jülich14 For the current analyses, we assume double-flip amplitude is zero The Coulomb phase is 0.02 The rho parameter is 0.02