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Forward Collisions and Spin Effects in Evaluating Amplitudes

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. Introduction. Polarized proton collisions probe dependence on spin

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Forward Collisions and Spin Effects in Evaluating Amplitudes

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

  2. Introduction • Polarized proton collisions probe dependence on spin • Analyticity relates low and high energy helicity amplitudes • Hadronicspin effectsare enhanced by photon exchange interference • Study forward spin dependence for cross section normalisation N Buttimore / Akchurin

  3. Peripheral Proton and Ion Collisions Hadronicspin 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 N. Buttimore, SPIN2010 Jülich

  4. Analyzing Power in CNI Region Interference value tc= 8pa /stot , hadronic slope B Bethe phase d ≈ 0.02, real-to-imaginary r≈ 0.02 Proton mass mand anomalous momentk= 1.7928 Analyses assume double-flip amplitude s are zero N. Buttimore, SPIN2010 Julich

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

  6. Phase Angle vs |r5| 1s 2s 3s N. Buttimore, SPIN2010 Jülich

  7. Conclusions • When all available small –tdata 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… • Systematic errors in pC data need study as the fourth quadrant spin-flip phase is very different from the second quadrant pp phase • …. N. Buttimore, SPIN2010 Jülich

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

  9. pCTojo Fit N. Buttimore, SPIN2010 Julich

  10. pCTojo Contours (1, 2 and 3 sigma) N. Buttimore, SPIN2010 Julich

  11. pCTojo Magnitude and Phase? N. Buttimore, SPIN2010 Julich

  12. pCJinnouchi Fit N. Buttimore, SPIN2010 Julich

  13. pCJinnouchi Contours (1, 2 and 3 sigma) N. Buttimore, SPIN2010 Julich

  14. pC Jinn Magnitude and Phase? N. Buttimore, SPIN2010 Julich

  15. Analyzing Power in CNI Region • 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 Jülich

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