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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 & 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 N Buttimore / Akchurin

  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 N. Buttimore, SPIN2010 Jülich

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

  5. Global Fit to Small –t Data |r5|= 0.059 ± 0.008 q5= 94.1 ± 1.6  E704 (p=200 GeV/c) RHIC (p=100 GeV/c) ☐ RHIC (√s= 200 GeV) N. Buttimore, SPIN2010 Jülich

  6. With fit values N. Buttimore, SPIN2010 Julich

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

  8. Proton Carbon Small Angle Asymmetry Advantages of using spinlessisosingletions in the case of elastic proton carbon scattering • Only isoscalart-channel exchanges are permitted • Spin zero carbon limits types of gluon exchanges • Pomeron contribution differs from the proton caseproviding more insight into high energy dynamicsKopeliovich and Trueman, Phys Rev D 64 (2001) N. Buttimore, SPIN2010 Julich

  9. Conclusions • All available small –tdata suggest that hadronicspin flip is small • It has magnitude |r5|= 0.059 ± 0.008 and phase q5= 94.1 ± 1.6 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 • more accurate pC asymmetry data; the RHIC polarimeter upgradeshould assist this enterprise. … N. Buttimore, SPIN2010 Jülich

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

  11. pCTojo Fit N. Buttimore, SPIN2010 Julich

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

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

  14. pCJinnouchi Fit N. Buttimore, SPIN2010 Julich

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

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

  17. Bad Contours… • I am having trouble with the contours of magnitude and phase angle plots for pC fits (Jinn below). They look wrong. Notice that theta scan gives two minima (~-20 and ~40 degrees)… Why? Need to think a little bit… N. Buttimore, SPIN2010 Julich

  18. 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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