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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 and Università di Trieste, Italy SPIN 2010 September 30 Julich. Introduction.

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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 and Universitàdi Trieste, Italy SPIN 2010 September 30 Julich

  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

  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

  4. Analyzing Power in CNI Region Analyses assume pp double-flip amplitudesare zero 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 N Buttimore

  5. Spin flip Ratio from Low –t AN for pp |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

  6. Phase & Magnitude for pp Spin flip 1s 2s 3s N Buttimore

  7. Overlay of Asymmetry Data at 6.8 GeV N Buttimore

  8. Proton Carbon Small Angle Asymmetry Advantages of using spinlessisosinglet ionsin 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 dynamics Kopeliovichand Trueman, Phys Rev D 64 (2001) N Buttimore

  9. pC Scattering at p=22 GeV/c Asymmetry data J. Tojo et al, PRL 89 (2002) 052302 Spin Flip Magnitude and Phase N Buttimore

  10. pC Scattering at p=22 GeV/c Asymmetry data J. Tojo et al, PRL 89 (2002) 052302 N Buttimore

  11. pC Scattering at p=22 GeV/c 2s 1s 3s Asymmetry data J. Tojo et al, PRL 89 (2002) 052302 N Buttimore

  12. pC Scattering atp=100 GeV/c Asymmetry data from O. Jinnouchi et al, SPIN2004 Spin Flip Magnitude and Phase N Buttimore

  13. pC Scattering atp=100 GeV/c Asymmetry data from O. Jinnouchi et al, SPIN2004 N Buttimore

  14. pC Scattering atp=100 GeV/c 2s 1s 3s Asymmetry data from O. Jinnouchi et al, SPIN2004 N Buttimore

  15. Conclusions • Available small –t data for ANsuggest that pphadronic spin flip is small • Magnitude |r5|= 0.059 ± 0.008 and phase q5= 94.1 ± 1.7 degrees • Only statistical experimental errors are considered in this analysis. Systematic errors need to be included • The pp data at 6.8 GeV indicate more substantial hadronic spin flip • Systematic errors in pC data also need study as the spin-flip phase is very different from the pp phase • More accurate pC asymmetry data should result from a RHIC polarimeter upgrade N Buttimore

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