forward collisions and spin effects in evaluating amplitudes

Forward Collisions and Spin Effects in Evaluating Amplitudes

N. Akchurin, Texas Tech University, USAN. Buttimore, Trinity College Dublin, Ireland A. Penzo, INFN & Dip di Fisica, Trieste, Italy

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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 Jülich

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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 Jülich

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Analyzing Power in CNI Region

September 30, 2010N. Buttimore, SPIN2010 Jülich

• 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 Julich 5September 30, 2010

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Global Fit to Small –t Data

September 30, 2010N. Buttimore, SPIN2010 Jülich

E704 (p=200 GeV/c) RHIC (p=100 GeV/c)☐ RHIC (√s= 200 GeV)

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Phase Angle vs |r5|

September 30, 2010N. Buttimore, SPIN2010 Jülich

1s 3s2s

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Conclusions• When all available small –t data 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…• pC data ….• ….

September 30, 2010N. Buttimore, SPIN2010 Jülich

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Overlay Alek6.8GeV (do we need this?) maybe save it as a back up

September 30, 2010N. Buttimore, SPIN2010 Julich

N. Buttimore, SPIN2010 Julich 10

pC Tojo Fit

September 30, 2010

N. Buttimore, SPIN2010 Julich 11

pC Tojo Contours (1, 2 and 3 sigma)

September 30, 2010

N. Buttimore, SPIN2010 Julich 12

pC Tojo Magnitude and Phase?

September 30, 2010

N. Buttimore, SPIN2010 Julich 13

pC Jinnouchi Fit

September 30, 2010

N. Buttimore, SPIN2010 Julich 14

pC Jinnouchi Contours (1, 2 and 3 sigma)

September 30, 2010

N. Buttimore, SPIN2010 Julich 15

pC Jinn Magnitude and Phase?

September 30, 2010