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XV Workshop on High Energy Spin Physics Dubna , Russia, October 8-12, 201 3

XV Workshop on High Energy Spin Physics Dubna , Russia, October 8-12, 201 3. Results on the Transverse Double Spin Asymmetries in the elastic pp-scattering at √s=200 GeV. Helicity amplitudes for spin ½ ½ → ½ ½. Matrix elements. Observables : cross sections and spin asymmetries.

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XV Workshop on High Energy Spin Physics Dubna , Russia, October 8-12, 201 3

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  1. XVWorkshop on High Energy SpinPhysics Dubna, Russia, October8-12, 2013 Results on the Transverse Double Spin Asymmetries in the elastic pp-scattering at √s=200 GeV Igor Alekseev (ITEP) for the STAR Collaboration

  2. Helicity amplitudes for spin ½ ½ → ½ ½ Matrix elements Observables: cross sections and spin asymmetries spin non–flip double spin-flip spin non–flip double spin-flip single spin-flip 2 Igor Alekseev (ITEP) for the STAR Collaboration

  3. Polarized cross-sections and spin parameters Cross-section azimutual angular dependence for transversely polarized beams: - is the normal vector to the scattering plane - is the vector in the scattering plane, normal to the initial momentum ; - polarizations of two colliding beams ANN – polarization normal to the scattering plane ASS – polarization vector in the scattering plane Double-spin asymmetry No angle dependence - luminosity normalization required ! 3 Igor Alekseev (ITEP) for the STAR Collaboration

  4. Probing Odderon S=5002 GeV2 No odderon E.Leader, T.L.Trueman “The Odderon and spin dependence of high-energy proton-proton scattering”, PR D61, 077504 (2000) S=2002 GeV2 S=200 GeV2 • Pomeron and Odderon are 90deg out of phase • 5% Odderon contribution → 5% ANN Odderon spin-flip coupling ≈ Pomeron spin-flip coupling T.L.Trueman “Double-spin asymmetry in elastic proton-proton scattering as a probe for the Odderon”, arXiv:hep-ph/0604153v1 (2006) Regge poles only Odderon spin-flip coupling ≈ ρ spin-flip coupling S=200 GeV2 100x ANN(No Odderon) ANN(Odderon flip=ρ flip) Regge poles and cuts Igor Alekseev (ITEP) for the STAR Collaboration

  5. ANN : existing data HJet@RHIC PRD79(09)094014 HJet@RHIC PRD79(09)094014 pp2pp@RHIC s = 200 GeV PLB647(07)98 5 Igor Alekseev (ITEP) for the STAR Collaboration

  6. detector Horz. RPs Horz. RPs Vert. RPs Vert. RPs Detector Package STAR Experimental conditions • Both beams were transversely polarized with 60% polarization. • Excellent detector performance – nearly 100% efficiency and only 5 dead/noisy stripsper ~14000 active strips. • 2π acceptance in φ. • Ideal optics β*= 21m and terms other than LEFF in the transport matrix were very small. • 0.003 < -t < 0.03 • A good statistics of about 2·107 elastic events with background less than 1%. PBPY= 0.372±0.052*Averaged for our fills from the official Run’09 CNI polarimeter results https://wiki.bnl.gov/rhicspin/Results Normalization using beam beam counters – critical issue: see presentation by D. Svirida for details Igor Alekseev (ITEP) for the STAR Collaboration

  7. Single spin asymmetry result Phys. Lett. B719 (2013) 62-69 • Double spin asymmetries analysis uses the same set of elastic events with the same cuts. • Single spin asymmetries from current analysis repeated those of published result which was based on square root formula Igor Alekseev (ITEP) for the STAR Collaboration

  8. Raw asymmetry STAR PRELIMINARY Only statistical errors shown Igor Alekseev (ITEP) for the STAR Collaboration

  9. r2 and r4 • Error bars represent statistical only errors (boxes) and total uncorrelated errors including those due to background subtraction. • Accurate formulas from: N.H. Buttimore et al. [hep-ph/9901339] • r5 taken from AN result from the same data sample at STAR: Phys. Lett. B719 (2013) 62-69 • Grey bar – common systematic uncertainty on (ANN+ASS)/2 due to luminosity normalization • (ANN+ASS)/2 is consistent with Hjet data, but higher precision. • Formally, r4 can be obtained from the fit, yet r4=0 is not a bad hypothesis • (ANN-ASS)/2 points average to a good zero Fit r2 STAR PRELIMINARY Fit r4 9 Igor Alekseev (ITEP) for the STAR Collaboration

  10. One-σ ellipses • Im r2 is well constrained – small negative value. • Re r2 is compatible with 0 • r4 components are only 1.2σ and 1.7σ from 0 • Re r4 is large because of kinematic factor m2/t. • Assumption r4=0 is reasonable STAR PRELIMINARY As a conclusion The most precise measurement of the transverse double spin asymmetries in the CNI region at collider energies performed. Over the whole interval ANN and ASS are small and (ANN+ASS)/2= –0.0051±0.0006(stat)±0.0012(sys) (ANN-ASS)/2= 0.0005±0.0009(stat)±0.0006(sys) Our result differs from the current theory predictions and could indicate non-zero Odderon spin-flip coupling. 10 Igor Alekseev (ITEP) for the STAR Collaboration

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