1. Results for Asymmetry Measurement in the Elastic Pion-proton Scattering in the Region of Differential Cross Section Minimum. I.G. Alekseev, P.E. Budkovsky, V.P. Kanavets, L.I. Koroleva, B.V. Morozov, V.M. Nesterov, V.V. Ryltsov, D.N. Svirida, A.D. Sulimov, V.V. Zhurkin. Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya 25, Moscow, 117218, Russia. Tel: 7(095)129-96-29, Fax: 7(095)883-96-01, E-mail : Vadim.Kanavets@itep.ru Yu.A. Beloglazov, E.A. Filimonov, A.I. Kovalev, S.P. Kruglov, D.V. Novinsky, V.A. Shchedrov, V.V. Sumachev, V.Yu. Trautman. Petersburg Nuclear Physics Institute, Gatchina, Leningrad district, 188350, Russia. N.A. Bazhanov, E.I. Bunyatova Joint Institute for Nuclear Research, Dubna, Moscow district, 141980, Russia. Vadim Kanavets (ITEP)

2.  New data on polarization (asymmetry)  Backward hemisphere, 1.78 & 2.07 GeV/c  The latest experiment in the series of the polarization parameter measurements by ITEP-PNPI collaboration in the last decade  Available momentum range (0.8-2.1) GeV/c  65 % of light quark resonances, 3 clusters of resonances  3 peaks in total crossection MAIN GOAL:  Data for the UNAMBIGUOUS RECONSTRUCTION of the elastic  p scattering amplitudes by PWA PHYSICS INTEREST to the LIGHT BARYON SPECTROSCOPY is enhanced by the observation of : resonance clusters with masses 1.7 and 1.9 GeV/c 2 resonances with negative parity in 1.9 GeV/c 2 peak parity doublets in these clusters missing resonances near 2 GeV/c 2 which do not fit well the constituent quark model Preface Vadim Kanavets (ITEP)

3.  Light baryon resonances in the latest PDG are based mainly on PWA’s KH80 and CMB80, both performed more than two decades ago.  More recent analyses by VPI/GWU group did not revealed 4 of 13 resonances in clusters  New data on polarization in   p and spin rotation parameters (D.Svirida, this conference) do not confirm KH80 and CMB80 in the backward scattering region Background Vadim Kanavets (ITEP) Experiment PRESENT MEASUREMENTS:   p,  cm =(149-171) o, P=1.78 GeV/c  cm =(151-170) o, P=2.07 GeV/c  No experimental information up to now  Main difficulty: small crossection in the explored domain  Notable background  Its careful subtraction The SETUP was presented by D.Novinsky on Thursday evening session

4. Data Processing 1 Vadim Kanavets (ITEP) ELASTIC EVENT SELECTION:  Coplanarity and kinematic correlation  joint  2 criterion: ,  – deviations from the elastic kinematics   and   – distribution widths  Optimal cut (minimal statistic error)  2 cut < 3  Additional background suppression by momentum analysis  factor 2 in S/B ratio NORMALIZATION:  Using  2 distribution wing (quasielastic background)  Using beam particle counts  The results of both are well concordant Quasielastic 20<  2 <80

5. Data Processing 2 Vadim Kanavets (ITEP) TWO DIFFERENT METHODS TO GET  ,   :  Using polarization information to subtract unpolarized background  Using  distribution after cut in  and vice versa  In both methods gaussian fit for the peak + polynomial for the background

6.  Correspondence to CMB80 and VPI/GWU recent analysis  Significant deviation from KH80  Agreement with our previous data Results: Asymmetry P at 1.78 GeV/c in   p Vadim Kanavets (ITEP)  cm

7.  Best agreement with VPI analysis SM90  Significant deviation from CMB80 and FA02  Contradiction to KH80  Agreement with previous data Results: Asymmetry P at 2.07 GeV/c in   p Vadim Kanavets (ITEP)  cm

8.  New polarization parameter data require NEW GLOBAL TYPE PWA, for example resurrection of KH80 analysis Conclusion Vadim Kanavets (ITEP) Acknowledgements  Our thanks to Professor G.Hoehler for very interesting and fruitful discussion  We are grateful to the ITEP accelerator team for providing us with the excellent beam conditions and to ITEP cryogenic laboratory for supply with liquid helium and nitrogen.  This work was partially supported by the Russian Fund for Basic Research grant 02-02-16111 and Russian State Scientific Program "Fundamental Nuclear Physics".  GREAT THANKS to the organizers of this interesting conference ! ! !