PION POLARIZABILITY AT CERN COMPASS Murray Moinester Tel Aviv University Institute of Nuclear Theory, University of Washington, August 2012

The polarizabilities [in fm 3 ] [1] J. Gasser et al., Nucl.Phys B 745 (2006) [2] L.V. Fil’kov et al., Eur. Phys. J. A5 (1999) 285 [3] M.J. Lavelle et al., Phys. Lett. B 335 (1994) 211 [4] W. Wilcox., Phys. Rev D 57 (1998) 6731 [5] A. Wilmot et al., Phys. Rev. C 65 (2002)

 + Z   ’ + Z +  The Primakoff reaction  + Z   ’ + Z +   Z,A  ’’ Inverse kinematics for the Compton scattering: γ*π → γπ’ In the incoming pion rest frame (Anti-laboratory system) Assuming (α π +β π )= 0 in the Laboratory system: Q 2 max depends on analysis cut E γ is the energy of the real photon ω is the energy of the virtual photon in the anti-laboratory sys. α π, β π independently βπβπβπβπ γ*γ* γ

ExperimentReaction  [10 -4 fm 3 ] Lebedev γp→γπ + n 20±12 PLUTO γγ→π + π ±4.8±5.7 DM1 γγ→π + π 17.2±4.6 DM2 γγ→π + π 26.3±7.4 MARK II γγ→π + π 2.2±1.6 Serpukhov πZ→πZγ 6.8 ± 1.4± 1.2 Experimental values ExperimentReaction (  +β) [10 -4 fm 3 ] Serpukhov πZ→πZγπZ→πZγ 1.4± 3.1±2.8 ExperimentReaction (  -β) [10 -4 fm 3 ] Serpukhov πZ→πZγπZ→πZγ 13.6 ± 2.8 MAMI-A2 γp → γπ + n 11.6±1.5±3.0±0. 5 The experiments are affected by too large statistical and/or systematic errors

COMPASS NA58 experiment at CERN SPS COmmon Muon and Proton Apparatus for Structure and Spectroscopy 20 Institutes/11 counties/~230 physicists Czech Republic, Finland, France, Germany, India, Israel, Italy, Japan, Poland, Portugal and Russia Bielefeld, Bochum, Bonn, Burdwan/Calcutta, CERN, Dubna, Erlangen, Freiburg, Lisbon, Mainz, Moscow, Munich, Prage, Protvino, Saclay, Tel Aviv, Torino, Trieste, Warsaw and Yamagata

Takahiro Iwata New Frontiers in QCD, February 5, /08/2015 BEACH08 26 june N SPS LHC CERN (Suisse) CERN (France) Lake LEMAN COMPASS COMPASS at CERN Airport p up to 400 GeV secondary hadrons ( , K,...): 2·10 7 /s tertiary  (polarized): 4·10 7 /s p up to 400 GeV secondary hadrons ( , K,...): 2·10 7 /s tertiary  (polarized): 4·10 7 /s

Trigger Experimental conditions during the 2004 hadron run (7 days) Beam Beam: 190 GeV/c; ~10 6 π/s, 4.8 s / 16 s spill structure 190 GeV/c; ~10 8 μ/s Targets Targets: 1.6 – (2+1) - 3 mm Pb, 7 mm Cu, 23 mm C Triggers: Primakoff 1 = Hodoscope hit x ECal2 (E>50 GeV) x HCal2 (E>18 GeV) Primakoff 2 = ECal2 (E>100 GeV) Saturated trigger rate (40-50k/spill)

THE RICH DETECTOR 5 m 6 m 3 m C 4 F 10 photon detectors threshold momenta ● p  = 2 GeV/c ● p K = 9 GeV/c ● p P =17 GeV/c radiator gas: C 4 F 10 mirror wall: 20 m 2 surface photon-detectors: outer part (75%) MWPC(pad RO) with CsI cathode inner part(25%) 576 MAPMTs with indiv. telescope Installed in 2005, Used in data taking from 2006

The Compass Spectrometer