Spin-averaged asymmetries in the azimuthal distributions of positive and negative hadrons produced in deep inelastic scattering were measured using the CERN SPS longitudinally polarised muon beam at 160 GeV/c160 GeV/c and a 6LiD target. The amplitudes of the three azimuthal modulations cos⁡ϕhcos⁡ϕh, cos⁡2ϕhcos⁡2ϕh and sin⁡ϕhsin⁡ϕh were obtained binning the data separately in each of the relevant kinematic variables x , z or View the MathML sourcepTh and binning in a three-dimensional grid of these three variables. The amplitudes of the cos⁡ϕhcos⁡ϕh and cos⁡2ϕhcos⁡2ϕh modulations show strong kinematic dependencies both for positive and negative hadrons

The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the π- π- π+ final state using a 190  GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420,000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1  GeV2/c2. The well-known resonances a1(1260), a2(1320), and π2(1670) are clearly observed. In addition, the data show a significant natural-parity exchange production of a resonance with spin-exotic quantum numbers J(PC)=1-+ at 1.66  GeV/c2 decaying to ρπ. The resonant nature of this wave is evident from the mass-dependent phase differences to the J(PC)=2-+ and 1++ waves. From a mass-dependent fit a resonance mass of (1660±10(-64)(+0))  MeV/c2 and a width of (269±21(-64)(+42))  MeV/c2 are deduced, with an intensity of (1.7±0.2)% of the total intensity.

Exclusive production of ηπ − and η π − has been studied with a 191 GeV/c π − beam impinging on a hydrogen target at COMPASS (CERN). Partial-wave analyses reveal different odd/even angular momentum (L) characteristics in the inspected invariant mass range up to 3 GeV/c 2 . A striking similarity between the two systems is observed for the L = 2, 4, 6 intensities (scaled by kinematical factors) and the relative phases. The known resonances a 2 (1320) and a 4 (2040) are in line with this similarity. In contrast, a strong enhancement of η π − over ηπ − is found for the L = 1, 3, 5 waves, which carry non-qq quantum numbers. The L = 1 intensity peaks at 1.7 GeV/c 2 in η π − and at 1.4 GeV/c 2 in ηπ − , the corresponding phase motions with respect to L = 2 are different.

A direct measurement of the helicity dependence of the total photoabsorption cross section on the proton was carried out at MAMI (Mainz) in the energy range 200 < Eγ < 800 MeV. The experiment used a 4π detection system, a circularly polarized tagged photon beam and a frozen spin target. The contributions to the Gerasimov-Drell-Hearn sum rule and to the forward spin polarizability γ0 determined from the data are 226±5(stat) ± 12(sys) µb and -187±8(stat) ± 10(sys) 10 −6 fm 4 , respectively, for 200 < Eγ < 800 MeV. PACS number(s): 13.60. Le, 13.60.Hb, 25.20.Lj