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The 3 He nucleus is a calculable nuclear system (Carlson and Schiavilla in Rev Mod Phys 70:743, 1998) for which our theoretical understanding can be compared with data to an increasingly accurate degree. In turn, the theory faces extensive precise data sets from a series of experiments. Two laboratories are leading the way: MAMI/A1 and the Thomas Jefferson National Accelerator Facility (TJNAF). This paper reviews some of the outstanding current experimental efforts with (polarized or unpolarized) electron scattering on (polarized or unpolarized) 3 He targets in these laboratories.

In a recent set of measurements at Jefferson Laboratory, we have studied the missing-momentum dependence of beam-target asymmetries in exclusive 3 He → ( e , e ′ p ) pn , 3 He → ( e , e ′ p ) d , and 3 He → ( e , e ′ d ) p channels at a previously unattainable level of precision and unreached range in missing momenta. We have also measured single-spin asymmetries in the processes 3 He → ( e → , e ′ ) and 3 He → ( e → , e ′ n ) , where the nuclei were polarized vertically. Preliminary results are presented.

Understanding the nucleon spin structure in the regime where the strong interaction becomes truly strong poses a challenge to both experiment and theory. At energy scales below the nucleon mass of about 1 GeV, the intense interaction among the quarks and gluons inside the nucleon makes them highly correlated. Their coherent behaviour causes the emergence of effective degrees of freedom, requiring the application of non-perturbative techniques such as chiral effective field theory1. Here we present measurements of the neutron’s generalized spin polarizabilities that quantify the neutron’s spin precession under electromagnetic fields at very low energy-momentum transfer squared down to 0.035 GeV2. In this regime, chiral effective field theory calculations2–4 are expected to be applicable. Our data, however, show a strong discrepancy with these predictions, presenting a challenge to the current description of the neutron’s spin properties.Measurements of observables sensitive to the neutron’s spin precession are extended to a regime that probes distances of the size of the nucleon. They are found to disagree with predictions from chiral effective field theory.

At the Mainz Microtron MAMI exploratory experiments on the spectroscopy of mesonic weak decays (MWD) of electroproduced Λ -hypernuclei were performed. A unique setup was realized to use the broad momentum-band kaon spectrometer K aos at zero degree angle with respect to the high-intensity electron beam direction to tag strangeness producing processes. A sample of order 10 3 MWD from a beryllium target was collected by the coincidence technique with the high-resolution multi-spectrometer facility of the A1 Collaboration. It is conjectured that this sample contains monochromatic two-body decays from stopped hyperfragment decays as well as a wide momentum distribution of quasi-free produced Λ - and Σ -hyperon decays and three-body decays from hyperfragments. Stopped hyperfragments will be identified as monochromatic peaks in the π − momentum spectrum from which their masses can be extracted with a precision of 50 keV/ c 2 .

In the K1.8 beam-line at Hadron Experimental Facility of J-PARC, a new magnetic spectrometer S-2S is being installed. S-2S was designed to achieve a high momentum resolution of Δ p / p = 6 × 10 −4 in FWHM. Several strangeness-physics programs which require the high resolution will be realized by S-2S. The present article introduces J-PARC E70 (missing-mass spectroscopy of Ξ 12 Be) and E94 (missing-mass spectroscopy of Λ 7 Li, Λ 10 B, and Λ 12 C) experiments.

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).In a recent set of measurements at Jefferson Laboratory, we have studied the missing-momentum dependence of beam-target asymmetries in exclusive ..., and ... channels at a previously unattainable level of precision and unreached range in missing momenta. We have also measured single-spin asymmetries in the processes ... and ..., where the nuclei were polarized vertically. Preliminary results are presented.

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Issue Title: The 22nd European Conference on Few-Body Problems in Physics, Kraków 2013 In a recent set of measurements at Jefferson Laboratory, we have studied the missing-momentum dependence of beam-target asymmetries in exclusive ..., and ... channels at a previously unattainable level of precision and unreached range in missing momenta. We have also measured single-spin asymmetries in the processes ... and ..., where the nuclei were polarized vertically. Preliminary results are presented.[PUBLICATION ABSTRACT]

We apply a coupled-channel formalism incorporating quasi-bound quark-model states to calculate pion scattering into eta N, K Lambda and K Sigma channels, as well eta p, eta n, K+Lambda, and K0Sigma+ photo-production processes. The meson-baryon and photon-baryon vertices are determined in a SU(3) version of the Cloudy Bag Model. Our model predicts sizable amplitudes in the P11, P13, P33 and S11 partial waves in agreement with the latest MAID isobar model and the recent partial-wave analyses of the Bonn-Gatchina group. We are able to give a quark-model explanation for the apparent resonance at 1685 MeV in the eta n channel.

Phenomenological amplitudes obtained in partial-wave analyses (PWA) of single-pion photoproduction are used to evaluate the contribution of this process to the Gerasimov-Drell-Hearn (GDH), Baldin and Gell-Mann-Goldberger-Thirring (GGT) sum rules, by integrating up to 2 GeV in photon energy. Our study confirms that the single-pion contribution to all these sum rules converges even before the highest considered photon energy, but the levels of saturation are very different in the three cases. Single-pion production almost saturates the GDH sum rule for the proton, while a large fraction is missing in the neutron case. The Baldin integrals for the proton and the neutron are both saturated to about four fifths of the predicted total strength. For the GGT sum rule, the wide variability in predictions precludes any definitive statement.