123621996
Large-angle p-d scattering at 580 Mev
121222499
Elastic pd Scattering at 316, 364, 470, and 590 MeV in the Backward Hemisphere
The results of an investigation of the elastic $\mathrm{pd}$ differential cross section for center-of-mass angles between 91 and 164\ifmmode^\circ\else\textdegree\fi{} at energies of 316, 364, 470, and 590 MeV are presented. For center-of-mass scattering angles larger than 130\ifmmode^\circ\else\textdegree\fi{}, the cross sections at any given angle are within 10% of each other for the three largest energies. The extrapolated 180\ifmmode^\circ\else\textdegree\fi{} differential cross section observed in this experiment remains nearly constant from 316 to 590 MeV. This is in marked contrast to the rapid decrease in cross section with increasing energy observed by other investigators for both larger and smaller energies. Possible theoretical explanations of this behavior are mentioned.
93503786
Quasi-Elastic Reactions with 600 MeV Protons
A measurement of the (p,2p) differential cross section dσ/dEdΩldΩ2 at 600 MeV on Deuterium and Helium-4 at the NASA Space Radiation Effects Laboratory is reported [1], [2]. Two coincident protons were detected with identical range telescopes. The energy sum of the outgoing protons was constrained to be equal to the incident energy minus the S-state proton separation energy, 2.2 and 20.4 MeV for D and He-4, respectively. By varying the detection angles symmetrically to the beam, events were selected with nuclear recoil momentum \(\vec q_r = \vec p_o - (\vec p_1 + \vec p_2 )\) along the beam line. Values of qr up to 370 MeV/c in D and 300 MeV/c in He-4 were observed.
120709149
Elastic scattering of 600-MeV protons from H, D, He-3, and He-4.
120869047
Elastic Scattering of 580-MeV Protons from He 3
The elastic differential cross section for $p$-$^{3}\mathrm{He}$ scattering has been measured at 580 MeV. The data are compared with a Glauber model calculation.
119191937
Photoproduction of meson pairs: First measurement of the polarization observable I**s
Abstract The polarization observable I s , a feature exclusive to the acoplanar kinematics of multi-meson final states produced via linearly polarized photons, has been measured for the first time. Results for the reaction γ → p → p π 0 η are presented for incoming photon energies between 970 MeV and 1650 MeV along with the beam asymmetry I c . The comparably large asymmetries demonstrate a high sensitivity of I s to the dynamics of the reaction. The sensitivity of these new polarization observables to the contributing partial waves is demonstrated by fits using the Bonn–Gatchina partial wave analysis.
122244010
Four-quark states in hyperon pair production
AbstractWe discuss the use of four-quark states as intermediates in the description ofp
$$\bar p$$
 scattering to exclusive hyperon anti-hyperon pairs. We use four energy-independent parameters to account for initial and final state interactions. Some experimentally observed features of these reactions are easily accounted for in this model, but a few features are not well described. We conclude that less crude initial and final state interactions may make the model more useful.
120605148
Partial-wave analysis of lepton-pair annihilation into two photons
The partial-wave (Jp) composition of the process l+l− → γγ is analyzed in lowest order quantum electrodynamics. The results for low-momentum leptons are as expected, the partial wave with Jp = 0− being dominant. At high energies, the partial wave with Jp = 2+ has the largest single partial cross section. At all energies, it is found that lepton pairs in the triplet state give rise exclusively to positive-parity final states, whereas pairs in the singlet state give rise to negative-parity final states.Some features of the differential cross section are also explained in terms of the spin state of the annihilating lepton pair. Possible implications for e+e− → γγ → hadrons and hadrons are briefly discussed.
118889987
Polarization Observables for Two-Pion Production off the Nucleon
We develop polarization observables for the processes {gamma}N {yields} {pi}{pi}N and {pi}N {yields} {pi}{pi}N, using both a helicity and hybrid helicity-transversity basis. Such observables are crucial if processes that produce final states consisting of a spin-1/2 baryon and two pseudoscalar mesons are to be fully exploited for baryon spectroscopy. We derive relationships among the observables, as well as inequalities that they must satisfy. We also discuss the observables that must be measured in ''complete'' experiments, and briefly examine the prospects for measurement of some of these observables in the near future.
8325726
Phenomenological Lagrangian approach to two kaon photoproduction and pentaquark searches
We examine cross sections for the processes {gamma} N {yields} NK{bar K} in the framework of a phenomenological Lagrangian. We include contributions from {Lambda} and {Sigma} resonances up to spin 3/2, as well as those from an exotic {Theta}{sup +}. We allow the {Theta}{sup +} to have spin 1/2 or 3/2, with either positive or negative parity in each case. We also allow the state to be either isovector or isoscalar. We find that the scenario that most closely matches observations at Jefferson Laboratory requires a very large coupling of the {Theta}{sup +} to NK*.