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.
123512923
Sequential fragmentation and rate oscillations in exclusive decays
Abstract We consider the decay of heavy quarkonia into two light mesons, and assume that quark-antiquark pairs are created sequentially when the final state is formed. We find quantum oscillations in the decay rate as a function of total energy. These oscillations can explain the energy dependence observed in the πϱ and K ∗ K channels at the J ψ and ψ ′ and predict the behaviour at the heavier Ψ family. In the mechanism we discuss, a given final state is produced only in a narrow range of the possible distances between the initial light quark and light antiquark.
121406128
Sequential pair creation and gluonium candidates
Abstract We discuss the energy dependence of sequential quark pair creation, which generates mass bumps in (Zweig forbidden) dimension final states. These bumps, which are not resonances, show many similarities to gluonium candicates observed in the J PC = 2 ++ channels φφ, ηη and K K .
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*.