0000000000809730
AUTHOR
Terry Mart
Kaon Photo- and Electroproduction on Nucleons
We extend previous models of kaon photo- and electroproduction in order to include all six isospin channels. It is found that the inclusion of the few available data for the reactions γp → K 0 Σ − in the fit leads to drastically reduced Born coupling constants g Λ and g Σ . The result suggests the need to include hadronic form factors in a gauge invariant fashion. It is also shown that the K 0 form factor can be seen in K 0 Λ electroproduction.
K+Λ and K+Σ0 photoproduction with fine center-of-mass energy resolution
Measurements of γp→K+Λγp→K+Λ and γp→K+Σ0γp→K+Σ0 cross-sections have been obtained with the photon tagging facility and the Crystal Ball calorimeter at MAMI-C. The measurement uses a novel K+K+ meson identification technique in which the weak decay products are characterized using the energy and timing characteristics of the energy deposit in the calorimeter, a method that has the potential to be applied at many other facilities. The fine center-of-mass energy (W) resolution and statistical accuracy of the new data results in a significant impact on partial wave analyses aiming to better establish the excitation spectrum of the nucleon. The new analyses disfavor a strong role for quark–diqua…
Constraints on Coupling Constants through Charged $\Sigma$ Photoproduction
The few available data for the reactions $\gamma p \rightarrow K^{0} \Sigma^{+}$ and $\gamma n \rightarrow K^{+} \Sigma^{-}$ are compared to models developed for the processes $\gamma p \rightarrow K^{+} \Sigma^{0}$ and $\gamma p \rightarrow K^{+} \Lambda$. It is found that some of these phenomenological models overpredict the measurements by up to a factor of 100. Fitting the data for all of these reactions leads to drastically reduced Born coupling constants.
Photoproduction of the hypertriton
In the framework of the impulse approximation we study the photoproduction of the hypertriton $^3_{\Lambda}$H by using realistic $^3$He wave functions obtained as solutions of Faddeev equations with the Reid soft-core potential for different $^3_{\Lambda}$H wave functions. We obtain relatively small cross sections of the order of 1 nb. We also find that the influence of Fermi motion is important, while the effect of different off-shell assumptions on the cross section is not too significant.
Electromagnetic Production of the Hypertriton
Kaon photoproduction on He3, gamma + He3 --> K+ + Hypertriton, is studied in the framework of the impulse approximation. Realistic He3 wave functions obtained as solutions of Faddeev equations with the Reid soft-core potential are used along with different Hypertriton wave functions. Results are compared for several elementary operator models, which can successfully describe the elementary kaon production off the proton up to a photon lab energy of k = 2.2 GeV. It is found that the corresponding cross sections are small, of the order of several nanobarns. It is also shown that the influence of Fermi motion is important, while the effect of different off-shell assumptions on the cross sec…