Pionic Decay of a Possible d'-Dibaryon

The pionic decay of a possible d'-dibaryon in the process d' --> pi + N + N is studied in the microscopic quark shell model and with a single-quark transition operator describing the transition q --> pi + q'. For the d' with quantum numbers J^P=0^-, T=0, we employ a six-quark shell-model wave function with a spatial s^5p [51]_X-configuration with N=1 harmonic oscillator quanta. It is shown that the pionic decay width depends strongly on the mass and size of the d'. In the case that the calculated d' mass is close to the experimental one a small pionic decay width of 0.04 MeV is obtained. This is an order of magnitude smaller than the experimentally suggested value of 0.5 MeV. Two possibilities to improve the calculated width are suggested. The effect of the nonstatic correction term in the transition operator and the influence of the form factor at the decay vertex on the decay width are also discussed.Comment: Latex, 15 pages, 1 postscript figure, accepted for publication in Nucl. Phys.

Search for Narrow NNpi Resonances in Exclusive p p -> p p pi+ pi- Measurements

Narrow structures in the range of a few MeV have been searched for in p p pi+ and p p pi- invariant mass spectra obtained from exclusive measurements of the p p -> p p pi+ pi- reaction at Tp = 725, 750 and 775 MeV using the PROMICE/WASA detector at CELSIUS. The selected reaction is particularily well suited for the search for NN and / or N Delta decoupled dibaryon resonances. Except for a possible fluctuation at 2087 MeV/c^2 in Mpppi- no narrow structures could be identified neither in Mpppi+ nor in Mpppi- on the 3 sigma level of statistical significance, giving an upper limit (95% C.L.) for dibaryon production in this reaction of sigma < 20 nb for 2020 MeV/c^2 < m(dibaryon) < 2085 MeV/c^2Comment: 3 pages, 4 figure

The d'-Dibaryon in the Nonrelativistic Quark Model

The narrow peak recently found in various pionic double charge exchange (DCX) cross sections can be explained by the assumption of a universal resonance at 2065 MeV, called d'. We calculate the mass of a six-quark system with J^P=0^-, T=0 quantum numbers employing a cluster model and a shell model basis to diagonalize the nonrelativistic quark model Hamiltonian.Comment: 7 pages, Latex, 2 figures, invited talk at 6th Int. Symp. on Mesons and Nucleons 1995, Blaubeuren, Germany, 10-14 July 1995, to be published in pi-N Newsletter

Three-body decay of the d* dibaryon

Under certain circumstances, a three-body decay width can be approximated by an integral involving a product of two off-shell two-body decay widths. This ``angle-average'' approximation is used to calculate the $\pi NN$ decay width of the $d^*(J^\pi=3^+, T=0)$ dibaryon in a simple $\Delta^2$ model for the most important Feynman diagrams describing pion emissions with baryon-baryon recoil and meson retardation. The decay width is found to be about 0.006 (0.07, 0.5) MeV at the $d^*$ mass of 2065 (2100, 2150) MeV for input dynamics derived from the Full Bonn potential. The smallness of this width is qualitatively understood as the result of the three-body decay being ``third forbidden''. The concept of $\ell$ forbiddenness and the threshold behavior of a three-body decay are further studied in connection with the $\pi NN$ decay of the dibaryon $d'(J^\pi=0^-, T=0 or 2)$ where the idea of unfavorness has to be introduced. The implications of these results are briefly discussed.Comment: 15 pages, RevTeX, two-column journal style, six figure

The Reaction 7Li(pi+,pi-)7B and its Implications for 7B

The reaction 7Li(pi+,pi-)7B has been measured at incident pion energies of 30-90 MeV. 7Li constitutes the lightest target nucleus, where the pionic charge exchange may proceed as a binary reaction to a discrete final state. Like in the Delta-resonance region the observed cross sections are much smaller than expected from the systematics found for heavier nuclei. In analogy to the neutron halo case of 11Li this cross section suppression is interpreted as evidence for a proton halo in the particle-unstable nucleus 7B.Comment: 4 pages, 4 figure

Possible Dibaryons with Strangeness s=-5

In the framework of $RGM$, the binding energy of the six quark system with strangeness s=-5 is systematically investigated under the SU(3) chiral constituent quark model. The single $\Xi^*\Omega$ channel calculation with spins S=0 and 3 and the coupled $\Xi\Omega$ and $\Xi^*\Omega$ channel calculation with spins S=1 and 2 are considered, respectively. The results show following observations: In the spin=0 case, $\Xi^* \Omega$ is a bound dibaryon with the binding energy being $80.0 \sim 92.4 MeV$. In the S=1 case, $\Xi\Omega$ is also a bound dibaryon. Its binding energy is ranged from $26.2 MeV$ to $32.9 MeV$. In the S=2 and S=3 cases, no evidence of bound dibaryons are found. The phase shifts and scattering lengths in the S=0 and S=1 cases are also given.Comment: 10 pages, late

Savory Grazing System: A Research Update

Livestock performance, forage use and soil compaction were studied in Repeated Seasonal (RSG) and High Performance Short Duration Grazing (HPSDG) systems on mixed prairie in good to excellent condition in western South Dakota. In May 1981 and 1982, yearling ewes were allocated to six RSG and six HPSDG pastures and removed in October of each year. Stocking rates in both systems were periodically adjusted to result in 40 to 50% terminal use of shortgrasses. In both years, the stocking rates in HPSDG were approximately twice those in RSG. Livestock performance was the same in both systems. Forage use was more uniform and higher proportions of midgrasses were grazed in HPSDG than in RSG. Soil compaction increased with grazing intensity in RSG but was constant at a value equivalent to moderate grazing intensity in HPSDG

Decision points for individualized hormonal stimulation with recombinant gonadotropins for treatment of women with infertility

It is essential that fertility treatment is individualized based on a thorough diagnostic work-up, with treatment tailored to the patients' requirements. This individualization should be kept in mind during the main decision points that occur before and during treatment. Treatment customization must include consideration of both the woman and her partner involved in the process together, including their collective treatment goals. Once treatment goals have been agreed and diagnostic evaluations performed, personalization based on patient characteristics, together with an understanding of treatment goals and patient preferences, enables the selection of appropriate treatments, protocols, products and their dosing. Following treatment initiation, monitoring and adaptation of product and dose can then ensure optimal outcomes. Currently, it is not possible to base treatment decisions on every characteristic of the patient and personalization is based on biomarkers that have been identified as the most relevant. However, in the future, the use of artificial intelligence coupled with continuous monitoring should enable greater individualization and improve outcomes. This review considers the current state-of-the-art related to decision points during individualized treatment of female infertility, before looking at future developments that might further assist in making individualized treatment decisions, including the use of computer-assisted decision making. ispartof: GYNECOLOGICAL ENDOCRINOLOGY vol:35 issue:12 pages:1027-1036 ispartof: location:England status: publishe

Hyperon-nucleon interactions in the pp→K+Λpp p \to K^+ \Lambda p reaction

We present calculations of the invariant mass spectra of the $\Lambda$p system for the exclusive $p p \to K^+ \Lambda p$ reaction with the aim of studying the final state interaction between the $\Lambda$-hyperon and the proton. The reaction is described within a meson exchange framework and the final state $\Lambda p$ interaction is incorporated through an off-shell t-matrix for the $\Lambda p \to \Lambda p$ scattering, constructed using the available hyperon-nucleon (YN) potentials. The cross sections are found to be sensitive to the type of YN potential used especially at the $\Lambda$ and $\Sigma$ production thresholds. Hence, data on this exclusive reaction, which can be used to constrain the YN potentials are desirable.Comment: 20 pages, Latex, 6 figures, revised manuscript (to appear in IJMP-E