Search

The reaction pp → dπ + η has been measured at a beam energy of T p = 2.65 GeV ( p p = 3.46 GeV/ c) using the ANKE spectrometer at COSY-Julich. The missing-mass distribution of the detected dπ + pairs exhibits a peak around the η mass on top of a strong background of multipion pp → dπ +( nπ) events. The differential cross section d 4 σ/ dΩd dΩ π + dp d dp π + for the reaction pp → dπ + η has been determined model independently for two regions of phase space. Employing a dynamical model for the a production allows one then to deduce a total cross section of σ( pp → da → dπ + η) = 1.1 ± 0.3stat ± 0.7syst µb for the production of π + η via the scalar a (980) resonance and σ( pp → dπ + µb for the nonresonant production. Using the same model as for the interpretation of recent results from ANKE for the reaction $$pp \to dK^ + \bar K^0 $$ , the ratio of the total cross sections is $$\sigma (pp \to d(K^ + \bar K^0 )_{L = 0} )/\sigma (pp \to da_0^ + \to d\pi ^ + \eta ) = 0.029 \pm 0.008_{stat} \pm 0.009_{syst} $$ , which is in agreement with branching ratios in the literature. [ABSTRACT FROM AUTHOR]stat ± 1.0syst µb for the nonresonant production. Using the same model as for the interpretation of recent results from ANKE for the reaction $$pp \to dK^ + \bar K^0 $$ , the ratio of the total cross sections is $$\sigma (pp \to d(K^ + \bar K^0 )_{L = 0} )/\sigma (pp \to da_0^ + \to d\pi ^ + \eta ) = 0.029 \pm 0.008_{stat} \pm 0.009_{syst} $$ , which is in agreement with branching ratios in the literature. [ABSTRACT FROM AUTHOR]

The reactions pn → dω) and pn → dφ) are investigated near the corresponding thresholds. The S-wave amplitudes are calculated within the two-step model described by a triangle graph with π, ρ, and ω) mesons in the intermediate state. The cross sections for the reactions pn → dω) and pn → dφ) are predicted to be significantly larger than the cross sections for the corresponding reactions pp → ppω) and pp → ppφ) at the same values of the c.m. excess energy Q. The phi-to-omega yield ratio is found to be (34 ± 10) x 10[sup -3]. [ABSTRACT FROM AUTHOR]