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  1. Measurement of the parity-violating asymmetry in inclusive electroproduction of π- near the Delta0 resonance

    Androic, D. ; Armstrong, D. S. ; Bailey, S. L. ; ... - Physical Review Letters
    The parity-violating (PV) asymmetry of inclusive π- production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360 MeV. The physics process dominating pion production for these kinematics is quasi-free photoproduction off the neutron via the Δ0 resonance. In the context of heavy-baryon chiral perturbation theory (HBχPT), this asymmetry is related to a low energy constant dΔ- that characterizes the parity-violating γNΔ coupling. Zhu et al. calculated dΔ- in a model benchmarked by the large asymmetries seen in hyperon weakmore » radiative decays, and predicted potentially large asymmetries for this process, ranging from Aγ- = -5.2 to +5.2 ppm. The measurement performed in this work leads to Aγ- = -0.36 ± 1.06 ± 0.37 ± 0.03 ppm (where sources of statistical, systematic and theoretical uncertainties are included), which would disfavor enchancements considered by Zhu et al. proportional to Vud/Vus. The measurement is part of a program of inelastic scattering measurements that were conducted by the G0 experiment, seeking to determine the N-Δ axial transition form-factors using PV electron scattering.« less

  2. Strange particle production in proton–proton collisions at $$\sqrt{s}=0.9$$ $$\mbox {$${\rm TeV}$$}$$ with ALICE at the LHC

    Aamodt, K. ; Abrahantes Quintana, A. ; Adamová, D. ; ... - European Physical Journal. C, Particles and Fields
    The production of mesons containing strange quarks ($$K^0_S$$, Φ) and both singly and doubly strange baryons ($$Λ, \overline Λ$$, and $$\Xi^– + \overline {\Xi}^+$$) are measured at mid-rapidity in pp collisions at $$\sqrt{s}$$ = 0.9 TeV with the $$\hbox{ALICE}$$ experiment at the $$\hbox{LHC}$$. The results are obtained from the analysis of about 250 k minimum bias events recorded in 2009. Measurements of yields (d$$N$$ / d$$y$$) and transverse momentum spectra at mid-rapidity for inelastic pp collisions are presented. For mesons, we report yields ($$\langle$$ d$$N$$ / d$$y\rangle$$) of $0.184 ± 0.002(stat.) ± 0.006(syst.)$ for $$K^0_S$$ and $0.021 ± 0.004(stat.) ±more » 0.003(syst.)$ for Φ. For baryons, we find ($$\langle$$ d$$N$$ / d$$y\rangle$$) = $0.048 ± 0.001(stat.)± 0.004(syst.)$ for $$Λ$$, $0.047 ± 0.002(stat.) ± 0.005(syst.)$ for $$\overline Λ$$ and $0.0101 ± 0.0020(stat.) ± 0.0009(syst.)$ for $$\Xi^– + \overline {\Xi}^+$$. The results are also compared with predictions for identified particle spectra from $$\hbox{QCD}$$-inspired models and provide a baseline for comparisons with both future pp measurements at higher energies and heavy-ion collisions.« less

  3. Dynamical Approach to the Unitary-Symmetry Mass Formula Based on ω − ϕ Mixing

    Sakurai, J. J. - Physical Review
    Possible dynamical mechanisms that give rise to the

  4. Hyperon-nucleon scattering

    de Swart, J. J. ; Dullemond, C. - Annals of Physics
    The hyperon-nucleon scattering is calculated for Λ-laboratory energies up to 315 Mev. The potentials used were those linear combinations of the nucleon-nucleon potentials as prescribed by global symmetry. Here, we have taken the mass difference between the Λ- and Σ-hyperon exactly into account in the kinematics. However, the mass differences between the Σ-hyperons and between the nucleons are neglected. Angular distributions and total cross sections are given for all possible hyperon-nucleon scattering reactions. Where possible a comparison with experiment is made.
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