Search results for "PION"
showing 10 items of 1304 documents
Electroproduction of low energy charged pions on9Be,12C and16O
1979
Measurements of electroproduced pions with an energy of 10MeV are presented. The results of a calculation based on the PWIA are compared with the presented data as well as with data at higher pion energies.
Clues to the nature of the Δ∗(1700) resonance from pion- and photon-induced reactions
2006
Abstract We make a study of the π − p → K 0 π 0 Λ , π + p → K + π + Λ , K + K ¯ 0 p , K + π + Σ 0 , K + π 0 Σ + , and η π + p reactions, in which the basic dynamics is given by the excitation of the Δ ∗ ( 1700 ) resonance which subsequently decays into K Σ ∗ ( 1385 ) or Δ ( 1232 ) η . In a similar way we also study the γ p → K 0 π + Λ , K + π − Σ + , K + π + Σ − , K 0 π 0 Σ + , and η π 0 p related reactions. The cross sections are proportional to the square of the coupling of Δ ∗ ( 1700 ) to Σ ∗ K ( Δη ) for which there is no experimental information but which is provided in the context of coupled channels chiral unitary theory where the Δ ∗ ( 1700 ) is dynamically generated. Within present…
T- and P-asymmetries in the (γ, π−) reaction on 13C and 15N
1995
Abstract A simultaneous theoretical analysis of the polarization observables for negative pion photoproduction off the 13 C and 15 N nuclei is performed. A sensitivity of the target and recoil asymmetries to different ingredients of the theory (the Fermi motion, the final state interaction and the nuclear model input) is investigated. The importance of the high (2 hω ) configurations in the nuclea ground states is shown.
Low-pT pion enhancement from partial thermalization in nuclear collisions
1991
Abstract We attribute the enhancement of pions measured at low transverse momenta and central rapidities in 200 A GeV nucleus-nucleus collisions to the partial thermal equilibration of a superdense pion fluid. Transport theory calculations are compared to recent S+S and O+Au data, and predictions are made for Pb+Pb.
Tau neutrino mass from semileptonic decays
1981
The semileptonic three particle decays of the tau provide determinations of the tau neutrino mass. The shift of the maximal energy of the observable final state particles islinear in the neutrino mass. The endpoint energy of the pion and a partially integrated decay rate in τ → πωvτ and τ → πρVτ are sensitive to a neutrino mass smaller than 100 MeV. Thus, the present bound on\(m_{v_\tau } \) can significantly be improved.
Dispersion Approach to Pion Photoproduction and GDH Sum Rule
1999
Pion photoproduction has been analyzed in the framework of dispersion relations at constant t. The results for S-wave pion production at threshold and P-wave production in the Δ (1232) resonance region are presented and compared to the data and theoretical expectations. The predictions for the GDH sum rule are shown to be very sensitive to the threshold S-wave amplitude.
$$N\bar N$$ annihilation at rest into five pions
1993
\(N\bar N\) annihilation at rest into five pions was studied in the ASTERIX spectrometer by stopping antiprotrons from LEAR in a H2 or D2 gas target. In\(\bar pp\) annihilations in H2 leading to the π+π−π+π−π0 final state, the invariant mass spectra of two, three, and four pions show no evidence for any new narrow states. In\(\bar pn \to \pi ^ + \pi ^ - \pi ^ + \pi ^ - \pi ^ - \) the difference of the four pion mass spectra recoiling against a π− and those recoiling against a π+ shows a resonance-like structure (“ζ (1480)”), confirming a previous analysis with a smaller event sample. The ζ (1480) mass is shown to depend strongly on the momentum of the spectator proton. In H2, we searched fo…
Statistical decay of hyperfragments
2011
Combining the unique features of the hypernuclear electro-production mechanism and the high precision in magnetic spectroscopy, the proposed E-08-012 experiment at Jefferson Lab, Virginia, and the scheduled hypernuclear experiment at MAMI, Germany, focus on the high-resolution spectroscopy of weak two-body decay pions from hypernuclei. These experiments will provide insight on a wide range of light hypernuclei via the production of hyperfragments from 9 Be, 6,7 Li and 12 C targets. In the present work we explore the production of Λ-hypernuclei following the micro-canonical break-up of an initially excited hypernucleus which is created by the electro/photo-production reaction. Finally the mo…
The pion electroproduction and the virtual-photon theory
1983
The double differential cross-section for pion electroproduction was measured for the processes p(e,π+n and12C(e,π+)12B. The proton-induced cross-section was evaluated by using the virtual-photon concept. The experimental data were used to test different formulae for the virtual-photon spectrum. We found significant deviations to a generally used formula (Dalitz-Yennie) and good agreement with a new formula (Tiator-Wright). In addition, we have measured pion production crosssections with real photons under equal kinematic conditions. Electro-and photoproduction measurements give the same results.
Hypernuclear physics at $\overline{\mbox{P}}$ ANDA
2012
Hypernuclear research will be one of the main topics addressed by the \(\overline{\mbox{P}}\) anda experiment at the planned Facility for Anti-proton and Ion Research FAIR at Darmstadt, Germany. A copious production of Ξ-hyperons at a dedicated internal target in the stored anti-proton beam is expected, which will enable the high-precision γ-spectroscopy of double strange systems for the first time. In addition to the general purpose \(\overline{\mbox{P}}\) anda setup, the hypernuclear experiments require an active secondary target of silicon layers and absorber material as well as high purity germanium (HPGe) crystals as γ-detectors. The design of the setup and the development of these det…