P. Cerello

n̄p annihilation in flight in two mesons in the momentum range between 50 and 400 MeV/c with OBELIX

Results on np annihilation frequencies into π + π 0 , π + η and K + K s final states in the n momentum range between 50 and 400 MeV/c are presented. Information about np annihilation dynamics at low energy have been extracted as well as the first determination of the D-wave contribution to the annihilation in flight below 400 MeV/c . This result is compared with an independent analysis of the np annihilation cross section data.

Study of the isovector scalar mesons in the channel p̄pK±KS0π‡ at three hydrogen target densities

The study of the I = 1, 0 ++ states with the OBELIX detector in the channel pp → K ±K 0 sπ ∓ at three different target densities is reported. We discuss in particular the results about a o (980) and the evidence of an extra scalar state with mass 1.29 ± 0.01 GeV/c 2 and width 0.080 ± 0.005 GeV/c 2

The A(Kstop−, Λd)A′ reaction, a tool to observe [\overline K NNN] clusters

This work presents experimental results obtained from a study of the K stop − A → ΛdA′ reaction, where A = 6Li. The study concerns the distributions of the Λd invariant mass, which allows us to determine the structure of bound [K − ppn] systems in nuclei. A candidate of such clusters is identified in the present measurement, and its mass (binding energy), decay width and yield are reported. The experiment was performed at the DAΦNE o-facility (LNF) by using the FINUDA spectrometer. The study depended on the capability of FINUDA to reconstruct the traces of all the particles involved in the decay of the nuclear cluster.

A study of Λ 7 Li production with FINUDA

The FINUDA experiment studies the production and decay of Λ-hypernuclei by stopping in thin targets the K −s coming from the decay of the Φ (1020) meson at the DAΦNE e + − e − collider at INFN Laboratori Nazionali di Frascati. In this paper we report the results concerning the production of Λ 7 Li. The absolute production rates for bound states and the best up-to-date hypernuclear spectrum obtained by means of the production π − spectroscopy, with an energy resolution of 1.1 MeV (FWHM), are unveiled.

Study of η and η′ production in anti-n p annihilations

The annihilation fractions and cross sections for the annihilation reaction in flight (∼50-400 MeV/c) into ηπ+ and η′π+ final states have been measured. The first ones follow the trend expected for P wave annihilations. From the ratios of the yields an evaluation of the pseudoscalar mixing angle in the standard form is possible. The value found shows that for pseudoscalar meson production from P wave the Quark Line Rule is not grossly violated

Study of anti-n.p -> phi.pi+ and anti-n.p -> omega.pi+ annihilation reactions in flight

Abstract The results of a study of the annihilation reactions n p → θπ + and n p → ωπ + are reported; the data were collected by the OBELIX apparatus, with antineutrons annihilating in flight (momenta from ∼ 50 MeV/ c to 405 MeV/ c ). Annihilation frequencies and annihilation cross sections have been deduced, for both channels, as a function of antineutron momentum. From the cross section ratio, a substantial deviation from OZI rule expectations is observed. An s s quark content in the nucleon offers a fairly plausible explanation for such an effect.The results of a study of the annihilation reactions and are reported; the data were collected by the OBELIX apparatus, with antineutrons annihilating in flight (momenta from ∼ 50 MeV/c to 405 MeV/c). Annihilation frequencies and annihilation cross sections have been deduced, for both channels, as a function of antineutron momentum. From the cross section ratio, a substantial deviation from OZI rule expectations is observed. An quark content in the nucleon offers a fairly plausible explanation for such an effect

Study of (n)over-barp -> phi pi(+) and (n)over-barp -> omega pi(+) annihilation reactions in flight

Abstract The results of a study of the annihilation reactions n p → θπ + and n p → ωπ + are reported; the data were collected by the OBELIX apparatus, with antineutrons annihilating in flight (momenta from ∼ 50 MeV/ c to 405 MeV/ c ). Annihilation frequencies and annihilation cross sections have been deduced, for both channels, as a function of antineutron momentum. From the cross section ratio, a substantial deviation from OZI rule expectations is observed. An s s quark content in the nucleon offers a fairly plausible explanation for such an effect.The results of a study of the annihilation reactions and are reported; the data were collected by the OBELIX apparatus, with antineutrons annihilating in flight (momenta from ∼ 50 MeV/c to 405 MeV/c). Annihilation frequencies and annihilation cross sections have been deduced, for both channels, as a function of antineutron momentum. From the cross section ratio, a substantial deviation from OZI rule expectations is observed. An quark content in the nucleon offers a fairly plausible explanation for such an effect

A preliminary spin-parity analysis on the anti-p.p -> pi+.pi-.eta annihilation at rest

Abstract A preliminary spin-parity analysis performed on the p p → π + π − η annihilation reaction at rest is presented. The data were acquired in Liquid and NTP hydrogen target densities with the OBELIX detector. The obtained results are in agreement with those existing in literature and support the introduction of new resonances.

Results on spin-parity analysis of n̄p → π+π−π+ in flight

We report in this paper the results of the study of the ƒ 0 (1500)/ƒ 2 (1565) resonances in the in-flight annihilation reaction np → 2 π + π − , taking into account a possible dependence on the n momentum.

Results on spin-parity analysis of p̄p → π+π−π0 annihilation at rest from different density hydrogen targets

The results of the spin-parity analysis of the annihilation reaction --> pi(+)pi(-)pi(0) at rest are presented. For the first time data from liquid, NTP and low pressure hydrogen are fitted simultaneously. This technique allows to disentangle unambiguously the contributions of the different initial atomic states. The results concern the weights of the partial waves, masses and widths of the 0(++), 1(--) and 2(++) resonances produced in the annihilation