W.B. Fretter

Inclusive ϱ° production in π−p interactions at 205 GeV/c

Abstract The inclusive ϱ ° production cross section has been measured in the reaction π − p → π + π − X at 205 GeV/ c . We find σ ( ϱ ° ) = 13.5 ± 3.4 mb, with most of the production occuring in the central region. Assuming σ ( ϱ + ) ≈ σ ( ϱ − ) ≈ σ ( ϱ ° ), it is concluded that approximately one-third of the pions at this energy come from ϱ -decay.

Properties of the A1 studied in 16 GeV/c π− interactions on nuclei

magnetic field 20.3 KG) was filled with C2F3C1 (density 1.2, radiation length 25 cm). This liquid was chosen mainly because: — its short radiation length permits > 95% efficiency for detection of at least one of the two y rays from a decaying jt°; — it contains no hydrogen, and thus offers no possibility of reactions on free protons which could be confused with the reactions on nuclei which we wanted to study.

Charge asymmetry in inelastic π−p interactions at 205 GeV/c for particles with transverse momentum > 1.0 GeVc

Abstract In 205 GeV / c π − p inelastic interactions, negative particles with transverse momentum greater than 1.0 GeV / c moving forward in the center of mass outnumber similar positive particles by a factor of 3.7 to 1, greatly in excess of the corresponding ratio for small transverse momentum. The asymmetry is reversed in the backward direction. The forward asymmetry is most prominent in 2-, 4-, and 6-prong interactions, but both forward and backward asymmetries are also substantial for higher multiplicity interactions.

Coherent production of 5-pion final states from nuclei at 16 GeV/c

Coherent production of 2π+3π occurs with cross section (0.1 ± 0.03) mb/nucleus in 16 GeV π- C2F5Cl collisions, compared with (4.0 ± 0.6) mb/nucleus for π+2π- coherent production. Comparison of 2π+3π- and π+2π− yields 90% confidence upper limits (γ0→2π+2π-)< 0.2% (γ0→π+π-) and (A1→2π+3π−)< <0.2% (A1→πγ0). The 5π mass peaks in the 1.9 GeV region. Indications of γ0 and A1 substructure are seen.

Observation of short-lived particles produced in high energy neutrino interactions

Abstract Examination of a sample of 89 high-energy, neutrino-induced dilepton events produced in the Fermilab 15 ft bubble chamber has resulted in the direct observation of the production and visible semi-leptonic decay of short-lived particles. One charged decay, two neutral decays, and one decay candidate of undetermined charge are found. Assuming these events and the remaining dilepton signal result from D meson decays, we obtain τ D + = 2.5 −1.5 +3.5 × 10 −13 s and τ D 0 = 3.5 −1.7 +3.5 × 10 −13 s, using a maximum likelihood analysis.

Pion and nucleon dissociation in π−p→π−π+π−p at 205 GeV/c

Abstract In a 48 000-picture exposure of the Fermilab 30-inch hydrogen bubble chamber to a 205 GeV/ c π − beam, we have measured 169 events of the reaction, π − p → π − π + π − p, with a cross section of 635 ± 61 μ b. This reaction proceeds almost entirely via low mass π − → 3 π and p → p ππ dissociation. Factorization is satisfied for p → pππ dissociation in πp and pp interactions.

Study of diffractively produced five-pion final states

Abstract Diffractively produced five-pion final states are studied in the reaction π−d → 3π−2π+d at 15 GeV/c and compared with predictions of the statistical dissociation model and multiperipheral models.

Production of a low-mass dπ+π− enhancement

A broad threshold dπ+π− enhancement has been observed in π−d → dπ+π−π− at 15 GeV/c. It can be described by a model which assumes terms involving intermediate N12∗ production, plus a Deck type enhancement. A simple calculation based on π±p data is successful in reproducing the main features of the data.

Diffractive dissociation and N∗ production in π−n → π−π−p at 15 GeV/c☆

Abstract Diffractive dissociation of neutrons and N ∗ production are studied in the reaction π − n → π − π − p at 15 GeV/ c . The reaction is dominated by a broad, low-mass diffractive enhancement in the pπ − mass. Evidence is presented for the production of at least one N ∗ resonance in the mass region 1.4–1.8 GeV. Comparison with ISR data suggest that this N ∗ resonance is produced by pomeron exchange. The N ∗ production occurs predominantly at t ′ > 0.1 GeV 2 which suggests a different coupling from the usual diffractive reactions. The non-resonant diffractive background is compared with a double-Regge model and the statistical dissociation model.

Study ofγp→pωwith Linearly Polarized Photons at 2.8 and 4.7 GeV

1. Vertical scales for the density matrix elements p:O, Re p;O and piwl * are incorrectly labeled in Fig. 4. Change 0.4 to 0.2 and -0.4 to -0.2. Other density matrix elements and Pa are correctly labeled. 2. There are two typographical errors in Table IV: In IV-a (2.8 GeV Gottfried-Jackson system) for 0.06 5 It I I 0.15 GeV2, the value of 0 Re PlO is given as -0.14 f 0.04; it should be +O. 14 f 0.04. In IV-e (4.7 GeV helicity system) for 0.014 5 It I ,< 0.06 the value of pi-l should be -0.04 f 0.12; it is shown correctly in Fig. 4.