Beaufays, J.
PI+ P --> A2(1320)+ P
Pion-Proton Scattering
[2.0, 5.0]
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Forward A2+ in Two-dimensions Production in $\pi^+ p \to K^+ \bar{K}(s$)0 $p$ at 12.7-{GeV}/$c$

Hyams, B. ; Jones, C. ; Weilhammer, P. ; et al.
Nucl.Phys.B 146 (1978) 303-326, 1978.
Inspire Record 132236 DOI 10.17182/hepdata.34849

Approximately 350 A 2 + events have been observed in the reaction π + p → K + K S 0 p ( K S 0 → π + π − ) at an incident π + laboratory momentum of 12.7 GeV/ c . The events are distributed over a range of four-momentum transfer squared 0.01 ⩽ − t ⩽ 0.60 (GeV/ c ) 2 and K + K S 0 mass 1.11 ⩽ m K + K S 0 ⩽ 1.51 GeV . A Breit-Wigner fit to the mass spectrum yields a mass for the A 2 + , m A 2 + = 1.324 ± 0.005 GeV, and a width Γ 0 = 0.110 ± 0.018 GeV. We find a cross section σ ( π + p → A 2 + p) = 1.71 ± 0.30 μb referring to the above-mentioned mass and t range and A 2 + → K + K S O with K S 0 → π + π − . The spin-space density matrix in the Gottfried-Jackson frame is practically saturated by ϱ 11 ⋍ ϱ 1−1 = 1 2 suggesting natural parity exchanges only. There is a forward dip in the angular distribution consistent with dominance of s -channel net helicity flip amplitudes and ϱ and f Regge exchanges suffice to describe adequately our differential cross sections.

5 data tables
Table 1

SUBTRACTED BACKGROUND IS PHASE SPACE. FITTED D(SIG)/DT SLOPE IS 9.5 +- 0.9 GEV**-2.

Table 2

SUBTRACTED BACKGROUND IS AN S-WAVE WITH SLOPE OF 8 GEV**-2. FITTED D(SIG)/DT SLOPE IS 6.9 +- 0.6 GEV**-2.

Table 3

FROM D(SIG)/DT. ERROR INCLUDES 15 PCT SCALE ERROR ADDED QUADRATICALLY.

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Partial, Total, and Resonance Production Cross-Sections for the Reactions pi+ p --> Four Prong Final States at 10.3-GeV/c

Kennedy, C.N. ; Zemany, P.D. ; Beaufays, J. ; et al.
Phys.Rev.D 17 (1978) 2888-2900, 1978.
Inspire Record 135353 DOI 10.17182/hepdata.24403

The major production channels of four-prong final states resulting from π+p interactions at a center-of-mass energy of 4.5 GeV are studied. In addition to total production cross sections, comprehensive listings of partial and resonance production cross sections are also given for each final state of interest. All final states, including nπ+π+π+π−, are found to exhibit copious resonance production.

2 data tables
Table 1

PARTIAL CROSS SECTIONS FROM PI+ P --> PI+ P PI+ PI-.

Table 2

PARTIAL CROSS SECTIONS FROM PI+ P --> PI+ P PI+ PI- PI0.


A2+ mass spectrum in pi+ p interactions at 3.7 gev/c

Barnham, K.W.J. ; Abrams, G.S. ; Butler, W.R. ; et al.
Phys.Rev.Lett. 26 (1971) 1494-1498, 1971.
Inspire Record 68979 DOI 10.17182/hepdata.21630

A study of the A2+ mass spectrum in π+p interactions at 3.7 GeVc is presented. For a cut of t′=0.1−2.0 GeV2 and on eliminating the Δ++ we find that the three-pion mass spectrum in the A2+ region is fitted by the dipole formula with a confidence level of 53% and a single Breit-Wigner formula with a confidence level of 11%. Our result thus favors A2+ splitting although a single Breit-Wigner fit cannot be ruled out. We also report the A2+ decay branching fractions measured over all t′ values. They are 0.78 ± 0.05, 0.15 ± 0.04, 0.06 ± 0.03, and < 0.02 for ρπ, ηπ, KK¯, and η′π, respectively, in good agreement with other experiments.

1 data table
Table 1

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