Highlights of the Reaction $\pi^- p \to \pi^- \pi^+ n$ at 100-{GeV}/$c$ and 175-{GeV}/$c$

Bromberg, C. ; Dickey, J.O. ; Fox, G.C. ; et al.
Phys.Rev.D 29 (1984) 588, 1984.
Inspire Record 13822 DOI 10.17182/hepdata.33875

We present a summary of the physics results from an experimental study of the reaction π−p→π−π+n at 100 and 175 GeV/c incident-beam momentum. Our data show the continuing dominance of one-pion exchange in these reactions with the characteristic 1Plab2 momentum dependence. We extract the pion Regge trajectory from our data on π−p→ρ0n and study the zero structure of the ππ differential cross section up to sππ=12 GeV2.

9 data tables

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SPHERICAL HARMONIC MOMENTS.

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Measurement and Analysis of the Reaction $\pi^- p \to \rho^0 n$ on a Polarized Target

The CERN-Munich collaboration Becker, H. ; Blanar, G. ; Blum, W. ; et al.
Nucl.Phys.B 150 (1979) 301-325, 1979.
Inspire Record 132603 DOI 10.17182/hepdata.34819

The reaction π − p→ π + π − n has been measured in a high-statistics experiment on a transversely polarized proton target at 17.2 GeV, and unexpectedly large nucleon polarization effects have been observed. Combining the results of this experiment with a measurement on a hydrogen target allows a model-independent partial-wave analysis in terms of the “nucleon transversity” amplitudes. Unique or at most twofold ambiguous solutions are obtained. In particular we find a high lower limit ( ⪆30% ) of the spin non-flip unnatural exchange amplitudes at low | t |. These amplitudes, interpreted as being due to the exchange of an object with the quantum numbers of the A 1 , have been assumed to be absent in previous analyses. In checking the consequences of this finding on the old results, we test the validity of the rank-two assumotions for the density matrix. We find a small but significant deviation, which shows the need for a new phase-shift analysis including the A 1 exchange contribution.

2 data tables

MASS DEPENDENCE OF NORMALIZED T-CHANNEL MOMENTS SCALED TO 100 PCT POLARIZED PROTONS.

T DEPENDENCE OF NORMALIZED T-CHANNEL MOMENTS IN THE RHO REGION SCALED TO 100 PCT POLARIZED PROTONS.


Backward Resonance Production in pi- p --> n pi+ pi- at 8-GeV/c

Eisenstein, Bob I. ; Elliott, J. ; Mollet, W. ; et al.
Phys.Rev.D 18 (1978) 1370-1381, 1978.
Inspire Record 136306 DOI 10.17182/hepdata.24374

We have studied backward meson and baryon production in π−p→nπ+π− at 8 GeV/c using a streamer chamber triggered by the detection of the interaction of the neutron in thick-plate optical spark chambers. Our data sample of 866 events is dominated by the quasi-two-body final states Δ−(1232)π+, nρ0, and nf0. We study the differential and total backward cross sections for these states and the decay angular distributions of the resonances. The results for the Δ− and ρ0 indicate that both nucleon and Δ exchange in the u channel are important in their production, while f0 production is, as expected, consistent with nucleon exchange.

5 data tables

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BACKWARD DIP.

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Reaction pi+ p ---> rho+ p at 2.67 gev/c - a study of isoscalar exchanges

Michael, W. ; Gidal, G. ;
Phys.Rev.Lett. 28 (1972) 1475-1479, 1972.
Inspire Record 75483 DOI 10.17182/hepdata.21443

Results are presented of a study of the reaction π+p→ρ+p at 2.67 GeV/c incident π+ momentum. The contributions due to given spin-parity exchanges are isolated; and, by combining these results with those of a similar π− experiment, the It=0 component of each series is separated. The ω (I=0, JPG=1−−) exchange contribution shows a pronounced dip at −t=0.4 (GeV/c)2. Evidence is presented for the exchange of a state of minimum quantum numbers, H (I=0, JPG=1+−).

6 data tables

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