PI- P --> A1(1270)- P
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Backward Production in $\pi^- p \to p_f \pi^+ \pi^- \pi^-$ Reaction at 9-{GeV}/$c$ and 12-{GeV}/$c$

Ferrer, A. ; Bouquet, B. ; D'Almagne, B. ; et al.
Nucl.Phys.B 142 (1978) 77-107, 1978.
Inspire Record 130740 DOI 10.17182/hepdata.34939

We have analyzed backward meson production in the reaction π − p → p f π + π − π − at 9 GeV/ c and 12 GeV/ c incident π − momenta, from an experiment performed at the CERN Ω Spectrometer using a fast proton (p f ) trigger device. We find strong production of quasi-two-body processes N ∗ ϱ and N ∗ f with a production mechanism consistent with u -channel nucleon exchange. At a lower level, we observe N ∗ π processes with a 3-body baryon decay through Δ(1232)π. In the (3π) − system, we find evidence for A 1 − and clear A 2 − backward production with similar cross sections (≈0.5 μb).

3 data tables
Table 1

No description provided.

Table 2

U-HELICITY JACKSON FRAME.

Table 3

U-HELICITY JACKSON FRAME.


PRISM Plot Analysis of the Reaction pi- p --> p pi+ pi- pi- at 16-GeV/c

The Aachen-Berlin-Bonn-CERN-Cracow-Heidelberg-Warsaw collaboration Grassler, H. ; Honecker, R. ; Kirk, H.G. ; et al.
Nucl.Phys.B 113 (1976) 365-377, 1976.
Inspire Record 109661 DOI 10.17182/hepdata.35583

A prism plot analysis of the reaction π − p→p π + π − π − at 16 GeV/ c has been made and the results are compared with those obtained in a similar analysis of the reaction π + p→ p π + π + π − at the same energy. The three dominating reaction mechanisms (pion dissociation, reggeon exchange, proton diffraction dissociation) appear to be well separated, while considerable residual overlaps are present inside these classes. The prism plot method is discussed as a means for detecting hidden structures and some evidence is presented for a broad three-pion enhancement around 2 GeV decaying primarily into ϱ 0 π − .

2 data tables
Table 1

No description provided.

Table 2

A4(1900) IS CALLED A*(1800) BY AUTHORS. PI+ P CROSS SECTIONS PREVIOUSLY PUBLISHED IN M. DEUTSCHMANN ET AL., NP B99, 397 (1975).


Partial-wave analyses of the (3π)-system in the reaction π − p → π − π − π + p at 11.2 GeV/ c

The Bologna-Florence-Genoa-Milan-Oxford-Pavia collaboration Thompson, G. ; Antich, P. ; Boldetti, A. ; et al.
Nucl.Phys.B 101 (1975) 285-303, 1975.
Inspire Record 2860 DOI 10.17182/hepdata.36138

The results are presented of two partial-wave analyses of the (3π) − system in 30 000 events of the reaction π − p → π − π − π + p at 11.2 GeV/ c . Both techniques incorporate the assumptions of the isobar model and are (a) the University of Illinois program which fits in terms of the (3π) density matrix elements and (b) an amplitude parametrisaton including possible effects of both spin non-flip and spin flip at the baryon vertex. The results obtained with these independent programs are found to be very close.

2 data tables
Table 1

NORMALIZED TO A TOTAL REACTION CROSS SECTION OF 1.17 +- 0.24 MB. ALL QUOTED CROSS SECTIONS ARE FOR INTEGRATED BREIT-WIGNERS.

Table 2

A2 2+D-WAVE FOR 1.2 < M(3PI) < 1.4 GEV. THE FIRST THREE COMBINATIONS OF DENSITY MATRIX ELEMENTS ARE FOR NATURAL PARITY EXCHANGE, AND THE REMAINDER UNNATURAL.


Backward Enhancement in the a1 Region and a2 Production in the Region pi- p --> p(f) pi+ pi- pi- at 9-GeV/c and 12-GeV/c

Ferrer, A. ; Bouquet, B. ; D'Almagne, B. ; et al.
Phys.Lett.B 74 (1978) 287-291, 1978.
Inspire Record 134669 DOI 10.17182/hepdata.27446

Results on backward (3 π ) - system produced in π - p→p f π + π - π - reaction at 9 and 12 GeV/ c are given. The ϱ 0 π - mass spectra show two clear signals at 1050 MeV (A 1 region) and 1303 MeV (A - 2 ). The width of the enhancement in the A 1 region (195±32 MeV) is narrower than found in diffractive experiments. Total backward cross sections for those signals are of the same order of magnitude (∼0.5 μb).

1 data table
Table 1

No description provided.


Experimental Proof of the Existence of the A1 Meson

The ACCMOR collaboration Daum, C. ; Hertzberger, L. ; Hoogland, W. ; et al.
Phys.Lett.B 89 (1980) 281-284, 1980.
Inspire Record 143044 DOI 10.17182/hepdata.27272

In partial wave analyses of the ( π − π − π + ) system, substantial shape changes of the 1 + S ( ϱπ ) intensity as a function of t , and relative phase changes of ≈ 90°, provide compelling evidence for a resonant A 1 of mass ≈ 1280 MeV and width ≈ 300 MeV.

1 data table
Table 1

No description provided.


Pion and Nucleon Dissociation in $\pi^- p \to \pi^- \pi^+ \pi^- p$ at 205 GeV/c

Bingham, H.H. ; Chew, D.M. ; Fretter, W.B. ; et al.
Phys.Lett.B 51 (1974) 397-401, 1974.
Inspire Record 90046 DOI 10.17182/hepdata.27930

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.

1 data table
Table 1

No description provided.


REACTION PI- P ---> PI- PI+ PI- P AT 8-GEV/C

Kitagaki, T. ; Tanaka, S. ; Yuta, H. ; et al.
Phys.Rev.D 26 (1982) 1554-1571, 1982.
Inspire Record 182973 DOI 10.17182/hepdata.23971

Results from a high-statistics experiment involving an exposure of the SLAC 82-in. hydrogen bubble chamber to a beam of 8-GeV/c π− yielding a final state of π−π+π−p are presented. Copious production of ρ, Δ++, and f is found. Considerable quasi-two-body production in which one particle decays to one of the above resonances is also observed. Some double-resonance production involving baryon and meson resonances is also seen. The production properties of ρ, Δ++, and f mesons are well described by a double-Regge model.

29 data tables
Table 1

TOPOLOGICAL CROSS SECTIONS. FIRST 2 PRONG VALUE CONTAINS ELASTIC. 0PRONG IS TAKEN FROM A SMALLER AND DIFFERENT PARTIAL SAMPLE.

Table 2

CROSS SECTION CALCULATED VIA THE OPTICAL THEOREM AS A CROSS CHECK.

Table 3

SPECIFIC CHANNEL CROSS SECTIONS.

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PRISM Plot Analysis of the Reaction pi- p --> pi- pi- pi+ p at 13-GeV/c

Gaidos, J.A. ; Yen, W.L. ;
Phys.Rev.D 19 (1979) 22-42, 1979.
Inspire Record 135845 DOI 10.17182/hepdata.24296

Fourteen reaction channels contributing to the final state have been separated by a prism-plot analysis of π−p→π−π−π+p interactions at 13.2 GeV/c. The results of this study are presented in terms of partial and differential cross sections, invariant-mass and decay-angular distributions, and comparisons with other separation techniques for the various resonant states.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


Meson Production by Delta Exchange in pi- p Interactions at 4-GeV/c

Scharre, D.L. ; Chapman, J.W. ; Ely, R.P. ; et al.
Phys.Rev.D 17 (1978) 2853, 1978.
Inspire Record 121388 DOI 10.17182/hepdata.24432

A streamer-chamber spectrometer is triggered by fast forward protons from 4-GeV/c π−p interactions at the Bevatron. Meson-resonance production in the backward, Iu=32 exchange reactions π−p→pM− are studied, where M− refers to π−, ρ−, A1−, A2−, and B−. Elastic scattering and ρ− production are observed and discussed in detail. No backward A1−, A2−, or B− production is observed at the level of approximately 5 βb.

5 data tables
Table 1

Axis error includes +- 15/15 contribution.

Table 2

No description provided.

Table 3

Axis error includes +- 15/15 contribution.

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Diffractive Production of 3 $\pi$ States at 63-{GeV} and 94-{GeV}

The ACCMOR collaboration Daum, C. ; Hertzberger, L. ; Hoogland, W. ; et al.
Nucl.Phys.B 182 (1981) 269-336, 1981.
Inspire Record 156369 DOI 10.17182/hepdata.34314

Diffractive production of the 3 π system has been studied at 63 and 94 GeV using a two magnet spectrometer with high, uniform acceptance. The total number of events used in the analysis is ∼600 000. The A 2 meson is shown to be diffractively produced. The existence of a resonant component in both the 1 + and 2 − enhancements is established and resonance parameters for the corresponding A 1 and A 3 mesons are given. There are several indications in the data of states which would correspond to radial excitations in the quark model.

4 data tables
Table 1

SEE C. DAUM ET AL., PL 89B, 276 (1980) (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+486> RED = 486 </a>), AND THE RECORD (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+420> RED = 420 </a>) OF THE GENEVA CONFERENCE PREPRINT, B. ALPER ET AL. (1979).

Table 2

SEE C. DAUM ET AL., PL 89B, 281 (1980) (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+487> RED = 487 </a>), AND THE RECORD (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+419> RED = 419 </a>) OF THE GENEVA CONFERENCE PREPRINT, G. THOMPSON ET AL. (1979).

Table 3

SEE C. DAUM ET AL., PL 89B, 285 (1980) (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+488> RED = 488 </a>), AND THE RECORD (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+421> RED = 421 </a>) OF THE GENEVA CONFERENCE PREPRINT, B. ALPER ET AL. (1979).

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