STUDY OF A2 PRODUCTION IN THE REACTION PI- P ---> K0 K- P AT 50-GEV/C, 100-GEV/C, AND 175-GEV/C

Bromberg, C. ; Dickey, J.o. ; Fox, G. ; et al.
Phys.Rev.D 27 (1983) 1-11, 1983.
Inspire Record 191493 DOI 10.17182/hepdata.23901

The reaction π−p→K0K−p has been measured from 50 to 175 GeV/c. The production characteristics of the A2 have been analyzed. We find spin and t dependence similar to lower energies, but the cross section falls rapidly with energy. In a Regge description of π−p→A2−p our data imply a rather small Pomeron-exchange component.

6 data tables

No description provided.

RAW CROSS SECTION WITHIN MASS CUTS.

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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

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).

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).

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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Elastic and total $\pi^{+}\pi^{-}$ cross-sections from a high statistics measurement of the reaction $\pi^{-}p \to \pi^{+}\pi^{-}n$ at 63 GeV/c

Weilhammer, P. ; Berglund, A. ; Chabaud, V. ; et al.
2 (1979) 628-635, 1979.
Inspire Record 148986 DOI 10.17182/hepdata.75420

A sample of about 230000 events of the reaction pi /sup -/p to pi /sup +/ pi /sup -/n, measured with a magnetic forward spectrometer set up in an unseparated pi /sup -/ beam with a momentum of 63 GeV/c at the SPS has been analysed in terms of one pion exchange. The elastic pi /sup +/ pi /sup -/ cross section has been determined using an extrapolation to the pion pole in the mass range up to m( pi /sup +/ pi /sup -/)=4 GeV. The total pi /sup +/ pi /sup -/ cross section is obtained via the optical theorem. (7 refs).

5 data tables

INTEGRATED 2- S-WAVE INTENSITY FOR 1500 TO 1800 MEV, INCLUDING SIGNIFICANT BACKGROUND.

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Study of A2- --> eta pi- in the Reaction pi- p --> pi- pi- pi+ pi0 p at 11.2-GeV/c

The Bologna-Florence-Genoa-Milan-Oxford-Pavia collaboration Forino, A. ; Gessaroli, R. ; Cartacci, A.M. ; et al.
Nuovo Cim.A 35 (1976) 465, 1976.
Inspire Record 109786 DOI 10.17182/hepdata.37635

The analysis of A2−→ηπ− at 11.2 GeV/c confirms that A2− is essentially produced by natural-parity exchange. In the differential cross-section as a function oft′ there is evidence of the dip at smallt′ values. The branching ratio (A2→ηπ)/(A2→ϱπ) is 0.18±0.05.

3 data tables

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NUMERICAL VALUES SUPPLIED BY G. THOMPSON. 100 EVENTS IN A2 REGION DEFINED BY 1.18 < M(ETA PI-) < 1.44 GEV.

ROUGH BACKGROUND SUBTRACTION TO REMOVE NON-TRUE ETA EVENTS. FIRST THREE DENSITY MATRIX COMBINATIONS ARE NATURAL-PARITY EXCHANGE, THE REMAINDER BEING UNNATURAL-PARITY EXCHANGE.


Study of the A2: An Analysis of the Reaction pi- p --> eta pi- p and a Missing Mass Spectrum at 6-GeV/c

Underwood, D. ; Conforto, G. ; Kramer, M.A. ; et al.
Phys.Rev.D 11 (1975) 2345-2366, 1975.
Inspire Record 103078 DOI 10.17182/hepdata.24888

The reaction π−p→X−p, X−→ηπ−, η→γγ has been studied in an optical spark-chamber experiment at the Argonne ZGS (Zero Gradient Synchrotron) at a beam momentum of 6.0 GeV/c and with 0.27≤|t|≤0.42 (GeV/c)2. The ηπ mass spectrum contains about 1400 events in the mass range 0.80<M(ηπ)<1.55 GeV/c2, and is dominated by approximately 1000 events of the type A2−→ηπ−. No structure is discernible within the A2 mass spectrum for an experimental resolution of 7.1 MeV/c2 [16.7 MeV/c2 FWHM (full width at half maximum)]. A single D-wave Breit-Wigner distribution fits the data with a high confidence level, yielding for the A2 the parameters M0=1.323±0.003 GeV/c2 and Γ0=0.108±0.009 GeV/c2. The angular distribution of the decay A2−→ηπ− is analyzed and the resultant density matrix elements have the values ρ11=0.45±0.02, ρ1−1=0.45±0.04, and ρ00=0.09±0.04. All other elements are consistent with zero. Finally, the missing-mass spectrum in the region of the A2 is presented. A signal of 230 events above background per 5-MeV/c2 interval is observed at the A2 peak, with a signal to background ratio of greater than 1:1. A single D-wave Breit-Wigner distribution together with a quadratic background fits the data well, with the parameters for the A2 being M0=1.324±0.003 GeV/c2 and Γ0=0.104±0.009 GeV/c2. Both A2 mass spectra are incompatible with the dipole shape.

2 data tables

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THIS FIT ASSUMES ALL OTHER DENSITY MATRIX ELEMENTS (RHO(2M) AND RE(RHO(10))) ARE ZERO SINCE THEY ARE QUITE CONSISTENT WITH ZERO IN A FULL FIT. QUOTED ERRORS INCLUDE SYSTEMATIC ERRORS, WHILE STATISTICAL FITTING ERRORS ARE SHOWN SEPARATELY.