HEPData Search

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Evidence for Narrow States Decaying Into ($\Lambda \bar{p}$ Pions) at 3.1-{GeV}/$c^2$ With Charges +1, 0 and -1

The Bristol-Geneva-Heidelberg-Lausanne-Rutherford collaboration Bourquin, M. ; Brown, Robert M. ; Burckhart, H.J. ; et al.

Phys.Lett.B 172 (1986) 113, 1986.

Inspire Record 228256 DOI 10.17182/hepdata.47311

Evidence for narrow states produced by Σ − interactions in beryllium, and decaying into ( Λ p + pions ), has been obtained in an experiment at the CERN SPS hyperon beam. At 3.1 GeV/ c 2 , the ( Λ p π + π + ), ( Λ p π + π + π − ) and ( Λ p π + π − ) effective mass distributions show an excess of 45, 19 and 62 events above a background of 50, 28 and 187, respectively. The possibility that these three signals are statistical fluctuations is remote. The observed widths of the signals are compatible with the mass resolution of the apparatus, 24 MeV/ c 2 FWHM. We have not been able to find an interpretation of the quantum numbers of the final states, which are baryon number 0, strangeness −1 and charge +1, 0 and −1.

1 data table

Table 1

The cross section times branching fraction. The differential cross section is fitted by the equation : D3(SIG)/D3(P) = (1-XL)**POWER*EXP(-SLOPE*PT**2).

EXCLUSIVE rho0 PRODUCTION IN DEEP INELASTIC MUON PROTON SCATTERING

The European Muon collaboration Aubert, J.J. ; Bassompierre, G. ; Becks, K.H. ; et al.

Phys.Lett.B 161 (1985) 203, 1985.

Inspire Record 214930 DOI 10.17182/hepdata.30353

Exclusive ϱ 0 production has been measured in 120, 200 and 280 GeV muon-proton interactions at high Q 2 (1 GeV 2 < Q 2 < 25 GeV 2 ) and W (6 GeV < W < 19 GeV). The photoproduction cross section decreases as 1/ Q 4 . A shallow t distribution, typical of a hard scattering process is observed and the ϱ 0 is found to be dominantly in the helicity zero spin state. The ϱ 0 s are mainly produced by transverse photons and s -channel helicity conservation seems to be invalid. The data cannot be described by the vector meson dominance model. These data show that at high Q 2 even exclusive ϱ 0 muoproduction is a hard scattering process and that the soft hadron-like properties of the photon have disappeared.

8 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

SYSTEMATIC ERROR ON SLOPE IN 0.8.

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Search for Anti-proton - Nucleus States With ($\bar{p}$, $p$) Reactions

Garreta, D. ; Birien, P. ; Bruge, G. ; et al.

Phys.Lett.B 150 (1985) 95-99, 1985.

Inspire Record 203156 DOI 10.17182/hepdata.49641

We have studied (p̄, p) reactions on 12 C , 63 Cu, and 209 Bi to search for possible nuclear states formed ny antiprotons and nuclei. The experiments used the 180 MeV antiproton beam from LEAR, and the high-resolution magnetic spectrometer, SPES II, to detect the outgoing protons. No evidence of antiproton-nucleus states was found. The gross features of the proton spectra are reasonably well described by intranuclear cascade model calculations, which consider proton emission following antiproton annihilations in the target nucleus.

1 data table

Table 1

Parameters resulting from the best fits to the proton spectra with the expression D2(SIG)/D(OMEGA)/D(E) = CONST*SQRT(E)*EXP(-E/SLOPE).

A Spin Parity Analysis of the $\omega \pi^0$ Enhancement Photoproduced in the Energy Range 20-{GeV} to 70-{GeV}

The Omega Photon collaboration Atkinson, M. ; Axon, T.J. ; Barberis, D. ; et al.

Nucl.Phys.B 243 (1984) 1-28, 1984.

Inspire Record 195216 DOI 10.17182/hepdata.33872

A study is made of the ωπ 0 system produced near threshold in the reaction γ p→ π + π − π 0 π 0 p. A spin-parity analysis shows that the ωπ 0 enhancement is consistent with predominant 1 + B(1235) production, with ∼20% J P = 1 − background.

2 data tables

Table 1

MEAN BEAM ENERGY IS 39 GEV.

Table 2

ESTIMATE OF B(1235) PRODUCTION CROSS SECTION ASSUMING 1+ CROSS SECTION OF 0.63 +- 0.20 MUB AND THAT 20 PCT OF THIS IS DUE TO BACKGROUND S-WAVE CONTRIBUTIONS.

Observation of a Peak at 1.28-{GeV} in the $\eta \pi \pi$ System in the Reaction $\gamma p \to \eta \pi^+ \pi^- p$

The Omega Photon collaboration Atkinson, M. ; Axon, T.J. ; Barberis, D. ; et al.

Nucl.Phys.B 242 (1984) 269-281, 1984.

Inspire Record 194474 DOI 10.17182/hepdata.33873

A peak is reported in the ηπ + π − system, produced in the reaction γ p→ ηπ + π − p, at a mass of 1.28 ± 0.01 GeV with a width of 0.08 ± 0.02 GeV. Possible spin-parity assignments for the peak are shown to be J π = 1 − , J π = 1 + or J π = 2 + and interpretations of these assignments are discussed.

2 data tables

Table 1

No description provided.

Table 2

No description provided.

EVIDENCE FOR RESONANT STRUCTURES IN THE LAMBDA anti-p SYSTEM

The Bari-Birmingham-CERN-Milan-Paris-Pavia collaboration Armstrong, T. ; Baubillier, M. ; Bloodworth, I.J. ; et al.

Nucl.Phys.B 227 (1983) 365-386, 1983.

Inspire Record 191867 DOI 10.17182/hepdata.33928

An analysis of the Λ p p system produced forward in the reaction K p → Λ p p at 18.5 GeV/ c is presented. The data come from an experiment using the CERN Ω′ spectrometer. Structures are observed in the Λ p mass spectrum and in the double moments H LMlm describing the decay of the Λ p system and the subsequent Λ decay, for L ⩽ 8. A partial wave analysis interprets these structures as resonances of spin parities 2 − and 3 + , masses and widths M = 2200 ± 40 MeV, Γ = 150 ± 30 MeV and M = 2330 ± 40 MeV, Γ = 150 ± 30 MeV respectively.

3 data tables

Table 1

UNCORRECTED DISTRIBUTION.

Table 2

FULLY CORRECTED CROSS SECTION.

Table 3

CROSS SECTIONS FOR RESONANCES. BREIT WIGNER FITTED WITH NO ADDITIONAL BACKGROUND.

Photoproduction of $\pi^+ \pi^- \pi^0$ on Hydrogen With Linearly Polarized Photons of Energy 20-{GeV} - 70-{GeV}

The Omega Photon & Bonn-CERN-Glasgow-Lancaster-Manchester-Paris-Rutherford-Sheffield collaborations Atkinson, M. ; Axon, T.J. ; Barberis, D. ; et al.

Nucl.Phys.B 231 (1984) 15-39, 1984.

Inspire Record 191169 DOI 10.17182/hepdata.33892

Results on photoproduction of π + π − π 0 in the photon energy range 20–70 GeV are presented. For the ω meson, the production cross-section is found to be 1010±15 (statistical)±290 (systematic) nb and is constant over the incident photon energy range. Spin-density matrix elements are evaluated for ω meson production. The φ meson is observed with a total photoproduction cross section (corrected for branching ratio to π + π − π 0 ) of 610±35±170 nb. A third resonance, at 1.67 GeV, is seen in the mass spectrum and its interpretation is discussed. The production of a broad π + π − π 0 continuum, mainly via ϱπ, and peaking at 1.2 GeV, contributes with a cross section of about 2.5 ωb. The spin-parity content is analysed by the moments of the π + π − π 0 decay angular distribution in the helicity frame and by maximum likelihood fits to the π + π − π 0 Dalitz plot. It is found that production of J P = 1 − states accounts for less than half of the total mass spectrum above 900 MeV. There is a broad enhancement in the 1 + wave around 1.15 GeV indicating photoproduction of the H(1190) meson.

6 data tables

Table 1

No description provided.

Table 2

EXPONENTIAL FITS TO D(SIG)/DT IN OMEGA MASS REGION.

Table 3

EXPONENTIAL FITS TO D(SIG)/DT OVER FULL ENERGY FOR THREE MASS REGIONS CORRESPONDING TO OMEGA, PHI AND OMEGA*.

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MEASUREMENT OF THE XI- P ELASTIC CROSS-SECTION AT 102-GEV/C AND 135-GEV/C

Biagi, S.F. ; Bourquin, M. ; Britten, A.J. ; et al.

Z.Phys.C 17 (1983) 113-119, 1983.

Inspire Record 192459 DOI 10.17182/hepdata.16368

TheΞ-p differential elastic cross section has been measured in the SPS hyperon beam at 102 and 135 GeV/c. In the range 0.01<−<0.42(GeV/c)2, thet distributions are found to be compatible with the formA exp(Bt) whereB is 7.7±0.4(GeV/c)−2 at 102 GeV/c and 8.2 ±0.5(GeV/c)−2 at 135 GeV/c. The corresponding total elastic cross sections areσel=4.9±0.7 mb andσel=5.6±0.9 mb, respectively. These results are compared with the predictions of phenomenological models.

2 data tables

Table 1

NUMERICAL VALUES OF DATA SUPPLIED BY P.ROSSELET.

Table 2

No description provided.

Photoproduction of $K^+ K^-$ Pairs on Hydrogen at Photon Energies of 20-{GeV} to 36-{GeV}

The Bonn-CERN-Ecole Poly-Glasgow-Lancaster-Manchester-Orsay-Paris-Rutherford-Sheffield collaboration Aston, D. ; Atkinson, M. ; Bailey, R. ; et al.

Nucl.Phys.B 172 (1980) 1-12, 1980.

Inspire Record 153022 DOI 10.17182/hepdata.34516

The reaction γ p→K + K − p has been investigated with photons in the energy range of 20< E γ <36 GeV and with K + K − pairs in the mass range of M K + K − <2.0 GeV. The production of the φ(1019) contributes with a cross section σ ( γ p → φ p) × BR( φ →K + K − ) = 240±6 nb with an additional systematic error of ±20 nb. In the higher mass range of 1.05< M K + K − <2.0 GeV the production of K + K − pairs yields a cross section σ ( γ p→K + K − p) = 160±8 nb with an additional systematic error of +40 −30 nb.

3 data tables

Table 1

No description provided.

Table 2

K+ K- PRODUCTION ABOVE PHI MASS.

Table 3

No description provided.