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

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).