In a joint effort the CERES/NA45 and TAPS collaborations have measured low-mass electron pairs in p–Be and p–Au collisions at 450 GeV/ at the CERN SPS. In the range covered up to 1.5 GeV/ the mass ...spectra from p–Be and p–Au collisions are well explained by electron pairs from decays of neutral mesons. For p–Au our result is new. For p–Be, the simultaneously measured electron pair inclusive pair spectrum in which instrumental uncertainties are highly reduced. We confirm the earlier finding of HELIOS-1 with significantly reduced systematic uncertainties of 23% in the mass range below 450 MeV/, and of 28% in the mass range above 750 MeV/ at 90% confidence limit. Any unconventional source of electron pairs is limited by these error margins as the percentage fraction of the hadronic contribution.
Analyzing DISTO data of $pp -> p Lambda K^+$ at $T_p = 2.50$ and 2.85 GeV to
populate a previously reported X(2265) resonance with $M_X = 2267$ MeV/$c^2$
and $Gamma_X = 118$ MeV at 2.85 GeV, we found ...that the production of X(2265) at
2.50 GeV is much less than that at 2.85 GeV (less than 10%), though it is
expected from a kinematical consideration to be produced as much as 33% of that
at 2.85 GeV. The small population of X(2265) at 2.50 GeV is consistent with the
very weak production of Lambda (1405) at the same incident energy toward its
production threshold, thus indicating that Lambda (1405) plays an important
role as a doorway state for the formation of X(2265).
We have analyzed data of the DISTO experiment on the exclusive pp -> p Lambda K+ reaction at 2.85 GeV to search for a strongly bound compact K-pp (= X) state to be formed in the pp -> K+ + X ...reaction. The observed spectra of the K+ missing-mass and the p Lambda invariant-mass with high transverse momenta of p and K+ revealed a broad distinct peak with a mass M_X = 2265 +- 2 (stat) +- 5 (syst) MeV/c2 and a width Gamma_X = 118 +- 8 (stat) +- 10 (syst) MeV.
DISTO data on Kpp Maggiora, M; Kienle, P; Suzuki, K ...
arXiv.org,
12/2009
Paper, Journal Article
Odprti dostop
The data from the DISTO Collaboration on the exclusive pp -> p K+ Lambda production acquired at T_p = 2.85 GeV have been re-analysed in order to search for a deeply bound K- pp (= X) state, to be ...formed in the binary process pp -> K+ X. The preliminary spectra of the DeltaM_{K+} missing-mass and of the M_{p Lambda} invariant-mass show, for large transverse-momenta of protons and kaons, a distinct broad peak with a mass M_X = 2265 +- 2 MeV/c^2 and a width Gamma_X = 118 +- 8 MeV/c^2.
Analyzing DISTO data of \(pp -> p Lambda K^+\) at \(T_p = 2.50\) and 2.85 GeV to populate a previously reported X(2265) resonance with \(M_X = 2267\) MeV/\(c^2\) and \(Gamma_X = 118\) MeV at 2.85 ...GeV, we found that the production of X(2265) at 2.50 GeV is much less than that at 2.85 GeV (less than 10%), though it is expected from a kinematical consideration to be produced as much as 33% of that at 2.85 GeV. The small population of X(2265) at 2.50 GeV is consistent with the very weak production of Lambda (1405) at the same incident energy toward its production threshold, thus indicating that Lambda (1405) plays an important role as a doorway state for the formation of X(2265).
Phys.Rev.Lett. 89 (2002) 092001 Total and differential cross sections for the exclusive reaction pp->pp rho^0
observed via the pi+pi- decay channel have been measured at beam momentum=3.67
GeV/c. The ...observed total meson production cross section is determined to be
23.4 +- 0.8 +-8 microb and is significantly lower than typical cross sections
used in model calculations for heavy ion collisions. The differential cross
sections measured indicate a strong anisotropy cos^2(theta^{CM}) in the rho^0
meson production.
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