C. Baglin

Upper limits of the proton magnetic form factor in the time-like region from p̄p→ e+e- at the CERN-ISR

Abstract From the measurement of e + e - pairs from the reaction pp→e + e - at the CERN-ISR, using an antiproton beam and a hydrogen jet target, we derived upper limits for the proton magnetic form factor in the time-like region at Q 2 ⋍8.9( GeV c ) 2 and Q 2 ⋍12.5( GeV c ) 2 .

Measurement of the φφ cross section in pp annihilations at ECM≈3 GeV

In an experiment performed at the CERN Intersecting Storage Rings as a part of an energy scan to detect the ηc formation in pp annihilation, we studied the reaction pp→φφ→K+K−K+K−. The total cross section has been determined to be 25.0± 7.4±3.8 nb.

Precision measurements of the antiproton-proton elastic scattering cross section at 90° in the incident momentum range between 3.5 GeV/c and 5.7 GeV/c

Abstract The high antiproton-proton luminosity obtained by using a target system consisting of a hydrogen gas-jet crossing a coasting beam of cooled antiproton circulating in one of the rings of CERNs ISR provides the possibility to measure low cross section reactions with very high precision. We present measurements of the antiproton-proton elastic cross section at 90° CM at incident momenta between 3.5 GeV/ c and 5.7 GeV/ c . The precision of these measurements is much higher than previously reported results. The data show that the cross section of this reaction decreases faster than s −12 over this momentum range.

Angular distributions in the reactions pp→χ1,2→γψ→γe+e−

Abstract In the experiment R704 at the CERN Intersecting Storage Rings, the two p-wave charmonium states χ1 and χ2 were formed directly in proton-antiproton annihilation, and detected through the decay chain χ j →γ+J ψ→ψ+ e + e − . The angular d istributions of the events found are studied here. A maximum likehood analysis shows that χ1 radiative transition to the J ψ is compatible with a pure dipole. Indications of a nonzero, positive quadropole contribution to the χ2 radiative transition are found. Finally, it is found that the χ2 data are consistent with the conventional assumption that a single quark radiates the photon in the transition from the χ2 to the J ψ .

Angular distributions in the reactions

Abstract In the experiment R704 at the CERN Intersecting Storage Rings, the two p-wave charmonium states χ1 and χ2 were formed directly in proton-antiproton annihilation, and detected through the decay chain χ j →γ+J ψ→ψ+ e + e − . The angular d istributions of the events found are studied here. A maximum likehood analysis shows that χ1 radiative transition to the J ψ is compatible with a pure dipole. Indications of a nonzero, positive quadropole contribution to the χ2 radiative transition are found. Finally, it is found that the χ2 data are consistent with the conventional assumption that a single quark radiates the photon in the transition from the χ2 to the J ψ .

Angular-distributions In the Reactions Ppbar-]chi-1,2-]gamma-psi-]gamma-ete-

Abstract In the experiment R704 at the CERN Intersecting Storage Rings, the two p-wave charmonium states χ1 and χ2 were formed directly in proton-antiproton annihilation, and detected through the decay chain χ j →γ+J ψ→ψ+ e + e − . The angular d istributions of the events found are studied here. A maximum likehood analysis shows that χ1 radiative transition to the J ψ is compatible with a pure dipole. Indications of a nonzero, positive quadropole contribution to the χ2 radiative transition are found. Finally, it is found that the χ2 data are consistent with the conventional assumption that a single quark radiates the photon in the transition from the χ2 to the J ψ .