GeV Center Of Mass Energy Research Articles

Measurement of the J/ψ radiative decay into f 0(1270)γ

The J/ψ decay modes f 0(1270)γ and ρπ have been studied in e +e − collision at 3.1 GeV center of mass energy leading to the π + π − γ and π + π − π 0 final states. The f 0γ decay branching ratio is measured to be (0.20 ± 0.07) × 10 −2, a value comparable to the J/ψ radiative decay rates into the ηγ and η′γ channels. The J/ψ decay branching ratio into ϱπ is measured to be (1.6 ± 0.4) × 10 −2.

Inclusive K s0-production in e +e − annihilation at energies of 3.6 to 5.0 GeV

We have measured the production cross section for K s 0 in e +e − annihilation from 3.6 to 5.0 GeV center of mass energy. A substantial increase of the K s 0 yield is observed around 4 GeV in qualitative agreement with the charm hypothesis.

The total hadronic cross section for e +e − annihilation between 3.1 and 4.8 GeV center of mass energy

Using the solenoidal magnetic detector PLUTO, we have measured the total cross section for e +e − annihilation into hadrons. Results are presented for center of mass energies between 3.6 and 4.8 GeV, and in the regions of the J ψ (3.1) and ψ(3.7) resonances. We also present results for the 2 prong cross section in the energy range 3.6 to 4.8 GeV.

Differential cross section of [formula omitted

The differential cross section of the reaction e + + e − → e + + μ − + ν μ + ν e is calculated to the lowest order in electromagnetic and weak interaction. The effective total cross section at 20 GeV center of mass energy is 0.38 × 10 −40 cm 2. 0.38 × 10 −40 cm 2.

The distribution in transverse momentum of 5 GeV/ c secondaries produced at 53 GeV in the centre of mass

Data are reported on the distribution in transverse momentum of 5 GeV/c π ±, K ±, p and p , produced in pro ton proton collisions at 53 GeV centre of mass energy at the CERN ISR. At this energy the magnitude and p T dependence of the invariant cross-section appears to be approximately equal to that at 19 GeV accelerator energy (at the same value of the Feynman variable x), for π ± and K + in the range 0.15 < p T < 0.95 GeV/ c.

Transverse momentum distribution of photons produced in proton-proton collisions at the intersecting storage rings

The energy spectrum of γ-rays produced in proton-proton collisions at the CERN Intersecting Storage Rings (ISR) has been measured at 90°. The spectrum is an exponential function of the transverse momentum. Its slope is found to be energy independent from 6.7 GeV to 53 GeV center of mass energy. It is shown that the same result holds for neutral pions.

Determination of the proton-proton elastic cross section at 30 GeV center of mass energy

The absolute luminosity of the CERN Intersecting Storage Rings has been determined by the Van der Meer method. Combining the measurement with small angle proton-proton elastic events, we find σ elastic = (6.8±0.6)mb.

Observation of small angle proton-proton elastic scattering at 30 GeV and 45 GeV center of mass energies

Small angle elastic scattering events have been observed at the CERN Intersecting Storage Rings. Directions of both particles as well as the collision vertex are reconstructed with the help of four sets of spark chambers, two for each of the two arms. The elastic nature of the events is demonstrated by a collinearity requirement. We find values for the (diffraction) slope parameter in disagreement with the simple linear extrapolation of lower energy (Surpukov) data.