R.T. Van de Walle

Study of the structure of hadronic events and determination of αS at s = 130 GeV and 136 GeV

We present a study of the structure of hadronic events recorded by the L3 detector at center-of-mass energies of 130 and 136 GeV. The data sample corresponds to an integrated luminosity of 5 pb-1 collected during the high energy run of 1995. The shapes of the event shape distributions and the energy dependence of their mean values are well reproduced by QCD models. From a comparison of the data with resummed O(alpha_s^2) QCD calculations, we determine the strong coupling constant to be alpha_s(133 GeV) = 0.107 +/- 0.005(exp) +/- 0.006(theor).

Inclusive production of neutral strange particles by 147 GeV/cπ+/K+/p interactions in hydrogen

Results are presented from a study of inclusive neutral strange particle production by a 147 GeV/c tagged π+/K+/p beam in the Fermilab 30-inch hydrogen bubble chamber. The experiment made use of the proportional hybrid spectrometer system. Results are based on 995 KS0, 485 Λ, and 83 Λ found in a sample of 132 000 pictures. Cross sections are given for inclusive production of these particles by each of the three beam particles, and comparisons are made with measurements at other energies. Topological cross sections are also calculated, and KNO multiplicity scaling is investigated. Distributions are presented of invariant cross sections as functions of the Feynman scaling variable x and c.m. rapidity y. The transverse momentum-squared distributions with their fitted slopes are also given. Comparisons are made of the production characteristics for the three beam types.

Backward production of a spin parity 1+ϱπ enhancement at 1.04 GeV

Abstract A spin-parity 1 + ϱπ enhancement is observed for the 3π mass spectrum in the reaction K − p → Σ − π + π + π − where events with a small (K − → Σ − ) momentum transfer are selected. The mass (1040 MeV) and width (230 MeV) of this enhancement are reminiscent of the A 1 → ϱπ bump which has mainly been observed in the diffractive-like processes. The cross section for this enhancement at 4.15 GeV/ c incident K − momentum is (3.6 ± 0.5) μ b.

The reactions K−p → Λπ0, Λη,Λη′ at 4.2 GeV/c

In a high statistics CERN 2 m bubble chamber experiment the differential cross sections and polarizations of the Λ for the reactions K−p → Λπ0, Λη, Λη′ at 4.2 GeV/c have been measured. The reaction K−p → Λη exhibits a pronounced dip around −t ∼0.5 (GeV/c)2 and all three reactions show a significant backward peaking (−u < 1.0 (GeV/c)2). The Λ polarization in the reaction K−p → Λπ0 is measured to be significantly different from zero throughout most of the available t-range. Forward cross sections enable a determination of RT, the ratio of singlet/octet coupling η1KK∗∗η8KK∗∗. Backward cross sections are utilized to estimate the effective η-nucleon coupling constant gηNN2 over the −u range 0–1.5 (GeV/c)2.

Search for new physics in energetic single photon production in

Using a sample of

e^{+}e^{-}

\mathrm{e^{+}e^{-}}

annihilation at the

annihilation events collected with the L3 detector at the Z resonance corresponding to an integrated luminosity of 137 pb

Z

^{-1}

resonance

, we have searched for anomalous production of

Search for neutralinos in Z decays

\gamma \mathrm{X}