Study of Z Boson Pair Production in e+e- Collisions at LEP at \sqrt{s}=189 GeV

The pair production of Z bosons is studied using the data collected by the L3 detector at LEP in 1998 in e+e- collisions at a centre-of-mass energy of 189 GeV. All the visible final states are considered and the cross section of this process is measured to be 0.74 +0.15 -0.14 (stat.) +/- 0.04 (syst.) pb. Final states containing b quarks are enhanced by a dedicated selection and their production cross section is found to be 0.18 +0.09 -0.07 (stat.) +/- 0.02 (syst.) pb. Both results are in agreement with the Standard Model predictions. Limits on anomalous couplings between neutral gauge bosons are derived from these measurements

Measurement of the Spectroscopy of Orbitally Excited B Mesons at LEP

We measure the masses, decay widths and relative production rate of orbitally excited B mesons using 1.25 million hadronic Z decays recorded by the L3 detector. B-meson candidates are inclusively reconstructed and combined with charged pions produced at the primary event vertex. An excess of events above the expected background in the B\pi mass spectrum in the region 5.6-5.8 GeV is interpreted as resulting from the decay B_u,d^** -> B^(*)\pi, where B_u,d^** denotes a mixture of l=1 B-meson states containing a u or a d quark. A fit to the mass spectrum yields the masses and decay widths of the B_1^* and B_2^* spin states, as well as the branching fraction for the combination of l=1 states. In addition, evidence is presented for the existence of an excited B-meson state or mixture of states in the region 5.9-6.0 GeV

Measurement of inclusive D*(+/-) production in two-photon collisions at LEP

Inclusive production of D*(+/-) mesons in two-photon collisions was measured by the L3 experiment at LEP. The data were collected at a centre-of-mass energy root s = 189 GeV with an integrated luminosity of 176.4 pb(-1). Differential cross sections of the process e(+)e- --> e(+)e(-) D* X+/- are determined as functions of the transverse momentum and pseudorapidity of the D*(+/-) mesons in the kinematic region 1 GeV <p(T)(D*) < 5 GeV and /eta(D*)/ < 1.4, The cross section integrated over this phase space domain is measured to be 132 +/- 22(stat.)+/- 26(syst.)pb. The differential cross sections are compared with next-to-leading order perturbative QCD calculations. (C) 1999 Published by Elsevier Science B.V, All rights reserved