Search for Charged Higgs Bosons in e+e- Collisions at \sqrt{s} = 189 GeV

A search for pair-produced charged Higgs bosons is performed with the L3 detector at LEP using data collected at a centre-of-mass energy of 188.6 GeV, corresponding to an integrated luminosity of 176.4 pb^-1. Higgs decays into a charm and a strange quark or into a tau lepton and its associated neutrino are considered. The observed events are consistent with the expectations from Standard Model background processes. A lower limit of 65.5 GeV on the charged Higgs mass is derived at 95 % confidence level, independent of the decay branching ratio Br(H^{+/-} -> tau nu)

Synthesis of 2-azidoethyl α-d-mannopyranoside orthogonally protected and selective deprotections

4 páginas, 1 figura, 2 esquemas.We present the synthesis of a fully orthogonally protected mannosyl glycoside 1 and the corresponding methods for selective deprotections. Mannosyl glycoside 1 contains a functionalized linker at the anomeric position to allow for the attachment of carbohydrate units to scaffolds in order to prepare carbohydrate multivalent systems.We would like to thank FIS (PI030093), for financial supportPeer reviewe

Correlations associated with small angle protons produced in proton- proton collisions at 31 gev total energy

High energy inelastic protons with x=2 p/sub L//s/sup 1/2/>0.99 observed in 15.3/15.3 GeV proton-proton collisions at the CERN ISR are accompanied by particles whose angular distribution is confined to a narrow cone in the opposite direction. In contrast, lower energy protons (0.72<x<0.84) are accompanied in addition, by particles emitted at larger angles. The ratio of the associated charged multiplicities is approximately 0.4. (3 refs)

Correlation between the pionization region and the fragmentation region in high energy proton proton collisions

Measurements are reported of two-particle correlations in high energy proton-proton collisions with one particle in the pionization region and the other a proton in the fragmentation region. The correlation function is independent of x of the fragmentation proton for 0.55<or approximately=x<or approximately=0.9 and rises at small x. There is an indication that the correlation is an energy-independent function of x. The measurements for two values of the rapidity of the pionization particle give similar results. (11 refs)

Negative particle production in the fragmentation region at the cern isr. chlm collaboration,

Data are reported on the production of pi /sup -/, K/sup -/ and p in proton-proton collisions at the CERN ISR. Measurements have been made at fixed c.m. angles in the range (x, p/sub T/)=(0.12, 0.16 GeV/c) to (x, p/sub T/)=(0.82, 1.1 GeV/c), over a range of squared c.m. energy 558<s<3950 GeV/sup 2/. Within this range Feynman scaling is a good description of the data for all particles. The approach to scaling is discussed. (7 refs)

MISSING MASS SPECTRA IN P P INELASTIC SCATTERING AT TOTAL ENERGIES OF 23-GEV AND 31-GEV. (TALK)

Results are reported of measurements of the momentum spectra of protons emitted at small angles in inelastic reactions at the CERN ISR. The data are for total energies s/sup 1///sub 2/ of 23 GeV and 31 GeV. The structure of the peak at low values of the missing mass M (of the system recoiling against the observed proton) is studied. The missing mass distributions have the form (M/sup 2/)-/sup B(t)/ where t is the four-momentum transfer squared. B(t) drops from 0.98+or-0.06 at t=-0.15 GeV/sup 2/ to 0.20+or-0.15 at t=-1.65 GeV/sup 2/. The results are compared with a simple triple-Regge formula. (12 refs)