Isabel Cristina Giehl

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The cross sections and forward-backward asymmetries of hadronic and leptonic events produced in ee collisions at centre-of-mass energies from 130 to 183 GeV are presented. Results for ee, μμ, ττ, qq̄, bb̄ and cc̄ production show no significant deviation from the Standard Model predictions. This enables constraints to be set upon physics beyond the Standard(More)
A search has been performed for the Standard Model Higgs boson in the data sample collected with the ALEPH detector at LEP, at centre-of-mass energies up to 209GeV. An excess of 3σ beyond the background expectation is found, consistent with the production of the Higgs boson with a mass near 114GeV/c2. Much of this excess is seen in the four-jet analyses,(More)
Growth of cells in 3-D porous scaffolds has gained importance in the field of tissue engineering. The scaffolds guide cellular growth, synthesize extracellular matrix and other biological molecules, and make the formation of tissues and functional organs easier. The aim of this study is to use α-tricalcium phosphate cement in order to obtain new types of(More)
Hadronic Z decay data taken with the ALEPH detector at LEP1 are used to measure the three-jet rate as well as moments of various event-shape variables. The ratios of the observables obtained from b-tagged events and from an inclusive sample are determined. The mass of the b quark is extracted from a fit to the measured ratios using a next-to-leading order(More)
A search for γγ decays of a Higgs boson is performed in the data sample collected at LEP with the ALEPH detector between 1991 and 1999. This corresponds to an integrated luminosity of 672 pb at centre-of-mass energies ranging from 88 to 202 GeV. The search is based on topologies arising from a Higgs boson produced in association with a fermion pair via the(More)
A sample of 3.6 million hadronic Z decays recorded between 1991 and 1995 with the ALEPH detector at LEP is used to investigate semileptonic decays of B mesons into nal states involving orbitally excited charm mesons. Topo-logical vertex criteria are used to search for decays involving narrow D states as well as wide D resonances and non-resonant D () nal(More)
The production of WW pairs is analysed in a data sample collected by ALEPH at a mean centre-of-mass energy of 188.6 GeV, corresponding to an integrated luminosity of 174.2 pb. Cross sections are given for different topologies of W decays into leptons or hadrons. Combining all final states and assuming Standard Model branching fractions, the total W-pair(More)
A search for Bs oscillations is performed using a sample of semileptonic b-hadron decays collected by the ALEPH experiment during 1991–1995. Compared to previous inclusive lepton analyses, the proper time resolution and b-flavour mistag rate are significantly improved. Additional sensitivity to Bs mixing is obtained by identifying subsamples of events(More)
Viral concentration method by adsorption-elution with negative membranes has been widely employed for concentrating viruses from environmental samples. In order to provide an adequate assessment of its recovery efficiency, this study was conducted to assess viral recovery rates for viral species commonly found in water (HAdV-5, EV, RV, BAdV and CAV-2),(More)
The production rates of D, D s , D , D/D̄, D±s , and Λ + c /Λ̄ − c in Z → cc̄ decays are measured using the LEP I data sample recorded by the ALEPH detector. The fractional energy spectrum of the D is well described as the sum of three contributions: charm hadronisation, b hadron decays and gluon splitting into a pair of heavy quarks. The probability for a(More)