Measurement of the B0 Lifetime and Oscillation Frequency using B0->D*+l-v decays

The lifetime and oscillation frequency of the B0 meson has been measured using B0->D*+l-v decays recorded on the Z0 peak with the OPAL detector at LEP. The D*+ -> D0pi+ decays were reconstructed using an inclusive technique and the production flavour of the B0 mesons was determined using a combination of tags from the rest of the event. The results t_B0 = 1.541 +- 0.028 +- 0.023 ps, Dm_d = 0.497 +- 0.024 +- 0.025 ps-1 were obtained, where in each case the first error is statistical and the second systematic.Comment: 17 pages, 4 figures, submitted to Phys. Lett.

WW Production Cross Section and W Branching Fractions in e+e- Collisions at 189 GeV

From a data sample of 183 pb^-1 recorded at a center-of-mass energy of roots = 189 GeV with the OPAL detector at LEP, 3068 W-pair candidate events are selected. Assuming Standard Model W boson decay branching fractions, the W-pair production cross section is measured to be sigmaWW = 16.30 +- 0.34(stat.) +- 0.18(syst.) pb. When combined with previous OPAL measurements, the W boson branching fraction to hadrons is determined to be 68.32 +- 0.61(stat.) +- 0.28(syst.) % assuming lepton universality. These results are consistent with Standard Model expectations.Comment: 22 pages, 5 figures, submitted to Phys. Lett.

Genuine Correlations of Like-Sign Particles in Hadronic Z0 Decays

Correlations among hadrons with the same electric charge produced in Z0 decays are studied using the high statistics data collected from 1991 through 1995 with the OPAL detector at LEP. Normalized factorial cumulants up to fourth order are used to measure genuine particle correlations as a function of the size of phase space domains in rapidity, azimuthal angle and transverse momentum. Both all-charge and like-sign particle combinations show strong positive genuine correlations. One-dimensional cumulants initially increase rapidly with decreasing size of the phase space cells but saturate quickly. In contrast, cumulants in two- and three-dimensional domains continue to increase. The strong rise of the cumulants for all-charge multiplets is increasingly driven by that of like-sign multiplets. This points to the likely influence of Bose-Einstein correlations. Some of the recently proposed algorithms to simulate Bose-Einstein effects, implemented in the Monte Carlo model PYTHIA, are found to reproduce reasonably well the measured second- and higher-order correlations between particles with the same charge as well as those in all-charge particle multiplets.Comment: 26 pages, 6 figures, Submitted to Phys. Lett.

Efeitos dos níveis de extrato etéreo no sucedâneo do leite sobre o desenvolvimento corporal de bezerros Jersey Effects of different ether extract levels of a milk replacer on body development of Jersey calves

Utilizaram-se 20 bezerros Jersey com o objetivo de avaliar o efeito dos níveis de extrato etéreo no sucedâneo comercial sobre o peso corporal, o ganho de peso médio diário, a altura na cernelha, o perímetro torácico e o consumo de concentrado, do 8º ao 90º dia de idade, visando determinar o melhor nível de extrato etéreo. Os animais foram distribuídos nos tratamentos, que consistiram de quatro dietas líquidas: leite integral (T1), sucedâneo lácteo comercial padronizado com gordura suína para 10 (T2), 15 (T3) e 20% (T4) de extrato etéreo (EE) na matéria seca, de acordo com a seqüência de nascimento. O delineamento experimental utilizado foi o de blocos ao acaso com arranjo fatorial desbalanceado, em que os fatores foram a dieta (n=4) e o sexo (n=2). Os dados de desenvolvimento corporal e consumo de alimento foram submetidos à análise de variância. Aos 56 dias de idade, os bezerros alimentados com leite integral e sucedâneo a 10% EE apresentaram diferença significativa no peso corporal e no ganho de peso médio diário (8-56 dias). Os bezerros que receberam leite integral apresentaram maior perímetro torácico e, após o desaleitamento, medidas de peso corporal, ganhos de peso médio diário (57 a 89 dias), perímetro torácico e altura na cernelha superiores às dos que receberam o sucedâneo. Na fase de aleitamento, o sucedâneo a 10% EE promoveu ganho de peso superior ao sucedâneo a 15 e 20% de EE na matéria seca e ganho de peso similar ao leite integral.<br>Twenty Jersey calves were used to investigate the effects of different ether extract levels of a commercial milk replacer on body weight, average daily weight gain, height at withers, heart girth, and starter intake from the 8th to the 90th day after birth. It was of particular interest to determine the optimum milk replacer ether extract level. This trial was conducted at EMBRAPA Clima Temperado, CPACT, from October 2000 to May 2001. Animals were assigned, according to their birth date, to one of four liquid diets as follows: whole milk (T1) or milk replacer plus different proportions of lard to yield 10 (T2), 15 (T3) or 20% (T4) ether extract on dry matter basis. Statistical analysis was performed as a randomized complete block design with an unbalanced factorial arrangement and diets (n=4) and sex (n=2) as factors. Data from body development and starter intake were both submitted to analysis of variance. Body weight at 56 days of age and average daily weight gain from eight to 56 days post-calving were significantly higher for animals receiving T1 and T2 than for those fed T3 and T4 liquid diets. In addition, heart girth at 56 days of age was greater on calves fed whole milk than on those fed milk replacer with different proportions of lard. After weaning, calves on T1 diet had increased body weight, average daily weight gain (57-89 days), heart girth, and height at withers compared to calves on milk replacer diets. In the weaning phase, feeding T2 to calves resulted in higher body weight gain than those fed T3 and T4 diets while no difference was observed comparing T2 andT1