Measurement of Z0 → b decay properties

Abstract

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Composite vector leptoquarks ine+e−,γe, andMontalvo1, Éboli2 1993Phys. Rev. D

“…(3) Another indirect way to look for the vector leptoquark V eb is studying the forwardbackward asymmetry in the production of bb pairs. Recently at LEP, this asymmetry has been measured [10], and it is in agreement with the standard model prediction. Imposing that the contribution of this vector leptoquark to this reaction is at most of the size of the experimental error (5%), we can exclude a region of the plane M V × F , as it is shown by the dotted line in Fig.…”

Next-to-leading order analysis of inclusive and semi-inclusive polarized data

“…The new SMC data [25], which cover the same kinematical range as given by the inclusive measurements, superseded previous presentations with reduced uncertainties. From a more theoretical point of view, the complete NLO QCD corrections to spin-dependent semi-inclusive asymmetries have recently been computed in a consistent factorization scheme [26,27].…”

“…In order to avoid possible higher-twist contributions, we have taken into account only measurements with Q 2 > 1 GeV 2 given a total of 133 data points. As semi-inclusive data we take those recently presented by SMC [25], parameter is not well determined by the data, we allow it to vary between −0.1 and 0.1 as a compromise between data and theoretical expectations; when left free it varies between −5% and −40% without modifying significantly the χ 2 value. Therefore it is not possible yet to determine accurately the nonsinglet axial current a 8 from the existing data.…”

“…The reasons for this very small impact are, basically, the fact that semi-inclusive data has not reached yet the precision and statistical significance of the inclusive one, and also that the data sets are not completely independent. This can be seen either in the correlations between inclusive and semiinclusive asymmetries [25], and also in the fact that parametrizations obtained using only inclusive data give a very good description of the semi-inclusive asymmetries.…”

First Measurement of a Long-Lived π+π− Atom Lifetime

“…Estimated in this way, the population of long-lived states at the Be exit is with a very conservatively chosen error band (6.29 +0. 33 −0.13 ) · 10 −2 [31]. An additional correction to this value may arise from the accuracy of atom-atom cross sections.…”