科研之友
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摘要
We investigate a number of observables that are and will be instrumental in the exploration of t (t) over bar production and decay at the Tevatron and the LHC. For this analysis we made a computer program that incorporates besides the NLO QCD corrections to t (t) over bar production and decay also mixed weak-QCD corrections to the production amplitudes, and that allows for studies of correlated versus uncorrelated t (t) over bar events. In this paper we analyze and compute observables mostly for dileptonic t (t) over bar final states to next-to-leading order in the strong and weak gauge couplings (NLOW), with selection cuts. We calculate charge asymmetries of the top quark and of l = e, u and we compare, where possible, with experimental results. We show that top-quark spin correlations affect a leptonic pair asymmetry (which has not been measured so far) by similar to 7%. We determine several dileptonic angular correlations, which reflect t (t) over bar spin correlations, namely the beam, off-diagonal and helicity correlation, and the opening angle distribution (defined in the t, (t) over bar rest frames) when selection cuts are applied. Our NLOW predictions for the beam, off-diagonal, and helicity correlation for the Tevatron agree with recent measurements by the CDF and DO experiments. In addition we make predictions for estimators of these correlations as functions of M(t (t$) over bar). These estimators may prove useful for the Tevatron and also in the early rounds of LHC data-analyses, where the event numbers will not be abundant. Furthermore, we compute to NLOW in the gauge couplings two dilepton angular correlations that are defined in the laboratory frame, for correlated and uncorrelated t (t) over bar events at the LHC. Finally, based on our SM results, we identify several observables that allow to search for non-standard parity- and CP-violating interactions, especially with future LHC data.
- 出版日期2010-9-21
- 单位山东大学
