ATLAS sensitivity to Wtb anomalous couplings in top quark decays
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Società Italiana di Fisica
Top quarkAtlas detector
Aguilar-Saavedra, J.A.; et al. ATLAS sensitivity to Wtb anomalous couplings in top quark decays. European Physical Journal C, 53(4): 689-699 (2008). [http://hdl.handle.net/10481/30672]
PatrocinadorThis work has been performed within the ATLAS Collaboration, and we thank collaboration members for helpful discussions. We have made use of the physics analysis framework and tools which are the result of collaborationwide efforts. The work of J.A.A.-S. has been supported by a MEC Ramón y Cajal contract and project FPA2006-05294, by Junta de Andalucía projects FQM 101 and FQM 437 and by the European Community’s Marie-Curie Research Training Network under contract MRTN-CT-2006-035505 “Tools and Precision Calculations for Physics Discoveries at Colliders”. The work of J.C., N.C. (grant SFRH/BD/13936/2003), A.O. and F.V. (grant SFRH/BD/18762/2004) has been supported by Fundaçao para a Ciência e a Tecnologia.
We study the sensitivity of the ATLAS experiment to Wtb anomalous couplings in top pair production with semileptonic decay, pp→tt̄→W+bW-b̄ with one of the W bosons decaying leptonically and the other hadronically. Several observables are examined, including the W helicity fractions and new quantities recently introduced, such as the ratios of helicity fractions and some angular asymmetries defined in the W rest frame. The dependence on anomalous couplings of all these observables has been previously obtained. In this work we show that some of the new observables also have smaller systematic uncertainties than the helicity fractions, with a similar or stronger dependence on anomalous couplings. Consequently, their measurement can significantly improve the limits on anomalous couplings. Moreover, the most sensitive measurements can be combined. In this case, the precision achieved in the determination of Wtb anomalous couplings can be of a few percent in the semileptonic channel alone.