Model-independent measurement of the W-boson helicity in top-quark decays at D0

We present the first model-independent measurement of the helicity of W bosons produced in top quark decays, based on a 1fb-1 sample of candidate tt̄ events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron pp̄ Collider. We reconstruct the angle θ* b...

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Bibliographic Details
Main Authors: Abazov, V, Abbott, B, Abolins, M, Acharya, B, Adams, M, Adams, T, Aguilo, E, Ahn, S, Ahsan, M, Alexeev, G, Alkhazov, G, Alton, A, Alverson, G, Alves, G, Anastasoaie, M, Ancu, L, Andeen, T, Anderson, S, Andrieu, B, Anzelc, MS, Amoud, Y, Arov, M, Arthaud, M, Askew, A, Asman, B
Format: Journal article
Language:English
Published: 2008
Description
Summary:We present the first model-independent measurement of the helicity of W bosons produced in top quark decays, based on a 1fb-1 sample of candidate tt̄ events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron pp̄ Collider. We reconstruct the angle θ* between the momenta of the down-type fermion and the top quark in the W boson rest frame for each top quark decay. A fit of the resulting cos θ* distribution finds that the fraction of longitudinal W bosons f0=0.425±0.166(stat)±0.102(syst) and the fraction of right-handed W bosons f+=0.119±0.090(stat)±0.053(syst), which is consistent at the 30% C.L. with the standard model. © 2008 The American Physical Society.