Measurement of the helicity fractions of **W** bosons from top quark decays using fully reconstructed <script type="math/tex">t\overline{t}</script> events with CDF II

Abulencia, A.; Van Remortel, N.; et al.

doi:10.1103/PHYSREVD.75.052001

Publication

Title

Measurement of the helicity fractions of **W** bosons from top quark decays using fully reconstructed $t\overline{t}$ events with CDF II

Author

Abulencia, A.

Van Remortel, N.

et al.

Institution/Organisation

CDF Collaboration

Abstract

We present a measurement of the fractions F0 and F+ of longitudinally polarized and right-handed W bosons in top-quark decays using data collected with the CDF II detector. The data set used in the analysis corresponds to an integrated luminosity of approximately 318 pb-1. We select tt̅ candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle θ*, which is defined as the angle between the momentum of the charged lepton in the W boson rest frame and the W momentum in the top-quark rest frame. The cos⁡θ* distribution in the data is determined by full kinematic reconstruction of the tt̅ candidates. We find F0=0.85-0.22+0.15(stat)±0.06(syst) and F+=0.05-0.05+0.11(stat)±0.03(syst), which is consistent with the standard model prediction. We set an upper limit on the fraction of right-handed W bosons of F+<0.26 at the 95% confidence level.

Language

English

Source (journal)

Physical review : D : particles, fields, gravitation, and cosmology / American Physical Society. - Ridge, N.Y., 2004 - 2015

Physical review : D : particles and fields. - Lancaster, Pa, 1970 - 2003

Publication

Ridge, N.Y. : American Physical Society , 2007

ISSN

1550-7998 [print]

1550-2368 [online]

Volume/pages

75 :5 (2007) , p. 052001,1-052001,11