Lancaster, M;
Nurse, E;
Waters, DCDFC;
(2007)
Measurement of the helicity fractions of W bosons from top quark decays using fully reconstructed ttbar events with CDF II.
Physical Review D
, 75
(5)
, Article 052001. 10.1103/PhysRevD.75.052001.
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Abstract
We present a measurement of the fractions F 0 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 t ¯ t 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 t ¯ t candidates. We find F 0 = 0.85 + 0.15 − 0.22 ( stat ) ± 0.06 ( syst ) and F + = 0.05 + 0.11 − 0.05 ( 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.
| Type: | Article |
|---|---|
| Title: | Measurement of the helicity fractions of W bosons from top quark decays using fully reconstructed ttbar events with CDF II |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1103/PhysRevD.75.052001 |
| Publisher version: | http://dx.doi.org/10.1103/PhysRevD.75.052001 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/131820 |
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