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) over bar candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle theta(*), 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 theta(*) distribution in the data is determined by full kinematic reconstruction of the t (t) over bar candidates. We find F(0)=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.

A., A., J., A., T., A., T., A., M. G., A., D., A., et al. (2007). Measurement of the helicity fractions of W bosons from top quark decays using fully reconstructed t(t)over-bar events with CDF II. PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY, 75(5), 052001-1-052001-11 [10.1103/PhysRevD.75.052001].

Measurement of the helicity fractions of W bosons from top quark decays using fully reconstructed t(t)over-bar events with CDF II

CIOCCI, MARIA AGNESE;
2007-01-01

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) over bar candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle theta(*), 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 theta(*) distribution in the data is determined by full kinematic reconstruction of the t (t) over bar candidates. We find F(0)=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.
2007
A., A., J., A., T., A., T., A., M. G., A., D., A., et al. (2007). Measurement of the helicity fractions of W bosons from top quark decays using fully reconstructed t(t)over-bar events with CDF II. PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY, 75(5), 052001-1-052001-11 [10.1103/PhysRevD.75.052001].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/36319
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