# DPF 2011

8-13 August 2011
Rhode Island Convention Center
US/Eastern timezone

## Measurement of the W boson helicity in top quark decays using 5.4 fb-1 of ppbar collision data

Aug 12, 2011, 9:20 AM
20m
553 (Rhode Island Convention Center)

### 553

#### Rhode Island Convention Center

Parallel contribution Top Quark Physics

### Speaker

Amitabha Das (University of Arizona)

### Description

We present a measurement of the helicity of the W boson produced in top quark decays using $t\bar{t}$ ~decays in the $\ell+$jets and dilepton final states selected from a sample of 5.4 fb$^{-1}$ of collisions recorded using the D0 detector at the Fermilab Tevatron $p\bar{p}$ collider. We measure the fractions of longitudinal and right-handed $W$ bosons to be $f_0 = 0.669 \pm 0.102 \mbox{ } [ \pm 0.078 \hbox{ (stat.)} \pm 0.065 \hbox{ (syst.)}]$ and $f_+ = 0.023 \pm 0.053\mbox{ }[\pm 0.041 \hbox{ (stat.)} \pm 0.034 \hbox{ (syst.)}]$, respectively. This result is consistent at the 98\% level with the standard model. A measurement with $f_0$ fixed to the value from the standard model yields $f_+ = 0.010 \pm 0.037 \mbox{ }[\pm 0.022 \hbox{ (stat.)} \pm 0.030 \hbox{ (syst.). }]$

### Primary author

Amitabha Das (University of Arizona)

 Slides