Research Papers in Physics and Astronomy


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Published in Physical Review Letters 103, 231802 (2009). Copyright © 2009 The American Physical Society. Used by permission.


We present a direct measurement of the width of the W boson using the shape of the transverse mass distribution of Wev candidate events. Data from approximately 1 fb-1 of integrated luminosity recorded at √s = 1.96 TeV by the D0 detector at the Fermilab Tevatron pp collider are analyzed. We use the same methods and data sample that were used for our recently published W boson mass measurement, except for the modeling of the recoil, which is done with a new method based on a recoil library. Our result, 2.028 ± 0.072 GeV, is in agreement with the predictions of the standard model.

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