Invariant Mass Distribution of Jet Pairs Produced in Association with a W boson in ppbar Collisions at √s = 1.96 TeV

Primary authors: A. Annovia, P. Catastinib, V. Cavalierec, L. Ristorid
a: INFN Frascati, Italy; b: Harvard University; c: University of Illinois at Urbana-Champaign; d: INFN Pisa, Italy and Fermilab

We report a study of the invariant mass distribution of jet pairs produced in association with a W boson using data collected with the CDF detector which correspond to an integrated luminosity of 4.3 fb−1. The observed distribution has an excess in the 120-160 GeV/c2 mass range which is not described by current theoretical predictions within the statistical and systematic uncertainties. In this letter we report studies of the properties of this excess.

The published paper, Phys.Rev.Lett.106:171801 (2011), is available here and from arxiv here. The analysis was presented by Viviana Cavaliere at a Joint Experimental-Theoretical Seminar at FNAL on April-6. A copy of that talk is here.

We have updated this result and present further studies of the excess using additional data collected through to November 2010 corresponding to an integrated luminosity of 7.3 fb-1. The significance of the excess increases from 3.2 (for 4.3 fb-1) to 4.1 standard deviations consistent with expectation from the increase in the data sample size. The event selection and analysis methodology remain unchanged from the original 4.3 fb-1publication. The 7.3 fb-1 analysis is available here.

Additional studies of these W+dijet event are presented in the thesis of Viviana Cavaliere and below we include plots of additional distributions not included in the PRL submission due to space restrictions.