"Invariant Mass Distribution of Jet Pairs Produced in Association with a W Boson in $p\bar{p}$ Collisions at $\sqrt{s}$ 1.96 TeV"

<!--HTML-->We present 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/c$^{2}$ mass range which is not described by current theoretical predictions within the statistical and systematic uncertainties. In particular we will discuss the properties of this excess.