Evidence for Diboson Production in the Lepton plus Heavy Flavor Jets Final State at CDF

TL;DR

This paper provides evidence at 3.08 sigma for diboson production in a lepton plus heavy flavor jets final state at CDF, confirming SM predictions and demonstrating advanced analysis techniques.

Contribution

It presents the first evidence of diboson production in this specific final state at a hadron collider and introduces improved methods for flavor discrimination and signal extraction.

Findings

Evidence at 3.08 sigma for diboson production

Consistent with Standard Model predictions

Enhanced analysis techniques applied to related searches

Abstract

This thesis presents the evidence, at 3.08 sigma, for the associate production of massive vector bosons (W and Z) in a final state with one lepton, MET and HF-tagged jets, measured with the complete CDF II dataset (9.4fb^-1 of data). The signals, both inclusive diboson production and WW vs WZ/ZZ separately, were extracted from the invariant mass distribution, M_inv(jet1,jet2), of single and double HF-tagged jet pairs. For single-tagged events the b quark vs c quark discrimination was obtained by using a bi-dimensional distribution M_inv(jet1,jet2) vs a flavor-serapator NN. The results, consistent with the SM prediction, confirm the CDF capability of identify a small signal in this challenging final state. In particular we also report the previous version of this analysis, performed with a dataset of 7.5fb^-1 that was the first evidence of diboson production in lnu+HF final state at a hadron collider. Beyond the pure testing of SM predicted processes, several of the techniques developed for this thesis were also applied to the WH search at CDF, with a relevant improvement of the sensitivity to this process.