Jet Vertex Charge Reconstruction Poster for LHCP 2015

B-jet reconstruction algorithms used so far in ATLAS data analyses do not provide the b-jet charge information, which could potentially play a major role in reducing the combinatorial backgrounds in final states with multiple b-jets. This missing point is addressed by the newly developed JetVertexCharge (JVC) algorithm presented in this poster. Inspired by the decay chain of B-hadrons, the JVC algorithm provides a multi-variate b-jet charge estimate relying on tracks, displaced vertices and muons contained in the jet. In this algorithm, the established concept of estimating jet charge as a transverse momentum weighted sum of track charges is used to reconstruct the charge of the jet as whole, as well as the charges of up to two displaced vertices in the jet, using the corresponding sets of associated tracks. The charge of the associated muon is interpreted as the same-sign or opposite-sign relative to the b-jet charge, according to its transverse momentum and geometrical match to vertices. Jets are divided into categories according to the availability of the basic reconstructed charges to best exploit the information at hand. Information from different categories is combined by the universal probability interpretation. The JVC discriminator outperforms each individual charge variable used. This concept has been tuned to the calorimeter jets containing at least one B-hadron, reconstructed in ttbar events simulated at 13 TeV. It can be applied to other types of jets as well.