Jet Reconstruction

In recent analyses jets are usually reconstructed using the inclusive $k_t$ algorithm [147,148]. Different schemes are available [149] which define the merging of two objects into a single object based on distance parameters, and the calculation of the 4-vector of the resulting jet. The distance parameters $d_{kl}$ are usually defined as momentum weighted distances in the $\eta$-$\phi$ plane, $d_{kl} = \min(p_{t,k}^2,p_{t,l}^2)((\Delta \eta)^2+(\Delta \phi)^2)$. In the $E$ recombination scheme the 4 vectors of the input objects are added to obtain the 4-vector of the massive jet. In the $p_t$ recombination scheme only the 3-vector components of the input objects are taken into account and the obtained jets are made massless by setting their energy equal to the magnitude of their 3-momentum.

There are no theoretical arguments to prefer one or the other recombination scheme. For final states with beauty quarks the results of the different recombination schemes have been seen to give the same quantitative results to better than 10%.