On the Top Mass Reconstruction Using Leptons

Taking advantage of large top production rates at the LHC, the leptonic final states with J/psi are explored for a precise determination of the top quark mass. The top is partially reconstructed by combining the isolated lepton from the W with the J/psi from the decays of the corresponding b-quark. The method relies, to a large extent, on the proper Monte-Carlo description of top production and decay. The main emphasis is put on the expected systematics uncertainties. Mass me...

I discuss a few issues related to the systematic error on the top mass measurement at hadron colliders, due to hadronization effects. Special care is taken about the impact of bottom-quark fragmentation in top decays, especially on the reconstruction relying on final states with leptons and J/psi in the dilepton channel. I also debate the relation between the measured mass and its theoretical definition, and report on work in progress, based on the Monte Carlo simulation of f...

I discuss theoretical issues related to the top mass measurements in hadronic collisions.

We analyse the impact of matrix-element corrections to top decays in HERWIG on several observables related to the jet activity in t-tbar events at the Tevatron and at the LHC. In particular, we study the effects induced by the higher-order corrections to top decays on the top mass reconstruction using the recently proposed J/psi+lepton final states.

I briefly discuss some theoretical aspects of top mass measurements at the LHC. In particular, I illustrate a recent theoretical study performed using next-to-leading order (NLO) calculations interfaced to shower generators (NLO+PS) of increasing accuracy, interfaced to both Pythia8 and Herwig7 Monte Carlo generators.

I discuss a few selected topics related to the reconstruction of the mass of the top quark at hadron colliders. In particular, the relation between the measured top mass and theoretical definitions, such as the pole or MSbar mass, is debated. I will also summarize recent studies on the Monte Carlo uncertainty due to the fragmentation of bottom quarks in top decays.

We discuss recent improvement in the treatment of gluon radiation in top production and decay in e+e- processes according to the HERWIG event generator and show studies on the top mass reconstruction at the future Linear Collider.

We present an up-to-date overview of the problem of top quark mass determination. We assess the need for precision in the top mass extraction in the LHC era together with the main theoretical and experimental issues arising in precision top mass determination. We collect and document existing results on top mass determination at hadron colliders and map the prospects for future precision top mass determination at e+e- colliders. We present a collection of estimates for the ul...

The top-quark mass is a fundamental parameter of the Standard Model, as it plays a crucial role in the electroweak precision tests, stability of the vacuum and inflation. I review the method and the main results contained in a recent ATLAS analysis which measures the top mass by using the invariant mass of the leptons coming from W and B-hadron decays. The extracted top mass turns out to be the most precise single measurement by ATLAS.

A new method to measure the mass of the top quark at the LHC is presented. This method uses lepton energy distribution and ideally does not depend on the velocity distribution of the top quark. We perform a simulation analysis of the top quark mass reconstruction using this method at the leading order, taking account of experimental circumstances. We estimate the sensitivity of the mass determination. The results show that this method is viable in realistic experimental condi...