Measurement of the top quark mass with lepton+jets final states using $$\mathrm {p}$$$$\mathrm {p}$$ collisions at $$\sqrt{s}=13\,\text {TeV} $$

Abstract

The mass of the top quark is measured using a sample of events collected by the CMS detector using proton-proton collisions at at the CERN LHC. Events are selected with one isolated muon or electron and at least four jets from data corresponding to an integrated luminosity of 35.9 . For each event the mass is reconstructed from a kinematic fit of the decay products to a hypothesis. Using the ideogram method, the top quark mass is determined simultaneously with an overall jet energy scale factor (JSF), constrained by the mass of the W boson in decays. The measurement is calibrated on samples simulated at next-to-leading order matched to a leading-order parton shower. The top quark mass is found to be . The dependence of this result on the kinematic properties of the event is studied and compared to predictions of different models of production, and no indications of a bias in the measurements are observed.

Neutral B -meson mixing from full lattice QCD at the physical point

“…The top quark mass to be used here is in the M S scheme, m t (m t ) [51]. Taking the current average [11] of direct experimental measurements [52][53][54] of the top quark mass (172.9(4) GeV) as the pole mass, gives m t (m t ) = 163.07(38) GeV using the 4-loop expressions in [55]. Evaluating the Inami-Lim function then gives: S 0 (4.116(19)) = 2.313 (8).…”

From the bottom to the top—reconstruction oftt̄ events with deep learning

“…Datasets comprised of millions of tt events allow for measurements with unprecedented precision. Examples are measurements of Standard Model (SM) parameters, such as the top-quark mass [2,3], and measurements of differential cross sections [4,5], which may unveil deviations from the SM predictions and provide evidence for physics beyond the SM.…”

“…It is often chosen because of its significant BR (≈ 30% if electrons and muons are considered) and its relatively low background. Several important measurements in the lepton+jets channel require a reconstruction of the tt decay, such as measurements of the top-quark mass [2,3], the W-helicity in top-quark decays [6,7], the tt charge asymmetry [8], and the top-quark width [9].…”

“…The added value of the work documented in this paper is threefold: We quantify the performance in reconstructing tt events with a DNN, which has a wide range of applications, as outlined above. We compare the performance to the standard approach (kinematic fitting), which has been used for many analyses at the LHC [2,3,[6][7][8][9][25][26][27][28]. We consider the simple sequential optimisation procedure that we perform and document ready-to-use for data analysis at LHC experiments.…”

Coherent showers in decays of colored resonances

“…IV. RESONANCE-AWARE MATCHING WITH POWHEG In order to seriously assess theoretical uncertainties, for example in the context of direct top mass measurements at the LHC [45][46][47][48][49][50][51][52][53], it is clearly desirable to attain the highest combined logarithmic and fixed-order accuracy that is currently available for the production of resonances.…”