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Abstract The first measurement of the jet mass $$m_{\\text {jet}}$$ m jet of top quark jets produced in $${\\mathrm{t}}\\overline{\\mathrm{t}} $$ t t ¯ events from pp collisions at $$\\sqrt{s}=8$$ s = 8 $$\\,\\text {TeV}$$ TeV is reported for the jet with the largest transverse momentum $$p_{\\mathrm{T}}$$ p T in highly boosted hadronic top quark decays. The data sample, collected with the CMS detector, corresponds to an integrated luminosity of 19.7 $$\\,\\text {fb}^{-1}$$ fb - 1 . The measurement is performed in the lepton+jets channel in which the products of the semileptonic decay $${\\mathrm{t}} \\rightarrow \\mathrm{b} \\mathrm {W}$$ t → b W with $$\\mathrm {W}\\rightarrow \\ell \\nu $$ W → ℓ ν where $$\\ell $$ ℓ is an electron or muon, are used to select $${\\mathrm{t}}\\overline{\\mathrm{t}} $$ t t ¯ events with large Lorentz boosts. The products of the fully hadronic decay $${\\mathrm{t}} \\rightarrow \\mathrm{b} \\mathrm {W}$$ t → b W with $$\\mathrm {W}\\rightarrow \\mathrm{q} \\overline{\\mathrm{q}} '$$ W → q q ¯ ′ are reconstructed using a single Cambridge–Aachen jet with distance parameter $$R=1.2$$ R = 1.2 , and $$p_{\\mathrm{T}} >400$$ p T > 400 $$\\,\\text {GeV}$$ GeV . The $${\\mathrm{t}}\\overline{\\mathrm{t}} $$ t t ¯ cross section as a function of $$m_{\\text {jet}}$$ m jet is unfolded at the particle level and is used to test the modelling of highly boosted top quark production. The peak position of the $$m_{\\text {jet}}$$ m jet distribution is sensitive to the top quark mass $$m_{{\\mathrm{t}}}$$ m t , and the data are used to extract a value of $$m_{{\\mathrm{t}}}$$ m t to assess this sensitivity.

Since the initial measurements of single-top quark production at the Tevatron in 2009, tremendous progress has been made at the LHC. While LHC Run 1 marked the beginning of a precision era for the single-top quark measurements in some of the main production mechanisms, LHC Run 2 witnessed the emergence and exploration of new processes associating top quark production with a neutral boson. In this paper, we review the measurements of the three main production mechanisms (t-channel, s-channel, and tW production), and of the associated production with a photon, a Z boson, or a Higgs boson. Differential cross-sections are measured for several of these processes and compared with theoretical predictions. The top quark properties that can be measured in single-top quark processes are scrutinized, such as Wtb couplings and top quark couplings with neutral bosons, and the polarizations of both the W boson and top quark. The effective field theory framework is emerging as a standard for interpreting property measurements. Perspectives for LHC Run 3 and the HL-LHC are discussed in the conclusions.

The production of four top quarks presents a rare process in the Standard Model that provides unique opportunities and sensitivity to Standard Model observables including potential enhancement of many popular new physics extensions. This article summarises the latest experimental measurements of the four-top quark production cross section at the LHC. An overview is provided detailing interpretations of the experimental results regarding the top quark Yukawa coupling in addition to the limits on physics beyond the Standard Model. Further, prospects for future measurements and opportunities offered by this challenging final state are given herein.

We present a next-to-leading order calculation of H+jet in gluon fusion including the effect of a finite top quark mass mt at large transverse momenta. Using the recently published two-loop amplitudes in the high energy expansion and our previous setup that includes finite mt effects in a low energy expansion, we are able to obtain mt-finite results for transverse momenta below 225 GeV and above 500 GeV with negligible remaining top quark mass uncertainty. The only remaining region that has to rely on the common leading order rescaling approach is the threshold region s ˆ 2 m t . We demonstrate that this rescaling provides an excellent approximation in the high pT region. Our calculation settles the issue of top quark mass effects at large transverse momenta. It is implemented in the parton level Monte Carlo code MCFM and is publicly available immediately in version 8.2.

Recent measurements in the top quark sector at the CERN Large Hadron Collider are discussed. This review discusses the most recent measurements of inclusive and differential top quark cross-sections in strong and electroweak production of top quarks and related measurements, such as top quark properties, as well as searches, including EFT approaches.

Recent measurements of the properties of the top quark at the CERN Large Hadron Collider are discussed. The results were measured for single and top quark pair production in their final states, including jets with either one or two leptons or only in hadronic final states. Top quark properties include angular correlations, top quark spin correlations, mass, and width. When looking towards the future, top quark properties open new and even interdisciplinary avenues for probing quantum information science.

The mass of the top quark is measured in a data set corresponding to 4.6 fb−1 of proton–proton collisions with centre-of-mass energy √s = 7 TeV collected by the ATLAS detector at the LHC. Events consistent with hadronic decays of top–antitop quark pairs with at least six jets in the final state are selected. The substantial background from multijet production is modelled with data-driven methods that utilise the number of identified b-quark jets and the transverse momentum of the sixth leading jet, which have minimal correlation. The top-quark mass is obtained from template fits to the ratio of three-jet to dijet mass. The three-jet mass is calculated from the three jets produced in a top-quark decay. Using these three jets the dijet mass is obtained from the two jets produced in the W boson decay. The top-quark mass obtained from this fit is thus less sensitive to the uncertainty in the energy measurement of the jets. A binned likelihood fit yields a top-quark mass of mt = 175.1 ± 1.4 (stat.) ± 1.2 (syst.) GeV.

In this study, the mass of the top quark is measured in a data set corresponding to 4.6 fb-1 of proton–proton collisions with centre-of-mass energy √s=7 TeV collected by the ATLAS detector at the LHC. Events consistent with hadronic decays of top–antitop quark pairs with at least six jets in the final state are selected. The substantial background from multijet production is modelled with data-driven methods that utilise the number of identified b-quark jets and the transverse momentum of the sixth leading jet, which have minimal correlation. The top-quark mass is obtained from template fits to the ratio of three-jet to dijet mass. The three-jet mass is calculated from the three jets produced in a top-quark decay. Using these three jets the dijet mass is obtained from the two jets produced in the W boson decay. The top-quark mass obtained from this fit is thus less sensitive to the uncertainty in the energy measurement of the jets. A binned likelihood fit yields a top-quark mass of mt=175.1±1.4(stat.) ±1.2(syst.) GeV.

The mass of the top quark is measured in a data set corresponding to 4.6  fb - 1 of proton–proton collisions with centre-of-mass energy s = 7  TeV collected by the ATLAS detector at the LHC. Events consistent with hadronic decays of top–antitop quark pairs with at least six jets in the final state are selected. The substantial background from multijet production is modelled with data-driven methods that utilise the number of identified b -quark jets and the transverse momentum of the sixth leading jet, which have minimal correlation. The top-quark mass is obtained from template fits to the ratio of three-jet to dijet mass. The three-jet mass is calculated from the three jets produced in a top-quark decay. Using these three jets the dijet mass is obtained from the two jets produced in the W boson decay. The top-quark mass obtained from this fit is thus less sensitive to the uncertainty in the energy measurement of the jets. A binned likelihood fit yields a top-quark mass of m t = 175.1 ± 1.4 (stat.) ± 1.2 (syst.) GeV .