Based on https://arxiv.org/abs/2403.09452.
The absolute and normalised differential cross-sections are measured for several variables characterising the photon, lepton and jet kinematics as well as the angular separation between those objects. The observables are found to be in good agreement with the Monte Carlo predictions. The photon transverse momentum differential distribution is used...
Based on https://arxiv.org/abs/2403.06742.
The analysis targets events containing two muons with the same electric charge, a hadronically decaying τ-lepton and at least one jet, with exactly one b-tagged jet, produced by a μτqt interaction. Agreement with the Standard Model expectation within 1.6σ is observed, and limits are set at the 95% CL on the charged-lepton-flavour violation...
Reference: https://arxiv.org/abs/2402.18461 (TOP-22-003)
A search is presented for baryon number violating interactions in top quark production and decay. Upper limits are placed on the strength of baryon number violating couplings. For the first time the production of single top quarks via baryon number violating interactions is studied. This allows the search to set the most stringent...
Based on https://arxiv.org/abs/2402.06528
We study the effects of four-heavy-quark operators in the production of top quarks in the framework of the Standard Model Effective Field Theory (SMEFT) at the LHC. In particular, we compute for the first time the total contribution of the four-top-quark operator which enters only at the one-loop level in the top-quark pair production process....
Reference: https://arxiv.org/abs/2402.08713
A combination of fifteen top quark mass measurements performed by the ATLAS and CMS experiments at the LHC is presented. The data sets used correspond to an integrated luminosity of up to 5 and 20−1 of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, respectively.
Reference: https://arxiv.org/abs/2311.05509
We extract the top-quark mass value in the on-shell renormalization scheme from the comparison of theoretical predictions for pp→tt_bar+X at next-to-next-to-leading order (NNLO) QCD accuracy with experimental data collected by the ATLAS and CMS collaborations for absolute total, normalized single-differential and double-differential...
Reference: https://arxiv.org/abs/2404.09856
To control the scheme of the Monte-Carlo (MC) top quark mass parameter several ingredients are mandatory, concerning the knowledge of the IR dynamics of the top mass sensitive observable, the MC parton shower and the MC hadronization evolution. I discuss these ingredients and their interplay for the simple case of 2-jettiness for boosted top...
A search for flavour-changing neutral-current interactions involving the top quark, the Higgs boson and an up-type quark (q = u,c) with the ATLAS detector at the Large Hadron Collider is presented. The analysis considers leptonic decays of the top quark along with Higgs-boson decays into two W bosons, two Z bosons or a τ+τ− pair. It focuses on final states containing either two leptons...
Reference: https://arxiv.org/abs/2403.02133
The ratio of branching ratios of the W boson to muons and electrons, Rμ/eW = B(W→μν)/B(W→eν), has been measured using 140 fb−1 of pp collision data at s√=13 TeV collected with the ATLAS detector at the LHC, probing the universality of lepton couplings.
Reference: https://arxiv.org/abs/2402.08652
In this talk, I will discuss a possible between dark matter (DM) and one-loop induced top quark FCNC decays. In a simplified t-channel DM model that extends the SM with one colored scalar mediator and one right-handed fermion both odd under an ad-hoc Z_2 symmetry, I will show that that moderate to large rates of the top quark FCNC decays are...
Reference: CMS-PAS-TOP-23-008 (https://cds.cern.ch/record/2893766)
Reference: CMS-PAS-TOP-23-004 (https://cds.cern.ch/record/2893862)
Reference: https://arxiv.org/abs/2309.01937
We present the first complete high-precision QCD corrections to the inclusive decay width Γ_t, the W-helicity fractions f_{L,R,0} and semi-inclusive distributions for the top-quark decay process t → b + W+ + X_QCD at NNNLO in the strong coupling constant α_s.
Reference: CMS-PAS-TOP-23-005 (https://cds.cern.ch/record/2895219)
Reference: https://arxiv.org/abs/2312.09794
We discuss the possibility that light new physics in the top quark sample at the LHC can be found by investigating with greater care well known kinematic distributions, such as the invariant mass m_bℓ of the b-jet and the charged lepton in fully leptonic tt_bar events. We demonstrate that new physics can be probed in the rising part of the already...
Reference: https://arxiv.org/abs/2401.10678
Triggered by the observation of four top-quark production at the LHC by the ATLAS and CMS collaboration we report on the calculation of the next-to-leading order QCD corrections to the Standard Model process pp→tt¯tt¯ in the 4ℓ top-quark decay channel. We take into account higher-order QCD effects in both the production and decays of the four top...
Reference: CMS-PAS-TOP-23-001 (https://cds.cern.ch/record/2893854)
Entanglement is an intrinsic property of quantum mechanics and its measurement probes the current understanding of the underlying quantum nature of elementary particles at a fundamental level. A measurement of the extent of entanglement in top quark-antiquark events produced in proton-proton collisions at a center-of-mass...
