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A measurement is presented of differential cross sections for -channel single top quark and antiquark production in proton-proton collisions at a centre-of-mass energy of 13 by the CMS experiment at the LHC. From a data set corresponding to an integrated luminosity of 35.9 , events containing one muon or electron and two or three jets are analysed. The cross section is measured as a function of the top quark transverse momentum ( ), rapidity, and polarisation angle, the charged lepton and rapidity, and the of the boson from the top quark decay. In addition, the charge ratio is measured differentially as a function of the top quark, charged lepton, and boson kinematic observables. The results are found to be in agreement with standard model predictions using various next-to-leading-order event generators and sets of parton distribution functions. Additionally, the spin asymmetry, sensitive to the top quark polarisation, is determined from the differential distribution of the polarisation angle at parton level to be , in agreement with the standard model prediction.
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http://dx.doi.org/10.1140/epjc/s10052-020-7858-1 | DOI Listing |
Rep Prog Phys
August 2025
CERN, Geneva, Switzerland.
A search for resonances in top quark pair (tt-) production in final states with two charged leptons and multiple jets is presented, based on proton-proton collision data collected by the CMS experiment at the CERN LHC ats=13TeV, corresponding to 138 fb. The analysis explores the invariant mass of thett-system and two angular observables that provide direct access to the correlation of top quark and antiquark spins. A significant excess of events is observed near the kinematictt-threshold compared to the non-resonant production predicted by fixed-order perturbative quantum chromodynamics (pQCD).
View Article and Find Full Text PDFEur Phys J C Part Fields
June 2025
Theoretical Physics Division, Institute of High Energy Physics, Beijing, 100049 China.
We propose a method for probing CP-violation in the heavy (pseudo)scalar sector of an extended Higgs model, in which we make simultaneous use of the ( ) and interactions of a heavy Higgs state . The CP-even component of can be probed through the tree-level interaction, while the CP-odd component of can be probed if the final pair can be tested to form a state. We can then confirm CP-violation if both CP-even and CP-odd components of are discovered.
View Article and Find Full Text PDFPhys Rev Lett
June 2025
Institute for High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, A-1050 Vienna, Austria.
The top quark mass is a key parameter of the standard model, yet measuring it precisely at the Large Hadron Collider (LHC) is challenging. Inspired by the use of standard candles in cosmology, we propose a novel energy correlator-based observable, which directly accesses the dimensionless quantity m_{t}/m_{W}. We perform a Monte Carlo study to demonstrate the feasibility of the top mass extraction from Run 2, 3, and High-Luminosity LHC datasets.
View Article and Find Full Text PDFPhys Rev Lett
June 2025
CERN, Theoretical Physics Department, 1211 Geneva 23, Switzerland.
The current projected sensitivity on the electromagnetic coupling α_{em}(m_{Z}^{2}) represents a bottleneck for the precision electroweak program at FCC-ee. We propose a novel methodology to extract this coupling directly from Z-pole data. By comparing the differential distribution of electrons, muons, and positrons in the forward region, the approach achieves a projected statistical sensitivity below the 10^{-5} level, representing a significant improvement over other methods.
View Article and Find Full Text PDFPhys Rev Lett
May 2025
King's College London, Theoretical Particle Physics and Cosmology, Strand, London WC2R 2LS, United Kingdom.
Models of scalar field dark matter where the scalar is a dilaton have a special behavior, since nontrivial couplings, d, to matter result in a contribution to the potential for the field that is proportional to the trace of the stress-energy tensor. We look in more detail at the dilaton mass, m_{ϕ}, and initial conditions required to yield the correct relic abundance for couplings that are not already excluded by terrestrial experiments. In minimal models with only couplings accessible to terrestrial searches, we find that dilaton dark matter with m_{ϕ}≳10^{-10} eV requires couplings suppressed compared to constraints from equivalence principle tests and fifth force searches in order to not produce too much dark matter, improving on the strongest current experimental constraints by up to ∼O(10), with consequences for the proposed mechanical resonator dilaton dark matter searches.
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