We present the third-order QCD prediction for the production of top antitop quark pairs in electron-positron collisions close to the threshold in the dominant S-wave state. We observe a significant reduction of the theoretical uncertainty and discuss the sensitivity to the top quark mass and width.
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http://dx.doi.org/10.1103/PhysRevLett.115.192001 | DOI Listing |
Phys Rev Lett
December 2024
Departament de Física Aplicada, Universitat d'Alacant, 03690 Alicante, Spain.
The existence of light QCD axions, whose mass depends on an additional free parameter, can lead to a new ground state of matter, where the sourced axion field reduces the nucleon effective mass. The presence of the axion field has structural consequences, in particular, it results in a thinner (or even prevents its existence) heat-blanketing envelope, significantly altering the cooling patterns of neutron stars. We exploit the anomalous cooling behavior to constrain previously uncharted regions of the axion parameter space by comparing model predictions with existing data from isolated neutron stars.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
School of Physics and Center of High Energy Physics, Peking University, Beijing 100871, China.
The BESIII Collaboration recently performed a precise measurement of the e^{+}e^{-}→DD[over ¯] Born cross sections, and confirmed the G(3900) structure reported by BABAR and Belle with high significance. We identify the G(3900) as the first P-wave DD[over ¯]^{*}/D[over ¯]D^{*} molecular resonance. The experimental and theoretical identification of the P-wave dimeson state holds paramount importance in enhancing our comprehension of the nonperturbative QCD and few-body physics.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Energy correlators provide a powerful observable to study fragmentation dynamics in QCD. We demonstrate that the leading nonperturbative corrections for projected N-point energy correlators are described by the same universal parameter for any N, which has already been determined from other event shape fits. Including renormalon-free nonperturbative corrections substantially improves theoretical predictions of energy correlators, notably the transition into the confining region at small angles.
View Article and Find Full Text PDFHeliyon
February 2024
Optics-Laser Science and Technology Research Center, Malek Ashtar University of Technology, Isfahan, Iran.
In this article, Hard-Wall AdS/QCD with 5 flavors is used to study pseudoscalar, vector and axial-vector meson. The mass and decay constants of , , , , , , , , , and as well as strong couplings of , , , , , , , , , , , , and vertices are estimated in this study. A comparison of the results of the masses, decay constants, and strong couplings with existing predictions is also made.
View Article and Find Full Text PDFPhys Rev Lett
November 2024
Physics Division, Argonne National Laboratory, Lemont, Illinois 60439, USA.
We report the first lattice QCD computation of pion and kaon electromagnetic form factors, F_{M}(Q^{2}), at large momentum transfer up to 10 and 28 GeV^{2}, respectively. Utilizing physical masses and two fine lattices, we achieve good agreement with JLab experimental results at Q^{2}≲4 GeV^{2}. For Q^{2}≳4 GeV^{2}, our results provide ab initio QCD benchmarks for the forthcoming experiments at JLab 12 GeV and future electron-ion colliders.
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