Zhang, G. et al, Algora, A., Nacher, E., Orrigo, S. E. A., Perez-Vidal, R. M., & Rubio, B. (2025). Approaching 100Sn: Structural evolution in 98,100Cd via lifetime measurements. Phys. Lett. B, 863, 139378–7pp.
Abstract: The lifetimes of low-lying excited states below the 8(+) seniority isomer were directly measured using fast timing detectors in the neutron-deficient isotopes Cd-98,Cd-100. This experiment was conducted with the DEcay SPECtroscopy (DESPEC) setup at GSI, where the ions of interest were produced via a fragmentation reaction and identified using the FRagment Separator (FRS) before being implanted in the AIDA active stopper system, and the gamma rays emitted during the de-excitation of isomeric states were detected by the LaBr3 FATIMA Array. The newly deduced values for the reduced transition probabilities were compared with shell-model calculations using different interactions and effective charges. The results indicate that, while Cd-98 aligns well with a seniority scheme description, in Cd-100 the transition strengths among low-lying states are not fully reproduced, and the nature of these states remains an open problem within the present theoretical description. Ultimately, a key element in the description of this region, crucial for nuclear physics and astrophysics, appears to be the proton-neutron term of the nuclear effective interaction.
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Bouchhar, N., Cabrera Urban, S., Cantero, J., et al. (2025). Constraint on the total width of the Higgs boson from Higgs boson and four-top-quark measurements in pp collisions at √s=13 TeV with the ATLAS detector. Phys. Lett. B, 861, 139277–21pp.
Abstract: This Letter presents a constraint on the total width of the Higgs boson (Gamma(H)) using a combined measurement of on-shell Higgs boson production and the production of four top quarks, which involves contributions from off-shell Higgs boson-mediated processes. This method relies on the assumption that the tree-level Higgs-top Yukawa coupling strength is the same for on-shell and off-shell Higgs boson production processes, thereby avoiding any assumptions about the relationship between on-shell and off-shell gluon fusion Higgs production rates, which were central to previous measurements. The result is based on up to 140 fb(-1) of proton-proton collisions at a centre-of-mass energy of root s = 13 TeV collected with the ATLAS detector at the Large Hadron Collider. The observed (expected) 95% confidence level upper limit on Gamma(H) is 450 MeV (75 MeV). Additionally, considering the constraint on the Higgs-top Yukawa coupling from loop-induced Higgs boson production and decay processes further yields an observed (expected) upper limit of 160 MeV (55 MeV).
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Gao, F., Miramontes, A. S., Papavassiliou, J., & Pawlowski, J. M. (2025). Heavy-light mesons from a flavour-dependent interaction. Phys. Lett. B, 863, 139384–8pp.
Abstract: We introduce a new framework for the physics of heavy-light mesons, whose key element is the effective incorporation of flavour-dependent contributions into the corresponding bound-state and quark gap equations. These terms originate from the fully-dressed quark-gluon vertices appearing in the kernels of these equations, and provide a natural distinction between “light” and “heavy” quarks. In this approach, only the classical form factor of the quark-gluon vertex is retained, and is evaluated in the so-called “symmetric” configuration. The standard Slavnov-Taylor identity links this form factor to the quark wave-function, allowing for the continuous transition from light to heavy quarks through the mere variation of the current quark mass in the gap equation. The method is used to compute the masses and decay constants of specific pseudoscalars and vector heavy-light systems, showing good overall agreement with both experimental data and lattice simulations.
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., et al. (2024). Measurement of t-channel single-top-quark production in pp collisions at √s=5.02 TeV with the ATLAS detector. Phys. Lett. B, 854, 138726–22pp.
Abstract: The observation of the electroweak production of single-top-quarks is made using 255 pb(-1) of proton-proton collision data recorded at root s = 5.02 TeV with the ATLAS detector at the Large Hadron Collider. An event selection is used to identify single-top-quark candidates arising from..-channel production with the top quark decaying semi-leptonically. Events passing the selection are then used to measure the inclusive cross-section for the combined production of single-top-quarks and antiquarks, sigma(tq + (t) over barq), and the ratio R-t between these two. They are measured to be sigma(tq + (t) over barq) = 27.1(-4.1)(+4.4)(stat.)(-3.7)(+4.4)(syst.) pb and R-t = 2.73(-0.82)(+1.43)(stat.)(-0.29)(+1.01)(syst.). The individual single-top-quark (tq) and single-top-antiquark ((t) over barq) production cross-sections are measured to be sigma(tq) = 19.8(-3.1)(+3.9)(stat.)(-2.2)(+2.9)(syst.) pb and sigma((t) over barq) = 7.3(-2.1)(+3.2)(stat.)(-1.5)(+2.8)(syst.) pb. All measurements are in good agreement with the Standard Model predictions.
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Song, J., Yang, Z. Y., & Oset, E. (2025). Searching for signals of an exotic I=1,JP=2+ state of D*K* nature and the structure of the Pc(4312) in the Λb→Σc plus plus D-K- reaction. Phys. Lett. B, 861, 139294–7pp.
Abstract: This paper investigates the decay process Lambda-Sigma++-- with the objective of finding a predicted molecular state with isospin = 1, = 2+ of nature, plus finding support for the (4312) state as made out of Sigma. The mass distribution of the -- system shows distinct features as a consequence of the existence of this 2+ state, while the Sigma distribution exhibits a significant peak near the threshold, much bigger than phase space expectations, which is linked to our assumed Sigma nature of the (4312) state below the Sigma threshold. The reaction has been measured at LHCb Collaboration, but only the branching ratio is measured. The present study shows that much valuable information can be obtained about the predicted 2+ (2834) of nature and the (4312) states from the measurements of the mass distributions in this reaction, which will be accessible in the planned updates of LHCb.
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