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ATLAS Collaboration(Aad, G. et al), Ahuja, S., Aikot, A., Cabrera Urban, S., Cantero, J., Carrion Martinez, C., et al. (2026). Search for decays of the Higgs boson into pair-produced pseudoscalar particles decaying into τ+τ-τ+τ- using pp collisions at √s=13 TeV with the ATLAS detector. New J. Phys., 28(6), 063801–24pp.
Abstract: A search for a pair of low-mass pseudoscalars a that promptly decay into tau-leptons is presented using 140 fb(-1) of proton-proton collision data at 13 TeV centre-of-mass energy recorded with the ATLAS detector at the Large Hadron Collider. The result is used to place constraints on exotic decays of the Higgs boson into four tau-leptons, H -> aa -> tau(+)tau(-)tau(+)tau(-). This search focuses on events with either one or two tau-leptons decaying into hadrons and neutrinos, and the remaining three or two tau-leptons decaying into either electron or muon and neutrinos. No significant excess is observed above the expected Standard Model background and upper limits at the 95% confidence level on B(H -> aa -> tau(+)tau(-)tau(+)tau(-)) are set ranging from 0.06 to 0.23, depending on the mass m(a) ranging from 15 to 60 GeV.
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LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Jashal, B. K., Libralon, S., Lucio Martinez, M., et al. (2026). B-jet fragmentation with B± → J/ψK± decays in √s=13 TeV pp collisions at LHCb. Phys. Rev. D, 113(11), 112006–21pp.
Abstract: The collinear and transverse-momentum-dependent jet fragmentation function and the radial profile for B-+/- mesons in jets are measured. The B-+/- mesons are reconstructed through the J/psi(-> mu(+) mu(-))K-+/- decay channel using proton-proton collision data collected during 2016-2018 with the LHCb detector at a centerof-mass (c.m.) energy of root s = 13 TeV, corresponding to an integrated luminosity of 5.4 fb(-1). The results complement recent measurements of jet fragmentation functions for heavy-flavor hadrons and suggest a growing contribution of gluon fragmentation to B-+/- mesons as the jet transverse momentum increases.
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Camacho Juarez, J. M., Moreno, M., & Vos, M. (2026). Quantum entanglement and radiation effects at linear colliders. Eur. Phys. J. Plus, 141(7), 770–5pp.
Abstract: Quantum entanglement, a fundamental aspect of quantum mechanics and quantum field theory, plays a central role in areas such as cryptography, quantum computation, and information theory. Recent measurements by the ATLAS and CMS collaborations have demonstrated entanglement in top-antitop quark pairs produced at the LHC, motivating further exploration of this phenomenon. This work investigates the entanglement properties of top-antitop systems at future e+e- colliders, highlighting two key findings: (i) Entanglement becomes significant at center-of-mass energies above 400 GeV, and (ii) its magnitude depends on the initial beam polarization, which can be tuned to enhance the quantum correlations by up to 9% between the eL+eR- and the eR+eL- case. We further analyze the impact of single final-state gluon radiation on entanglement, finding that high-energy emissions can substantially reduce it, potentially transforming an entangled state into a separable one. A complementary statistical analysis shows that this radiation-induced entanglement loss, interpreted as an experimentally accessible indicator of gluon-induced decoherence effects, could be observed with a significance exceeding 5 sigma at the expected LCF configurations, using hadronic polarimetry in leptonic+hadronic and fully hadronic channels. Consistent results are obtained for two robust quantum observables, establishing linear colliders as gateways to further investigate quantum entanglement and probe signatures of quantum decoherence in particle physics in the decades to come.
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Orrigo, S. E. A., Tain, J. L., Mont-Geli, N., Tarifeño-Saldivia, A., Fraile, L. M., Grieger, M., et al. (2026). Measurement of the ambient neutron flux and spectral distribution at the Canfranc Underground Laboratory. Eur. Phys. J. C, 86(7), 834–5pp.
Abstract: We report on the measurement of the ambient neutron flux and its energy distribution over a broad range of neutron energies, conducted in Hall A of the Canfranc Underground Laboratory using the High Efficiency Neutron Spectrometry Array (HENSA), with a total livetime of 248 days. In particular, we obtained a thermal neutron flux of 3.4(2)& times;10-6 cm -2 s -1 and a total energy-integrated flux of 14.8(2)& times;10-6 cm -2 s -1 . This work represents the first long-term measurement of the ambient neutron flux that includes a full spectral characterization across a wide energy interval (from 10-4 eV to 20 MeV), performed in an underground laboratory to date. The results are relevant for rare-event search experiments located underground, ranging from nuclear astrophysics to astroparticle physics.
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TAMBO collaboration(Argüelles, C. A. et al), & Garcia, A. (2026). Measuring the high-energy neutrino sky using the deep-valley neutrino observatory TAMBO. Nat. Astron., 10, 947–951.
Abstract: Although the field of neutrino astronomy has blossomed in the past decade, physicists have struggled to fully map the high-energy neutrino sky. The Tau Air-shower Mountain-Based Observatory (TAMBO), a mountain-based neutrino observatory, aims to solve that issue-and find clues of new physics along the way.
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