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Pich, A. (2021). Challenges for tau physics at the TeraZ. Eur. Phys. J. Plus, 136(11), 1117–8pp.
Abstract: The very high statistics, low backgrounds and clean back-to-back kinematics of a TeraZ facility would provide an optimal laboratory for precision measurements of the tau properties. A few important topics in tau physics where very relevant contributions could be made are highlighted.
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Desai, N., Domingo, F., Kim, J. S., Ruiz de Austri, R., Rolbiecki, K., Sonawane, M., et al. (2021). Constraining electroweak and strongly charged long-lived particles with CheckMATE. Eur. Phys. J. C, 81(11), 968–19pp.
Abstract: Long-lived particles have become a new frontier in the exploration of physics beyond the Standard Model. In this paper, we present the implementation of four types of long-lived particle searches, viz. displaced leptons, disappearing track, displaced vertex with either muons or with missing transverse energy, and heavy charged tracks. These four categories cover the signatures of a large range of physics models. We illustrate their potential for exclusion and discuss their mutual overlaps in mass-lifetime space for two simple phenomenological models involving either a U(1)-charged or a coloured scalar.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2021). Angular analysis of the rare decay B-s(0) -> phi mu(+)mu(-). J. High Energy Phys., 11(11), 043–45pp.
Abstract: An angular analysis of the rare decay B-s(0) -> phi mu(+)mu(-) is presented, using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13TeV, corresponding to an integrated luminosity of 8.4 fb(-1). The observables describing the angular distributions of the decay B-s(0) -> phi mu(+)mu(-) are determined in regions of q(2), the square of the dimuon invariant mass. The results are consistent with Standard Model predictions.
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Holz, S., Plenter, J., Xiao, C. W., Dato, T., Hanhart, C., Kubis, B., et al. (2021). Towards an improved understanding of eta -> gamma*gamma *. Eur. Phys. J. C, 81(11), 1002–15pp.
Abstract: We argue that high-quality data on the reaction e(+)e(-) -> pi(+) pi(-) eta will allow one to determine the doubly-virtual form factor eta -> gamma*gamma* in a model-independent way with controlled accuracy. This is an important step towards a reliable evaluation of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of themuon. When analyzing the existing data for e(+) e(-) -> pi(+) pi(-) eta for total energies squared k(2) > 1GeV(2), we demonstrate that the effect of the a(2) meson provides a natural breaking mechanism for the commonly employed factorization ansatz in the doubly-virtual form factor F-eta gamma*gamma* (q(2), k(2)). However, better data are needed to draw firm conclusions.
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Lin, J. X., Li, J. T., Jiang, S. J., Liang, W. H., & Oset, E. (2021). The D-s(+) -> a(0)(980)e(+)nu(e) reaction and the a(0)(980) – f(0)(980) mixing. Eur. Phys. J. C, 81(11), 1017–8pp.
Abstract: We perform a study of the D-s(+) -> a(0)(980) (f(0)(980))e(+)nu(e) reactions investigating the different sources of isospin violation which make the production of the a0(980) possible. We find that loops involving kaons in the production mechanism provide a source of isospin violation since they do not cancel due to the different mass of charged and neutral kaons, but we also find that the main source comes from the breaking of isospin in the meson-meson transition T matrices, which contain information on the nature of the low lying scalar mesons. The reaction is thus very sensitive to the nature of the a(0)(980) and f(0)(980) resonances. Our results are consistent with the present upper bound for a(0)(980) production and only a factor three smaller, indicating that future runs with more statistics should find actual numbers for this reaction from where we can learn more about the origin of the scalar resonances and their nature.
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