LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2019). Amplitude analysis of the B0 (s)! K0K0 decays and measurement of the branching fraction of the B0! K0K0 decay. J. High Energy Phys., 07(7), 032–31pp.
Abstract: The B0 K0K0 and B0 s K0K0 decays are studied using proton-proton collision data corresponding to an integrated luminosity of 3 fb. An untagged and timeintegrated amplitude analysis of B0 (s) (K+)(K) decays in two-body invariant mass regions of 150MeV/c2 around the K0 mass is performed. A stronger longitudinal polarisation fraction in the B0 K0K0 decay, fL = 0 : 724 0 : 051 (stat) 0 : 016 (syst), is observed as compared to fL = 0 : 240 0 : 031 (stat) 0 : 025 (syst) in the B0 s K0K0 decay. The ratio of branching fractions of the two decays is measured and used to determine B (B0 K0K0) = (8 : 0 0 : 9 (stat) 0 : 4 (syst)) x 10(-7).
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Cirigliano, V., Gisbert, H., Pich, A., & Rodriguez-Sanchez, A. (2020). Isospin-violating contributions to epsilon '/epsilon. J. High Energy Phys., 02(2), 032–44pp.
Abstract: The known isospin-breaking contributions to the K -> pi pi amplitudes are reanalyzed, taking into account our current understanding of the quark masses and the relevant non-perturbative inputs. We present a complete numerical reappraisal of the direct CP-violating ratio is an element of(')/is an element of, where these corrections play a quite significant role. We obtain the Standard Model prediction Re (is an element of(')/is an element of) = (14 +/- 5) <bold> </bold>10(-4), which is in very good agreement with the measured ratio. The uncertainty, which has been estimated conservatively, is dominated by our current ignorance about 1/N-C-suppressed contributions to some relevant chiral-perturbation-theory low-energy constants.
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Miralles, V., Miralles Lopez, M., Moreno Llacer, M., Peñuelas, A., Perello, M., & Vos, M. (2022). The top quark electro-weak couplings after LHC Run 2. J. High Energy Phys., 02(2), 032–24pp.
Abstract: Recent measurements at the Large Hadron Collider allow for a robust and precise characterisation of the electro-weak interactions of the top quark. We present the results of a global analysis at next-to-leading order precision including LHC, LEP/SLD and Tevatron data in the framework of the Standard Model Effective Field Theory. We include a careful analysis of the impact of correlations among measurements, as well as of the uncertainties in the Effective Field Theory setup itself. We find remarkably robust global fit results, with central values in good agreement with the Standard Model prediction, and 95% probability bounds on Wilson coefficients that range from +/- 0.35 to +/- 8 TeV-2. This result represents a considerable improvement over previous studies, thanks to the addition of differential cross-section measurements in associated production processes of top quarks and neutral gauge bosons.
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Boudet, S., Bombacigno, F., Olmo, G. J., & Porfirio, P. (2022). Quasinormal modes of Schwarzschild black holes in projective invariant Chern-Simons modified gravity. J. Cosmol. Astropart. Phys., 05(5), 032–29pp.
Abstract: We generalize the Chern-Simons modified gravity to the metric-affine case and impose projective invariance by supplementing the Pontryagin density with homothetic curvature terms which do not spoil topologicity. The latter is then broken by promoting the coupling of the Chern-Simons term to a (pseudo)-scalar field. The solutions for torsion and nonmetricity are derived perturbatively, showing that they can be iteratively obtained from the background fields. This allows us to describe the dynamics for the metric and the scalar field perturbations in a self-consistent way, and we apply the formalism to the study of quasi normal modes in a Schwarzschild black hole background. Unlike in the metric formulation of this theory, we show that the scalar field is endowed with dynamics even in the absence of its kinetic term in the action. Finally, using numerical methods we compute the quasinormal frequencies and characterize the late-time power law tails for scalar and metric perturbations, comparing the results with the outcomes of the purely metric approach.
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Coloma, P., Gonzalez-Garcia, M. C., Maltoni, M., Pinheiro, J. P., & Urrea, S. (2023). Global constraints on non-standard neutrino interactions with quarks and electrons. J. High Energy Phys., 08(8), 032–42pp.
Abstract: We derive new constraints on effective four-fermion neutrino non-standard interactions with both quarks and electrons. This is done through the global analysis of neutrino oscillation data and measurements of coherent elastic neutrino-nucleus scattering (CE & nu;NS) obtained with different nuclei. In doing so, we include not only the effects of new physics on neutrino propagation but also on the detection cross section in neutrino experiments which are sensitive to the new physics. We consider both vector and axial-vector neutral-current neutrino interactions and, for each case, we include simultaneously all allowed effective operators in flavour space. To this end, we use the most general parametrization for their Wilson coefficients under the assumption that their neutrino flavour structure is independent of the charged fermion participating in the interaction. The status of the LMA-D solution is assessed for the first time in the case of new interactions taking place simultaneously with up quarks, down quarks, and electrons. One of the main results of our work are the presently allowed regions for the effective combinations of non-standard neutrino couplings, relevant for long-baseline and atmospheric neutrino oscillation experiments.
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