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Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/186476
Test of lepton universality with B 0 → K *0 ℓ + ℓ - decays
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A test of lepton universality, performed by measuring the ratio of the branching fractions of the B 0 → K *0 μ + μ - and B 0 → K *0 e + e - decays, {R}_{K^{*0}} , is presented. The K *0 meson is reconstructed in the final state K + π -, which is required to have an invariant mass within 100 MeV /c 2 of the known K *(892)0 mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of about 3 fb-1, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The ratio is measured in two regions of the dilepton invariant mass squared, q 2, to be {R}_{K^{*0}}= 0.66-+_{0.07}^{0.11}(stat)± 0.03(syst) for .045<{q}^2<1.1 GeV^2/{c}^4, 0.69-+_{0.07}^{0.11}(stat)± 0.05(syst) for 1.1<{q}^2<6.0 GeV^2/{c}^4. The corresponding 95.4% confidence level intervals are [0 .52 , 0 .89] and [0 .53 , 0 .94]. The results, which represent the most precise measurements of {R}_{K^{*0}} to date, are compatible with the Standard Model expectations at the level of 2.1-2.3 and 2.4-2.5 standard deviations in the two q 2 regions, respectively.
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CAMBONI, Alessandro, COQUEREAU, S., FERNANDEZ, G., GARRIDO BELTRÁN, Lluís, GASCON, D., GRACIANI DIAZ, Ricardo, GRAUGÉS POUS, Eugeni, MARIN BENITO, Carla, PICATOSTE OLLOQUI, Eduardo, RIVES MOLINA, Vicente josé, SANCHEZ GONZALO, D., ALFONSO ALBERO, Alejandro, CALVO GOMEZ, M., GIRONELLA GIRONELL, P., VAZQUEZ GOMEZ, R., LHCb Collaboration. Test of lepton universality with B 0 → K *0 ℓ + ℓ - decays. _Journal of High Energy Physics_. 2017. Vol. 2017, núm. 55, pàgs. 1-31. [consulta: 8 de gener de 2026]. ISSN: 1126-6708. [Disponible a: https://hdl.handle.net/2445/186476]