The first test of lepton flavor universality between muons and electrons using B+→K+π+π-ℓ+ℓ- (ℓ=e, μ) decays is presented. The measurement is performed with data from proton-proton collisions collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb-1. The ratio of branching fractions between B+→K+π+π-e+e- and B+→K+π+π-μ+μ- decays is measured in the dilepton invariant-mass-squared range 1.1<7.0 GeV2/c4 and is found to be RKππ-1=1.31-0.17+0.18(stat) -0.09+0.12(syst), in agreement with the standard model prediction. The first observation of the B+→K+π+π-e+e- decay is also reported. [The LHCb Collaboration]
Test of Lepton Flavor Universality with B⁺→ K⁺ π⁺ π⁻ ℓ⁺ ℓ⁻ Decays / R. Aaij, A. . .A.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 134:18(2025 May 09), pp. 181803.1-181803.13. [10.1103/physrevlett.134.181803]
Test of Lepton Flavor Universality with B⁺→ K⁺ π⁺ π⁻ ℓ⁺ ℓ⁻ Decays
S. Cesare;C. Mancuso;D. Marangotto;A. Merli;N. Neri;G. Tonani;T. Tork;Z. Wang;
2025
Abstract
The first test of lepton flavor universality between muons and electrons using B+→K+π+π-ℓ+ℓ- (ℓ=e, μ) decays is presented. The measurement is performed with data from proton-proton collisions collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb-1. The ratio of branching fractions between B+→K+π+π-e+e- and B+→K+π+π-μ+μ- decays is measured in the dilepton invariant-mass-squared range 1.1<7.0 GeV2/c4 and is found to be RKππ-1=1.31-0.17+0.18(stat) -0.09+0.12(syst), in agreement with the standard model prediction. The first observation of the B+→K+π+π-e+e- decay is also reported. [The LHCb Collaboration]| File | Dimensione | Formato | |
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PhysRevLett134181803.pdf
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