We present a determination of the Cabibbo-Kobayashi-Maskawa matrix element |V-cb| from the decay B -> Dl nu(l) using a 365 fb(-1) e(+)e(-) -> Upsilon(4S) -> B (B) over bar data sample recorded by the Belle II experiment at the SuperKEKB collider. The semileptonic decay of one B meson is reconstructed in the modes B-0 -> D-(-> K+pi(-)pi(-))l(+)nu(l) and B+ -> (D) over bar (0)(-> K+ pi(-))l(+)nu(l), where l denotes either an electron or a muon. Charge conjugation is implied. The second B meson in the Upsilon(4S) event is not reconstructed explicitly. Using an inclusive reconstruction of the unobserved neutrino momentum, we determine the recoil variable w = v(B) . v(D), where v(B) and v(D) are the four-velocities of the B and D mesons. We measure the total decay branching fractions to be B(B-0 -> D(-)l(+)nu(l)) = (2.06 +/- 0.05(stat) +/- 0.10(sys))% and B(B+ -> (D) over bar (0)l(+)nu(l)) = (2.31 +/- 0.04(stat) +/- 0.09(sys))%. We probe lepton flavor universality by measuring B(B -> De nu(e))/B(B -> D mu nu(mu)) = 1.020 +/- 0.020(stat) +/- 0.022(sys). Fitting the partial decay branching fraction as a function of w and using the average of lattice QCD calculations of the B -> D form factor, we obtain |V-cb| = (39.2 +/- 0.4(stat) +/- 0.6(sys) +/- 0.5(th)) x 10(-3).
Determination of |Vcb| using B → Dℓνl decays at Belle II
F. Bianchi;A. Boschetti;M. Destefanis;M. Maggiora;S. Marcello;S. Spataro;F. Testa;
2025-01-01
Abstract
We present a determination of the Cabibbo-Kobayashi-Maskawa matrix element |V-cb| from the decay B -> Dl nu(l) using a 365 fb(-1) e(+)e(-) -> Upsilon(4S) -> B (B) over bar data sample recorded by the Belle II experiment at the SuperKEKB collider. The semileptonic decay of one B meson is reconstructed in the modes B-0 -> D-(-> K+pi(-)pi(-))l(+)nu(l) and B+ -> (D) over bar (0)(-> K+ pi(-))l(+)nu(l), where l denotes either an electron or a muon. Charge conjugation is implied. The second B meson in the Upsilon(4S) event is not reconstructed explicitly. Using an inclusive reconstruction of the unobserved neutrino momentum, we determine the recoil variable w = v(B) . v(D), where v(B) and v(D) are the four-velocities of the B and D mesons. We measure the total decay branching fractions to be B(B-0 -> D(-)l(+)nu(l)) = (2.06 +/- 0.05(stat) +/- 0.10(sys))% and B(B+ -> (D) over bar (0)l(+)nu(l)) = (2.31 +/- 0.04(stat) +/- 0.09(sys))%. We probe lepton flavor universality by measuring B(B -> De nu(e))/B(B -> D mu nu(mu)) = 1.020 +/- 0.020(stat) +/- 0.022(sys). Fitting the partial decay branching fraction as a function of w and using the average of lattice QCD calculations of the B -> D form factor, we obtain |V-cb| = (39.2 +/- 0.4(stat) +/- 0.6(sys) +/- 0.5(th)) x 10(-3).| File | Dimensione | Formato | |
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