Abstract
The first observation of the Bc+→J/ψπ+π0
B
c
+
→
J
/
ψ
π
+
π
0
decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 9 fb−1, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV. The ratio of its branching fraction relative to the Bc+→J/ψπ+
B
c
+
→
J
/
ψ
π
+
channel is measured to beBBc+→J/ψπ+BBc+→J/ψπ+π0=2.80±0.15±0.11±0.16,
B
B
c
+
→
J
/
ψ
π
+
π
0
B
B
c
+
→
J
/
ψ
π
+
=
2.80
±
0.15
±
0.11
±
0.16
,
where the first uncertainty is statistical, the second systematic and the third related to imprecise knowledge of the branching fractions for B+ → J/ψK*+ and Bc+→J/ψπ+
B
c
+
→
J
/
ψ
π
+
decays, which are used to determine the π0 detection efficiency. The π+π0 mass spectrum is found to be consistent with the dominance of an intermediate ρ+ contribution in accordance with a model based on QCD factorisation.</jats:p