Observation of time-dependent CP violation and measurement of the branching fraction of B0→J/ψπ0 decays

Abstract

We present a measurement of the branching fraction and time-dependent charge-parity (CP) decay-rate asymmetries in B0→J/ψπ0 decays. The data sample was collected with the Belle II detector at the SuperKEKB asymmetric e+e− collider in 2019–2022 and contains (387±6)×106 BB¯ meson pairs from ϒ(4S) decays. We reconstruct 392±24 signal decays and fit the CP parameters from the distribution of the proper-decay-time difference of the two B mesons. We measure the branching fraction to be (B0→J/ψπ0)=(2.00±0.12±0.09)×10−5 and the direct and mixing-induced CP asymmetries to be CCP=0.13±0.12±0.03 and SCP=−0.88±0.17±0.03, respectively, where the first uncertainties are statistical and the second are systematic. We observe mixing-induced CP violation with a significance of 5.0 standard deviations for the first time in this mode.

Related Papers

• → Measurement on $$\pi ^ + \pi ^ - \pi ^0 \pi ^0 $$ , $$\pi ^ + \pi ^ - \pi ^ + \pi ^ - \pi ^0 $$ , $$\pi ^ + \pi ^ - \pi ^ + \pi ^ - \pi ^0 \pi ^0 $$ , $$\pi ^ + \pi ^ - \pi ^ + \pi ^ - \pi ^ + \pi ^ - $$ production cross-sections in e+e− annihilation at (1.45÷1.80) GeV c.m. Energyproduction cross-sections in e+e− annihilation at (1.45÷1.80) GeV c.m. Energy(1981)11 cited
• Experimental study of [pi]-p --> [pi]+[pi]-[pi]0n and [pi]+[pi]-[eta]n processes at 8.06 GeV/c(2007)
• Effects of $pi$-$pi$ Interaction on S- and p-Waves in $pi$-N Scattering; VLIYANIE $pi$$pi$-VZAIMODEISTVIYA NA S-i p-VOLNY $pi$-N RASSEYANIYA(1962)
• Susquehanna Chorale Spring Concert "Roots and Wings"(2017)
• Energy-independent phase-shift analysis of the pi - pi 0 interaction from the reaction pi - p --> pi - pi 0 p(1977)