Quadrupole and octupole collectivity in the semi-magic nucleus 80206 Hg126

We report a measurement of decay-time-dependent charge-parity (

C P

) asymmetries in

B^{0} \to K_{S}^{0} K_{S}^{0} K_{S}^{0}

decays. We use

387 \times 10^{6}

B \bar{B}

pairs collected at the

ϒ (4 S)

resonance with the Belle II detector at the SuperKEKB asymmetric-energy electron-positron collider. We reconstruct 220 signal events and extract the

C P

-violating parameters

S

and

C

from a fit to the distribution of the decay-time difference between the two

B

mesons. The resulting confidence region is consistent with previous measurements in

B^{0} \to K_{S}^{0} K_{S}^{0} K_{S}^{0}

and

B^{0} \to (c \bar{c}) K^{0}

decays and with predictions based on the standard model. Published by the American Physical Society2024