Measurement of the resonant and CP components in $\overline{B}^0\rightarrow J/\psi \pi^+\pi^-$ decays

Understand

The resonant structure of the reaction $\overline{B}^0\rightarrow J/\psi \pi^+\pi^-$ is studied using data from 3 fb$^{-1}$ of integrated luminosity collected by the LHCb experiment, one-third at 7 Tev center-of-mass energy and the remainder at 8 Tev.

• The invariant mass of the $\pi^+\pi^-$ pair and three decay angular distributions are used to determine the fractions of the resonant and non-resonant components.
• Six interfering $\pi^+\pi^-$ states: $\rho(770)$, $f_0(500)$, $f_2(1270)$, $\rho(1450)$, $\omega(782)$ and $\rho(1700)$ are required to give a good description of invariant mass spectra and decay angular distributions.
• The positive and negative CP fractions of each of the resonant final states are determined.