Observation of the suppressed ADS modes $B^\pm \to [\pi^\pm K^\mp \pi^+\pi^-]_D K^\pm$ and $B^\pm \to [\pi^\pm K^\mp \pi^+\pi^-]_D \pi^\pm$

TL;DR

This paper reports the first observation of suppressed ADS decay modes in B meson decays involving D mesons reconstructed in a four-body final state, using LHCb data, and measures related CP asymmetries and amplitude ratios.

Contribution

The study presents the first observation of suppressed ADS modes with four-body D decays in B mesons and provides measurements of CP asymmetries and amplitude ratios.

Findings

First observation of suppressed ADS modes with 5.1σ and >10σ significance.

Measurement of the amplitude ratio r^K_B = 0.097 ± 0.011.

Determination of CP asymmetries and ratios of partial widths.

Abstract

An analysis of $B^{\pm}\to DK^{\pm}$ and $B^{\pm}\to D\pi^{\pm}$ decays is presented where the $D$ meson is reconstructed in the four-body final state $K^{\pm}\pi^{\mp} \pi^+ \pi^-$. Using LHCb data corresponding to an integrated luminosity of $1.0{\rm \,fb}^{-1}$, first observations are made of the suppressed ADS modes $B^{\pm}\to [\pi^{\pm} K^{\mp}\pi^+\pi^-]_D K^{\pm}$ and $B^{\pm}\to [\pi^{\pm} K^{\mp} \pi^+\pi^- ]_D\pi^{\pm}$ with a significance of $5.1\sigma$ and greater than $10\sigma$, respectively. Measurements of CP asymmetries and CP-conserving ratios of partial widths from this family of decays are also performed. The magnitude of the ratio between the suppressed and favoured $B^{\pm}\to DK^{\pm}$ amplitudes is determined to be $r^K_B = 0.097 \pm{0.011}$.