Abstract

Measurements of $CP$ asymmetry in charmless $B\to PV$ decays are presented, where $P$ and $V$ denote a pseudoscalar and a vector meson, respectively. Five different $B\to PV$ decays from four final states, $B^\pm \to \pi^\pm \pi^+ \pi^-$, $B^\pm \to K^\pm \pi^+ \pi^-$, $B^\pm \to K^\pm K^+ K^-$ and $B^\pm \to \pi^\pm K^+ K^-$ are analyzed. The measurements are based on a method that does not require full amplitude analyses, and are performed using proton-proton collision data at a center-of-mass energy of 13 TeV collected by LHCb between 2015 and 2018, corresponding to an integrated luminosity of 5.9 fb$^{-1}$. In the $\pi^+ \pi^-$ $\textit{P}$-wave, in the region dominated by the $B^\pm \to \rho(770)^0 K^\pm$ decay, a $CP$ asymmetry of $ $A_{CP}$ = +0.150 $\pm$ 0.019 $\pm$ 0.011$ is measured, where the first uncertainty is statistical and the second is systematic. This is the first observation of $CP$ violation in this process. For the other four decay channels, in regions dominated by the $B^\pm \to \rho(770)^0 \pi^\pm$, $B^\pm \to \overset{(-)}{K^*}(892)^0 \pi^\pm$, $B^\pm \to \overset{(-)}{K^*}(892)^0 K^\pm$ and $B^\pm \to \phi(1020) K^\pm$ decays, $CP$ asymmetries in the $\textit{P}$-wave compatible with zero are measured.

Figures and captions

Distribution of $ s_\bot$ for $B^+$ and $B^-$ candidates and the corresponding quadratic fits for (a) $\rho(770)^0$ in $ { B ^\pm \rightarrow \pi ^\pm \pi ^+ \pi ^- }$ , (b) $\rho(770)^0$ in $ { B ^\pm \rightarrow K ^\pm \pi ^+ \pi ^- }$ , (c) $\optbar{ K }{} ^*(892)^0$ in $ { B ^\pm \rightarrow K ^\pm \pi ^+ \pi ^- }$ , (d) $\optbar{ K }{} ^*(892)^0$ in $ { B ^\pm \rightarrow \pi ^\pm K ^+ K ^- }$ and (e) $\phi(1020)$ in $ { B ^\pm \rightarrow K ^\pm K ^+ K ^- }$ . In the symmetric channels, the phase space distribution and its projections are presented with the two axes being the squares of the low-mass $m_{\textrm{low}}$ and high-mass $m_{\textrm{high}}$ combinations of the opposite-sign particle pairs, for visualization purposes.	Fig1a.pdf [18 KiB] HiDef png [263 KiB] Thumbnail [220 KiB] *.C file
	Fig1b.pdf [18 KiB] HiDef png [253 KiB] Thumbnail [205 KiB] *.C file
	Fig1c.pdf [22 KiB] HiDef png [264 KiB] Thumbnail [214 KiB] *.C file
	Fig1d.pdf [19 KiB] HiDef png [277 KiB] Thumbnail [215 KiB] *.C file
	Fig1e.pdf [17 KiB] HiDef png [257 KiB] Thumbnail [226 KiB] *.C file
Animated gif made out of all figures.	PAPER-2021-050.gif Thumbnail

Tables and captions

Number of $B^+$ and $B^-$ candidates in the signal region of 5247 to 5315 $\text{ Me V /}c^2$ and the corresponding purities.	Table_1.pdf [58 KiB] HiDef png [26 KiB] Thumbnail [12 KiB] tex code
Summary of $ C P$ -asymmetry measurements for the vector resonance channels and their associated final-state $B^\pm \rightarrow R(\rightarrow h_1^-h_2^+)h_3^\pm$ decays. For comparison purposes, the previous measurements from other experiments are also included.	Table_2.pdf [62 KiB] HiDef png [69 KiB] Thumbnail [32 KiB] tex code

Created on 20 April 2024.