A search for $CP$ and $P$ violation in charmless four-body $B^{0} \to p \bar p K^{+} \pi^{-}$ decays is performed using triple-product asymmetry observables. It is based on proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of $7$, $8$ and $13$ TeV, corresponding to a total integrated luminosity of $8.4$ fb$^{-1}$. The $CP$- and $P$-violating asymmetries are measured both in the integrated phase space and in specific regions. No evidence is seen for $CP$ violation. $P$-parity violation is observed at a significance of 5.8 standard deviations
Feynman diagrams for the $B^{0}\rightarrow p\bar{p}K^{+}\pi^{-}$ decay in the charmless region: penguin (left) and tree (right). |
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Distributions for combined Run 1 and Run 2 data of the $p\bar{p}K^{+}\pi^{-}$ invariant mass in the four samples defined by $B^{0}$ ($\bar{B}^{0}$) flavour and the sign of $C_{\hat{T}}$ ($\bar{C}_{\hat{T}}$). The results of the fit, as described in the legend, are overlaid on the data. |
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The $a^{\hat{T}\text{-odd}}_{ C P }$ (left) and $a^{\hat{T}\text{-odd}}_{P}$ (right) asymmetry parameters in each region of the phase space for Run 1 and Run 2 data combined for binning scheme A. The error bars represent the sum in quadrature of the statistical and systematic uncertainties. The $\chi^{2}$ per number of degrees of freedom (ndf) is calculated with respect to the null hypothesis. |
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The $a^{\hat{T}\text{-odd}}_{ C P }$ (left) and $a^{\hat{T}\text{-odd}}_{P}$ (right) asymmetry parameters in each region of the phase space for Run 1 and Run 2 data combined for binning scheme B. The error bars represent the sum in quadrature of the statistical and systematic uncertainties. The $\chi^{2}$ per ndf is calculated with respect to the null hypothesis. |
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Background-subtracted distributions of $B^{0}$ ($\bar{B}^{0}$) candidates in the variables $m_{p \bar p}$, $m_{K^{+}\pi^{-}}$, $\cos\theta_{p \bar p}$, $\cos\theta_{K^{+}\pi^{-}}$ and $\phi$ with $C_{\hat{T}}>0$ and $C_{\hat{T}}<0$ ($-\bar{C}_{\hat{T}}>0$ and $-\bar{C}_{\hat{T}}<0$). |
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Animated gif made out of all figures. |
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Sources of systematic uncertainty and their relative contributions expressed as a percentage of the statistical uncertainty. In order to obtain the absolute systematic uncertainty assigned to specific region of the phase space, the numbers reported here have to be multiplied by the corresponding statistical uncertainties. $\Delta a^{\hat{T}\text{-odd}}_{ C P }$ and $\Delta a^{\hat{T}\text{-odd}}_{P}$ indicate the uncertainty assigned to $a^{\hat{T}\text{-odd}}_{ C P }$ and $a^{\hat{T}\text{-odd}}_{P}$ respectively. |
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Definition of the 24 regions that form scheme A for the $B^{0}\rightarrow p\bar{p}K^{+}\pi^{-}$ decay. |
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Measurements of $a^{\hat{T}\text{-odd}}_{CP}$ and $a^{\hat{T}\text{-odd}}_{P}$ in specific phase-space regions for the $B^{0}\rightarrow p\bar{p} K^{+}\pi^{-}$ decay for binning scheme A. Each value is obtained through an independent fit to the $B^{0}$ invariant-mass distribution of the candidates in the corresponding region of the phase space. The uncertainties are only statistical. |
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Definition of the 40 regions that form scheme B for the $B^{0}\rightarrow p\bar{p}K^{+}\pi^{-}$ decay. |
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Measurements of $a^{\hat{T}\text{-odd}}_{CP}$ and $a^{\hat{T}\text{-odd}}_{P}$ in specific phase-space regions for the $B^{0}\rightarrow p\bar{p} K^{+}\pi^{-}$ decay for binning scheme B. Each value is obtained through an independent fit to the $B^{0}$ invariant-mass distribution of the candidates in the corresponding region of the phase space. |
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Created on 27 April 2024.