# Measurements of indirect CP asymmetries in $D^0\to K^-K^+$ and $D^0\to\pi^-\pi^+$ decays

LHCb Collaboration; Bernet, R; Müller, K; Steinkamp, O; Straumann, U; Vollhardt, A; et al (2014). Measurements of indirect CP asymmetries in $D^0\to K^-K^+$ and $D^0\to\pi^-\pi^+$ decays. Physical Review Letters, 112:041801.

## Abstract

A study of indirect CP violation in $D^0$ mesons through the determination of the parameter $A_\Gamma$ is presented using a data sample of $pp$ collisions, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected with the LHCb detector and recorded at the centre-of-mass energy of 7 TeV at the LHC. The parameter $A_\Gamma$ is the asymmetry of the effective lifetimes measured in decays of $D^0$ and $\bar{D}^0$ mesons to the CP eigenstates $K^-K^+$ and $\pi^-\pi^+$. Fits to the data sample yield $A_\Gamma(KK)=(-0.35\pm0.62\pm0.12)\times 10^{-3}$ and $A_\Gamma(\pi\pi)=(0.33\pm1.06\pm0.14)\times 10^{-3}$, where the first uncertainties are statistical and the second systematic. The results represent the world's best measurements of these quantities. They show no difference in $A_\Gamma$ between the two final states and no indication of CP violation.

## Abstract

A study of indirect CP violation in $D^0$ mesons through the determination of the parameter $A_\Gamma$ is presented using a data sample of $pp$ collisions, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected with the LHCb detector and recorded at the centre-of-mass energy of 7 TeV at the LHC. The parameter $A_\Gamma$ is the asymmetry of the effective lifetimes measured in decays of $D^0$ and $\bar{D}^0$ mesons to the CP eigenstates $K^-K^+$ and $\pi^-\pi^+$. Fits to the data sample yield $A_\Gamma(KK)=(-0.35\pm0.62\pm0.12)\times 10^{-3}$ and $A_\Gamma(\pi\pi)=(0.33\pm1.06\pm0.14)\times 10^{-3}$, where the first uncertainties are statistical and the second systematic. The results represent the world's best measurements of these quantities. They show no difference in $A_\Gamma$ between the two final states and no indication of CP violation.

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## Additional indexing

Item Type: Journal Article, refereed, original work 07 Faculty of Science > Physics Institute 530 Physics Physical Sciences > General Physics and Astronomy English 2014 24 Feb 2015 14:43 30 Jul 2020 17:24 American Physical Society 0031-9007 Hybrid https://doi.org/10.1103/PhysRevLett.112.041801

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