Elsevier, Nuclear Physics B - Proceedings Supplements, (210-211), p. 141-146
DOI: 10.1016/j.nuclphysbps.2010.12.062
Proceedings of Flavor Physics and CP Violation 2010 — PoS(FPCP 2010)
DOI: 10.22323/1.116.0010
Proceedings of 35th International Conference of High Energy Physics — PoS(ICHEP 2010)
DOI: 10.22323/1.120.0243
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7 pages, 3 figures, submitted to Phys. Rev. Lett., please refer this paper together with arXiv:1005.2757 [hep-ex] (2010) (submitted to Phys. Rev. D) ; We measure the charge asymmetry $A≡(N^{++} - N^{--})/(N^{++} + N^{--})$ of like-sign dimuon events in 6.1~fb$^{-1}$ of $p\bar{p}$ collisions recorded with the D0 detector at a center-of-mass energy $\sqrt{s}=1.96$~TeV at the Fermilab Tevatron collider. From $A$ we extract the like-sign dimuon charge asymmetry in semileptonic $b$-hadron decays: $\aslb=-0.00957±0.00251\thinspace({\rm stat})±0.00146\thinspace({\rm sys})$. It differs by 3.2~standard deviations from the standard model prediction $\aslb({\rm SM})=(-2.3^{+0.5}_{-0.6})\times10^{-4}$, and provides first evidence of anomalous $CP$ violation in the mixing of neutral $B$ mesons.