Simultaneous measurement of theB0meson lifetime and mixing frequency withB0→

Abstract

We measure the B 0 lifetime B 0 and the B 0 -B 0 oscillation frequency ⌬m d with a sample of approximately 14000 exclusively reconstructed B 0 →D* Ϫ ᐉ ϩ ᐉ signal events, selected from 23 million BB pairs recorded at the ⌼(4S) resonance with the BABAR detector at the Stanford Linear Accelerator Center. The decay position of the other B is determined with the remaining tracks in the event, and its b-quark flavor at the time of decay is determined with a tagging algorithm that exploits the correlation between the flavor of the b quark and the charges of its decay products. The lifetime and oscillation frequencies are measured simultaneously with an unbinned maximum-likelihood fit that uses, for each event, the measured difference in decay times of the two B mesons (⌬t), the calculated uncertainty on ⌬t, the signal and background probabilities, and b-quark tagging information for the other B. The results are B 0ϭ (1.523 Ϫ0.023 ϩ0.024 Ϯ0.022) ps and ⌬m d ϭ(0.492Ϯ0.018 Ϯ0.013) ps Ϫ1 . The statistical correlation coefficient between B 0 and ⌬m d is Ϫ0.22.

Averages of $b$-hadron, $c$-hadron, and $τ$-lepton properties as of summer 2014

“…It should be noted that the most recent (and precise) analyses at the asymmetric B factories measure ∆m d as a result of a multi-dimensional fit. Two BABAR analyses [90,92], based on fully and partially reconstructed B 0 → D * ν decays respectively, extract simultaneously ∆m d and τ (B 0 ) while the latest Belle analysis [93], based on fully reconstructed hadronic B 0 decays and B 0 → D * ν decays, extracts simultaneously ∆m d , τ (B 0 ) and τ (B + ). The measurements of ∆m d and τ (B 0 ) of these three analyses are displayed in Table 16 and in Fig.…”

“…7. Their two-dimensional average, taking into account all statistical and systematic correlations, and expressed at τ (B + ) = 1.638 ± 0.004 ps, is [90,92,93], after adjustment to a common set of parameters (see text). Statistical and total uncertainties are represented as dashed and solid contours respectively.…”

“…Table 15: Time-dependent measurements included in the ∆m d average. The results obtained from multi-dimensional fits involving also the B 0 (and B + ) lifetimes as free parameter(s) [90,92,93] have been converted into one-dimensional measurements of ∆m d . All the measurements have then been adjusted to a common set of physics parameters before being combined.…”

“…Figure 7: Simultaneous measurements of ∆m d and τ (B 0 )[90,92,93], after adjustment to a common set of parameters (see text). Statistical and total uncertainties are represented as dashed and solid contours respectively.…”

Averages of b-hadron, c-hadron, and $$\tau $$ τ -lepton properties as of summer 2016

“…Definitions of the set of angles (α s , β s , γ s ) can be obtained using equivalent relations to those of Eq. (98). However, this gives a value of β s that is negative in the Standard Model, so that the sign is usually flipped in the literature; this convention, i.e.…”