B CP-Violation, Mixing and Lifetime Results from Belle

TL;DR

This paper reports measurements of B-meson CP violation, mixing parameters, and lifetimes using data from the Belle detector, providing key insights into B physics and CP violation phenomena.

Contribution

First measurement of multiple B-meson parameters including CP violation, mixing, and lifetimes with new data from Belle at KEKB.

Findings

Measured B-meson lifetimes: τ(B0) = 1.548 ps, τ(B±) = 1.656 ps.

Determined B0_d–B̄0_d mixing frequency Δm_d ≈ 0.52 ps⁻¹.

Estimated sin2φ₁ ≈ 0.58 with statistical and systematic uncertainties.

Abstract

Recent results on the $B$ CP-violation parameter $\sin2\phi_1$, the $B^0_d$-$\overline{B}^0_d$ mixing parameter $\Delta m_d$ and $B$-meson lifetimes are reported. The results are based on 10.5 $fb^{-1}$ of data collected with the Belle detector at KEKB. Using both semileptonic and hadronic decay modes the neutral and charged $B$-meson lifetimes are measured to be $\taubz=1.548\pm0.035 (\mathrm{stat.})$~ps and $\taubm=1.656\pm0.038 (\mathrm{stat.})$~ps. The oscillation frequency $\Delta m_d$ for $B^0_d$-$\overline{B}^0_d$ mixing is measured to be $0.522\pm0.026 (\mathrm{stat.})$~ps$^{-1}$ using semileptonic modes and $0.527\pm0.032 (\mathrm{stat.})$~ps$^{-1}$ using hadronic modes. The above results are preliminary. The time evolution of $B^0_d$ decays into $J/\psi K^0_S$, $\psi(2S) K^0_S$, $\chi_{c1} K^0_S$, $\eta_{c} K^0_S$, $J/\psi K^0_L$ and $J/\psi \pi^0$ modes are studied to obtain $\sin2\phi_1$. Using 282 fully reconstructed events, $\sin2\phi_1$ is measured to be $$\sin 2\phi_1=0.58^{+0.32}_{-0.34} (\mathrm{stat.})^{+0.09}_{-0.10} (\mathrm{syst.} ).$$