Measurement of the $B^0$--$\bar B^0$ oscillation frequency $\Delta m_d$ with the decays $B^0 \to D^- \pi^+$ and $B^0 \to J/ \psi K^{*0}$

TL;DR

This paper reports a precise measurement of the $B^0$--$ar B^0$ oscillation frequency $\Delta m_d$ using specific decay channels in proton-proton collisions at the LHCb experiment, contributing to understanding of flavor oscillations.

Contribution

The first measurement of $\Delta m_d$ using these decay modes at LHCb with a 7 TeV dataset, improving precision over previous results.

Findings

$\Delta m_d = 0.5156 \, ext{ps}^{-1}$ with statistical and systematic uncertainties

Analysis of $B^0 o D^- o K^+ \pi^-\pi^-$ decay channel

Analysis of $B^0 o J/\psi K^{*0}$ decay channel

Abstract

The $B^0$--$\bar B^0$ oscillation frequency $\Delta m_d$ is measured by the LHCb experiment using a dataset corresponding to an integrated luminosity of $1.0\,$fb$^{-1}$ of proton-proton collisions at $\sqrt{s} = 7\,$TeV, and is found to be $\Delta m_d = 0.5156 \pm 0.0051\,($stat.$) \pm 0.0033\,($syst.$)\,$ps$^{-1}$. The measurement is based on results from analyses of the decays $B^0 \to D^- \pi^+$ ($D^- \to K^+ \pi^- \pi^-$) and $B^0 \to J/ \psi K^{*0}$ ($ J/ \psi \to \mu^+ \mu^-$, $K^{*0} \to K^+ \pi^-$) and their charge conjugated modes.