Measurement of the B^0_s - \bar{B}^0_s oscillation frequency Delta m_s in B^0_s -> D_s^-(3) pi decays

TL;DR

This paper reports a precise measurement of the B_s^0-ar{B}_s^0 oscillation frequency using data from the LHCb experiment, observing a significant oscillation signal and providing a key parameter for understanding B meson behavior.

Contribution

The study provides the first measurement of Delta m_s with high statistical significance using B_s decays at the LHCb, improving the precision of this fundamental parameter.

Findings

Measured Delta m_s = 17.63 ± 0.11 (stat) ± 0.02 (syst) ps^{-1}

Observed oscillation with 4.6 sigma significance

Reconstructed 1381 B_s decay signals

Abstract

The B^0_s-\bar{B}^0_s oscillation frequency Delta m_s is measured with 36 pb^{-1} of data collected in pp collisions at \sqrt{s} = 7 TeV by the LHCb experiment at the Large Hadron Collider. A total of 1381 B^0_s -> D_s^- \pi^+ and \B^0_s -> D_s^- pi^+ pi^- pi^+ signal decays are reconstructed, with average decay time resolutions of 44 fs and 36 fs, respectively. An oscillation signal with a statistical significance of 4.6 sigma is observed. The measured oscillation frequency is Delta m_s = 17.63 \pm 0.11 (stat) \pm 0.02 (syst) ps^{-1}.