Measurement of the $Λ_c^+$ lifetime

TL;DR

The Lambda+c lifetime is measured using 9.0 fb(-1) of e+e- annihilation data collected on or just below the Upsilon(4S) resonance with the CLEO II.V detector at CESR using an unbinned maximum likelihood fit.

Abstract

An absolute measurement of the $Λ^{+}_c$ lifetime is reported using $Λ_c^+\rightarrow pK^-π^+$ decays in events reconstructed from data collected by the Belle II experiment at the SuperKEKB asymmetric-energy electron-positron collider. The total integrated luminosity of the data sample, which was collected at center-of-mass energies at or near the $Υ(4S)$ resonance, is $207.2~\mbox{fb}^{-1}$. The result, $τ(Λ^{+}_c) = 203.20 \pm 0.89 \,\mathrm{(stat)} \pm 0.77 \,\mathrm{(syst)}$ fs, is the most precise measurement to date and is consistent with previous determinations.

Figures (3)

• Figure 1: Mass distribution of $焃^{+}_c\xspace\rightarrow\xspace p\xspace K^-\xspace\pi^+\xspace$ candidates with fit projections overlaid. The vertical dashed lines enclose the signal region and the short, vertical dotted lines enclose the sidebands.
• Figure 2: Decay-time distribution of $焃^{+}_c\xspace\rightarrow\xspace p\xspace K^-\xspace\pi^+\xspace$ events in the signal region (top) and sidebands (bottom) with fit projections overlaid.
• Figure 3: Decay-time uncertainty distribution of $焃^{+}_c\xspace\rightarrow\xspace p\xspace K^-\xspace\pi^+\xspace$ events in the signal region (top) and sidebands (bottom). The $\sigma_t$ PDF used in the fit is shown by the solid blue histogram and the background $\sigma_t$ PDF is shown by the dashed red histogram.