ausblenden:
Schlagwörter:
High Energy Physics - Experiment, hep-ex
MPINP:
LHCb - Abteilung Hofmann
Zusammenfassung:
Using a proton-proton collision data sample corresponding to an integrated
luminosity of 3 fb$^{-1}$ collected by LHCb at center-of-mass energies of 7 and
8 TeV, about 3800 $\Xi_b^0\to\Xi_c^+\pi^-$, $\Xi_c^+\to pK^-\pi^+$ signal
decays are reconstructed. From this sample, the first measurement of the
$\Xi_b^0$ baryon lifetime is made, relative to that of the $\Lambda_b^0$
baryon. The mass differences $M(\Xi_b^0)-M(\Lambda_b^0)$ and
$M(\Xi_c^+)-M(\Lambda_c^+)$ are also measured with precision more than four
times better than the current world averages. The resulting values are
$\frac{\tau_{\Xi_b^0}}{\tau_{\Lambda_b^0}} = 1.006\pm0.018\pm0.010$,
$M(\Xi_b^0) - M(\Lambda_b^0) = 172.44\pm0.39\pm0.17 MeV/c^2$, $M(\Xi_c^+) -
M(\Lambda_c^+) = 181.51\pm0.14\pm0.10 MeV/c^2$, where the first uncertainty is
statistical and the second is systematic. The relative rate of $\Xi_b^0$ to
$\Lambda_b^0$ baryon production is measured to be
$\frac{f_{\Xi_b^0}}{f_{\Lambda_b^0}}\frac{{\cal{B}}(\Xi_b^0\to\Xi_c^+\pi^-)}{{\cal{B}}(\Lambda_b^0\to\Lambda_c^+\pi^-)}\frac{{\cal{B}}(\Xi_c^+\to
pK^-\pi^+)}{{\cal{B}}(\Lambda_c^+\to pK^-\pi^+)} =
(1.88\pm0.04\pm0.03)\times10^{-2}$, where the first factor is the ratio of
fragmentation fractions, $b\to\Xi_b^0$ relative to $b\to\Lambda_b^0$. Relative
production rates as functions of transverse momentum and pseudorapidity are
also presented.
