The particle is a "doubly
strange"
baryon containing two strange quarks and a
bottom quark. A discovery of this particle was first claimed in September 2008 by physicists working on the
DØ experiment at the
Tevatron facility of the
Fermi National Accelerator Laboratory. However, the reported mass of was significantly higher than expected in the
quark model. The apparent discrepancy from the
Standard Model has since been dubbed the " puzzle". In May 2009, the
CDF collaboration made public their results on the search for the based on analysis of a data sample roughly four times the size of the one used by the
DØ experiment.
CDF measured the mass to be , which was in excellent agreement with the Standard Model prediction. No signal has been observed at the DØ reported value. The two results differ by , which is equivalent to 6.2 standard deviations and are therefore inconsistent. Excellent agreement between the CDF measured mass and theoretical expectations is a strong indication that the particle discovered by CDF is indeed the . In February 2013 the
LHCb collaboration published a measurement of the mass that is consistent with, but more precise than, the CDF result. In March 2017, the LHCb collaboration announced the observation of five new narrow states decaying to , where the was reconstructed in the decay mode . The states are named (3000)0, (3050)0, (3066)0, (3090)0 and (3119)0. Their masses and widths were reported, but their quantum numbers could not be determined due to the large background present in the sample. ==See also==