Observation of two new $Ξ_b^-$ baryon resonancesстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 22 октября 2015 г.
Аннотация:Two structures are observed close to the kinematic threshold in the Ξ0bπ− mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb−1 , recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content bds are expected in this mass region: the spin-parity JP=12+ and JP=32+ states, denoted Ξ′−b and Ξ∗−b. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be
m(Ξ′−b)−m(Ξ0b)−m(π−)m(Ξ∗−b)−m(Ξ0b)−m(π−)Γ(Ξ∗−b)===3.653±0.018±0.006MeV/c2,23.96±0.12±0.06MeV/c2,1.65±0.31±0.10MeV,
where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of Γ(Ξ′−b)<0.08 MeV at 95\% confidence level. Relative production rates of these states are also reported.