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Crkovska, Jana

Publications and source records attributed to Crkovska, Jana.

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Evidence of a $J/ψΛ$ structure and observaton of excited $Ξ_{b}^{-}$ → $J/ψΛΚ^{-}$ decay

First evidence of a structure in the $J/ψΛ$ invariant mass distribution is obtained from an amplitude analysis of $Ξ_{b}^{-}$ → $J/ψΛΚ^{-}$ decays. The observed structure is consistent with being due to a charmonium pentaquark with strangeness with a significance of 3.1σ including systematic uncertainties and look elsewhere effect. Its mass and width are determined to be 4458.8 ± $2.9_{-1.1}^{+4.7}$ MeV and 17.3 ± $6.5_{-5.7}^{+8.0}$ MeV respectively, where the quoted uncertainties are statistical and systematic. The structure is also consistent with being due to two resonances. In addition, the narrow excited $Ξ^{-}$ states, $Ξ(1690)^{-}$ and $Ξ(1820)^{-}$, are seen for the first time in a $Ξ_{b}^{-}$ decay, and their masses and widths are measured with improved precision. The analysis is performed using $pp$ collision data corresponding to a total integrated luminosity of 9 fb -1 , collected with the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Observation of structure in the J/ψ-pair mass spectrum

Using proton-proton collision data at centre-of-mass energies of $\sqrt{s}$ = 7, 8 and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 9 fb -1 , the invariant mass spectrum of J/ψ pairs is studied. A narrow structure around 6.9 GeV/c 2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed. The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6.2 and 7.4 GeV/c 2 , covering predicted masses of states composed of four charm quarks. The mass and natural width of the narrow X(6900) structure are measured assuming a Breit-Wigner lineshape.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Observation of a new baryon state in the $Λ^0_bπ^+π^-$ mass spectrum

A new baryon state is observed in the $Λ^0_bπ^+π^-$ mass spectrum with high significance using a data sample of pp collisions, collected with the LHCb detector at centre-of-mass energies $\sqrt{s}$ = 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb -1 . The mass and natural width of the new state are measured to be m = 6072.3 ± 2.9 ± 0.6 ± 0.2 MeV , Γ = 72 ± 11 ± 2 MeV , where the first uncertainty is statistical and the second systematic. The third uncertainty for the mass is due to imprecise knowledge of the $Λ^0_b$ baryon mass. The new state is consistent with the first radial excitation of the $Λ^0_b$ baryon, the Λ b (2S) 0 resonance. Updated measurements of the masses and the upper limits on the natural widths of the previously observed Λ b (5912) 0 and Λ b (5920) 0 states are also reported.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗