Observation of an Excited $B_c^{\pm }$ Meson State with the ATLAS Detector

Abstract

A search for excited states of the $B_c^{\pm }$ meson is performed using 4.9 fb${}^{-1}$ of 7 TeV and 19.2 fb${}^{-1}$ of 8 TeV $pp$ collision data collected by the ATLAS experiment at the LHC. A new state is observed through its hadronic transition to the ground state, with the latter detected in the decay $B_c^{\pm }\to J/\psi {\pi }^{\pm }$. The state appears in the $m(B_c^{\pm }{\pi }^{+}{\pi }^{-})-m(B_c^{\pm })-2m({\pi }^{\pm })$ mass difference distribution with a significance of 5.2 standard deviations. The mass of the observed state is $6842\pm 4\pm 5$ MeV, where the first error is statistical and the second is systematic. The mass and decay of this state are consistent with expectations for the second $S\mbox{-}$wave state of the $B_c^{\pm }$ meson, $B_c^{\pm }(2S)$.

6 pages plus author list + cover pages (20 pages total), 2 figures, 1 table, published version, all figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/BPHY-2012-04/

References in corpus (5)

• PYTHIA 6.4 Physics and Manual
• Measurement of the Bc meson mass in the exclusive decay Bc --> Jpsi Pi
• First observation of the decay $B_c^{+}\to J/\psi K^{+}$
• Observation of the decay Bc+ -> Bs0 pi+
• Observation of the decay $B_c\to J/\psi K^{+}{K}^{-}{\pi }^{+}$

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