Observation of an Excited Meson State with the ATLAS Detector

G. Aad, B. Abbott, J. Abdallah, S. Abdel Khalek, O. Abdinov, R. Aben, B. Abi, Mogens Dam, Jørn Dines Hansen, Jørgen Beck Hansen, Stefania Xella, Peter Henrik Hansen, Troels Christian Petersen, Lotte Ansgaard Thomsen, Sascha Mehlhase, Morten Dam Jørgensen, Almut Maria Pingel, Ask Emil Løvschall-Jensen, Alejandro Alonso Diaz, James William MonkLars Egholm Pedersen, Gorm Aske Gram Krohn Galster, Graig Wiglesworth

77 Citations (Scopus)

Abstract

A search for excited states of the B±c 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→J/ψπ±. The state appears in the m(B±cπ+π−)−m(B±c)−2m(π±) mass difference distribution with a significance of 5.2 standard deviations. The mass of the observed state is 6842±4±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-wave state of the B±c meson, B±c(2S).
Original languageEnglish
Article number212004
JournalPhysical Review Letters
Volume113
ISSN0031-9007
DOIs
Publication statusPublished - 21 Nov 2014

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