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Location: Northwest AR (USA)
|Posted: Sat Dec 24, 2011 9:17 pm Post subject: LHC News!
High Energy Physics - Experiment
Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS
(Submitted on 21 Dec 2011)
The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.539+/-0.004 (stat.)+/-0.008 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.
22 December 2011 Last updated at 05:59 ET
LHC reports discovery of its first new particle
|The Large Hadron Collider (LHC) on the Franco-Swiss border has made its first clear observation of a new particle since opening in 2009.
It is called Chi_b (3P) and will help scientists understand better the forces that hold matter together.