Jan 25 – 29, 2016
Bormio, Italy
Europe/Berlin timezone

Exotic quarkonium states in CMS

Jan 28, 2016, 6:45 PM
Bormio, Italy

Bormio, Italy

Short Contribution Relativistic Heavy Ion Physics Thursday Afternoon


Mr Leonardo Cristella (CERN)


Using large data samples of di-muon events, CMS has performed detailed measurements and searches for new states in the field of exotic quarkonium. We present our results on the production of prompt and non-prompt X(3872), detected in the J/ψ ππ decay channel, which extend to higher pT values than in any previous measurement. The cross-section ratio with respect to the ψ(2S) is given differentially in pT (as well as pT integrated). For the first time at the LHC, the fraction of X(3872) coming from B hadron decays has been measured. The analysis includes a measurement of the di-pion mass spectrum, establishing that the decay takes the form J/ψ ρ. After these studies of the charmonium X, we present a new search for its bottomonium counterpart, denoted as Xb, based on a data sample of pp collisions at 8 TeV collected by CMS in 2012. In analogy to the X(3872) studies, the analysis uses the Xb to Υ(1S) ππ exclusive decay channel, with the Υ(1S) decaying to μμ pairs. We will also report from the two structures found in the J/ψ φ decay channel, accessed through the exclusive B+ → J/ψ φ K+ decay. One of the structures confirms a previous observation by the CDF experiment, while the second structure has been observed by CMS for the first time. These contribute to the "systematic" studies of new structures in the search for new exotic quarkonium states, which provides an effective method to test QCD predictions. There have been several proposals explaining these states as hybrid (𝑞𝑞𝑔) or four-quark (𝑞𝑞 𝑞𝑞) exotic mesons. These two results clearly demonstrate CMS' capability to perform detailed studies on exotic quarkonium production. CMS is currently extending these studies to other exotic quarkonium states and new results are very likely to be ready in view of the present conference

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