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Search for muoproduction of $X (3872)$ at COMPASS and indication of a new state $\widetilde{X}(3872)$
We have searched for exclusive production of exotic charmonia in the reaction μ+N→μ+(J/ψπ+π−)π±N′ using COMPASS data collected with incoming muons of 160 GeV/ c and 200 GeV/ c momentum. In the J/ψπ+π− mass distribution we observe a signal with a statistical significance of 4.1 σ . Its mass and width...
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Lenguaje: | eng |
Publicado: |
2018
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Materias: | |
Acceso en línea: | https://dx.doi.org/10.1016/j.physletb.2018.07.008 http://cds.cern.ch/record/2273255 |
Sumario: | We have searched for exclusive production of exotic charmonia in the reaction μ+N→μ+(J/ψπ+π−)π±N′ using COMPASS data collected with incoming muons of 160 GeV/ c and 200 GeV/ c momentum. In the J/ψπ+π− mass distribution we observe a signal with a statistical significance of 4.1 σ . Its mass and width are consistent with those of the X(3872) . The shape of the π+π− mass distribution from the observed decay into J/ψπ+π− shows disagreement with previous observations for X(3872) . The observed signal may be interpreted as a possible evidence of a new charmonium state. It could be associated with a neutral partner of X(3872) with C=−1 predicted by a tetraquark model. The product of cross section and branching fraction of the decay of the observed state into J/ψπ+π− is determined to be 71±28(stat)±39(syst) pb. |
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