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
Search for muoproduction of X (3872) at COMPASS and indication of a new state X˜(3872)
Birsa, R.;Bradamante, F.;Bressan, A.;Chatterjee, C.;Dalla Torre, S.;Dasgupta, S. S.;Dasgupta, S.;Huber, S.;Ivanov, A.;Kerbizi, A.;Levorato, S.;Maggiora, A.;Makke, N.;Martin, A.;Matoušek, J.;Pereira, F.;Ramos, S.;Santos, C.;Sbrizzai, G.;Schiavon, P.;Szabelski, A.;Tessaro, S.;Tessarotto, F.;
2018-01-01
Abstract
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| File | Dimensione | Formato | |
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