A search for the Z(3930) resonance in γγ production of the DD̅ system has been performed using a data sample corresponding to an integrated luminosity of 384 fb-1 recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The DD̅ invariant mass distribution shows clear evidence of the Z(3930) state with a significance of 5.8σ. We determine mass and width values of (3926.7±2.7±1.1) MeV/c2 and (21.3±6.8±3.6) MeV, respectively. A decay angular analysis provides evidence that the Z(3930) is a tensor state with positive parity and C parity (JPC=2++); therefore we identify the Z(3930) state as the χc2(2P) meson. The value of the partial width Γγγ×B(Z(3930)→DD̅ ) is found to be (0.24±0.05±0.04) keV.
Observation of the χc2(2P) meson in the reaction γγ→DD̅ at BABAR
GAZ A;SIMI, GABRIELE;MARGONI, MARTINO;SIMONETTO, FRANCO;STROILI, ROBERTO;VOCI, CESARE;
2010
Abstract
A search for the Z(3930) resonance in γγ production of the DD̅ system has been performed using a data sample corresponding to an integrated luminosity of 384 fb-1 recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The DD̅ invariant mass distribution shows clear evidence of the Z(3930) state with a significance of 5.8σ. We determine mass and width values of (3926.7±2.7±1.1) MeV/c2 and (21.3±6.8±3.6) MeV, respectively. A decay angular analysis provides evidence that the Z(3930) is a tensor state with positive parity and C parity (JPC=2++); therefore we identify the Z(3930) state as the χc2(2P) meson. The value of the partial width Γγγ×B(Z(3930)→DD̅ ) is found to be (0.24±0.05±0.04) keV.
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