Mario Gaspero
Published 2010-05-13Version 1
A narrow peak in the pi+ pi- mass distribution was seen by the Rome-Syracuse Collaboration in pbar n --> 2 pi+ 3 pi- annihilation at rest in 1970. It was ignored for 40 years. The reanalysis of this peak finds that it has the mass 757.4 +- 2.8_stat +- 1.1_sys MeV/c**2 and a width consistent with the experimental resolution. The evidence of the peak is 5.2 standard deviations. The peak is generated in (1.03 +- 0.21_stat +- 0.21_sys)% of the pbar n annihilations at rest. No spin analysis is possible with the statistics of the experiment but there are arguments suggesting that it has JP = 0+.
Comments: 8 pages, 3 figures, talk given at the 13.th International Conference on Hadron Spectroscopy, Tallahassee, FL, USA, November 29 - December 4, 2009. Superseeds arXiv:0902.1126 [hep-ex].
Study of a narrow pi+ pi- peak at about 755 MeV/c^2 in bar-p n --> 2 pi+ 3 pi- annihilation at rest
Spin Analysis of the Process e+e- --> tau+tau- at LEP
Tests of Power Corrections for Event Shapes in e+e- Annihilation
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