Observation of a Broad Structure in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>π</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>π</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi></mml:math>Mass Spectrum around<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>4.26</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>GeV</mml:mi><mml:mo>/</mml:mo><mml:ms
- B. Aubert
- R. Barate
- D. Boutigny
- F. Couderc
- Y. Karyotakis
- J. P. Lees
- V. Poireau
- V. Tisserand
- A. Zghiche
- E. Graugés
- A. Palano
- M. Pappagallo
- A. Pompili
- J. C. Chen
- N. D. Qi
- G. Rong
- P. Wang
- Y. S. Zhu
- G. Eigen
- I. Ofte
- B. Stugu
- G. S. Abrams
- M. Battaglia
- A. B. Breon
- D. N. Brown
- J. Button‐Shafer
- R. N. Cahn
- E. Charles
- C. T. Day
- M. S. Gill
- A. V. Gritsan
- Y. Groysman
- R. G. Jacobsen
- R. W. Kadel
- J. A. Kadyk
- L. T. Kerth
- Yu. G. Kolomensky
- G. Kukartsev
- G. Lynch
- L. M. Mir
- P. J. Oddone
- T. J. Orimoto
- M. Pripstein
- N. A. Roe
- M. T. Ronan
- W. A. Wenzel
- M. Barrett
- K. E. Ford
- T. Harrison
- A. John Hart
- C. M. Hawkes
- S. E. Morgan
- A. T. Watson
- M. Fritsch
- K. Goetzen
- T. Held
- H. Koch
- B. Lewandowski
- M. Pelizaeus
- Κ. Peters
- T. Vazquez Schroeder
- M. Steinke
- J. Boyd
- J. P. Burke
- N. Chevalier
- W. N. Cottingham
- T. Çuhadar-Dönszelmann
- B. G. Fulsom
- C. Hearty
- N. S. Knecht
- T. S. Mattison
- J. A. McKenna
- A. Khan
- P. Kyberd
- M. Saleem
- L. Teodorescu
- A. E. Blinov
- V.E. Blinov
- A. D. Bukin
- V. P. Druzhinin
- V. B. Golubev
- E. A. Kravchenko
- A. P. Onuchin
- S. I. Serednyakov
- Yu. I. Skovpen
- E. P. Solodov
- A. N. Yushkov
- David Best
- M. Bondioli
- M. Bruinsma
- M. Chao
- S. Curry
- I. Eschrich
- D. Kirkby
- A. J. Lankford
- P. Lund
- M. Mandelkern
- R. K. Mommsen
- W. Roethel
- D. P. Stoker
- STS. Tosi
- PJP. Jackson
- STS. Tosi
- PJP. Jackson
- EREnrico Robutti
- PBP. K. Behera
Physical Review Letters · 2005 · American Physical Society
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Abstract
We study initial-state radiation events, ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\gamma}}_{\mathrm{ISR}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}J/\ensuremath{\psi}$, with data collected with the BABAR detector. We observe an accumulation of events near $4.26\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ in the invariant-mass spectrum of ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}J/\ensuremath{\psi}$. Fits to the mass spectrum indicate that a broad resonance with a mass of about $4.26\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ is required to describe the observed structure. The presence of additional narrow resonances cannot be excluded. The fitted width of the broad resonance is 50 to $90\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, depending on the fit hypothesis.