Observation of Two Resonant Structures in $e^{+} e^{-} \to π^{+} π^{-} ψ (2 S)$ via Initial-State Radiation at Belle

1 October 2007

journal article
research article
Published by American Physical Society (APS) in Physical Review Letters

Vol. 99 (14) , 142002
https://doi.org/10.1103/physrevlett.99.142002

Abstract

The cross section for

e^{+} e^{-} \to π^{+} π^{-} ψ (2 S)

between threshold and

\sqrt{s} = 5.5 GeV

is measured using

673 {fb}^{- 1}

of data on and off the

Υ (4 S)

resonance collected with the Belle detector at KEKB. Two resonant structures are observed in the

π^{+} π^{-} ψ (2 S)

invariant-mass distribution, one at

4361 \pm 9 \pm 9 MeV / c^{2}

with a width of

74 \pm 15 \pm 10 MeV / c^{2}

, and another at

4664 \pm 11 \pm 5 MeV / c^{2}

with a width of

48 \pm 15 \pm 3 MeV / c^{2}

, if the mass spectrum is parametrized with the coherent sum of two Breit-Wigner functions. These values do not match those of any of the known charmonium states.

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This publication has 13 references indexed in Scilit:

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Observation of Two Resonant Structures ine+e−→π+π−ψ(2S)via Initial-State Radiation at Belle

Abstract

Keywords

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Observation of Two Resonant Structures in $e^{+} e^{-} \to π^{+} π^{-} ψ (2 S)$ via Initial-State Radiation at Belle