Resonance Structure in the $γγ$ Invariant Mass Spectrum in $p$C- and $d$C-Interactions

Kh. U. Abraamyan; M. I. Baznat; A. V. Friesen; K. K. Gudima; M. A. Kozhin; S. A. Lebedev; M. A. Nazarenko; S. A. Nikitin; G. A. Ososkov; S. G. Reznikov; A. N. Sissakian; A. S. Sorin; V. D. Toneev

doi:10.1103/physrevc.80.034001

arXiv · 0806.2790

Resonance Structure in the $γγ$ Invariant Mass Spectrum in $p$C- and $d$C-Interactions

Kh. U. Abraamyan·M. I. Baznat·A. V. Friesen·K. K. Gudima·M. A. Kozhin·S. A. Lebedev·M. A. Nazarenko·S. A. Nikitin·G. A. Ososkov·S. G. Reznikov·A. N. Sissakian·A. S. Sorin·V. D. Toneev

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Abstract

Along with $π^0$ and $η$ mesons, a resonance structure in the invariant mass spectrum of two photons at $M_{γγ}= 360 \pm 7 \pm 9$ MeV is observed in the reaction $d C\toγ+ γ+X$ at momentum 2.75 GeV/c per nucleon. Estimates of its width and production cross section are $Γ= 63.7 \pm 17.8$ MeV and $σ_{γγ}=98\pm24^{+93}_{-67} {\rm μb}$, respectively. The collected statistics amount to $2339 \pm 340$ events of $1.5\cdot 10^6$ triggered interactions of a total number $\sim 10^{12}$ of $d$C-interactions. This resonance structure is not observed in $p$C collisions at the beam momentum 5.5 GeV/c. Possible mechanisms of this ABC-like effect are discussed.

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Kh. U. Abraamyan, M. I. Baznat, A. V. Friesen, K. K. Gudima, M. A. Kozhin, S. A. Lebedev, M. A. Nazarenko, S. A. Nikitin, G. A. Ososkov, S. G. Reznikov, A. N. Sissakian, A. S. Sorin, V. D. Toneev. 2009-09-28. Resonance Structure in the $γγ$ Invariant Mass Spectrum in $p$C- and $d$C-Interactions. https://doi.org/10.1103/physrevc.80.034001

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