2011 QCD and High Energy Interactions - Rencontres de Moriond ...

η → π + π − π 0 η ′ → γπ + π −
a)
η → π0π0π 0 η ′ → π + π− b)
η
c)
d)
π 0 → γγ e)
Figure 5: Mass distributions of the pseudo-scalar meson candidates for ψ ′ → γP : γη [ a): η → π + π − π 0 ; b):
η → π 0 π 0 π 0 ], γη ′ [ c): η ′ → γπ + π − ; d): η ′ → π + π − η, η → γγ], γπ 0 [ e): π 0 → γγ]. For more details see 12 .
and B(χ c1 → φω) = (2.2 ± 0.6 ± 0.2) × 10 −5 are also observed for the first time. This analysis
is described in details in 10 .
7 ψ ′ → γP, P = π 0 , η, η ′ ; η → π + π − π 0 , η → 3π 0 , η ′ → γπ + π − , η ′ →
π + π − η (η, π 0 → γγ)
The processes ψ ′ → γπ 0 and ψ ′ → γη are observed for the first time with signal significances
of 4.6σ and 4.3σ (Fig. 5), and branching fractions B(ψ ′ → γπ 0 ) = (1.58 ± 0.40 ± 0.13) × 10 −6
and B(ψ ′ → γη) = (1.38 ± 0.48 ± 0.09) × 10 −6 , respectively; the first errors are statistical and
the second ones systematic. The branching fraction B(ψ ′ → γη ′ ) = (126 ± 3 ± 8) × 10 −6 is
measured as well, leading for the first time to the determination of the ratio of the η and η ′
production rates from ψ ′ decays, Rψ ′ = B(ψ′ → γη)/B(ψ ′ → γη ′ ) = (1.10 ± 0.38 ± 0.07)%; such
ratio is below the 90% C.L. upper bound determined by the CLEO Collaboration 11 and one
order of magnitude smaller w.r.t the corresponding η − η ′ production ratio for the J/ψ decays,
R J/ψ = (21.1 ± 0.9)% 11 . For a detailed description of this analysis see 12 .
References
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