Partial wave analysis of J/ψ→γ(K+K−π+π−)

Abstract

BES data on J/ψ → γ(K + K − π + π − ) are presented. The K * K * contribution peaks strongly near threshold. It is fitted with a broad 0 −+ resonance with mass M = 1800 ± 100 MeV, width Γ = 500 ± 200 MeV. A broad 2 ++ resonance peaking at 2020 MeV is also required with width ∼ 500 MeV. There is further evidence for a 2 −+ component peaking at 2.55 GeV. The non-K * K * contribution is close to phase space; it peaks at 2.6 GeV and is very different from K * K * .PACS numbers: 14.40. Cs, 12.39.Mk, 13.25.Jx, 13.40.Hq Typeset using REVT E X [4]. There, we also find a broad 2 The analysis in this paper uses 7.8 × 10 6 J/ψ triggers collected by the Beijing Spectrometer(BES). This detector has been described in detail in Ref [12]. Here we describe briefly those detector elements crucial to this measurement. Tracking is provided by a 10 superlayer main drift chamber (MDC). Each superlayer contains four layers of sense wires measuring both the position and the ionization energy loss (dE/dx) of charged particles.The momentum resolution is σ P /P = 1.7% A positive identification of at least one K ± and one π ± is required using time of flight and/or dE/dx. If two tracks are ambiguous, both alternative identifications are tried. Events are fitted kinematically to the 4C hypothesis J/ψ → γ(, requiring a confidence level > 5%. If there is more than one photon, the fit is repeated using all permutations.Events with two or more photons are also fitted to J/ψ → γγKThose giving a better fit than to γ(K + K − π + π − ) are rejected, as are events fitting the final stateNext, we require | U miss |=| E miss − P miss |< 0.12 GeV/c 2 , so as to reject the events with multi-photons or more or less than two charged kaons; here, E miss and P miss are, respectively, the missing energy and missing momentum of all charged particles; they are calculated by assuming the charged particles are(GeV/c) 2 is required in order to remove the background J/ψ → π 0

The BES f0(1810): a new glueball candidate

“…The Mark III KK and ππ spectra featured a prominent f 0 (1710) but no f 0 (1810) state. Somewhat perplexing, BES reported a low statistics study of the K * K * spectrum in radiative J/ψ decays [14] with the 0 ++ channel not significantly populated. We also note that the more recent 294 γωφ events cleanly isolated by BES, although only part of the total produced, represent an extremely small branching fraction compared to, for example, B(J/ψ → γK * K * ) = 4(1) × 10 −3 .…”

Dynamical coupled-channels study ofK*K*¯andωφstates in a chiral quark model

“…In Ref. [36], BES collaboration has reported a broad 0 − resonance with mass M = 1800 MeV and width Γ = 500 ± 200 MeV on the decay J/ψ → γK * K * . Here we have performed a study of the P -wave K * K * states.…”

Possible mechanism for producing the threshold enhancement inJ/ψ→γpp¯

“…On the other hand, there exists an interesting phenomenon that may be related to the J/ψ → γpp decay. We notice that in the process of J/ψ radiative decays J/ψ → γVV , where VV represent ρρ, ωω or K * K * and so on, the VV invariant mass distribution is dominated by the 0 − components in all of these channels [16,17,18,19,20]. Nevertheless, these vector mesons generally have strong couplings with the nucleons and/or hyperons.…”

“…It is worth noting that the experimental values of BR(J/ψ → γη(1405/1475))×BR(η(1405/1475) → ρρ) and BR(J/ψ → γη(1760)) × BR(η(1760) → ρρ) are extracted from J/ψ → 4πγ, where the results greatly depend on the fitting methods [20]. A similar problem is also with the data for BR(J/ψ → γ0 − ) × BR(0 − → K * K * ) [18]. In this sense, the branching ratios displayed in Table I still have large uncertainties at the order of 10 −3 .…”

“…This forms our motivation in this work to study the role played by vector meson VV rescatterings in J/ψ → γpp. [20] γη(1760) → γρρ 1.44 ± 0.33 [20] γη(1760) → γωω 1.98 ± 0.33 [17] γ0 − → γK * K * 2.3 ± 0.9 [18] As follows, we first provide details of our theoretical model in Sect. II.…”