Study of the process e+e−→π+π−η using initial state radiation

Abstract

We study the process e þ e − → π þ π − ηγ, where the photon is radiated from the initial state. About 8000 fully reconstructed events of this process are selected from the BABAR data sample with an integrated luminosity of 469 fb −1 . Using the π þ π − η invariant mass spectrum, we measure the e þ e − → π þ π − η cross section in the e þ e − center-of-mass energy range from 1.15 to 3.5 GeV. The cross section is well described by the Vector-Meson dominance model with four ρ-like states. We observe 49 AE 9 events of the J=ψ decay to π þ π − η and measure the product Γ J=Ψ→e þ e − B J=Ψ→π þ π − η ¼ 2.34 AE 0.43 stat AE 0.16 syst eV.

Study of the reactions e+e−→π+π−Lees1, Poireau2, Tisserand3 et al. 2018Phys. Rev. DSelf Cite240180View full textAdd to dashboardCite

“…Systematic uncertainties in this measurement are the same as those listed in Table II. Figure 17(b) shows our measurement in comparison to our previous results [14,20] and to those from the SND experiment [31]. These previous results are based on different η decay modes than that considered here.…”

“…Previous measurements of the e þ e − → π þ π − π 0 π 0 π 0 cross section were reported by the M3N [18] and MEA [19] experiments, but with very limited precision, leading to a large uncertainty in the corresponding HVP contribution. The BABAR experiment previously measured the e þ e − → ηπ þ π − reaction in the η → π þ π − π 0 [14] and η → γγ [20] decay channels. Below, we present the measurement of e þ e − → ηπ þ π − with η → π 0 π 0 π 0 : this process contributes to e þ e − → π þ π − π 0 π 0 π 0 .…”

Long distance effects in inclusive rare B decays and phenomenology of $$ \overline{B} $$→ Xdℓ+ℓ−

“…The BESII data [79] dominates the statistics in the charm threshold region. The broad oscillation at √ s ∼ 1.6 GeV due to the phase space enhancements of isobar processes including e + e − → ρ + ρ − → π + π − π 0 π 0 has been resolved by precise measurements of multi-body final states at BABAR [80][81][82][83][84][85][86][87][88][89]. The total nonstrange vector spectral function from τ decays is taken from ALEPH [90].…”

Measurement of the e+e−→ ηπ+π− cross section with the CMD-3 detector at the VEPP-2000 collider

“…The calculation of the τ − → ηπ − π 0 ν τ branching fraction using the CMD-3 data leads to the following result: B(τ − → ηπ − π 0 ν τ ) = (0.168 ± 0.006 ± 0.011)%, (8.25) where the first uncertainty is statistical and the second is systematic. This result can be compared with the world average value 0.139 ± 0.01 % [39], the BaBar result 0.163 ± 0.008 % [12], the SND result 0.156±0.004±0.010 % [1] and with the CVC result 0.153± 0.018 % based on the earlier e + e − → ηπ + π − data [42].…”

“…The process e + e − → ηπ + π − was studied earlier in several experiments [1,2,[7][8][9][10][11][12][13]. The most precise measurements of its cross section have been performed at the PEP-II B-factory by the BaBar collaboration [12].…”