JHEP01(2020)112 The cross section of the process $e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}$ is
measured using the data collected with the CMD-$3$ detector at the VEPP-$2000$
collider in the ...center-of-mass energy range from $1.1$ to $2.0$ GeV. The decay
mode $\eta\rightarrow\gamma\gamma$ is used for $\eta$ meson reconstruction in
the data sample corresponding to an integrated luminosity of $78.3$ pb$^{-1}$.
The energy dependence of the $e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}$ cross
section is fitted within the framework of vector meson dominance in order to
extract the
$\Gamma(\rho(1450)\rightarrow{^{+}e^{-}})\mathcal{B}(\rho(1450)\rightarrow\eta\pi^{+}\pi^{-})$
and the
$\Gamma(\rho(1700)\rightarrow{e^{+}e^{-}})\mathcal{B}(\rho(1700)\rightarrow\eta\pi^{+}\pi^{-})$
products. Based on conservation of vector current, the analysed data are used
to test the relationship between the $e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}$
cross section and the spectral function in
$\tau^-\rightarrow\eta\pi^-\pi^0\nu_\tau$ decay. The
$e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}$ cross section measured with the
CMD-$3$ detector is in good agreement with the previous measurements.
The Cryogenic Magnetic Detector (CMD-2) is shortly described. Preliminary results for the cross sections of
e
+
e
− annihilation into hadrons and leptons are presented in the c.m. energy range from ...0.37 to 1.39 GeV. The total integrated luminosity of about 26
pb
−1 has been collected. The new results for the ϱ and ω meson parameters are reported. The major decay modes of the f meson as well as its rare decays have been observed. The tagged kaons and η mesons in f meson decays were used to look for some decay modes of
K
S
o
and η mesons.
Upgrading the SuperKEKB electron-positron collider with polarized electron beams opens a new program of precision physics at a center-of-mass energy of 10.58 GeV. This white paper describes the ...physics potential of this `Chiral Belle' program. It includes projections for precision measurements of \(\sin^2\theta_W\) that can be obtained from independent left-right asymmetry measurements of \(e^+e^-\) transitions to pairs of electrons, muons, taus, charm and b-quarks. The \(\sin^2\theta_W\) precision obtainable at SuperKEKB will match that of the LEP/SLC world average, but at the centre-of-mass energy of 10.58 GeV. Measurements of the couplings for muons, charm, and \(b\)-quarks will be substantially improved and the existing \(3\sigma\) discrepancy between the SLC \(A_{LR}\) and LEP \(A_{FB}^b\) measurements will be addressed. Precision measurements of neutral current universality will be more than an order of magnitude more precise than currently available. As the energy scale is well away from the \(Z^0\)-pole, the precision measurements will have sensitivity to the presence of a parity-violating dark sector gauge boson, \(Z_{\rm dark}\). The program also enables the measurement of the anomalous magnetic moment \(g-2\) form factor of the \(\tau\) to be made at an unprecedented level of precision. A precision of \(10^{-5}\) level is accessible with 40~ab\(^{-1}\) and with more data it would start to approach the \(10^{-6}\) level. This technique would provide the most precise information from the third generation about potential new physics explanations of the muon \(g-2\) \(4\sigma\) anomaly. Additional \(\tau\) and QCD physics programs enabled or enhanced with having polarized electron beams are also discussed in this White Paper. This paper includes a summary of the path forward in R&D and next steps required to implement this upgrade and access its exciting discovery potential.
Phys. Rev. D 97, 032011 (2018) The $e^+e^- \rightarrow K_S K_L \pi^0$ cross section is measured in the
center-of-mass energy range $\sqrt{s}=1.3-2.0$ GeV. The analysis is based on
the data sample ...with an integrated luminosity of 33.5 pb$^{-1}$ collected with
the SND detector at the VEPP-2000 $e^+e^-$ collider.
The cross section of the process \(e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}\) is measured using the data collected with the CMD-\(3\) detector at the VEPP-\(2000\) collider in the center-of-mass ...energy range from \(1.1\) to \(2.0\) GeV. The decay mode \(\eta\rightarrow\gamma\gamma\) is used for \(\eta\) meson reconstruction in the data sample corresponding to an integrated luminosity of \(78.3\) pb\(^{-1}\). The energy dependence of the \(e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}\) cross section is fitted within the framework of vector meson dominance in order to extract the \(\Gamma(\rho(1450)\rightarrow{^{+}e^{-}})\mathcal{B}(\rho(1450)\rightarrow\eta\pi^{+}\pi^{-})\) and the \(\Gamma(\rho(1700)\rightarrow{e^{+}e^{-}})\mathcal{B}(\rho(1700)\rightarrow\eta\pi^{+}\pi^{-})\) products. Based on conservation of vector current, the analysed data are used to test the relationship between the \(e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}\) cross section and the spectral function in \(\tau^-\rightarrow\eta\pi^-\pi^0\nu_\tau\) decay. The \(e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}\) cross section measured with the CMD-\(3\) detector is in good agreement with the previous measurements.
PDF
