The process $e^+e^-toetapi^0gamma$ is studied in the center-of-mass energy range 1.05-2.00 GeV using data with an integrated luminosity of 94.5 pb$^{-1}$ collected by the SND detector at the VEPP-2000 $e^+e^-$ collider. The $e^+e^-toetapi^0gamma$ cro
ss section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the $omegaeta$ intermediate state. The measured cross section of the subprocess $e^+e^-toomegaetatoetapi^0gamma$ is consistent with previous measurements in the $e^+e^-topi^+pi^-pi^0eta$ mode. It is found, with a significance of 5.6$sigma$, that the process $e^+e^-toetapi^0gamma$ is not completely described by hadronic vector-pseudoscalar intermediate states. The cross section of this missing contribution, which can originate from radiation processes, e. g. $e^+e^-to a_{0}(1450)gamma$, is measured. It is found to be 15-20 pb in the wide energy range from 1.3 to 1.9 GeV.
The SND is a non-magnetic detector deployed at the VEPP-2000 $e^+e^-$ collider (BINP, Novosibirsk) for hadronic cross-section measurements in the center of mass energy region below 2 GeV. The important part of the detector is a three-layer hodoscopic
electromagnetic calorimeter (EMC) based on NaI(Tl) counters. Until the recent EMC spectrometric channel upgrade, only the energy deposition measurement in counters was possible. A new EMC signal shaping and digitizing electronics based on FADC allows us to obtain also the event time structure. The new electronics and supporting software, including digital signal processing algorithms, are used for data taking in the ongoing experiment. We discuss the amplitude and time extraction algorithms, the new system performance on experimental events and physical analysis applications.
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 technique of discrimination of the $e^+e^-to e^+e^-$ and $e^+e^-to pi^+pi^-$ events in energy range $0.5 < sqrt{s} < 1$ GeV by energy deposition in the calorimeter of SND detector was developed by applying machine learning method. Identification
efficiency for $e^+e^-to e^+e^-$ and $e^+e^-to pi^+pi^-$ events in the range from 99.3 to 99.8 % has been achived.
The process $e^+e^-toomegaetapi^0$ is studied in the energy range $1.45-2.00$ GeV using data with an integrated luminosity of 33 pb$^{-1}$ accumulated by the SND detector at the $e^+e^-$ collider VEPP-2000. The $e^+e^-toomegaetapi^0$ cross section is
measured for the first time. The cross section has a threshold near 1.75 GeV. Its value is about 2 nb in the energy range $1.8-2.0$ GeV. The dominant intermediate state for the process $e^+e^- to omegaetapi^0$ is found to be $omega a_0(980)$.
The process $e^+e^- to pi^0gamma$ has been studied in the experiment with the SND detector at the VEPP-2M $e^+e^-$ collider. The $e^+e^- to pi^0gamma$ cross section has been measured in the center-of-mass energy range from 0.60 to 1.38 GeV. The cross
section is well described by the vector meson dominance model. From the fit to the cross section data we have determined the branching fractions $B(rhotopi^0gamma)=(4.20pm0.52)times10^{-4}$, $B(omegatopi^0gamma)=(8.88pm0.18)%$, $B(phitopi^0gamma)=(1.367pm0.072)times10^{-3}$, and the relative phase between the $rho$ and $omega$ amplitudes $varphi_{rho}=(-12.7pm4.5)^circ$. Our data on the process $e^+e^- to pi^0gamma$ are the most accurate to date.
Using a data sample of $1.31 times 10^{9}$ $J/psi$ events accumulated with the BESIII detector, the decay $J/psito pbar{p}phi$ is studied via two decay modes, $phito K^{0}_{S}K^{0}_{L}$ and $phito K^{+}K^{-}$. The branching fraction of $J/psito pbar{
p}phi$ is measured to be $mathcal{B}(J/psito pbar{p}phi)=[5.23pm0.06(mbox{stat})pm0.33(mbox{syst})]times10^{-5}$, which agrees well with a previously published measurement, but with a significantly improved precision. No evident enhancement near the $pbar{p}$ mass threshold, denoted as $X(pbar{p})$, is observed, and the upper limit on the branching fraction of $J/psito X(pbar{p})phito pbar{p}phi$ is determined to be $mathcal{B}(J/psito X(pbar{p})phito pbar{p}phi)<2.1times10^{-7}$ at the 90% confidence level.
Based on 2.93 fb$^{-1}$ $e^+e^-$ collision data taken at center-of-mass energy of 3.773 GeV by the BESIII detector, we report searches for the singly Cabibbo-suppressed decays $D^{+}toomegapi^{+}$ and $D^{0}toomegapi^{0}$. A double tag technique is u
sed to measure the absolute branching fractions $mathcal{B}(D^{+}toomegapi^{+})=(2.79pm0.57pm0.16)times 10^{-4}$ and $mathcal{B}(D^{0}toomegapi^{0})=(1.17pm0.34pm0.07)times 10^{-4}$, with statistical significances of $5.5sigma$ and $4.1sigma$, respectively. We also present measurements of the absolute branching fractions for the related $eta pi$ decay modes. We find $mathcal{B}(D^{+}toetapi^{+})=(3.07pm0.22pm0.13)times10^{-3}$ and $mathcal{B}(D^{0}toetapi^{0})=(0.65pm0.09pm0.04)times10^{-3}$, which are consistent with the current world averages. The first and second uncertainties are statistical and systematic, respectively.
In the study of the reaction $e^+e^-to K_{S}K_{L}$ at the VEPP-2M $e^+e^-$ collider with the SND detector the nuclear interaction length of $K_{L}$ meson in NaI(Tl) has been measured. Its value is found to be 30--50 cm in the $K_{L}$ momentum range 0
.11--0.48 GeV/$c$. The results are compared with the values used in the simulation programs GEANT4 and UNIMOD.
The system for insertion of a laser beam into the vacuum chamber of high-energy storage ring is described. The main part of the system is the high-vacuum viewport for the IR radiation, based on ZnSe or GaAs crystals. The design of the viewports is presented.
