The $ρ^{\pm}-ρ^0$ Mass Splitting Problem
It is discussed the problem of the $ρ^\pm-ρ^0$ mass splitting. It is suggested to use the $ϕ\toρπ\to 3π$ decay to measure the $ρ^{\pm}-ρ^0$ mass splitting.
hep-ph↗
arXiv subjects
M. N. Achasov
Publications and source records attributed to M. N. Achasov.
First Observation of PHI(1020)--->PI0+PI0+GAMMA Decay
In the SND experiment at the VEPP-2M electron-positron collider the PHI(1020)--->PI0+PI0+GAMMA decay was studied. The branching ratio B(PHI--->PI0+PI0+GAMMA)=(1.14+-0.10+-0.12)x10^{-4} was measured. It was shown, that the F0(980)GAMMA mechanism dominates in this decay and the 4-quark model of F0(980) describes our data most consistently.
hep-ex↗
Experiments at VEPP-2M with SND detector
Short overview of experiments with SND detector at VEPP-2M e^+e^- collider in the energy range 2E = 400 - 1400 MeV and preliminary results of data analysis are presented.
hep-ex↗
Evidence of the PHI(1020)--->ETA+PI0+GAMMA Decay
Signal of the rare radiative decay PHI--->ETA+PI0+GAMMA was observed in the SND experiment at VEPP-2M electron-positron collider.The result is based on the analysis of data, corresponding to a total integrated luminosity of 4 pb^{-1}, or 8x10^6 PHI mesons produced. The measured branching ratio of PHI--->ETA+PI0+GAMMA decay is equal to (0.83+-0.23)x10^{-4}.
hep-ex↗
Experimental study of the decay PHI(1020)--->ETA+GAMMA in multi-photon final state
In the SND experiment at VEPP-2M e^+e^- collider the phi(1020) ---> eta+gamma ---> 3pi^0+gamma decay was studied. The branching ratio B(phi--->eta+gamma) = (1.246 +- 0.025 +- 0.057)% was measured.
hep-ex↗
Energy calibration of the NaI(Tl) calorimeter of the SND detector using $e^+e^- \to e^+e^-$ events
Calibration of the three layer NaI(Tl) spherical calorimeter of the SND detector using electron -- positron scattering events is described. Energy resolution of $5 % (FWHM/2.36)$ for 500 MeV photons was achieved.
physics.ins-det↗
Energy calibration of the NaI(Tl) calorimeter of the SND detector using cosmic muons
The general purpose spherical nonmagnetic detector (SND) is now taking data at VEPP-2M $e^+e^-$ collider in BINP (Novosibirsk) in the centre of mass energy range of $0.2 ÷1.4$ GeV. The energy calibration of the NaI(Tl) calorimeter of the SND detector with cosmic muons is described. Using this method, the energy resolution of $5.5 % (σ)$ for 500 MeV photons was achieved.
physics.ins-det↗
Study of $Δ(1232)$ isobar electroproduction at VEPP-2M $e^+e^-$ collider
Results from the Spherical Nonmagnetic Detector (SND) on $Δ(1232)$ isobar electroproduction in the collisions of beam electrons (positrons) and residual gas nuclei in the VEPP-2M $e^+e^-$ collider are presented. On the basis of the obtained data the expected counting rate of this process in future high luminosity $e^+e^-$ colliders (~$ϕ$-, $c$-$τ$- and $b$-factories) was estimated.
hep-ex↗
Upper limit on the eta -> pi^0 pi^0 decay
Upper bound 6*10^{-4} with 90% confidence is reported for the eta -> pi^0 pi^0 decay from the SND experiment at the VEPP-2M collider.
hep-ex↗
Evidence of phi --> pi0 pi0 gamma and phi --> pi0 eta gamma decays in SND experiment at VEPP-2M
Preliminary results on the study of e+e- --> phi(1020) --> pi0 pi0 gamma, eta pi0 gamma processes from SND experiment at VEPP-2M collider in Novosibirsk are presented. Branching ratios of rare radiative phi --> pi0 pi0 gamma and phi --> pi0 eta gamma decays are measured: B(phi --> pi0 pi0 gamma ) = (1.1 +- 0.2) * 10^-4 (invariant mass (pi0 pi0) < 800 MeV), B(phi --> eta pi0 gamma ) = (1.3 +- 0.5) * 10^-4.
hep-ex↗
First Physical Results from SND Detector at VEPP-2M
The paper describes experiments with the SND detector at VEPP-2M collider, carried out during the period from October 1995 until June 1997. The total integrated luminosity of 6.4 pb^{-1} was collected in the energy range 2E=0.4-1.4 GeV (MHAD97 experiment), corresponding to 4*10^5 mu^+ mu^- pairs produced. Preliminary results of the 1996 phi-meson experiment (FI96) are presented. The total number of phi-mesons produced is 4*10^6. New data on rare decays of phi and eta (550) mesons, in particular B(phi -> eta gamma) = (1.30+-0.06+-0.07)%, B(phi -> pi^0 pi^0 gamma) = (1.1+-0.2)*10^{-4}, (M_{pi^0 pi^0} > 800 MeV), B(phi -> f^0 gamma) = (4.7+-1.0)*10^{-4}, B(phi -> eta pi^0 gamma) = (1.3+-0.5)*10^{-4}, B(phi -> eta' gamma) < 1.7*10^{-4}, B(phi -> 2 pi^0 ) < 6*10^{-4} were obtained.
hep-ex↗
Isobar Electroproduction as a Background from Interaction of Beams with Residual Gas at $ϕ$-Factories
It is shown that when beams interact with a residual gas at $ϕ$-factories the reaction of the electroproduction of the $Δ(1232)$ isobar proceeds vigorously. The isobar decay gives $\sim 10^7$ pions during an effective year of $10^7$ s per meter of a residual gas. These pions are emitted largely across the beam axis and have a resonance energy distribution with a peak nearby 265 MeV of a width close to 120 MeV in the isobar rest system. There are presented formulae for the distributions of the four-momentum transfer square, the angles, the energies and the momentum of the decay products, that is all required for the simulation of the process under consideration.
hep-ph↗