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↗
arXiv subjects
Z. K. Silagadze
Publications and source records attributed to Z. K. Silagadze.
$B_s^0 \to D_s^-a_1^+(D_s^- \to ϕπ^-, D_s^- \to K^{*0}K^-)$ decay channel in the ATLAS $B_s^0$-mixing studies
It is shown, using a track-level simulation, that the use of the $D_s^- \to K^{*0}K^-$ decay channel for $D_s^-$ reconstruction, in additioon with the previously studied $D_s^- \to ϕπ^-$ mode, enables two fold gain in the ATLAS $B_s^0$-mixing signal statistics through $B_s^0 \to D_s^-a_1$ $B_s^0$-decay channel. A new modification of the amplitude fit method is suggested for the $x_s$ determination. Some general aspects of the $B_s^0$-mixing phenomenon is illustrated by pictures of Casimir Malevich, Maurits Cornelis Escher and Salvador Dali.
hep-ph↗
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↗
The OZI Rule Violation in $N \bar N$ Annihilation at Rest and the Skyrme Model
The question is raised if a large violation of the OZI rule, recently observed in many channels in $N \bar N$ annihilation at rest, can be explained in the framework of the Skyrme model.
hep-ph↗
$B_s^0 \to D_s^-a_1^+$ decay channel in the $B_s^0$-mixing studies
The usefulness of the $B_s^0 \to D_s^-a_1^+, D_s^- \to ϕπ^- \to K^+K^-π^-, a_1^+ \to ρ^0 π^+ \to π^+ π^- π^+$ decay chain is investigated for the $B_s$-reconstruction in the future ATLAS $B_s$-mixing experiment. It is shown that this decay channel is almost as suitable for this purpose as previously studied $B_s^0 \to D_s^-π^+$.
hep-ph↗
Do Maxicharged particles exist?
The critical charge $Z_c$ is estimated for elementary particles using a Newton-Wigner position operator inspired model. Particles with $Z \sim Z_c$ (maxicharged particles), if they exist at all, can have unusual properties which turn them into elusive objects not easy to detect. Dirac's magnetic poles have a (magnetic) charge $g\gg Z_c$. This gives one more argument that it is unexpected that pointlike monopoles to be found in our world, where $ α^{-1}\simeq 137$.
hep-ph↗
A new algorithm for automatic photopeak searches
A new, "quantum mechanical" algorithm is proposed for automatic photopeak location in gamma-ray spectra from semiconductor and scintillator detectors.
hep-ex↗
On the Four--Photon Decay of the Neutral Pion
The dominant contribution to the $π^0 \to 4γ$ branching ratio, coming from purely electromagnetic photon-splitting graph, is calculated. The result $Br(π^0 \to 4γ) \simeq (2.6 \pm 0.1) \cdot 10^{-11}$ is about three orders of magnitude below the present experimental limit.
hep-ph↗
Once more about the $ω\to 3π$ contact term
The manifestations of the $ω\to 3π$ contact term and its unitary partners are investigated in the framework of the chiral effective lagrangian theory with vector mesons. We conclude that nowadays the existence and magnitude of the contact term can be extracted neither from theory, nor experiment. The theoretical uncertainty is caused by the one-loop corrections. Some speculations about them lead to the generalized KSRF relation $\frac{f_π^2g^2_{ρππ}}{m_ρ^2}=\frac{m_K}{2\sqrt{2} πf_π}$.
hep-ph↗
$ρ\to 4π$ DECAY
The decay modes $ρ^0 \to 2π^+ 2π^-$ and $ρ^0 \to 2π^0 π^+ π^-$ are considered in the framework of the low energy effective chiral Lagrangian. The obtained values of the decay widths $Γ(ρ^0\to 2 π^+ 2 π^-)=$ $(16 \pm 1){\rm keV}$ and $Γ(ρ^0\to 2 π^0 π^+ π^-)= (6.0 \pm 0.2)$keV do not contradict the existing upper limits and seem to be big enough for the corresponding processes to be observed in future high luminosity experiments.
hep-ph↗
Spin-Momentum Correlation (Handedness) in the Process of Four Pions Production in the Electron-Positron Collisions
We discuss special type of polarization asymmetry (``handedness") in the process $e^+e^-\to 4π$, when one of initial particles is longitudinally polarized. The asymmetry is proportional to the degree of polarization and to the width to mass ratio of rho-meson. It can reach 4-5\% in some kinematical region. Both channels $2 π^+ 2 π^-$ and $2 π^0 π^+ π^-$ are considered in the framework of the effective chiral lagrangian with vector mesons, in the energy range $\sim 1$ GeV. The corresponding total cross sections are also calculated.
hep-ph↗
Pionium in the elementary particle decays
Some atomic decays of elementary particles with pionium ($π^+π^-$-dimesoatom) in the final state are considered. Only for K-meson atomic decays are the corresponding branching ratios big enough to make their experimental study realistic. The $O(α)$ order corrections to the lifetime of pionium are also calculated.
hep-ph↗