arXiv subjects
Publications and source records attributed to Z. K. Silagadze.
There are three astroparticle physics puzzles which fire the imagination: the origin of the ``Great Positron Producer'' in the galactic bulge, the nature of the gamma-ray bursts central engine and the mechanism of supernova explosions. We show that the mirror matter model has the potential to solve all three of these puzzles in one beautifully simple strike.
Vector-Meson-Dominance model contribution to $π^0 \to 4γ$ is calculated. The result confirms old estimates that this contribution is much smaller than the purely electromagnetic photon spliting graph contribution calculated earlier.
Two-dimensional generalization of the original peak finding algorithm suggested earlier is given. The ideology of the algorithm emerged from the well known quantum mechanical tunneling property which enables small bodies to penetrate through narrow potential barriers. We further merge this ``quantum'' ideology with the philosophy of Particle Swarm Optimization to get the global optimization algorithm which can be called Quantum Swarm Optimization. The functionality of the newborn algorithm is tested on some benchmark optimization problems.
One of great mysteries of the Tunguska event is its genetic impact. Some genetic anomalies were reported in the plants, insects and people of the Tunguska region. Remarkably, the increased rate of biological mutations was found not only within the epicenter area, but also along the trajectory of the Tunguska Space Body (TSB). At that no traces of radioactivity were found, which could be reliably associated with the Tunguska event. The main hypotheses about the nature of the TSB, a stony asteroid, a comet nucleus or a carbonaceous chondrite, readily explain the absence of radioactivity but give no clues how to deal with the genetic anomaly. A choice between these hypotheses, as far as the genetic anomaly is concerned, is like to the choice between ``blue devil, green devil and speckled devil'', to quote late Academician N.V. Vasilyev. However, if another mysterious phenomenon, electrophonic meteors, is evoked, the origin of the Tunguska genetic anomaly becomes less obscure.
The process e^+e^-\toπ^0γin the energy range \sqrt{s}=0.60-1.06 GeV was studied at VEPP-2M collider with SND detector using 14 pb^{-1} of integrated luminosity. Data were analyzed in the framework of the vector meson dominance model. Preliminary results on obtained cross-section and parameters of ρ^0, ω,ϕ\to π^0γradiative decays are presented.
The review of the SND results of the $e^+e^-\toπ^+π^-π^0$ process study in the energy range $\sqrt[]{s}=0.42$ -- 1.38 GeV at VEPP-2M collider, based on about $2\times 10^6$ selected events, is presented. The total cross section, parameters of the $ρ$, $ω$, $ϕ$ resonances, and $ω^\prime$, $ω^{\prime\prime}$ states were obtained. It was found that $ρπ$ and $ωπ^0$ intermediate states describe the reaction dynamics. The experimental data cannot be described by a sum of only $ω$, $ϕ$, $ω^\prime$ and $ω^{\prime\prime}$ resonances contributions. This can be interpreted as a manifestation of the $ρ\to 3π$ decay, suppressed by $G$-parity, with relative probability $B(ρ\to 3π) = (1.01\pm^{0.54}_{0.36}\pm 0.034) \times 10^{-4}$.
The process of the muon (pion) pair production with small invariant mass in the electron--positron high--energy annihilation, accompanied by emission of hard photon at large angles, is considered. We find that the Drell--Yan picture for differential cross section is valid in the charge--even experimental set--up. Radiative corrections both for electron block and for final state block are taken into account.
A new candidate for the gamma-ray bursts central engine is proposed: if in some energetic cosmic event a macroscopic amount of bubbles of the disoriented chiral condensate can be formed, then their subsequent decays will produce a relativistic fireball without the baryon loading problem. The neutron star to strange star transition is considered as a candidate example of such cosmic event.
The cross section of the process $e^+e^-\to π^+π^-π^0$ was measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2M collider in the energy region $\sqrt[]{s}$ below 980 MeV. This measurement was based on about $1.2 \times 10^6$ selected events. The obtained cross section was analyzed together with the SND and DM2 data in the energy region $\sqrt[]{s}$ up to 2 GeV. The $ω$-meson parameters: $m_ω=782.79\pm 0.08\pm 0.09$ MeV, $Γ_ω=8.68\pm 0.04\pm 0.15$ MeV and $σ(ω\to 3π)=1615\pm 9\pm 57$ nb were obtained. It was found that the experimental data cannot be described by a sum of only $ω$, $ϕ$, $ω^\prime$ and $ω^{\prime\prime}$ resonances contributions. This can be interpreted as a manifestation of $ρ\to 3π$ decay, suppressed by $G$-parity, with relative probability $B(ρ\to 3π) = (1.01\pm^{0.54}_{0.36}\pm 0.034) \times 10^{-4}$.
Results of the study of the e+e-->pi0 gamma process with SND detector at VEPP-2M collider in the c.m.s. energy range sqrt(s)=0.60-0.97 GeV are presented. Using 36513 selected events corresponding to a total integrated luminosity of 3.4 pb^-1 the e+e-->pi0 gamma cross section was measured. The energy dependence of the cross section was analyzed in the framework of the vector meson dominance model. The data are well described by a sum of phi,omega,rho0->pi0 gamma decay contributions with measured decay probabilities: Br(omega->pi0 gamma)=(9.34+-0.15+-0.31)% and Br(rho0->pi0 gamma)=(5.15+-1.16+-0.73)*10^-4 . The rho-omega relative interference phase is phi(rho,omega}=(-10.2+-6.5+-2.5) degree.
The aim of this paper is twofold: to provide a rather detailed and self-contained introduction into the physics of the Disoriented Chiral Condensate (DCC) for the photon (and linear) collider community, and to indicate that such physics can be searched and studied at photon colliders. Some side tracks are also occasionally followed during the exposition, if they lead to interesting vistas. For gourmets, the Baked Alaska recipe is given in the appendix.
We consider the $π^+π^-π_0γ$ final state in electron-positron annihilation at cms energies not far from the threshold. Both initial and final state radiations of the hard photon is considered but without interference between them. The amplitude for the final state radiation is obtained by using the effective Wess-Zumino-Witten Lagrangian for pion-photon interactions valid for low energies. In real experiments energies are never such small that $ρ$ and $ω$ mesons would have negligible effect. So a phenomenological Breit-Wigner factor is introduced in the final state radiation amplitude to account for the vector mesons influence. Using radiative 3$π$ production amplitudes, a Monte Carlo event generator was developed which could be useful in experimental studies.
The cross section of the process $e^+e^-\to π^+π^-π^0$ was measured in the Spherical Neutral Detector experiment at the VEPP-2M collider in the energy region $\sqrt[]{s} = 980 ÷1380$ MeV. The measured cross section, together with the $e^+e^-\to π^+π^-π^0$ and $ωπ^+π^-$ cross sections obtained in other experiments, was analyzed in the framework of the generalized vector meson dominance model. It was found that the experimental data can be described by a sum of $ω$, $ϕ$ mesons and two $ω^\prime$ and $ω^{\prime\prime}$ resonances contributions, with masses $m_{ω^\prime}\sim 1490$,$m_{ω^{\prime\prime}}\sim 1790$ MeV and widths $Γ_{ω^\prime}\sim 1210$, $Γ_{ω^{\prime\prime}}\sim 560$ MeV. The analysis of the $π^+π^-$ invariant mass spectra in the energy region $\sqrt[]{s}$ from 1100 to 1380 MeV has shown that for their descriptionone should take into account the $e^+e^-\toωπ^0\toπ^+π^-π^0$ mechanism also. The phase between the amplitudes corresponding to the $e^+e^-\toωπ$ and $e^+e^-\toρπ$ intermediate states was measured for the first time. The value of the phase is close to zero and depends on energy.
The e+e- -> pi0 pi0 gamma process was studied in the SND experiment at VEPP-2M e+e- collider in the energy region 0.60-0.97 GeV. From the analysis of the energy dependence of measured cross section the branching ratios B(omega -> pi0 pi0 gamma)= (6.6 +1.4-0.8(stat) +-0.6(syst))x10^-5 and B(rho -> pi0 pi0 gamma)=(4.1 +1.0-0.9(stat) +-0.3(syst))x10^-5 were obtained.
It is shown that multi-dimensional generalization of the vector product is only possible in seven dimensional space.
This talk was given at the Tunguska-2001 international conference but it is not about the Tunguska event. Instead we tried to give some flavor of mirror matter, which is predicted to exist if parity is an unbroken symmetry of nature, to non-experts. The possible connection of the mirror matter ideas to the Tunguska phenomenon was indicated by Foot and Gninenko some time ago and was elaborated by Foot in the separate talk at this conference. If the mirror world interpretation of the Tunguska like events is indeed correct then the most fascinating (but very speculative) possibility is that some well known celestial bodies with strange properties are in fact made mostly from mirror matter, and so maybe the mirror world was discovered long ago and we just have not suspected this.
The $e^+e^-\toηγ\to 7γ$ process was studied in the energy range $2E=600÷1060$ MeV with an SND detector on a VEPP-2M $e^+e^-$ collider. The decay branching ratios $B(ϕ\toηγ)=(1.343\pm 0.012\pm 0.055)\cdot 10^{-2}$, $B(ω\toηγ)=(4.60\pm 0.72\pm 0.19)\cdot 10^{-4}$, and $B(ρ\toηγ)=(2.69\pm 0.32\pm 0.16)\cdot 10^{-4}$ were measured.
It is shown that Feynman's derivation of Maxwell equations admits a generalization to the case of extra spatial dimensions. The generalization is unique and is only possible in seven dimensional space.