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V. Savinov

Publications and source records attributed to V. Savinov.

26 records · Page 2Linked to original sources
arXiv2015

Tunka-Rex: the Cost-Effective Radio Extension of the Tunka Air-Shower Observatory

Tunka-Rex is the radio extension of the Tunka cosmic-ray observatory in Siberia close to Lake Baikal. Since October 2012 Tunka-Rex measures the radio signal of air-showers in coincidence with the non-imaging air-Cherenkov array Tunka-133. Furthermore, this year additional antennas will go into operation triggered by the new scintillator array Tunka-Grande measuring the secondary electrons and muons of air showers. Tunka-Rex is a demonstrator for how economic an antenna array can be without losing significant performance: we have decided for simple and robust SALLA antennas, and we share the existing DAQ running in slave mode with the PMT detectors and the scintillators, respectively. This means that Tunka-Rex is triggered externally, and does not need its own infrastructure and DAQ for hybrid measurements. By this, the performance and the added value of the supplementary radio measurements can be studied, in particular, the precision for the reconstructed energy and the shower maximum in the energy range of approximately $10^{17}-10^{18}\,$eV. Here we show first results on the energy reconstruction indicating that radio measurements can compete with air-Cherenkov measurements in precision. Moreover, we discuss future plans for Tunka-Rex.

astro-ph.IM↗
arXiv2015

Search for the decay $B^+\rightarrow\overline{K}{}^{*0}K^{*+}$ at Belle

We report a search for the rare charmless decay $B^+\rightarrow\overline{K}{}^{*0}K^{*+}$ using a data sample of $772\times10^6$ $B\bar{B}$ pairs collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. No statistically significant signal is found and a 90% confidence-level upper limit is set on the decay branching fraction as $ \mathcal{B}(B^+\rightarrow\overline{K}{}^{*0}K^{*+}) <1.31\times 10^{-6}$.

hep-ex↗
arXiv2013

Search for the process $e^+e^-\to J/ψ+ X(1835)$ at $\sqrt{s}\approx10.6$GeV

We report the results of a search for the $X(1835)$ state in the process $e^+e^-\to J/ψ+X(1835)$ using a data sample of 672 fb$^{-1}$ collected with the Belle detector at and near the $Υ(4S)$ resonance at the KEKB asymmetric-energy $e^+e^-$ collider. No significant evidence is found for this process, and an upper limit is set on its cross section times the branching fraction: $σ_{\rm Born}(e^+e^- \to J/ψX(1835)) \cdot$ {${\cal B}(X(1835)\to \ge 3$ charged tracks)} $< 1.3 \ {\rm fb}$ at 90% confidence level.

hep-ex↗
arXiv2013

Macroscopic electromagnetic response of metamaterials with toroidal resonances

Toroidal dipole, first described by Ia. B. Zeldovich [Sov. Phys. JETP 33, 1184 (1957)], is a distinct electromagnetic excitation that differs both from the electric and the magnetic dipoles. It has a number of intriguing properties: static toroidal nuclear dipole is responsible for parity violation in atomic spectra; interactions between static toroidal dipole and oscillating magnetic dipole are claimed to violate Newton's Third Law while non-stationary charge-current configurations involving toroidal multipoles have been predicted to produce vector potential in the absence of electromagnetic fields. Existence of the toroidal response in metamaterials was recently demonstrated and is now a growing field of research. However, no direct analytical link has yet been established between the transmission and reflection of macroscopic electromagnetic media and toroidal dipole excitations. To address this essential gap in electromagnetic theory we have developed an analytical approach linking microscopic and macroscopic electromagnetic response of a metamaterial and showed, using a case study, the key role of the toroidal dipole in shaping the electromagnetic properties of the metamaterial.

physics.optics↗
arXiv2013

Tunka-Rex: a Radio Antenna Array for the Tunka Experiment (ARENA 2012)

Tunka-Rex, the Tunka radio extension, is an array of 20 antennas at the Tunka experiment close to Lake Baikal in Siberia. It started operation on 08 October 2012. The antennas are connected directly to the data acquisition of the Tunka main detector, a 1 square-km large array of 133 non-imaging photomultipliers observing the Cherenkov light of air showers in dark and clear nights. This allows to cross-calibrate the radio signal with the air-Cherenkov signal of the same air showers - in particular with respect to the energy and the atmospheric depth of the shower maximum, Xmax. Consequently, we can test whether in rural regions with low radio background the practically achievable radio precision comes close to the precision of the established fluorescence and air-Cherenkov techniques. At a mid-term perspective, due to its higher duty-cycle, Tunka-Rex can enhance the effective observing time of Tunka by an order of magnitude, at least in the interesting energy range above 100 PeV. Moreover, Tunka-Rex is very cost-effective, e.g., by using economic Short Aperiodic Loaded Loop Antennas (SALLAs). Thus, the results of Tunka-Rex and the comparison to other sophisticated radio arrays will provide crucial input for future large-scale cosmic-ray observatories, for which measurement precision as well as costs per area have to be optimized. In this paper we shortly describe the Tunka-Rex setup and discuss the technical and scientific goals of Tunka-Rex.

astro-ph.IM↗
arXiv2012

Non-Trivial Non-Radiating Excitation as a Mechanism of Resonant Transparency in Toroidal Metamaterials

We demonstrate theoretically and confirm experimentally a new mechanism of resonant electromagnetic transparency, which yields extremely narrow isolated symmetric Lorentzian lines of full transmission in metamaterials. It exploits the long sought non-trivial non-radiating charge-current excitation based on toroidal dipole moment, predicted to generate waves of gauge-irreducible vector potential in the complete absence of scattered electromagnetic fields.

physics.optics↗
arXiv2000

Search for a Scalar Bottom Quark with Mass 3.5-4.5 GeV/$c^{2}$

We report on a search for a supersymmetric $\tilde{B}$ meson with mass between 3.5 and 4.5 GeV/$c^2$ using 4.52 ${\rm fb}^{-1}$ of integrated luminosity produced at $\sqrt{s}=10.52$ GeV, just below the $e^+e^-\to B\bar{B}$ threshold, and collected with the CLEO detector. We find no evidence for a light scalar bottom quark.

hep-ex↗