arXiv subjects

Vladimir Kulikovskiy

Publications and source records attributed to Vladimir Kulikovskiy.

6 recordsLinked to original sources

arXiv2024

Zero-Point Energy Density at the Origin of the Vacuum Permittivity and Photon Propagation Time Fluctuation

We give a vacuum description with zero-point density for virtual fluctuations. One of the goals is to explain the origin of the vacuum permittivity and permeability and to calculate their values. In particular, we improve on existing calculations by avoiding assumptions on the volume occupied by virtual fluctuations. We propose testing of the models that assume a finite lifetime of virtual fluctuation. If during its propagation, the photon is stochastically trapped and released by virtual pairs, the propagation velocity may fluctuate. The propagation time fluctuation is estimated for several existing models. The obtained values are measurable with available technologies involving ultra-short laser pulses, and some of the models are already in conflict with the existing astronomical observations. The phase velocity is not affected significantly, which is consistent with the interferometric measurements.

quant-ph↗

arXiv2021

Towards automatic detection and classification of orca (Orcinus orca) calls using cross-correlation methods

Orca (Orcinus orca) is known for complex vocalisation. Their social structure consists of pods and clans sharing unique dialects due to geographic isolation. Sound type repertoires are fundamental for monitoring orca populations and are typically created visually and aurally. An orca pod occurring in the Ligurian Sea (Pelagos Sanctuary) in December 2019 provided a unique occasion for long-term recordings. The numerous data collected with the bottom recorder were analysed with a traditional human-driven inspection to create a repertoire of this pod and to compare it to catalogues from different orca populations (Icelandic and Antarctic) investigating its origins. Automatic signal detection and cross-correlation methods (R package warbleR) were used for the first time in orca studies. We found the Pearson cross-correlation method to be efficient for most pairwise calculations (> 85%) but with false positives. One sound type from our repertoire presented a high positive match (range 0.62-0.67) with one from the Icelandic catalogue, which was confirmed visually and aurally. Our first attempt to automatically classify orca sound types presented limitations due to background noise and sound complexity of orca communication. We show cross-correlation methods can be a powerful tool for sound type classification in combination with conventional methods.

q-bio.QM↗

arXiv2021

Sensitivity estimates for diffuse, point-like and extended neutrino sources with KM3NeT/ARCA

The identification of cosmic objects emitting high energy neutrinos could provide new insights about the Universe and its active sources. The existence of these cosmic neutrinos has been proven by the IceCube collaboration, but the big question of which sources these neutrinos originate from, remains unanswered. The KM3NeT detector for Astroparticle Research with Cosmics in the Abyss (ARCA), with a cubic kilometer instrumented volume, is currently being built in the Mediterranean Sea. It will excel at identifying cosmic neutrino sources due to its unprecedented angular resolution for muon neutrinos (< 0.2 degree for E > 10 TeV events). KM3NeT has a view of the sky complementary to IceCube, and is sensitive to neutrinos across a wide range of energies. In order to identify the signature of cosmic neutrino sources in the background of atmospheric neutrinos and muons, statistical methods are being developed and tested with Monte-Carlo pseudo experiments. This contribution presents the most recent sensitivity estimates for diffuse, point-like and extended neutrino sources with KM3NeT/ARCA.

astro-ph.IM↗

arXiv2020

Paving Through the Vacuum

Using the model in which the vacuum is filled with virtual fermion pairs we propose an effective description of photon propagation compatible with the wave-particle duality and the quantum field theory. In this model the origin of the vacuum permittivity and permeability appear naturally in the statistical description of the gas of the virtual pairs. Assuming virtual gas in thermal equilibrium at temperature corresponding to the Higgs field vacuum expectation value, $kT\approx246.22\, \rm{GeV}$, the deduced value of the vacuum magnetic permeability (magnetic constant) appears on the same order of the experimental value. One of the features that makes this model attractive is the expected fluctuation of the speed of light propagation that is at the level of $σ\approx 1.9\,\mathrm{as\,m}^{-1/2}$. This non-classical light propagation property is reachable with the available technologies.

quant-ph↗

arXiv2020

Combining neutrino experimental light-curves for pointing to the next Galactic Core-Collapse Supernova

The multi-messenger observation of the next galactic core-collapse supernova will shed light on the different physical processes involved in these energetic explosions. Good timing and pointing capabilities of neutrino detectors would help in the search for an electromagnetic or gravitational-wave counterparts. An approach for the determination of the arrival time delay of the neutrino signal at different experiments using a direct detected neutrino light-curve matching is discussed. A simplified supernova model and detector simulation are used for its application. The arrival time delay and its uncertainty between two neutrino detectors are estimated with chi-square and cross-correlation methods. The direct comparison of the detected light-curves offers the advantage to be model-independent. Millisecond time resolution on the arrival time delay at two different detectors is needed. Using the computed time delay between different combinations of currently operational and future detectors, a triangulation method is used to infer the supernova localisation in the sky. The combination of IceCube, Hyper-Kamiokande, JUNO and KM3NeT/ARCA provides a 90% confidence area of 140$\pm$20 deg$^2$. These low-latency analysis methods can be implemented in the SNEWS alert system.

astro-ph.HE↗

arXiv2013

Adding a systematic uncertainty to the signal estimation in the on/off-zone measurements

The measurements with the background estimation from an off-zone are widely used in astrophysics, accelerator physics and other areas. Usually, the expected number of the background events in the off-zone and in the on-zone is known with a limited precision. This fact should be included as a systematic uncertainty. In this note an overview of the statistical methods which estimate the range and the significance of the measured signal is done. The method which includes a systematic uncertainty is developed for the on/off-zone measurements and compared with other existing methods.

stat.AP↗