When calculating characteristics of various physical processes involving particle interactions, one must deal with the production and decay of unstable particles participating in these processes, such as W and Z bosons, the top quark, the Higgs boson, and others. Unlike stable particles, unstable particles are characterized not only by their mass but also by partial and total decay widths. The...
According to the modern physics, our Universe is baryo-asymmetric. That phenomenon can not be described in the frameworks of the Standard Model of particle physics. Globally, the Universe consists of baryon matter. However,some scenarios can lead to the existence of local antimatter domains. In the research chemical evolution of such domain is studied. The size of the domain is estimated...
We present an implementation of the hyperspherical harmonics method for computing binding energies of three-body nuclear systems, specifically ³H and ³He. The approach is based on expanding the three-body wave function in a hyperspherical harmonics basis, which reduces the many-body Schrödinger equation to a system of coupled ordinary differential equations in the hyperradial coordinate. Using...
Coherent Elastic neutrino Nucleus Scattering (CEvNS) is the perspective technology for neutrino monitoring of nuclear reactors all over the world. Using the inorganic scintillators, as a target of detector opens the way to create simple constructions, in compare with liquid noble gases and HpGe detectors, as main target materials. In this work, were considered and modeled in Geant4 new...
We present a new iterative method for conversion photon energy scale calibration in the CMS experiment. The channel pi0—>gamma gamma is used for the calibration. The obtained calibration can be used in a wide variety of analyses at CMS.
Photoelectron circular dichroism (PECD) [1] is a well-known phenomenon resulting in asymmetry in the angular distribution of photoelectrons produced in the ionization of randomly oriented chiral molecules in a gas by circularly polarized light relative to the direction of light propagation. Recent advances have extended this concept to vortex electrons, where the ejected photoelectron has a...
We present a numerical comparison between the Faddeev method—implemented via direct integration of homogeneous integral equations for the three-body T-matrix without partial-wave decomposition—and the hyperspherical harmonics (HH) method for computing binding energies of the three-nucleon systems (^3)H and (^3)He. Both approaches are applied using model nucleon–nucleon potentials. In the...
The aim of this work is to determine the optimal chemical-etching exposure time required to produce an efficient reflective surface on scintillator strips. To achieve this goal, we investigated the light yield efficiency, optical transparency, and reflectivity of strips with varying reflective-layer thicknesses formed through controlled chemical etching. Light yield measurements were performed...
The angular distributions of Drell-Yan lepton pairs allow to determine precisely the dynamics of vector boson production in quantum chromodynamics. The dependence of the angular coefficients $A_{i}$ on the transverse momentum of $J/\psi$ mesons was obtained at the energy of the first stage of the SPD experiment using the Pythia generator. The $J/\psi$ mesons produced in pp collisions at...
In this work, the model for calculating the dynamics of the energy spectrum of $\beta^-$ particles and $\bar{\nu}_e$ from nuclear fuel fission products is developed using the Monte Carlo method. The influence of the time dependence on the shape of the spectrum of fission products of $^{235}\text{U}$ and $^{239}\text{Pu}$ is investigated. The obtained spectra $\bar{\nu}_e$ of $^{235}\text{U}$ ...
Cherenkov detectors are pivotal for particle identification and velocity
measurement in high-energy physics, astrophysics, and neutrino experiments.
Their performance is critically dependent on the efficiency of the optical modules
used to detect Cherenkov photons. Modern Cherenkov detectors have an
incredible active volume like 258 kton of water in Hyper-Kamiokande. The veto
system of...
Black holes formed in the early Universe (primordial black holes, PBHs) may simultaneously explain several astrophysical anomalies. These include, for example, the existence of supermassive black holes in the young Universe ($z>6$, [Mazzucchelli C. et al., (2017, ApJ)][1]) and black holes with masses of $∼100\ M_\odot$ detected by gravitational-wave observatories [(LVK Scientific...
We derive recurrence relations for leading logarithmic all-loop quantum corrections in the case of $SO(N)$ symmetric scalar theory with arbitrary potential in a curved spacetime. On this basis, a system of renormalisation group (RG) equations in the general approach for the effective potential in the large $N$ limit and $N=1$ is obtained. As a simplest illustration, we analyse the case of...
The interaction of primordial plasma, exemplified by scalar particles and fermions, with a closed domain wall during the radiation-dominated stage of the Universe is considered. Possible forms of the interaction Lagrangian are analyzed. Various scenarios are presented, including both conventional scattering and the “locking” effect of gas inside the wall: when the particle temperature drops...
The Large Volume Detector (LVD) is located in the underground Gran Sasso Laboratory in Italy. The detector has a modular design and consists of 840 liquid-scintillation counters arranged in three towers, 280 counters per tower. Every eight counters form a “portatank” module, which is surrounded by a tracking system. This geometry, together with the underground location, enables studies of the...
The optical modules will be used for the outer water Cherenkov detector of Hyper-Kamiokande. This solution increases light collection in the detector's volume. The aim of the study is to create an optical module made of a wavelength-shifting (WLS) plate (an acrylic plate with a wavelength-shifting dopant) and a photomultiplier tube (PMT) that meets the requirements for usage in water Cherenkov...
Supersymmetry is a promicing extention of the Standard Model. Since no superpartners have been found, it is tempting to explore the possibility that SUSY can manifest itself at low energy through a hidden sector which is responsible for the supersymmetry breaking. It is interesting that possible interactions of such a hidden sector with SM particles can be observed at relatively low...
We derive a system of generalized renormalization-group equations for the effective potential of an arbitrary scalar field theory with mass based on the Bogoliubov-Parasiuk theorem on locality of counterterms. These equations sum up the leading logarithmically divergent contributions and represent a system of nonlinear partial differential equations of the second order. We show that in some...
We investigate the sensitivity of the Compact Linear Collider (CLIC) at √s = 3 TeV to heavy vector-like B quarks produced in pairs and decaying via B → bh and B → bZ in fully hadronic channels. A cut-based analysis is performed in both boosted Higgs and Z channels. We find that CLIC can achieve high statistical significance for VLQ-B masses in the TeV range and exclude masses up to about 1.5...
The $\nu$GeN and RED-100 experimental setups deployed at Kalinin Nuclear Power Plant (KNPP) constitute sub-keV threshold detectors suitable for probing hypothetical beyond Standard Model particles known as millicharged particles ($\chi_{q}$). The setups leverage intense reactor antineutrino fluxes from a 3.1 GWth reactor with the aim to observe coherent elastic neutrino nucleus scattering...
The Multipurpose Detector of Muons (MDM) is being developed at the Experimental complex NEVOD (MEPhI). It is made up of 2 pairs of orthogonally oriented layers of drift chambers interleaved with 2 layers of steel absorbers. The MDM is designed to detect single and multi-particles events of cosmic ray muons up to 60º zenith angle.
The sequential model of the MDM consists of: the detector...
The $\nu$GeN experiment searches for coherent elastic neutrino-nucleus scattering (CE$\nu$NS) at the Kalinin Nuclear Power Plant. To reduce background conditions, an upgrade in the form of an active anti-coincidence system based on NaI crystals is proposed. It will cover the low-threshold 1.41 kg high-purity germanium detector from all sides and suppress different backgrounds. This work...
The goals of the νGeN experiment, carried out at the Kalinin NPP, include a measurement of coherent elastic neutrino-nucleus scattering and the search for electromagnetic properties of neutrinos, in particular its magnetic moment. The experiment relies on comparison of the spectra obtained with the reactor running and stopped to reveal the neutrino-induced signal. Thus, the components of...
The results of a Monte Carlo simulation of the upgraded DANSS detector were used to construct a model of the detector signal. It was then analysed, a positron cluster was reconstructed for each IBD event. The simulation of the registration of monoenergetic neutrinos allowed to use the signal model to estimate the energy resolution of the detector.
This study investigates the stability of background conditions in the νGeN experiment at the Kalinin Nuclear Power Plant. It is demonstrated that fluctuations of the background count rate of the germanium detector inside the passive shielding are correlated with the intensity of photoabsorption peaks from radon-related gamma rays. Using data from periods with different intensity of these...
The gauge symmetry is said unfree if the gauge transformation leaves the action functional invariant, provided that the gauge parameters are constrained by a system of partial differential equations. The most known example of this phenomenon is the volume-preserving diffeomorphism, being the gauge symmetry of unimodular gravity. Given the distinctions of the unfree gauge symmetry from the...
Quasi-plane-wave beams of elementary particles are the simplest to produce and control. Therefore, calculating decay width and scattering cross-sections for particles with defined momenta remains a relevant and important task.
More complex types of beams can be constructed, such as twisted or vortex beams. In such beams the projection of the momentum onto the beam's propagation direction...
We present the results of a spectral and timing analysis of the X-ray emission from the actively accreting supermassive black hole in RX J1301.9+2747, which exhibits quasi-periodic X-ray burst-like eruptions. To investigate the features of the X-ray spectrum formation in this source during the bursts, data from ASCA, ROSAT, XMM-Newton, and NICER observations were used with a Comptonization...
