Search

At NRNU MEPhI, the world's largest coordinate detector TREK is being created using drift chambers to study cosmic ray muons. The basis of the installation is multiwire drift chambers (DC), previously used in the neutrino detector at the Institute of High Energy Physics (Protvino, Moscow oblast) at the U-70 accelerator. To study the characteristics of DCs before installation in the TREK and the projected MDM detector, a stand was created that makes it possible to determine their efficiency, coordinate and angular accuracy, and zone characteristics. The article presents the design of the stand and the results of testing 394 DCs for the TREK and MDM installations. [ABSTRACT FROM AUTHOR]

The study of spin effects in elastic proton–proton and antiproton–proton scattering in the SPASCHARM experiment at U-70 accelerator facility (Institute for High Energy Physics, National Research Centre Kurchatov Institute, Protvino, Moscow oblast) is discussed. Polarized beams or a polarized target of the experiment will be used to measure the analyzing power of elastic scattering of protons and antiprotons. The possibility of using two different types of the detectors to register recoil particles of elastic scattering of protons is analyzed. In the first case, it is proposed to use scintillation counters, the second option is a detector based on proportional chambers. A comparison of the registration efficiency of elastic scattering for two configurations of the experimental setup is carried out, and the required measurement time is determined. [ABSTRACT FROM AUTHOR]

The paper analyzes the double-differential cross sections for the emission of cumulative protons, pions, kaons, and antiprotons in collisions of carbon nuclei on a fixed target at an energy of 19.6 GeV/nucleon obtained in the IHEP experiment at the U-70 accelerator (Institute for High Energy Physics, National Research Centre Kurchatov Institute). When describing these spectra, the nonequilibrium approach was taken into account as a result of the joint solution of the kinetic equation with the equations of hydrodynamics. Comparison with other approaches are made. [ABSTRACT FROM AUTHOR]

The imaging method based on the absorption and scattering of atmospheric muons (muography method) uses the natural flow of muons formed in the interactions of cosmic rays in the atmosphere. The method is at the junction of elementary particle physics and research in other very diverse fields of natural science, in particular, in archaeology. The paper presents the first results of an experiment to study a unique underground structure in the Holy Dormition Pskov-Caves Monastery, which is a cultural object with a centuries-old history. [ABSTRACT FROM AUTHOR]

A software infrastructure for analysis of experimental data in high energy physics is tightly connected with the specifics of the experiment: detector setup, collision system, reconstructed event and track information. However the aspects of physics analysis are common for different experiments. This fact suggests the development of a universal (in terms of independence from experiments) software, which may be helpful in a number of research cases. A framework for correlation femtoscopy technique, that could be applicable for any experiment, is presented in this work. A polymorphic behavior of the framework encapsulates the data differences, providing a universal way to manage analyses. C++ language and CERN ROOT libraries are used for implementation. [ABSTRACT FROM AUTHOR]

Trackers built of straw drift tubes are a perfect solution for precise track measurements in High Energy and Neutrino Physics experiments operating at low and moderate event rate. Straw Trackers will play crucial roles in such future detectors as Near-Detector Complex of the DUNE experiment, Hidden Sector Detector of the SHiP experiment and the NICA SPD detector. Performance requirements on a Tracker and its readout electronics are defined by the Physics goals. Proper evaluation of the designed Tracker performance demands realistic simulation and studies with tracker prototypes. Preliminary results of the muon beam measurements done with straw tube chambers at the CERN SPS test beam line are compared to predictions obtained with GARFIELD simulation package interfaced to LTSpice program for electronics circuit modeling. [ABSTRACT FROM AUTHOR]

The ALICE experiment at the LHC is designed to explore the hot and dense medium produced in heavy-ion collisions, the so-called quark–gluon plasma (QGP). Antineutron production is a poorly explored domain of high energy physics, although it is interesting in the context of hadrons decaying into antineutrons, the interaction of antineutrons with hadrons, and searching for bound states of antineutrons. We present a method for measuring antineutrons by the electromagnetic calorimeter PHOS of the ALICE experiment. An antineutron can be identified by the cluster shape and the energy deposition in the calorimeter, and its momentum can be reconstructed using the time-of-flight information. The proposed method was verified via the reconstruction of through decays and with an antineutron identified in the PHOS. [ABSTRACT FROM AUTHOR]

New NICA accelerator complex at JINR (Dubna), based on the existing upgraded Nuclotron accelerator, will allow conducting all types of research in the field of high-energy physics. The main tasks of this project are study of the properties of the deconfinement phase transition, experimental investigation on medium modification of vector mesons, and search for the QCD critical end point. Thus, two interaction points are foreseen in the NICA collider: one for studying the collision of heavy ions on the Multipurpose detector MPD, the other for polarized beams for the experiment on the SPD installation. The ambitious physical goals of MPD require excellent particle identification at the maximum possible range of phase space. Identification of charged hadrons is achieved by combining time-of-flight measurements and energy loss measurements from the time-projection camera TPC. The Time-of-Flight system is based on multigap resistive plate chambers (MRPC), which are successfully used to identify particles in similar experiments around the world. A production site has been organized at the Laboratory of High Energy Physics of JINR for serial production of TOF MPD modules including 10 MRPCs. This site includes the entire cycle of work from preparing materials for the assembly of detectors to testing the assembled modules on cosmic radiation. This report presents the structure of the TOF system, its main parameters, the current state and the results of decoding and processing data obtained at the module testing facility. [ABSTRACT FROM AUTHOR]

The results of numerical simulation of the characteristics of a superconducting CORC cable under synchronous cyclic loading by electric current and magnetic field under liquid neon cooling are presented. Distributions of the magnetic field and currents in the system, mechanical stresses and deformations, and energy losses occurring during remagnetization by the magnetic field and electric current are calculated. The features of electrodynamic and thermophysical processes occurring in the system under synchronous current and magnetic-field loading at different winding angles of HTS tapes are shown. The simulation was performed by the finite element method in the Comsol Multiphysics software. The model is designed for calculating the magnetic system of a superconducting inductive energy storage system as part of the Nuclotron based Ion Collider fAcility (NICA), which is under construction at the Laboratory of High Energy Physics (HEPL) of the Joint Institute for Nuclear Research (JINR). [ABSTRACT FROM AUTHOR]

Data on the production of positively charged particles emitted at an angle of 40 (in the laboratory frame) with transverse momenta of up to 2.7 GeV in the interaction of 50-GeV protons with carbon, aluminum, copper, and tungsten nuclear targets are presented. Particular attention is given to studying the production of light nuclear fragments, such as deuterons () and tritons (). An analysis of data on and particles gives grounds to state that these fragments arise via a local mechanism of their direct knockout from nuclei. The results were obtained in the SPIN experiment at the Institute for High Energy Physics (IHEP, Protvino). [ABSTRACT FROM AUTHOR]

The high statistics collected by the LHCb experiment in proton-proton collisions during Run 1 and 2 of the Large Hadron Collider provides a unique opportunity for study of beauty baryons and to broaden knowledge about their spectroscopy. The paper presents the recent results of searches for new beauty particles decays, as well as the results of searches for new excited states of b-hadrons. In particular, the first observation of excited states, the observation of two narrow and states, the observation of new state consistent with the prediction for the baryon, and the observation of the decay are presented. [ABSTRACT FROM AUTHOR]

The Baikal-GVD deep-water neutrino telescope of the cubic kilometer scale, focused on research in the field of astrophysics and particle physics, is being built in Lake Baikal. As of 2021, the effective volume of the detector reaches 0.4 km3 for cascades generated by high-energy astrophysical neutrinos. The paper describes the design and basic characteristics of the telescope data acquisition system, discusses some aspects of deep-water engineering related to the deployment of the detector, and presents selected results obtained with the partially complete detector. [ABSTRACT FROM AUTHOR]

A signal kinematical region is analyzed by the Higgs Boson Working Group (HWW) within the framework of a study of the Standard Model Higgs boson properties in the H → WW* → evεv decay channel in the ATLAS experiment on the Large Hadron Collider (LHC). The analysis is based on the full statistics of proton-proton collision data during exposures in 2015–2016 at the center-of-mass energy of 13 TeV. As compared to our previous analysis, the reconstruction software is updated and the simulation accuracy of backgrounds is improved. Events taken at low and high LHC luminosity are studied separately. In addition, the kinematics at the later stages of event selection is investigated in detail and systematic uncertainties are fully estimated. It is shown that the Monte Carlo modeling satisfactorily describes the experimental data at different selection stages. Kinematic distributions for hadron jets are studied also in the Z-boson control region, where the acquired data reach the order of ten million events. As compared to the previous investigation, the modeling accuracy of Z and background processes is noticeably improved, and events at low and high LHC luminosities are studied separately. Furthermore, all systematic uncertainties related to jets are estimated as well. As a whole, good agreement between experimental results and Monte Carlo simulation data is observed. No problems that would be caused by high luminosity are observed. [ABSTRACT FROM AUTHOR]

A method for reconstruction of the volume density distribution in dynamic targets from their proton radiography image is considered. The reconstruction can be carried out using the inverse Abel transform under the assumption that the studied object and processes have radial symmetry. To increase the accuracy of reconstructed data, algorithms for correction of basic types of distortions of proton radiography images are proposed. The results of processing experimental data obtained on proton radiography facilities PUMA at ITEP and PRIOR at GSI are presented. [ABSTRACT FROM AUTHOR]

The design and the procedures for assembling and testing drift tubes 15 mm in diameter made of 125-µm-thick Mylar film with a double-sided aluminum coating are presented. The technology of assembling three-layer chambers made of such tubes with a length of up to 2.5 m intended for use in experiments at the accelerator facility at the Institute for High Energy Physics of the National Research Center Kurchatov Institute—IHEP is described. Some results obtained during detection of cosmic muon tracks in the chambers are presented. [ABSTRACT FROM AUTHOR]

The SHiP experiment (for Search for Hidden Particles) which will operate at the CERN Super Proton Synchrotron (SPS) is one of the most promising projects in the field of particle physics. The SPS 400-GeV/c proton beam will be dumped onto the molybdenum-tungsten target of the SHiP detector, and the data corresponding to 2 × 1020 protons on the target will be accumulated in five years of running. The experiment is aimed at a search for very weakly interacting neutral particles beyond the Standard Model framework referred to as novel physics particles: massive neutral leptons, axions, and "dark" photons. Possible existence of such particles can help explain such firmly established phenomena as the baryon asymmetry of the Universe, nonzero neutrino masses, and the presence of dark matter. Beyond that, the experimental program envisages extensive studies in neutrino physics. In particular, we aim at directly detecting the tau antineutrino—the only Standard Model particle which until now has escaped experimental detection. The envisaged search for the right-handed neutrino partners is particularly interesting: theoretically, their existence can help explain some observed phenomena not predicted by the Standard Model. Experimental investigations in the fields of tau-neutrino interactions (as the least studied sector of neutrino physics) and production of charmed particles and a search for interactions of particles of light dark matter will be carried out with a neutrino detector based on relativistic nuclear emulsion. The τ- and τ+ production events will be discriminated (whereby the production of tau antineutrinos will be directly detected) using special magnets developed for the SHiP emulsion detector. Presently, a prototype of the emulsion detector as a key element of the SHiP neutrino detector is being simulated, constructed, and tested. The nuclear-emulsion technology provides a record-high spatial resolution as required for detecting charged particles with extremely short lifetimes. The nuclear-emulsion data will be processed with the advanced automatic equipment available at the participating laboratories. Efficient scanning of large areas on nuclear emulsion relies on modern scanning equipment such as the PAVICOM measuring complex developed at the Lebedev Physical Institute. Thereby, one can efficiently process the data collected with any track detectors, including those irradiated by accelerator beams. On the whole, the construction of the SHiP detector poses a number of nontrivial physical and technical problems addressed by physicists from 62 laboratories operating in 16 countries. [ABSTRACT FROM AUTHOR]

Chern-Simons gravities and gravitational Chern-Simons densities are constructed using the non-Abelian Yang-Mills Chern-Simons densities. As such, they are defined only in odd dimensions. We propose instead an analogous construction employing what we term Higgs-Chern-Simons (HCS) densities, which are defined in all dimensions. This enables the definition of extended versions of Chern-Simons gravities in all dimensions. Employing the same prescription, the definition of gravitational Chern-Simons densities is extended to all even dimensions, but only to 4p − 1 odd dimensions. All our considerations are restricted to vacuum fields. [ABSTRACT FROM AUTHOR]

Solutions of the cosmological model are considered within the framework of the modified Jordan-Brans-Dicke theory with a cosmological scalar. A special solution of the model describing an exponential expansion at the early stages and a power-law decelerating expansion at late stages is found. A comparison of the expansion features in the Jordan and Einstein representations is made. At the late stages of the evolution, the scale factor in the Jordan representation tends to a finite value. [ABSTRACT FROM AUTHOR]

We discuss the problem of the time variable in the nearly standard formulation of the quantum mechanics. In order to be able to describe the outcome of some of the experiments, we have used a novel formulation of the time evolution of quantum states called the projection evolution. As an example a delayed-choice experiment is described. We show that this description recreates the experimental results without relaying on the spatial parts of the wave functions. [ABSTRACT FROM AUTHOR]

Using continuous wavelet transform it is possible to construct a regularization procedure for scale-dependent quantum field theory models, which is complementary to the functional renormalization group method in the sense that it sums up the fluctuations of larger scales in order to get the effective action at small observation scale. The standard RG results for ϕ4 model are reproduced. The fixed points of the scale-dependent theory are studied in the one-loop approximation. [ABSTRACT FROM AUTHOR]

The temperature effect is studied for the muon detectors of the Yakutsk cosmic-ray spectrograph, which consists of an ionization chamber and ground-level and undergroundmuon counter telescope deployed at depths of 0, 7, 20, 40, and 60 mwe. This array makes it possible to study muon fluxes over a wide energy range (from 2 to 200 GeV). The dependence of the temperature effect for muon component on the depth and on the zenith angle (that is, on the energy of detected particles, as well as on the solar-activity cycle) is studied. A brief description of the muon detector database (mddb) created at IZMIRAN is given. This database includes observational data from muon detectors and data on the atmospheric pressure and vertical profiles of the atmospheric temperature at standard isobaric levels. [ABSTRACT FROM AUTHOR]

By employing the method of spectrographic global survey, the spectra of protons and anisotropy of cosmic rays during the firstGround-Level Enhancement (GLE) of the intensity of cosmic rays in the solar cycle 24 onMay 17, 2012, a GLE71 event, are studied on the basis of data from ground-based observations of cosmic rays by means of the worldwide network of stations and data from spacecrafts. The rigidity spectra of cosmic rays and relative variations in the intensity of cosmic rays with rigidity 2 GV in the solarecliptic geocentric coordinate system are presented within individual periods of the event under study. It is shown that, in GLE71 periods, protons were accelerated to rigidities in the range of R ~ 2.3−2.5 GV and that the respective differential rigidity spectra of solar cosmic rays are not described by a power-law or an exponential function of the particle rigidity. During the event being considered, the Earth was in the loop-shaped structure of the interplanetary magnetic field. [ABSTRACT FROM AUTHOR]

We propose a new Standard Model (SM) extension based on D4 flavor symmetry in which all of SM quarks have consistent masses and the observed quark mixing pattern can be explained at the first order of perturbation theory with re-normalizable interactions. [ABSTRACT FROM AUTHOR]

The inclusive decays of doubly heavy baryons are studied on the basis of the operator-productexpansion method. The lifetimes of these particles are calculated, and the dependence of the respective theoretical predictions on the quark masses is studied. Theoretical uncertainties that arise in the predictions of the widths with respect to different channels and of the total lifetimes owing to the aforementioned dependence are also estimated. [ABSTRACT FROM AUTHOR]

The problem of the dependence of multiparticle reaction-product formation on the interactionregion size is considered both at cosmic-ray and accelerator energies. In cosmic rays, a comparative analysis of interactions induced by protons and light nuclei was performed on the basis of data obtained by the Stratosphere Collaboration. At accelerator energies, the problem was studied by employing data of the EMU Collaboration. The results revealed a substantial distinction between the production processes in these event groups. An analysis of interactions between light nuclei, (C, O, Ne) + (C/N/O); between intermediate and light nuclei, (Si, S) + (C/N/O); and between heavy nuclei, (Au, Pb) + (Ag/Br), showed that there is a sizable enhancement of fluctuations as the size of the interaction region becomes smaller. A sharp growth of multiplicity and pseudorapidity correlations in the most central interactions, (C, O, Ne) + (C/N/O), is interpreted as a manifestation of internal virtual alpha-particle clustering of light nuclei. [ABSTRACT FROM AUTHOR]

New results of the PAMELA experiment revealed significant difference in the electron and positrons flux and fraction between trapped particles of the radiation belt and quasitrapped particles. A decrease in the ratio of the electron-to-positron fluxes both with increasing altitude and with decreasing energy was observed for the inner radiation belt, but this does not fit in currently used models. The residual atmosphere density in the trapping region for L ~ 1.15−1.2 is estimated on the basis of calculations of trapped-particle trajectories in the Earth’s magnetosphere. It is shown that processes leading to the energy loss for trapped electrons and positrons in the interactions with residual-atmosphere atoms play an important role in the formation of fluxes of these particles, but these processes cannot cause the reduction of the positron fraction in the total flux at energies below some 100 MeV. The role of the process of δ-electron production in the formation of the belt of trapped electrons and positrons is considered. Allowance for this process makes it possible to explain the above reduction at least partly. [ABSTRACT FROM AUTHOR]

The use of ultracold neutrons opens unique possibilities for studying fundamental interactions in particles physics. Searches for the neutron electric dipole moment are aimed at testing models of CP violation. A precise measurement of the neutron lifetime is of paramount importance for cosmology and astrophysics. Considerable advances in these realms can be made with the aid of a new ultracold-neutron (UCN) supersource presently under construction at Petersburg Nuclear Physics Institute. With this source, it would be possible to obtain an UCN density approximately 100 times as high as that at currently the best UCN source at the high-flux reactor of the Institute Laue-Langevin (ILL, Grenoble, France). To date, the design and basic elements of the source have been prepared, tests of a full-scale source model have been performed, and the research program has been developed. It is planned to improve accuracy in measuring the neutron electric dipole moment by one order of magnitude to a level of 10−27 to 10−28e cm. This is of crucial importance for particle physics. The accuracy in measuring the neutron lifetime can also be improved by one order of magnitude. Finally, experiments that would seek neutron-antineutron oscillations by employing ultracold neutrons will become possible upon reaching an UCN density of 103 to 104 cm−3. The current status of the source and the proposed research program are discussed. [ABSTRACT FROM AUTHOR]

The γ* → γf2(1270) and γ* → γa2(1320) transition form factors are considered up to high energies, along with the cross sections for the respective processes e+e− → γ* → f2γ and e+e− → γ* → a2γ. It is shown that QCD asymptotic behavior of the amplitudes for the reactions e+e− → γ* → f2γ and e+e− → γ* → a2γ can be reached after the compensation of the contributions of the ρ(770) and ω(782) mesons with the contributions of their radial excitations. The ratio σ(e+e− → γ* → f2γ)/σ(e+e− → γ* → a2γ) ≈ 25/9, obtained on the basis of the two-quark model of a2 and f2 and within QCD, is used to determine σ(e+e− → γ* → a2γ) at high energies. Recent data from the Belle detector on the γ*(Q2)γ → f2 transition over the region extending up to Q2 = 30 GeV2 are taken into account. A substantial improvement of experimental accuracies is required for a detailed comparison of our predictions with experimental data at high energies. A recent measurement of the e+e− → f2γ → π+π−γ cross section at 10.58 GeV with the BaBar detector gives grounds to hope for this. [ABSTRACT FROM AUTHOR]

The isobaric model, which describes well the experimental cross sections for η'-meson photoproduction at photon energies between 1500 and 2300 MeV, is refined with allowance for new experimental data on the beam asymmetry for this reaction. [ABSTRACT FROM AUTHOR]

New relativistic semiclassical conditions and leptonic decay widths are obtained within quantum chromodynamics for nonsingular confining quasipotentials and funnel-type potentials (instantoninteraction approximation). The respective analysis is performed within a fully covariant quasipotential approach in quantum field theory. This approach is formulated in the relativistic configuration representation for the case of interaction between two relativistic spinless particles of arbitrary mass. [ABSTRACT FROM AUTHOR]

The latest results of searching for exotic multiquark states with heavy quarks obtained in the D0 experiment (Fermi National Accelerator Laboratory, USA) are presented. In particular, the evidence of existence of a possible four-quark state X(5568) → B0sπ± in the cases with hadronic and semileptonic decay channels of B0s meson is considered, as well as the results of searching for the five-quark states in the J /ΨΛ system. [ABSTRACT FROM AUTHOR]

BM@N (Baryonic Matter at Nuclotron) is the first experiment to be realized at the NICA-Nuclotron accelerator complex. The aim of the BM@N experiment is to study relativistic heavy ion beam interactions with fixed targets. The BM@N setup, results of Monte Carlo simulations, and the BM@N experimental program are presented. [ABSTRACT FROM AUTHOR]

Among various types of Cherenkov detectors (solid, liquid and gaseous) created for different studies, the most impressive development was gained by water detectors: from the first detector with a volume of several liters in which the Cherenkov radiation was discovered, to the IceCube detector with a volume of one cubic kilometer. The review of the development of Cherenkov water detectors for various purposes and having different locations - ground-based, underground and underwater - is presented in the paper. The prospects of their further development are also discussed. [ABSTRACT FROM AUTHOR]