Physics of Particles and Nuclei最新文献

The status of the detector designed to measure the absolute luminosity at the interaction point of the MPD experiment at the NICA collider (JINR) [1] is discussed. The main tasks and performance requirements for the detector are considered. Results of tests of the detector prototypes using cosmic muons and test beams are presented; plans for further work are discussed.

The FTF model is an implementation of the well-known FRITIOF model of Lund University. It is used in the Geant4 package for simulations of hadron–nucleon, hadron–nucleus and nucleus–nucleus interactions at high energies. Thus, for various practical applications, it is important to have correct simulation results. This aim can be reached in a fine tuning of model parameters. In the presented paper, probabilities of strange meson production in quark and diquark fragmentations, and a probability of meson emission by diquarks are determined. A good description of the NA61/SHINE data on production of ({{pi }^{ pm }}) mesons in (pp), (p{text{C}}) and (AA) interactions has been achieved. However, there remains the problem of describing yields of strange mesons in nucleus–nucleus collisions. The model significantly underestimates yields of ({{K}^{ + }}) and ({{K}^{ - }}) mesons in (^{{40}}{text{Ar}} + ,{{,}^{{45}}}{text{Sc}}) interactions.

We investigate the radiative QED corrections to the lepton ((L = e,,, mu ), and (tau )) anomalous magnetic moment arising from vacuum polarization diagrams by four closed lepton loops. The method is based on the consecutive application of dispersion relations for the polarization operator and the Mellin–Barnes transform for the propagators of massive particles. This allows one to obtain, for the first time, exact analytical expressions for the radiative corrections to the anomalous magnetic moments of leptons from diagrams with insertions of four identical lepton loops all of the same type (ell ) different from the external one, (L). The result is expressed in terms of the mass ratio (r = {{{{m}_{ell }}} mathord{left/ {vphantom {{{{m}_{ell }}} {{{m}_{L}}}}} right. kern-0em} {{{m}_{L}}}}). We investigate the behaviour of the exact analytical expressions at (r to 0) and (r to infty ) and compare with the corresponding asymptotic expansions known in the literature.

We have studied hidden-charm strong decays of the charmonium-like resonant state (Y(4320)) within the framework of a confined quark model by interpreting the resonance as a four-quark state with molecular-type interpolating current. The strong decay of (Y) into a vector and a scalar resonance, with the latter decaying, subsequently to a pair of charged pseudoscalar states, has been investigated. We have calculated the partial widths of the strong decays (Y to {{pi }^{ + }}{{pi }^{ - }}{J mathord{left/ {vphantom {J Psi }} right. kern-0em} Psi }) and (Y to {{K}^{ + }}{{K}^{ - }}{J mathord{left/ {vphantom {J Psi }} right. kern-0em} Psi }), and their branching ratio, which is recently determined by the BESIII Collaboration. The estimated proportion of branching and the calculated partial strong decay widths are in reasonable agreement with the most recent experimental results.

Main goals of beam energy scan programs with relativistic heavy ions at energies (sqrt {{{s}_{{NN}}}} ) = 2–11 GeV, like the one planned at the Multi-Purpose Detector (MPD) at the NICA collider, are the investigation of the Equation of State (EOS) and the search for potential phase transitions in dense baryonic matter. In this work, we discuss the layout of the MPD experiment in the fixed-target mode and the anticipated performance for differential anisotropic flow measurements of identfied hadrons at energies (sqrt {{{s}_{{NN}}}} ) = 2.3–3.5 GeV.

A new method for deuteron spin-flip is proposed, which uses the spin resonance crossing with betatron frequencies. The resonance is induced by quadrupole correctors of the Nuclotron, which make it possible to control simultaneously the detuning from the resonance and its power. The deuteron spin-flip is due to adiabatic resonance crossing by the slow variation of the betatron frequency. An advantage of this method is that the beam energy remains constant at the induced resonance crossing; it is determined by the chosen frequency of vertical betatron oscillations. The possibility of experimental verification of the deuteron spin-flip in the Nuclotron is discussed.

The article considers the production of ({{eta }_{{text{c}}}}) mesons at LHC energies using the parton Reggeization approach and the leading order perturbation theory of quantum chromodynamics. The hadronization of a quark–antiquark pair ((cbar {c})) in ({{{{eta }}}_{{text{c}}}}) is described in the framework of nonrelativistic quantum chromodynamics and with the using of color evaporation model. The calculation results are compared with experimental data for the ({{eta }_{{text{c}}}}) production cross section in proton–proton collisions obtained by the LHCb collaboration. Predictions have been made for the kinematic conditions of the LHCb and ATLAS collaboration experiments at an energy (sqrt s = ) 13 TeV.

We present the further development of the vacuum massless integrations. In particular, in the Gorishny–Isaev formula, it has been shown that the delta function representing UV-regime should be treated within the sequential approach. It allows us to resolve the problem of vacuum integrations related to the analytical continuation of diagram indices.

Abstract

MPDRoot is an off-line software framework for simulation, reconstruction, and physical analysis of the simulated or experimental data for MPD experiment at NICA collider. The experiment is projected to run for a few decades and to obtain ~10⁸ events of heavy ion collisions, collecting the data for physics analysis at the 100 PB scale. For overall experiment success it is imperative to have state of the art data analysis software, which integrates best of available latest technologies, while adhering to time-proven, most effective development methodologies. In this paper, we introduce the MPD Data Lab—the technological integration of Acceptance Test Driven Development and Rapid Development concepts into the MPDRoot framework. At the beginning, we standardized the existing codebase by designing and writing API. This was a necessary step to be able to plug-in the external diagnostic software entities and to make the in-depth comparison of different realizations of the reconstruction modules possible. The logic of the diagnostics is encapsulated into the separate controller—the QA Engine, while its visualization is provided by JupyterLab framework. We show how full integration of MPDRoot’s libraries into JupyterLab enables to use the power of rapid development provided by JupyterLab technology to enhance productivity by fast prototyping of MPDRoot’s algorithms. The combination of these technologies together with the existing development environment form a software complex, providing means to accomplish the long term strategic objectives—competent software development with reliable quality control and algorithm innovation.

Abstract

The results of calculations and their comparison with experimental data of proton scattering on ²⁸Si, ⁴⁰Ca, ⁵⁸Ni and ²⁰⁸Pb nuclei at energies from 200 to 1000 MeV are investigated based on the optical potential model in which the amplitude of scattering of an incident proton on a bound nuclear nucleon is explicitly revealed. This amplitude depends on three parameters, namely, the total nucleon-nucleon scattering cross section, the ration of real to imaginary parts of scattering amplitude at forward angles, and on the slope parameter. This analysis of proton-nucleus scattering data allows one to establish these parameters and compare them with those from the analysis of proton scattering on a free unbounded nucleon.