Hadronic Generators Research Articles

Shell‐type supernova remnants and very high energy cosmic rays

AbstractThe investigation of very high energy (VHE) γ‐ray sources by any methods, including mirror Cherenkov telescopes, touches on the problem of the cosmic‐ray origin and, accordingly, the role of the Galaxy in their generation. The SHALON observations have yielded the results on Galactic supernova remnants (SNR) of different ages. Among them are: the shell‐type SNRs Tycho's SNR, Cas A, IC 443, γCygni SNR, G166.0+4.3. For each of SNRs, the observation results are presented with spectral energy distribution by SHALON in comparison with other experiment data and images by SHALON in together with data from X‐ray by Chandra and radio‐data by CGPS. The experimental data presented here have confirmed the prediction of the theory about the hadronic generation mechanism of VHE 800 GeV–100 TeV γ‐rays in Tycho's SNR, Cas A and IC 443, and also the collected experimental data help to make clear the origin of TeV γ‐ray emission in the older SNRs like γCygni SNR and G166.0+4.3.

On connection between the collider long-range near-side \u201cridge\u201d effect at |eta | < 2.4 and cosmic-ray coplanarity of most energetic particles

Some coplanarity of most energetic subcores of gamma -ray–hadron families is observed in cosmic-ray experiments at E_0 gtrsim 10^{16} eV (sqrt{s} gtrsim 5 TeV). This effect requires appearance of some coplanar generation of most energetic particles in hadron-nucleus interactions. On the other hand, a long-range near-side “ridge” effect was observed in pp collisions at sqrt{s} = 7 TeV by the CMS Collaboration in two-particle varDelta eta - varDelta varphi correlation functions at |varDelta eta | gtrsim 3 and |varDelta varphi | approx 0. To improve a research for possible relationship of these phenomena, a phenomenological FANSY 2.0 model is designed to simulate hadron interactions using both traditional and coplanar modes for the hadron generation, QGSJ and CPG, respectively. The FANSY 2.0 reproduces LHC data on generation of unflavoured, strange and charmed hadrons. Model parameters of coplanar hadron generation are given. It is shown that the FANSY 2.0 CPG reproduces the near-side “ridge” effect at sqrt{s} = 7 TeV.

Simulation of atmospheric pressure dependence on GRAPES-3 particle density

The high density extensive air shower array along with large area (560 m2) muon telescope of GRAPES-3 at Ooty is used to make precise measurements of cosmic ray properties by using the secondaries produced through cascades in the Earth’s atmosphere. The observed particle density at detector level is affected by atmospheric effects primarily due to variations in the pressure and temperature. Here, an attempt is made to simulate these phenomena that can provide a deeper understanding of these effects. In this study, the pressure dependence of the observed particle densities at GRAPES-3 is simulated by varying the atmospheric profiles available in CORSIKA for proton showers in the energy range of 1013–1016 eV. A comparative study of various combinations of hadronic interaction generators available in CORSIKA has been used to investigate the consistency of the results obtained and their broad implications have been intensely discussed.

Does superhigh-energy cosmic-ray coplanarity contradict LHC data?

One of phenomena observed in cosmic-ray experiments at E_0 gtrsim 10^{16} eV (sqrt{s} gtrsim 5 TeV) is a so-called coplanarity of most energetic subcores of gamma -ray–hadron families. This effect requires appearance of some coplanar generation of most energetic particles in hadron-nucleus interactions. To improve research for this phenomenon, a few versions of the new phenomenological FANSY 2.0 model are designed. This model makes it possible to simulate interactions via both traditional and coplanar hadron generation modes. The model reproduces ALICE, ATLAS, CMS, TOTEM data on low-rapidity particle generation, LHCf’s high-x_text {F} and high-eta data on gamma -rays and neutron-like hadrons as well as low-energy data on generation of stable and resonance hadrons, light-quark, strange and charmed particles. Features of coplanar particle generation of hadrons at superhigh energies are discussed. A test experiment at the LHC is proposed.

Do LHC data contradict superhigh-energy cosmic-ray coplanarity of most energetic particles?

To research for a coplanarity of most energetic subcores of γ-ray–hadron families observed in cosmic-ray experiments at E0 ≳ 1016 eV (√s ≳ 5 TeV), a new phenomenological FANSY 2.0 model is designed. The model makes it possible to simulate interactions for both traditional and coplanar hadron generation options, reproduces LHC data, including high-η and xF data on γ-rays and neutrons. An experiment at the LHC is proposed to test the model.

Status of R value measurement at BESIII

The dominant systematic error of R value measurement comes from the hadronic generator simulations. This paper reviews the present status of R value measurement from 2.232 to 3.671 GeV at 14 energy points, especially describes the calculations of initial state radiative correction and the issue of the parameter tuning for the Lund area law generator LUARLW.

Cosmic ray origin: Supernova remnants through the electromagnetic spectrum

Supernova Remnants have long been considered as unique candidates for cosmic-ray sources. Recent observations of several SNRs in X-rays and TeV gamma-rays will help in solving the problem of the origin of cosmic rays and are key to understanding the mechanism of particle acceleration at a propagating shock wave. The observation results of Galactic shell-type supernova remnants at different evolution stages Cas A, Tycho's SNR, γCygni SNR, IC 443 and G166.0+4.3 by the SHALON mirror Cherenkov telescope are presented. For each SNR the SHALON observation results are given with its spectral energy distribution compared with other experimental data and images by SHALON together with data from X-ray by Chandra and radio-data by Canadian Galactic Plane Survey DRAO (CGPS). The comparison of the source's morphology in different energy bands could reveal its essential features as a forward and reverse shock or the location of swept out dense molecular cloud. The experimental data presented here have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy 800 GeV-100 TeV gamma-rays in Tycho's SNR, Cas A and IC 443. Also the collected experimental data help to make clear the origin of TeV gamma-ray emission in the SNRs like γCygni SNR and G166.0+4.3.

Shell-type supernova remnants as sources of cosmic rays

The investigation of VHE gamma-ray sources by any methods, including mirror Cherenkov telescopes, touches on the problem of the cosmic ray origin and, accordingly, the role of the Galaxy in their generation. The SHALON observations have yielded the results on Galactic supernova remnants (SNR) of different ages. Among them are: the shell-type SNRs Tycho’s SNR (1572y), Cas A (1680y), IC 443 (age∼(3–30)×103y), γCygni SNR (age∼(5–7)×103y), G166.0+4.3 (age∼24×103y) and classical nova GK Per (Nova 1901). For each of SNRs the observation results are presented with spectral energy distribution by SHALON in comparison with other experiment data and images by SHALON in together with data from X-ray by Chandra and radio-data by CGPS. The collected experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy 800GeV–100TeV gamma-rays in Tycho’s SNR, Cas A and IC 443. For the first time, unique data on GK Per (Nova 1901) TeV gamma-ray emission were obtained with SHALON experiment. The X-ray data shows that, the nova remnant of GK Per could be a younger remnant that will resemble older SNRs like IC 443 which interact with molecular clouds. GK Per is supposed to be a candidate for TeV gamma-ray emission due to the accelerated particles in the reverse shock region.

Shell-type SNRs as sources of cosmic rays

Investigations of VHE gamma-ray sources by any methods, including mirror Cherenkov telescopes, touch on the problem of the cosmic ray origin and, accordingly, the role of the Galaxy in their generation. SHALON observations have yielded results on Galactic supernova remnants (SNR) of different ages. Among them are: the shell-type SNRs Tycho's SNR (1572y), Cas A (1680y), IC 443 (age ∼ (3 ÷ 30) × 10 3 y), Cygni SNR (age ∼ (5 ÷ 7) × 10 3 y), G166.0 + 4.3 (age ∼ 24 × 10 3 y) and the classical nova GK Per (Nova 1901). Observation results are presented for each of the SNRs with spectral energy distributions by SHALON in comparison with other experiment data and images by SHALON together with data from X-rays by Chandra and radio-data by CGPS. The collected experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy 800 GeV–100 TeV gamma-rays in Tycho's SNR, Cas A and IC443. For the first time, unique data on GK Per (Nova1901) TeV gamma-ray emission were obtained with the SHALON experiment. The X-ray data shows that the nova remnant of GK Per could be a younger remnant that will resemble older SNRs like IC 443 which interact with molecular clouds. GK Per is supposed to be a candidate for TeV gamma-ray emission due to accelerated particles in the reverse shock region.

Results of observations of shell supernova remnants at ultrahigh energies with the SHALON mirror Cherenkov telescopes

The investigation of VHE gamma-ray sources by any methods, including mirror Cherenkov telescopes, touches on the problem of the cosmic ray origin and, accordingly, the role of the Galaxy in their generation. The SHALON observations have yielded the results on Galactic shell-type supernova remnants (SNR) on different evolution stages. Among them are: SNRs Tycho's SNR, Cas A, IC 443, $\gamma$Cygni SNR and classical nova GK Per (Nova 1901). For each of SNRs the observation results are presented with spectral energy distribution by SHALON in comparison with other experiment data and images by SHALON. The collected experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy 800 GeV - 100 TeV $\gamma$-rays in Tycho's SNR, Cas A and IC443.

Calculation of beams of positrons, neutrons, and protons associated with terrestrial gamma ray flashes

AbstractPositron beams have been observed by the Fermi satellite to be correlated with lightning leaders, and neutron emissions have been attributed to lightning and to laboratory sparks as well. Here we discuss the cross sections to be used for modeling these emissions, and we calculate the emissions of positrons, neutrons, and also protons from lightning leaders. Neutrons were first erroneously attributed to fusion reactions, but the photonuclear reaction responsible for neutrons should create protons as well. We predict them here; they have not been observed yet. In the paper, we first revisit the model for stepped lightning leaders of Xu, Celestin, and Pasko with updated cross sections, we analyze the spatial and energetic structure of the electron beam, and we calculate the spectrum of the generated gamma ray beam at 16 km altitude. Then we review the scattering processes of photons with emphasis on the processes above 5 MeV, in particular the photon energy losses in Compton scattering events and the generation of leptons and hadrons. We provide simple approximations for photon energy loss and lepton and hadron production for any photon with energy above 5 MeV passing through an arbitrary air layer. Finally, we launch a gamma ray beam with the earlier calculated spectrum of the negative stepped lightning leader from 16 km upward and calculate the production and energy of positrons, neutrons, and protons as well as the propagation of positrons.

Cosmic ray production in Historical Supernova Remnants

We present the results of observations of two types of Galactic supernova remnants with the SHALON mirror Cherenkov telescope of Tien-Shan high-mountain Observatory: the shell-type supernova remnants Tycho, Cas A and IC 443; plerions Crab Nebula, 3c58(SN1181) and Geminga (probably plerion). The experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy (800 GeV − 100 TeV) gamma-rays in Tycho's supernova remnant. The data obtained suggest that the very high energy gamma-ray emission in the objects being discussed is different in origin.

Confinement, chiral symmetry breaking and the mass generation of hadrons

A key question to QCD is what mechanism generates the hadron mass in the light quark sector, where both confinement and chiral symmetry breaking are in the game. Are confinement and chiral symmetry breaking in the vacuum uniquely interconnected? Can hadrons survive chiral symmetry restoration? If yes, what happens with their mass and what symmetries beyond the chiral symmetry are there? We review our recent insights. In particular, in a dynamical lattice simulation we artificially restore chiral symmetry by removing the low-lying Dirac modes of the valence quark propagators, which is a well defined procedure and keep gluodynamics intact. Hadrons survive this artificial chiral restoration and their mass is surprisingly large. All hadrons fall into chiral multiplets and some of them are degenerate, i.e. the spectrum reveals some higher symmetry, that includes the chiral symmetry as a subgroup. The U(1)_A symmetry does not get restored after removal of the chiral modes from the valence quarks.

Generation of Cosmic rays in Historical Supernova Remnants

We present the results of observations of two types of Galactic supernova remnants with the SHALON mirror Cherenkov telescope of Tien-Shan high-mountain Observatory: the shell-type supernova remnants Tycho, Cas A and IC 443; plerions Crab Nebula, 3c58(SN1181) and Geminga (probably plerion). The experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy (800 GeV - 100 TeV) gamma-rays in Tycho's supernova remnant. The data obtainedsuggest that the very high energy gamma-ray emission in the objects being discussedis different in origin.

Equation of state in the PNJL model with the entanglement interaction

The equation of state and the phase diagram in two-flavor quantum chromodynamics (QCD) are investigated by the Polyakov-loop extended Nambu–Jona-Lasinio (PNJL) model with an entanglement vertex between the chiral condensate and the Polyakov loop. The entanglement-PNJL (EPNJL) model reproduces lattice QCD (LQCD) data at μ ⩾ 0 better than the PNJL model. Hadronic degrees of freedom are taken into account by the free-hadron-gas approximation with the volume-exclusion effect due to the hadron generation. The hadron degrees of freedom improve agreement of the EPNJL model with LQCD data particularly at low temperature. The quarkyonic phase survives, even if the correlation between the chiral condensate and the Polyakov loop is strong and hadron degrees of freedom are taken into account. However, the location of the quarkyonic phase is sensitive to the strength of the volume exclusion.

Validation of Geant4 Hadronic Generators versus Thin Target Data

The GEANT4 toolkit is widely used for simulation of high energy physics (HEP) experiments, in particular, those at the Large Hadron Collider (LHC). The requirements of robustness, stability and quality of simulation for the LHC are demanding. This requires an accurate description of hadronic interactions for a wide range of targets over a large energy range, from stopped particle reactions to low energy nuclear interactions to interactions at the TeV energy scale. This is achieved within the Geant4 toolkit by combining a number of models, each of which are valid within a certain energy domain. Comparison of these models to thin target data over a large energy range indicates the strengths and weaknesses of the model descriptions and the energy range over which each model is valid.Software has been developed to handle the large number of validation tests required to provide the feedback needed to improve the models. An automated process for carrying out the validation and storing/displaying the results is being developed and will be discussed.

Supernova remnants: The Crab Nebula, Cassiopeia A, and Tycho as sources of cosmic rays in our galaxy

We present the results of our observations of two types of Galactic supernova remnants with the ShALON mirror Cherenkov telescope: the plerion Crab Nebula and the shell-type supernova remnants Cassiopeia A and Tycho. The experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy (0.8–100 TeV) gamma rays in Tycho’s supernova remnant. The data obtained suggest that the very high energy gamma-ray emission in the objects being discussed is different in origin.

Hidden Local Field Theory and Dileptons in Relativistic Heavy Ion Collisions

The notion of freedom is introduced based on the vector manifestation of hidden local symmetry and is used to suggest that the dileptons measured in relativistic heavy-ion collisions do not provide {\em direct} information on the spontaneous breaking of chiral symmetry and hence on the mechanism for mass generation of light-quark hadrons. We give arguments how the dileptons emitted from those vector mesons whose masses are shifted a la Brown-Rho (BR) scaling by the change in temperature -- as in heavy-ion collisions -- and/or density -- as in cold compressed matter -- could be strongly suppressed in the hadronic free region between the chiral restoration and the flash point at which the vector mesons recover $\gsim 90%$ of their free-space on-shell masses and the full strong coupling strength. It may seem ironical that the very mechanism i.e., the vector manifestation in hidden local symmetry, that is to make the mass drop and modify the spectral function is in turn responsible for the dilepton suppression. A possible falsification of this drastic prediction will be indicated. We also briefly discuss the potential role played by the holographic dimension intrinsic in gravity-gauge duality that provides a unified field theory description of hadrons -- both mesons and baryons -- under extreme conditions. Baryons arise as coherent states of pions and vector mesons of holographic QCD which define the ground state or the vacuum on which mesonic excitations could undergo BR scaling.

Comparison of Geant4 hadron generation with data from the interactions with beryllium nuclei of +8.9 GeV/c protons and pions and −8.0 GeV/c pions

Hadron generation in the Geant4 simulation tool kit is compared with inclusive spectra of secondary protons and pions from the interactions with beryllium nuclei of +8.9 GeV/c protons and pions, and of −8.0 GeV/c pions. The data were taken in 2002 at the CERN Proton Synchrotron with the HARP spectrometer. We report on significant disagreements between data and Monte Carlo simulation especially in the polar-angle distributions of secondary protons and pions.

Testing suite for validation of Geant4 hadronic generators

The testing suite for validation of Geant4 hadronic generators with the data for thin target experiments has been updated. We automated and extended the suite providing a production mode of operation. The new data sets for incident proton beam momentum up to 12.9 GeV/c have been included. The results of comparisons with the inclusive neutron and pion production data for different Geant4 hadronic generators are shown.