Dynamics of Anti-Proton -- Protons and Anti-Proton -- Nucleus Reactions

A short review of simulation results of anti-proton-proton and anti-proton-nucleus interactions within the framework of Geant4 FTF (Fritiof) model is presented. The model uses the main assumptions of the Quark-Gluon-String Model or Dual Parton Model. The model assumes production and fragmentation of quark-anti-quark and diquark-anti-diquark strings in the mentioned interactions. Key ingredients of the model are cross sections of string creation processes and an usage of the LUND string fragmentation algorithm. They allow one to satisfactory describe a large set of experimental data, especially, a strange particle production, Lambda hyperons and K mesons.Comment: 7 pages, 8 figure

Production of strange particles in hadronic interactions

The NA61/SHINE collaboration has recently published high precision data on production of $\pi^\pm$ and $K^\pm$ mesons, protons, antiprotons and $\Lambda$ hyperons in ${\rm pp}$ interactions at 20, 31, 40, 80 and 158 GeV/c, and in ${\rm pC}$ interactions at 31 GeV/c. The collaboration also presented experimental data on production of particles - $\pi^\pm$, $K^\pm$, $p^\pm$, $\rho^0$, $\omega$ and $K^{*0}$ in $\pi^-{\rm C}$ collisions at 158 and 350 GeV/c. The collaboration has compared these data with various Monte Carlo model calculations: UrQMD, EPOS, GiBUU, and others. All of the models have various problems. The latest version of the FTF (Fritiof) model of Geant4 solves most of these problems. In the FTF model, we have improved the fragmentation of quark-gluon strings with small masses and introduced dependencies of probabilities of strange mesons and baryon-antibaryon pair's creation on string masses. Due to these changes, we describe the data of the NA61/SHINE collaboration on particle production in ${\rm pp, pC}$, and $\pi^-{\rm C}$ interactions. The improved Geant4 FTF model also well reproduces experimental data on inclusive cross sections of $\Lambda, \bar{\Lambda}$ and $K^{0}$ production in antiproton-proton interactions at various energies. The modified FTF model allows one to simulate realistic processes with two particle productions - $\bar{p}p \rightarrow \Lambda \bar{\Lambda}$, $\bar{p}p \rightarrow K^{+} K^{-}$, $\bar{p}p \rightarrow \Lambda \bar{\Sigma}$, and $\bar{p}p \rightarrow\Sigma \bar{\Sigma}$, which will be studied in the future by the PANDA experiment at FAIR (GSI, Germany).Comment: 10 pages, 8 figures, IWNT-37, Rila, 2018, Bulgari

Simulation of neutron production in hadron-nucleus and nucleus-nucleus interactions in Geant4

Studying experimental data obtained at ITEP [1] on neutron production in interactions of protons with various nuclei in the energy range from 747 MeV up to 8.1 GeV, we have found that slow neutron spectra have scaling and asymptotic properties [2]. The spectra weakly depend on the collision energy at momenta of projectile protons larger than 5 - 6 GeV/c. These properties are taken into account in the Geant4 Fritiof (FTF) model. The improved FTF model describes as well as the Geant4 Bertini model the experimental data on neutron production by 1.2 GeV and 1.6 GeV protons on targets (Fe, Pb) [3] and by 3.0 GeV protons on various targets (Al, Fe, Pb) [4]. For neutron production in antiproton-nucleus interactions, it was demonstrated that the FTF results are in a satisfactory agreement with experimental data of the LEAR collaboration [5]. The FTF model gives promising results for neutron production in nucleus - nucleus interactions at projectile energy 1 - 2 GeV per nucleon [6]. The observed properties allow one to predict neutron yields in the nucleus-nucleus interactions at high and very high energies. Predictions for the NICA/MPD experiment at JINR are presented.Comment: 6 pages, 5 figures. Contribution to Proceedings of Baldin ISHEPP XXI

Description of the Totem experimental data on elastic pp-scattering at sqrt(s)=7 TeV in the framework of unified systematic of elastic scattering data

An unified systematic of elastic (anti)proton-proton scattering data is proposed based on a simple expression for the process amplitude - f(q)=A[(\pi dq)/sh(\pi dq)][i J_1(Rq)/(Rq)+\rho J_0(Rq)]. The parameters R and d are obtained at a fitting of (anti)proton-proton experimental data on differential cross sections from Plab=1 GeV/c up to ISR energies. The fitting gives extra-ordinary good results, \chi^2/NoF ~ 1 of below at |t|< 1.75 (GeV/c)^2. An extrapolation of the parameter's energy dependencies to the LHC energies allows excellent description of the Totem data up to the second diffraction maximum. Predictions for other LHC energies are presented also. The amplitude provides one with parameterizations of total and elastic cross sections. Its impact parameter representation corresponds to the 2-dimensional Fermi-function - 1/[1+exp((b-R)/d)], which is very useful for Glauber calculations of nucleus-nucleus cross sections at super high energies. It is shown for the first time that experimental high |t| elastic scattering has a weak energy dependency. This allows to describe high |t| tail of the Totem data.Comment: 13 pages of a text, total - 31 page

The effect of uu diquark suppression in proton splitting in Monte Carlo event generators

Monte Carlo event generators assume that protons split into (uu)-diquarks and d-quarks with a probability of 1/3 in strong interactions. It is shown in this paper that using a value of 1/6 for the probability allows one to describe at a semi-quantitative level the NA49 Collaboration data for $p+p\rightarrow p+X$ reactions at 158 GeV/c. The Fritiof (FTF) model of Geant4 was used to simulate the reactions. The reduced weight of the (uu)-diquarks in protons is expected in the instanton model.Comment: 2 pages, weight of uu-diquark in protons has to be about 1/6 in Monte Carlo event generator