Medium Influence of the Nucleon—Nucleon Cross Section on the Fragmentation

Based on an isospin-dependent quantum molecular dynamics model we studied the influence of a medium correction of an isospin-dependent nucleon-nucleon cross section on the fragmentation at the intermediate energy heavy-ion collisions. We found that the medium correction from an isospin-dependent nucleon-nucleon cross section, at the same time, the momentum-dependent interaction also produces an important role for enhancing the influence of the medium correction on the isospin effect of two-body collisions in the fragmentation process.     

Dependence of Isoscaling Parameters on Nucleon-Nucleon Cross Section and Momentum-Dependent Interaction

Inltuences of the isospin dependence of the in-medium nucleon-nucleon cross section and the momentum-dependent interaction （MDI） on the isotope scaling are investigated by using the isospin-dependent quantum molecular dynamics model （IQMD）. The results show that both the isospin dependence of the in-medium nucleon-nucleon cross section and the momentum-dependent interaction affect the isoscaling parameters appreciably and indepen- dently. The inltuence caused by the isospin dependence of two-body collision is relatively larger than that from the MDI in the mean tield. Aiming at exploring the implication of isoscaling behaviour, which the statistical equilibrium in the reaction is reached, the statistical properties in the mass distribution and the kinetic energy distribution of the fragments simulated by IQMD are presented.     

Search for Delayed and Advanced Particles in the Interaction of Ultrahigh-Energy Cosmic Rays with the Earth’s Atmosphere in the Flow of EAS Muons at the MSU EAS Setup

Physics of Atomic Nuclei - The results obtained by studying temporal distributions of particles of energy in excess of 5 GeV in extensive air showers (EAS) of energy above $$10^{15}$$ eV at...     

Differential Cross Section for Elastic Deuteron–Proton Scattering at the Energy of 700 MeV per Nucleon

The results of measurements of the differential cross section for elastic deuteron–proton scattering at the energy of 700 MeV per nucleon that were performed at the internal target station of the nuclotron at the Joint Institute for Nuclear Research (JINR, Dubna) are presented. These data were obtained at angles in the range between 70? and 120? in the c.m. frame. The angular dependence obtained in this way is compared with world-averaged data at similar energies and with the results of theoretical calculations performed within the relativistic theory of multiple scattering.     

Lambda-Nucleon and Nucleon–Nucleon Interactions on the Lattice

Lattice QCD study of nuclear potentials is reported. A lattice QCD method to calculate realistic nuclear potentials is developed. In this method, Bethe–Salpeter wave functions generated on the lattice are used to reconstruct nuclear potentials by using Schrödinger equation. It is one of the possible extensions of Lüscher’s finite volume method for scattering phase shifts. Hence the resulting potential can reproduce the scattering data. The method was first applied to the central potential in NN system. It is now applied to various objects, such as tensor potential, hyperon potentials both in quenched QCD and 2 + 1 flavor QCD generated by PACS-CS Collaboration.     

Nucleon–Deuteron Breakup Differential Cross Sections Derived from the Quark-Model NN Interaction

The nd and pd breakup differential cross sections for E _N ≤ 65 MeV are examined using the energy-independent quark-model nucleon–nucleon interaction fss2. The Coulomb effect is incorporated by the sharp cut-off Coulomb force, acting between quarks, without the phase-shift renormalization for the breakup amplitudes. Our model yields the results very similar to the meson-exchange potentials, including disagreement for some specific kinematical configurations. This includes the notorious space star anomaly of the nd and pd scattering at E _N  = 13 MeV. The KVI data for the breakup differential cross sections of E _d  = 130 MeV dp scattering are reasonably reproduced by taking the Coulomb cut-off radius ρ = 16 fm.     

Infinite-Cutoff Renormalization of the Chiral Nucleon–Nucleon Interaction up to N3LO

Naively, the “best” method of renormalization is the one where a momentum cutoff is taken to infinity while maintaining stable results due to a cutoff-dependent adjustment of counterterms. We have applied this renormalization method in the non-perturbative calculation of phase-shifts for nucleon–nucleon (NN) scattering using chiral NN potentials up to next-to-next-to-next-to-leading order (N³LO). For lower partial waves, we find that there is either no convergence with increasing order or, if convergence occurs, the results do not always converge to the empirical values. For higher partial waves, we always observe convergence to the empirical phase shifts (except for the ³G₅ state). Furthermore, no matter what the order is, one can use only one or no counterterm per partial wave, creating a rather erratic scheme of power counting that does not allow for a systematic order-by-order improvement of the predictions. The conclusion is that infinite-cutoff renormalization is inappropriate for chiral NN interactions, which should not come as a surprise, since the chiral effective field theory (chiral EFT), these interactions are based upon, is designed for momenta below the chiral-symmetry breaking scale of about 1 GeV. Therefore, this value for the hard scale should also be perceived as the appropriate upper limit for the momentum cutoff.     

Study of Different Forms of Density Distributions in Proton–Nucleus Total Reaction Cross Section and the Effect of Phase in NN Amplitude

Proton total-reaction cross-section (σR), measurements for about five nuclei in the range ¹²C to ²⁰⁸Pb at beam energies spanning 40–800 MeV have been analyzed in a systematic way by using the optical limit approximation of the Coulomb-modified Glauber multiple scattering theory. Two different phenomenological nuclear density distributions of the target nucleus in addition to the realistic one have been used in the present analysis. By applying the energy dependence in the slope parameter of nucleon–nucleon (NN) scattering amplitude, it is found that in general, the predictions of σ _R with the phenomenological Gambhir and Patil density distribution agree fairly well with the experimental data. The inclusion of phase in the NN amplitude improves the theoretical results. Our analysis shows that the calculated total reaction cross sections closely reproduce the measured data over the whole range of energy considered in this work. To validate our analyses, we have also obtained a fairly good representation of elastic p-nucleus differential scattering cross section data. The effect of a Coulomb energy shift in the proton beam has also been studied.     

Calculation of Total Cross Section for γγ→γZ Scattering at High Energy

The total cross sections of γγ→γZ process for γγ c.m.s. energy 91.2—2000GeV are presented. W loop contribution is dominating when γγ c.m.s. energy is larger than 140GeV. The total cross section has a maximum, 220 fb(|cosθ|33cm^－2·s^－1 in which case more than 6000 events for γγ→γZ would be observable. In principle this process provides a test of the non-abelian nature of the standard model, especially the anomalous triple and quartic W-boson vertices.     

Strange Quark Matter and the Astrophysical Nature of Anomalous Effects in 1–100 PeV Cosmic Rays

JETP Letters - Energy, pulse duration, and frequency of the spectral maximum are important characteristics of pulsed terahertz radiation. The unipolarity of radiation is another characteristic that...     

Asymptotic Behavior of the Magnetization Near Critical and Tricritical Points via Ginzburg–Landau Polynomials

The purpose of this paper is to prove connections among the asymptotic behavior of the magnetization, the structure of the phase transitions, and a class of polynomials that we call the Ginzburg–Landau polynomials. The model under study is a mean-field version of a lattice spin model due to Blume and Capel. It is defined by a probability distribution that depends on the parameters β and K, which represent, respectively, the inverse temperature and the interaction strength. Our main focus is on the asymptotic behavior of the magnetization m(β _n ,K _n ) for appropriate sequences (β _n ,K _n ) that converge to a second-order point or to the tricritical point of the model and that lie inside various subsets of the phase-coexistence region. The main result states that as (β _n ,K _n ) converges to one of these points (β,K), . In this formula γ is a positive constant, and is the unique positive, global minimum point of a certain polynomial g. We call g the Ginzburg–Landau polynomial because of its close connection with the Ginzburg–Landau phenomenology of critical phenomena. For each sequence the structure of the set of global minimum points of the associated Ginzburg–Landau polynomial mirrors the structure of the set of global minimum points of the free-energy functional in the region through which (β _n ,K _n ) passes and thus reflects the phase-transition structure of the model in that region. This paper makes rigorous the predictions of the Ginzburg–Landau phenomenology of critical phenomena and the tricritical scaling theory for the mean-field Blume–Capel model.     

Asymptotic Behavior of the One-Dimensional Fisher–Kolmogorov–Petrovskii–Piskunov Equation with Anomalouos Diffusion

Russian Physics Journal - Asymptotic solutions of the nonlocal, one-dimensional Fisher–Kolmogorov–Petrovskii–Piskunov equation with fractional derivatives in the diffusion...     

Experimental and Theoretical Study of the Electrochemical Behavior of o‐Benzoquinone and Pyrocatechol

The geometric parameters, vibrational frequencies, and the thermochemical values of o‐benzoquinone (o‐BQ), p‐benzoquinone (p‐BQ), pyrocatechol (PC), and p‐hydroquinone (p‐HQ) were computed using ab initio calculation (HF) and density functional theory (DFT) with the 6‐31G (d) and 6‐31G (d, p) basis sets, respectively. Cyclic voltammetry with a gold electrode of PC solutions in phosphate buffers at pH 7.30 showed that the standard electrode potential of half reaction for o‐BQ and PC is 0.813 V. The standard electrode potential of half reaction for o‐BQ and PC with a p‐BQ, H⁺/p‐hydroquinone (p‐HQ) reference electrode, using the solvation energies and the sum of electronic and thermal free energies of o‐BQ and PC, is consistent with the experimental one.     

Systematic Study of Three-Nucleon Systems Dynamics in the Cross Section of the Deuteron–Proton Breakup Reaction

An experiment to investigate the ¹H(d, pp)n breakup reaction using a deuteron beam of 340, 380 and 400 MeV and the WASA detector has been performed at the Cooler Synchrotron COSY–Jülich. The main goal was the detailed study of various aspects of few-nucleon dynamics in the medium energy region, with particular emphasis on relativistic effects and their interplay with three nucleon forces. These effects become more important with increasing available energy in the three nucleon system. Therefore the investigations at high energies are crucial to understand their nature. The almost 4π geometry of the WASA detector gives an unique possibility to study various aspects of dynamics of processes in the three-nucleon reaction. Preliminary results obtained using the WASA detector are presented.