Rescaling of Nuclear Structure Functions S.V.Akulinichev
It is shown that nucleonic structure functions are x − and Q2−rescaled in nuclei. The x−rescaling accounts for nuclear effects in the case of exact scaling, while the Q2−rescaling is responsible for a corresponding modification of quantum corrections. This result is obtained in the leading order for all flavour combinations and connects the two known models for the EMC-effect. Electroproduction and gluonic nuclear structure functions are calculated. 1 1. There is still no consensus on the origin of the nuclear EMC-effect. In addition to the theoretical importance of this phenomenon, it is now becoming practically important to know nuclear quark...
Short-Range Correlations in Nuclear Matter at Finite Temperatures and High Densities ∗
- F. Frömel; H. Lenske; U. Mosel
The density and temperature dependence of the nucleonic single particle spectral function in symmetric nuclear matter at finite temperatures and densities beyond normal nuclear matter density is investigated in a model emphasizing short-range correlations and phase space aspects. A simple but self-consistent approach based on quantum transport theory is used. In particular we consider the density and temperature regime occuring e.g. during the core collapse in a supernova explosion and the subsequent formation of a neutron star. Mean-field effects are incorporated by a Skyrme type potential. 1
Quaiselastic scattering from relativistic bound nucleons: Transverse-longitudinal response
- J. M. Udias; J. A. Caballero; E. Moya De Guerra; J. E. Amaro; T. W. Donnelly
Predictions for electron induced proton knockout from the p 1/2 and p 3/2 shells in 16 O are presented using various approximations for the relativistic nucleonic current. Results for the differential cross section, transverse-longitudinal response (RTL) and left-right asymmetry ATL are compared at |Q 2 | = 0.8 (GeV/c) 2 corresponding to TJNAF experiment 89-003. We show that there are important dynamical and kinematical relativistic effects which can be tested by experiment. PACS: 25.30.Fj; 25.30.Rw; 24.10.-i; 21.60.Cs Keywords: Quasielastic electron scattering; Negative-energy components; Transverse-longitudinal response; Left-right asymmetry. Under quasielastic conditions the (e, e ′ p) reaction can be treated with...
GROUND STATE CORRELATIONS AND FINAL STATE INTERACTIONS IN TWO-NUCLEON EMISSION PROCESSES OFF
The two nucleon emission process from 3 He, 3 He(e, e ′ N2N3)N1, has been theoretically analyzed using realistic three-nucleon wave functions and taking the final state interaction into account. Various kinematical conditions have been considered in order to clarify the question whether the effects of the final state interaction could be minimized by a proper choice of the kinematics of the process. 1. GROUND STATE CORRELATIONS IN NUCLEI The investigation of Ground State Correlations (GSC) in nuclei, in particular those which originate from the most peculiar features of the Nucleon-Nucleon (NN) interaction, i.e. its strong short range repulsion and...
Neutron stars and quark matter
- Gordon Baym
Abstract. Recent observations of neutron star masses close to the maximum predicted by nucleonic equations of state begin to challenge our understanding of dense matter in neutron stars, and constrain the possible presence of quark matter in their deep interiors.
MSUCL-1143 Determination of the Mean-Field Momentum-Dependence using Elliptic Flow
Midrapidity nucleon elliptic flow is studied within the Boltzmann-equation simulations of symmetric heavy-ion collisions. The simulations follow a lattice Hamiltonian extended to relativistic transport. It is demonstrated that in the peripheral heavy-ion collisions the high-momentum elliptic flow is strongly sensitive to the momentum dependence of mean field at supranormal densities. The high transverse-momentum particles are directly and exclusively emitted from the high-density zone in the collisions, while remaining particles primarily continue along the beam axis. The elliptic flow was measured by the KaOS Collaboration as a function of the transverse momentum at a number of impact parameters in Bi +...
Regularity and chaos in the nuclear masses
- Patricio Leboeuf
Summary. Shell effects in atomic nuclei are a quantum mechanical manifestation of the single–particle motion of the nucleons. They are directly related to the structure and fluctuations of the single–particle spectrum. Our understanding of these fluctuations and of their connections with the regular or chaotic nature of the nucleonic motion has greatly increased in the last decades. In the first part of these lectures these advances, based on random matrix theories and semiclassical methods, are briefly reviewed. Their consequences on the thermodynamic properties of Fermi gases and, in particular, on the masses of atomic nuclei are then presented. The structure...
Equation of State of Nuclear Matter at high baryon density
- M Baldo; C Maieron
Abstract. A central issue in the theory of astrophysical compact objects and heavy ion reactions at intermediate and relativistic energies is the Nuclear Equation of State (EoS). On one hand, the large and expanding set of experimental and observational data is expected to constrain the behaviour of the nuclear EoS, especially at density above saturation, where it is directly linked to fundamental processes which can occur in dense matter. On the other hand, theoretical predictions for the EoS at high density can be challenged by the phenomenological findings. In this topical review paper we present the many-body theory of nuclear...
STRANGENESS PRODUCTION VIA ELECTROMAGNETIC PROBES: 40 YEARS LATER ∗
- B. Saghai
A brief review of the associated strangeness electromagnetic production is presented. Very recent K + Λ photoproduction data on the proton from threshold up to Elab γ = 2.6 GeV are interpreted within a chiral constituent quark formalism, which embodies all known nucleonic and hyperonic resonances. The preliminary results of this work are reported here. 1.
Scaling of Anisotropic Flow and Momentum-Space Densitiesfor Light Particles in Intermediate Energy Heavy Ion Collisions
Anisotropic flows (v2 and v4) of light nuclear clusters are studied by Isospin-Dependent Quantum Molecular Dynamics model for the system of 86 Kr + 124 Sn at intermediate energy and large impact parameters. Number-of-nucleon scaling of the elliptic flow (v2) are demonstrated for the light fragments up to A = 4, and the ratio of v4/v2 2 shows a constant value of 1/2. In addition, the momentum-space densities of different clusters are also surveyed as functions of transverse momentum, in-plane transverse momentum and azimuth angle relative to the reaction plane. The results can be essentially described by momentum-space power law....
Light Front Quantization–A Technique for Relativistic and Realistic Nuclear Physics
- Gerald A. Miller
Applications of relativistic light front dynamics to computing the nucleonic and mesonic components of nuclear wave functions are reviewed. In this approach the fields are quantized at equal values of τ = x 0 + x 3. Our method is to use a Lagrangian, and its associated energy-momentum tensor T + µ to define the total momentum operators P µ with P + as the plus-momentum and P − the τ-development operator. The motivation for unusual treatment of nuclear physics is the desire to use wave functions, expressed in terms of plusmomentum variables, which are used to analyze high energy...
Chiral symmetry restoration and parity mixing
- G. Chanfray; J. Delorme; M. Ericson
We derive the expressions of the vector and axial current from a chiral Lagrangian restricted to nucleons and pions. They display mixing terms between the axial and vector currents. We study how the modification of the quark condensate affects the coupling constants of the axial current, namely the pion decay constant and the nucleonic axial one. In the second case and in a dense medium, we express the renormalization as a meson exchange current. By doing so we show what part of the scalar density of the quarks contributes to the renormalization. We give an estimate for the quenching of...
A nucleonic NJL model for finite nuclei: dynamic mass generation and ground-state observables T. J. Bürvenich a and D. G. Madland a
Correlations in hypernuclear matter
- P. Konrad; H. Lenske
We investigate short range correlations in nuclear and hypernuclear matter. Self-energies due to short range correlations and their influence on the nucleon and Λ-hyperon spectral functions are described in an approach accounting for a realistic treatment of mean-field dynamics and a self-consistently derived quasi-particle interaction. Landau-Migdal theory is used to derived the short range interaction from a phenomenological Skyrme energy density functional, subtracting the long range pionic contributions to the nucleonic spectral functions. We discuss our results for different hyperon-baryon ratios to show the influence of strangeness on the correlations in hypernuclear matter. 1
MSUCL-1004 The Dynamical Structure of the ∆-Resonance and its Effect on Two- and Three-Nucleon Systems
- G. Kortemeyer; P. U. Sauer; A. Stadler
The pion-nucleon interaction in the P33 partial wave is assumed to proceed simultaneously through the excitation of the ∆-isobar and through a phenomenologically introduced non-resonant background potential. The introduction of the background potential allows a more realistic parameterization of the pion-nucleon- ∆ vertex compared with the previously used one without 1 background. It also modifies the propagation of the ∆-isobar in the nuclear medium and gives rise to novel effective nucleon- ∆ interactions. Their consequences on predictions for observables in the two-nucleon system at intermediate energies and in the three-nucleon bound state are studied. 2 Internal nucleonic degrees of freedom...
1 Analysis of flow effects in relativistic heavy-ion collisions within the CBUU approach
- A. Hombach; W. Cassing; S. Teis; U. Mosel
We study flow phenomena in relativistic heavy-ion collisions, both in transverse and radial direction, in comparison to experimental data. The collective dynamics of the nucleus-nucleus collision is described within a transport model of the coupled channel BUU type (CBUU). This recently developed version includes all nucleonic resonances up to 1.95 GeV in mass and mean-field potentials both of the Skyrme and momentum dependent MDYI type. We find that heavy resonances play an important role in the description of transverse flow above 1 AGeV incident energy. For radial flow we analyse reaction times and equilibration and extract the parameters T and...
aDepartamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de
- J. M. Udias; J. A. Caballero; E. Moya De Guerra; J. E. Amaro; T. W. Donnelly
Predictions for electron induced proton knockout from the p 1/2 and p 3/2 shells in 16 O are presented using various approximations for the relativistic nucleonic current. Results for the differential cross section, transverse-longitudinal response (RTL) and left-right asymmetry ATL are compared at |Q2 | = 0.8 (GeV/c) 2 corresponding to TJNAF experiment 89-003. We show that there are important dynamical and kinematical relativistic effects which can be tested by experiment. PACS: 25.30.Fj; 25.30.Rw; 24.10.-i; 21.60.Cs Keywords: Quasielastic electron scattering; Negative-energy components; Transverse-longitudinal response; Left-right asymmetry. Under quasielastic conditions the (e, e ′ p) reaction can be treated with confidence...
- A. De Pace
Quasielastic (QE) studies at intermediate energies are an important tool to study both nucleonic and nuclear physics issues. In particular, the reasons to consider K +-nucleus scattering have been twofold. On the one hand, the elementary K + N cross section is relatively small compared to other hadronic probes, thus allowing the kaons to penetrate deeper inside the nucleus, making them more suitable to study collective effects. Furthermore, since the K + N cross section is dominated by the scalar-isoscalar channel, kaons turn out to be a quasi-pure probe of this mode. On the other hand, the excess of cross...
PARITY-VIOLATING LONGITUDINAL RESPONSE
- A. De Pace
The parity-violating quasielastic electron scattering response is explored within the context of a model that builds antisymmetrized random phase approximation and Hartree-Fock correlations on a relativistic Fermi gas basis. Particular emphasis is put on the weak-neutral longitudinal response function, since this observable displays a strong sensitivity to isospin correlations: specifically, it is shown how, through a diagrammatic cancellation/filtration mechanism, this response acts as a magnifier of pionic correlations in the nuclear medium. The parity-violating longitudinal response function also displays appreciable sensitivity to the electric strangeness content of the nucleon, thus making quasielastic electron scattering a possible candidate to measure the...
Centro Física Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto,
- L. P. Yuan; K. Chmielewski; M. Oelsner; P. U. Sauer; A. C. Fonseca; J. Adam
Abstract. Radiative nucleon-deuteron capture and photo disintegration of the three-nucleon bound state with two-body final states are described. The description uses nucleon degrees of freedom extended to include the excitation of a single nucleon to a ∆-isobar. The baryonic interaction and the electromagnetic current couple nucleonic states and states with a ∆-isobar. Exact solutions of three-particle scattering equations are employed for the initial or final states of the reactions. The current has one-baryon and two-baryon contributions. The role of the ∆-isobar in the description of the considered photo reactions is discussed and found to be moderate. The spin observables Ayy...