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1

Spinodal in asymmetric nuclear matter

International Nuclear Information System (INIS)

The phase diagram of nuclear matter is quite rich; it shows such phenomena as phase-transitions, formation of condensates, clustering, etc. >From the analysis of the spinodal instability, one can learn about the region of liquid-gas coexistence in nuclear matter at low densities and finite isospin asymmetries. In a recent paper, we have shown that asymmetric nuclear matter at sub-nuclear densities should undergo only one type of instability. The associated order parameter is dominated by the isoscalar density and so the transition is of liquid-gas type. The instability goes in the direction of a restoration of the isospin symmetry leading to a fractionation phenomenon. The nuclear interaction is very similar to the Van der Waals potential which acts between molecules. For this reason, below saturation density, the nuclear interaction is also expected to lead to a liquid-gas phase transition. Recently, a converging ensemble of experimental signals seems to have established the phase transition. One is the spinodal decomposition which considers volume instabilities (domain of negative incompressibility). One expects that the system which enters such a forbidden region will favorably breakup into nearly equally-sized 'primitive' fragments in relation to the wavelengths of the most unstable modes. How the simple picture is modified by the asymmetry charge and whether we can expect new signals related to the collision of very asymmetric nuclei are the questions which the aetric nuclei are the questions which the author finally poses. (author)

2

Thermal properties of asymmetric nuclear matter

The thermal properties of asymmetric nuclear matter are investigated in a relativistic mean-field approach. We start from free-space N N interactions and derive in-medium self-energies by the Dirac-Brueckner theory. By the density-dependent relativistic hadron procedure we derive in a self-consistent approach density-dependent meson-baryon vertices. At the mean-field level, we include isoscalar and isovector-scalar and vector interactions. The nuclear equation of state is investigated for a large range of total baryon densities up to the neutron star regime, the full range of asymmetries ? =Z /A from symmetric nuclear matter to pure neutron matter, and temperatures up to T ˜100 MeV. The isovector-scalar self-energies are found to modify strongly the thermal properties of asymmetric nuclear matter. A striking result is the change of phase transitions when isovector-scalar self-energies are included.

Fedoseew, A.; Lenske, H.

2015-03-01

3

Symmetry energy coefficients for asymmetric nuclear matter

Symmetry energy coefficients of asymmetric nuclear matter are investigated as the inverse of nuclear matter polarizabilities with two different approaches. Firstly a general calculation shows they may depend on the neutron-proton asymmetry itself. The choice of particular prescriptions for the density fluctuations lead to certain isospin (n-p asymmetry) dependences of the polarizabilities. Secondly, with Skyrme type interactions, the static limit of the dynamical polarizabil...

Braghin, Fa?bio L.

2003-01-01

4

Magnetic properties of strongly asymmetric nuclear matter

International Nuclear Information System (INIS)

We investigate stability of neutron matter containing a small proton admixture with respect to spin fluctuations. We establish conditions under which strongly asymmetric nuclear matter could acquire a permanent magnetization. It is shown that if the protons are localized, the system becomes unstable to spin fluctuations for arbitrarily weak proton-neutron spin interactions. For non-localized protons there exists a threshold value of the spin interaction above which the system can develop a spontaneous polarization. 12 refs., 2 figs. (author)

5

Spinodal instability in asymmetric nuclear matter

International Nuclear Information System (INIS)

We demonstrate that the instabilities of asymmetric nuclear matter at sub-saturation densities do not present two types of instabilities as usually discussed but a unique one. The associated order parameter is everywhere dominated by the isoscalar density and so the transition is of liquid-gas type even in the so-called chemical instability region. However, the instability goes in the direction of a restoration of the isospin symmetry leading to a fractionation phenomenon. (authors)

6

Meson mixing amplitudes in asymmetric nuclear matter

Using a purely hadronic model, we study the charge-symmetry-breaking $\\rho$-$\\omega$, $\\sigma$-$\\delta$, $\\sigma$-$\\rho$ and $\\delta$-$\\omega$ mixing amplitudes in isospin asymmetric nuclear matter. The basic assumption of the model is that the mixing amplitude is generated by nucleon and anti-nucleon loops and hence driven entirely by the difference between proton and neutron Fermi momenta and the proton-neutron mass difference. We find that the behavior of the mixing ampli...

Mori, Yoshiharu; Saito, Koichi

2002-01-01

7

Response Function of Asymmetric Nuclear Matter

The charge longitudinal response function is examined in the framework of the random-phase approximation in an isospin-asymmetric nuclear matter where proton and neutron densities are different. This asymmetry changes the response through both the particle-hole interaction and the free particle-hole polarization propagator. We discuss these two effects on the response function on the basis of our numerical results in detail.

Takayanagi, Kazuo; Cheon, Taksu

1995-01-01

8

Isobaric incompressibility of isospin asymmetric nuclear matter

International Nuclear Information System (INIS)

The isospin dependence of the saturation properties of asymmetric nuclear matter, particularly the incompressibility K?(X)=K?+K?X2+O(X4) at saturation density, is systematically studied using density-dependent M3Y interaction. K? characterizes the isospin dependence of the incompressibility at saturation density ?0. The approximate expression Kasy?Ksym-6L is often used for K? where L and Ksym represent the slope and curvature parameters of the symmetry energy at ?0, respectively. It can be expressed accurately as K?=Ksym-6L-(Q0/K?)L, where Q0 is the third-order-derivative parameter of symmetric nuclear matter at ?0. The results of this addendum to [Phys. Rev. C 80, 011305(R) (2009)] indicate that the Q0 contribution to K? is not insignificant.

9

Symmetry energy coefficients for asymmetric nuclear matter

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Symmetry energy coefficients of asymmetric nuclear matter generalized are investigated as the inverse of nuclear matter polarizabilities with two different approaches. Firstly a general calculation shows they may depend on the neutron-proton asymmetry itself. The choice of particular prescriptions f [...] or the density fluctuations lead to certain isospin (n-p asymmetry) dependences of the polarizabilities. Secondly, with Skyrme type interactions, the static limit of the dynamical polarizability is investigated corresponding to the inverse symmetry energy coefficient which assumes different values at different asymmetries (and densities and temperatures). The symmetry energy coefficient (in the isovector channel) is found to increase as n-p asymmetries increase. The spin symmetry energy coefficient is also briefly investigated.

Fábio L., Braghin.

2003-06-01

10

Phase transitions in warm, asymmetric nuclear matter

International Nuclear Information System (INIS)

A relativistic mean-field model of nuclear matter with arbitrary proton fraction is studied at finite temperature. An analysis is performed of the liquid-gas phase transition in a system with two conserved charges (baryon number and isospin) using the stability conditions on the free energy, the conservation laws, and Gibbs' criteria for phase equilibrium. For a binary system with two phases, the coexistence surface (binodal) is two dimensional. The Maxwell construction through the phase-separation region is discussed, and it is shown that the stable configuration can be determined uniquely at every density. Moreover, because of the greater dimensionality of the binodal surface, the liquid-gas phase transition is continuous (second order by Ehrenfest's definition), rather than discontinuous (first order), as in familiar one-component systems. Using a mean-field equation of state calibrated to the properties of nuclear matter and finite nuclei, various phase-separation scenarios are considered. The model is then applied to the liquid-gas phase transition that may occur in the warm, dilute matter produced in energetic heavy-ion collisions. In asymmetric matter, instabilities that produce a liquid-gas phase separation arise from fluctuations in the proton concentration (chemical instability), rather than from fluctuations in the baryon density (mechanical instability)

11

Charmonium mass in hot asymmetric nuclear matter

We calculate the in-medium masses of J/$\\psi$ and of the excited states of charmonium ($\\psi$(3686) and $\\psi$(3770)) in isospin asymmetric nuclear matter at finite temperatures. These mass modifications arise due to the interaction of the charmonium states with the gluon condensates of QCD, simulated by a scalar dilaton field introduced to incorporate the broken scale invariance of QCD within an effective chiral model. The change in the mass of J/$\\psi$ in the nuclear matter with density is seen to be rather small, as has been shown in the literature by using various approaches, whereas, the masses of the excited states of charmonium ($\\psi$(3686) and $\\psi$(3770)) are seen to have considerable drop at high densities. The dependence of the masses of the charmonium states on the isospin asymmetry has also been investigated in the hot nuclear matter and is seen to be appreciable at moderate temperatures and high densities. These medium modifications of the charmonium states should modify the experimental obser...

Mishra, Amruta

2010-01-01

12

Pseudo-Goldstone modes in isospin-asymmetric nuclear matter

International Nuclear Information System (INIS)

The authors analyze the chiral limit in dense isospin-asymmetric nuclear matter. It is shown that the pseudo-Goldstone modes in this system are qualitatively different from the case of isospin-symmetric matter

13

Higher order bulk characteristic parameters of asymmetric nuclear matter

The bulk parameters characterizing the energy of symmetric nuclear matter and the symmetry energy defined at normal nuclear density $\\rho_0 $ provide important information on the equation of state (EOS) of isospin asymmetric nuclear matter. While significant progress has been made in determining some lower order bulk characteristic parameters, such as the energy $E_0(\\rho_0)$ and incompressibility $K_0$ of symmetric nuclear matter as well as the symmetry energy $E_{sym}(\\rho...

Chen, Lie-wen

2011-01-01

14

Quantal Effects on Spinodal Instabilities in Charge Asymmetric Nuclear Matter

Quantal effects on growth of spinodal instabilities in charge asymmetric nuclear matter are investigated in the framework of a stochastic mean field approach. Due to quantal effects, in both symmetric and asymmetric matter, dominant unstable modes shift towards longer wavelengths and modes with wave numbers larger than the Fermi momentum are strongly suppressed. As a result of quantum statistical effects, in particular at lower temperatures, magnitude of density fluctuations...

Ayik, S.; Er, N.; Yilmaz, O.; Gokalp, A.

2008-01-01

15

Quantal Effects on Spinodal Instabilities in Charge Asymmetric Nuclear Matter

Quantal effects on growth of spinodal instabilities in charge asymmetric nuclear matter are investigated in the framework of a stochastic mean field approach. Due to quantal effects, in both symmetric and asymmetric matter, dominant unstable modes shift towards longer wavelengths and modes with wave numbers larger than the Fermi momentum are strongly suppressed. As a result of quantum statistical effects, in particular at lower temperatures, magnitude of density fluctuations grows larger than those calculated in semi-classical approximation.

Ayik, S; Yilmaz, O; Gökalp, A

2008-01-01

16

Quantal effects on spinodal instabilities in charge asymmetric nuclear matter

Energy Technology Data Exchange (ETDEWEB)

Quantal effects on growth of spinodal instabilities in charge asymmetric nuclear matter are investigated in the framework of a stochastic mean field approach. Due to quantal effects, in both symmetric and asymmetric matter, dominant unstable modes shift towards longer wavelengths and modes with wave numbers larger than the Fermi momentum are strongly suppressed. As a result of quantum statistical effects, in particular at lower temperatures, magnitude of density fluctuations grows larger than those calculated in semi-classical approximation.

Ayik, S. [Physics Department, Tennessee Technological University, Cookeville, TN 38505 (United States)], E-mail: ayik@tntech.edu; Er, N.; Yilmaz, O.; Gokalp, A. [Physics Department, Middle East Technical University, 06531 Ankara (Turkey)

2008-11-01

17

Quantal effects on spinodal instabilities in charge asymmetric nuclear matter

International Nuclear Information System (INIS)

Quantal effects on growth of spinodal instabilities in charge asymmetric nuclear matter are investigated in the framework of a stochastic mean field approach. Due to quantal effects, in both symmetric and asymmetric matter, dominant unstable modes shift towards longer wavelengths and modes with wave numbers larger than the Fermi momentum are strongly suppressed. As a result of quantum statistical effects, in particular at lower temperatures, magnitude of density fluctuations grows larger than those calculated in semi-classical approximation

18

Asymmetric nuclear matter based on chiral effective field theory interactions

International Nuclear Information System (INIS)

We investigate the properties of asymmetric nuclear matter with small proton fractions (high asymmetries). Our calculations are based on two- and three-nucleon forces from chiral effective field theory. We compare our microscopic results, including theoretical uncertainties, to a quasi-parabolic approximation developed to interpolate between pure neutron and symmetric nuclear matter. Our investigations are important for neutron-rich matter in astrophysics and as constraints for energy density functionals.

19

A microscopic calculation of incompressibility of asymmetric nuclear matter

International Nuclear Information System (INIS)

We have investigated the incompressibility of asymmetric nuclear matter within the Brueckner-Hartree-Fock approach extended to include a microscopic three-body force. The isospin-dependence and density-dependence of the nuclear incompressibility have been obtained and discussed. It is shown that the incompressibility at a fixed density increases monotonically as a function of isospin asymmetry. The isospin asymmetry dependence of the equilibrium properties of asymmetric nuclear matter is also predicted and compared with the results of other theoretical approaches. (authors)

20

Equation of state and phase transitions in asymmetric nuclear matter

The structure of the 3-dimension pressure-temperature-asymmetry surface of equilibrium of the asymmetric nuclear matter is studied within the thermal Thomas-Fermi approximation. Special attention is paid to the difference of the asymmetry parameter between the boiling sheet and that of the condensation sheet of the surface of equilibrium. We derive the condition of existence of the regime of retrograde condensation at the boiling of the asymmetric nuclear matter. We have performed calculations of the caloric curves in the case of isobaric heating. We have shown the presence of the plateau region in caloric curves at the isobaric heating of the asymmetric nuclear matter. The shape of the caloric curve depends on the pressure and is sensitive to the value of the asymmetry parameter. We point out that the experimental value of the plateau temperature T \\approx 7 MeV corresponds to the pressure P = 0.01 MeV/fm^3 at the isobaric boiling.

Kolomietz, V M; Shlomo, S; Firin, S A

2001-01-01

21

Phase transitions in warm, asymmetric nuclear matter

A relativistic mean-field model of nuclear matter with arbitrary proton fraction is studied at finite temperature. An analysis is performed of the liquid-gas phase transition in a system with two conserved charges (baryon number and isospin) using the stability conditions on the free energy, the conservation laws, and Gibbs' criteria for phase equilibrium. For a binary system with two phases, the coexistence surface (binodal) is two-dimensional. The Maxwell construction through the phase-separation region is discussed, and it is shown that the stable configuration can be determined uniquely at every density. Moreover, because of the greater dimensionality of the binodal surface, the liquid-gas phase transition is continuous (second order by Ehrenfest's definition), rather than discontinuous (first order), as in familiar one-component systems. Using a mean-field equation of state calibrated to the properties of nuclear matter and finite nuclei, various phase-separation scenarios are considered. The model is th...

Müller, H; Mueller, Horst; Serot, Brian D

1995-01-01

22

Short-range correlations in asymmetric nuclear matter

The spectral function of protons in the asymmetric nuclear matter is calculated in the self-consistent T-matrix approach. The spectral function per proton increases with increasing asymmetry. This effect and the density dependence of the spectral function partially explain the observed increase of the spectral function with the mass number of the target nuclei in electron scattering experiments.

Bozek, P.

2003-01-01

23

Microscopic three-body force for asymmetric nuclear matter

Brueckner calculations including a microscopic three-body force have been extended to isospin asymmetric nuclear matter. The effects of the three-body force on the equation of state and on the single-particle properties of nuclear matter are discussed with a view to possible applications in nuclear physics and astrophysics. It is shown that, even in the presence of the three-body force, the empirical parabolic law of the energy per nucleon vs isospin asymmetry $\\beta=(N-Z)/A...

Zuo, W.; Lejeune, A.; Lombardo, U.; Mathiot, J. F.

2002-01-01

24

Momentum distribution of nucleons in asymmetric nuclear matter

International Nuclear Information System (INIS)

We calculate the momentum distribution of nucleons in asymmetric nuclear matter within the framework of the extended Brueckner-Hartree-Fock approximation at zero temperature, use Argonne V18 potential as two nucleons potential. The isospin-asymmetry dependence of the nuc-leon momentum distribution predicted and discussed. It is shown that as the asymmetry increases, the proton momentum distribution become smaller while the neutron one gets higher below their respective Fermi surfaces with respect to their common values in symmetric nuclear matter. The quasi-particle strength at the Fermi momentum also calculated and discussed, we got an improved fulfillment of the Migdal-Luttinger theorem and nucleon number conservation. (authors)

25

Spinodal decomposition of low-density asymmetric nuclear matter

We investigate the dynamical properties of asymmetric nuclear matter at low density. The occurrence of new instabilities, that lead the system to a dynamical fragment formation, is illustrated, discussing in particular the charge symmetry dependence of the structure of the most important unstable modes. We observe that instabilities are reduced by charge asymmetry, leading to larger size and time scales in the fragmentation process. Configurations with less asymmetric fragments surrounded by a more asymmetric gas are favoured. Interesting variances with respect to a pure thermodynamical prediction are revealed, that can be checked experimentally. All these features are deeply related to the structure of the symmetry term in the nuclear Equation of State (EOS) and could be used to extract information on the low density part of the EOS.

Baran, V; Di Toro, M; Larionov, A B

1998-01-01

26

Symmetric and asymmetric nuclear matter in the relativistic approach

International Nuclear Information System (INIS)

Symmetric and asymmetric nuclear matter is studied in the framework of the relativistic Brueckner-Hartree-Fock and in the relativistic version of the so-called ?00 approximation. The equations are solved self-consistently in the full Dirac space, so avoiding the ambiguities in the choice of the effective scattering amplitude in matter. The calculations were performed for some modern meson-exchange potentials constructed by Brockmann and Machleidt. In some cases we used also the Groningen potentials. First, we examine the outcome for symmetric matter with respect to other calculations, which restrict themselves to positive-energy states only. The main part is devoted to the properties of asymmetric matter. In this case we obtain additionally to the good agreement with the parameters of symmetric matter, also a quite satisfactory agreement with the semiempirical macroscopic coefficients of asymmetric matter. Furthermore, we tested the assumption of a quadratic dependence of the asymmetry energy for a large range of asymmetries. Included is also the dependence of nucleon self-energies on density and neutron excess. For the purpose of comparison we discuss further the similarities and differences with relativistic Hartree and Hartree-Fock calculations and nonrelativistic Skyrme calculations

27

Pairing effects on spinodal decomposition of asymmetric nuclear matter

We investigate the impact of pairing correlations on the behavior of unstable asymmetric nuclear matter at low temperature. We focus on the relative role of the pairing interaction, coupling nucleons of the same type (neutrons or protons), with respect to the symmetry potential, which enhances the neutron-proton attraction, along the clusterization process driven by spinodal instabilities. It is found that, especially at the transition temperature from the normal to the supe...

Burrello, Stefano; Colonna, Maria; Matera, Francesco

2013-01-01

28

A unique spinodal region in asymmetric nuclear matter

International Nuclear Information System (INIS)

Asymmetric nuclear matter at sub-saturation densities is shown to present only one type of instabilities. The associated order parameter is dominated by the isoscalar density and so the transition is of liquid-gas type. The instability goes in the direction of a restoration of the isospin symmetry leading to a fractionation phenomenon. These conclusions are model independent since they can be related to the general form of the symmetry energy. They are illustrated using density functional approaches. (authors)

29

Pairing effects on spinodal decomposition of asymmetric nuclear matter

We investigate the impact of pairing correlations on the behavior of unstable asymmetric nuclear matter at low temperature. We focus on the relative role of the pairing interaction, coupling nucleons of the same type (neutrons or protons), with respect to the symmetry potential, which enhances the neutron-proton attraction, along the clusterization process driven by spinodal instabilities. It is found that, especially at the transition temperature from the normal to the superfluid phase, pairing effects may induce significant variations in the isotopic content of the clusterized matter. This analysis is potentially useful for gathering information on the temperature dependence of nuclear pairing and, in general, on the properties of clusterised low-density matter, which are of interest also in the astrophysical context.

Burrello, S.; Colonna, M.; Matera, F.

2014-05-01

30

Pairing effects on spinodal decomposition of asymmetric nuclear matter

We investigate the impact of pairing correlations on the behavior of unstable asymmetric nuclear matter at low temperature. We focus on the relative role of the pairing interaction, coupling nucleons of the same type (neutrons or protons), with respect to the symmetry potential, which enhances the neutron-proton attraction, along the clusterization process driven by spinodal instabilities. It is found that, especially at the transition temperature from the normal to the superfluid phase, pairing effects may induce significant variations in the isotopic content of the clusterized matter. This analysis is potentially useful to gather information on the temperature dependence of nuclear pairing and, in general, on the properties of clusterized low-density matter, of interest also in the astrophysical context.

Burrello, Stefano; Matera, Francesco

2013-01-01

31

Asymmetric Nuclear Matter from Extended Brueckner-Hartree-Fock Approach

The properties of isospin-asymmetric nuclear matter have been investigated in the framework of the extended Brueckner-Hartree-Fock approximation at zero temperature. Self-consistent calculations using the Argonne $V_{14}$ interaction are reported for several asymmetry parameters $\\beta = \\frac{N - Z}{A}$ ranging from symmetric nuclear matter to pure neutron matter. The binding energy per nucleon fulfills the $\\beta^2$ law in the whole asymmetry range. The symmetry energy is calculated for different densities and discussed in comparison with other predictions. At the saturation point it is in fairly good agreement with the empirical value. The present approximation, based on the Landau definition of quasiparticle energy, is investigated in terms of the Hugenholtz-Van Hove theorem, which is proved to be fulfilled with a good accuracy at various asymmetries. The isospin dependence of the single-particle properties is discussed, including mean field, effective mass, and mean free path of neutrons and protons. The...

Zuo, W; Lombardo, U

1999-01-01

32

D mesons in asymmetric nuclear matter at finite temperatures

We study the in-medium properties of $D$ and $\\bar{D}$ mesons in isospin-asymmetric nuclear matter at finite temperatures using an effective chiral SU(4) model. The interactions of $D$ and $\\bar{D}$ mesons with nucleons, scalar isoscalar meson $\\sigma$, and scalar iso-vector meson $\\delta$ are taken into consideration. It is found that as compared to the $\\bar{D}$ mesons, the properties of the $D$ mesons are observed to be quite sensitive to the isospin-asymmetry at high den...

Kumar, Arvind; Mishra, Amruta

2009-01-01

33

Onset of superfluidity in hot asymmetric nuclear matter

International Nuclear Information System (INIS)

The onset of superfluidity in hot asymmetric nuclear matter is studied within a generalized Beth-Uhlenbeck approach. The finite tempeature t-matrix is of the Bethe-Goldstone type and contains hole-hole propagation not considered in the Brueckner G-matrix approach. It is shown that the phase contour for the onset of superfluidity in this approach is identical to that obtained within Gorkov's approach to BCS theory. Results for the realistic Paris potential imply that the critical temperature in the neutron-proton triplet channel is on the order of 6-8 MeV and thus much larger than that for singlet pairing. (orig.)

34

Microscopic three-body force for asymmetric nuclear matter

Brueckner calculations including a microscopic three-body force have been extended to isospin asymmetric nuclear matter. The effects of the three-body force on the equation of state and on the single-particle properties of nuclear matter are discussed with a view to possible applications in nuclear physics and astrophysics. It is shown that, even in the presence of the three-body force, the empirical parabolic law of the energy per nucleon vs isospin asymmetry $\\beta=(N-Z)/A$ is fulfilled in the whole asymmetry range $0\\le\\beta\\le 1$ up to high densities. The three-body force provides a strong enhancement of symmetry energy increasing with the density in good agreement with relativistic approaches. The Lane's assumption that proton and neutron mean fields linearly vary vs the isospin parameter is violated at high density in the presence of the three-body force. Instead the momentum dependence of the mean fields is rather insensitive to three body force which brings about a linear isospin deviation of the neut...

Zuo, W; Lombardo, U; Mathiot, J F

2002-01-01

35

Surface characteristics of semi-infinite asymmetric nuclear matter at low temperature

International Nuclear Information System (INIS)

For applying to semi-infinite asymmetric nuclear matter, simple analytical relations for the surface and surface symmetry energies and their evolution with temperature using a number of Skyrme interactions are obtained. (M.G.B.)

36

Effective Nucleon Masses in Symmetric and Asymmetric Nuclear Matter

The momentum and isospin dependence of the in-medium nucleon mass are studied. Two definitions of the effective mass, i.e. the Dirac mass $m^*_D$ and the nonrelativistic mass $m^*_{NR}$ which parameterizes the energy spectrum, are compared. Both masses are determined from relativistic Dirac-Brueckner-Hartree-Fock calculations. The nonrelativistic mass shows a distinct peak around the Fermi momentum. The proton-neutron mass splitting in isospin asymmetric matter is $m^*_{D,n}...

Dalen, E. N. E.; Fuchs, C.; Faessler, Amand

2005-01-01

37

From asymmetric nuclear matter to neutron stars: A functional renormalization group study

A previous study of nuclear matter in a chiral nucleon-meson model is extended to isospin-asymmetric matter. Fluctuations beyond mean-field approximation are treated in the framework of the functional renormalization group. The nuclear liquid-gas phase transition is investigated in detail as a function of the proton fraction in asymmetric matter. The equations of state at zero temperature of both symmetric nuclear matter and pure neutron matter are found to be in good agreement with realistic many-body computations. We also study the density dependence of the pion mass in the medium. The question of chiral symmetry restoration in neutron matter is addressed; we find a stabilization of the phase with spontaneously broken chiral symmetry once fluctuations are included. Finally, neutron-star matter including ? equilibrium is discussed. The model satisfies the constraints imposed by the existence of two-solar mass neutron stars.

Drews, Matthias; Weise, Wolfram

2015-03-01

38

From asymmetric nuclear matter to neutron stars: a functional renormalization group study

A previous study of nuclear matter in a chiral nucleon-meson model is extended to isospin-asymmetric matter. Fluctuations beyond mean-field approximation are treated in the framework of the functional renormalization group. The nuclear liquid-gas phase transition is investigated in detail as a function of the proton fraction in asymmetric matter. The equations of state at zero temperature of both symmetric nuclear matter and pure neutron matter are found to be in good agreement with realistic many-body computations. We also study the density dependence of the pion mass in the medium. The question of chiral symmetry restoration in neutron matter is addressed; we find a stabilization of the phase with spontaneously broken chiral symmetry once fluctuations are included. Finally, neutron star matter including beta equilibrium is discussed. The model satisfies the constraints imposed by the existence of two-solar-mass neutron stars.

Drews, Matthias

2014-01-01

39

A study on the thermodynamics of liquid-gas phase transition for asymmetric polarized nuclear matter

International Nuclear Information System (INIS)

The equation of state, developed before, for asymmetric polarized nuclear matter revealed a liquid-gas phase transition behaviour. Such transition is typical to that described by Van der Waal equation of real gas. In the present work, the analogy between nuclear matter and real macroscopic gas is examined. The nuclear matter equation of state is compared to Van der Waal equation to find the corresponding values of the real gas constants. Results are analysed in terms of the physical meanings of such constants. The latent heat of vaporization and entropy of transformation are calculated for symmetric nuclear matter. The critical point data and Van der Waal constants are estimated for asymmetric polarized nuclear matter. (author). 17 refs, 9 figs, 4 tabs

40

Can we determine the EOS of asymmetric nuclear matter using unstable nuclei?

Energy Technology Data Exchange (ETDEWEB)

This paper shows that nuclear radii and neutron skins do directly reflect the saturation density of asymmetric nuclear matter. The proton distributions in a nucleus have been found to be remarkably independent of the equation of state (EOS) of the asymmetric matter. It is the neutron distributions that are dependent on the EOS. Macroscopic model calculations have been performed over the entire range of the nuclear chart based on two popular phenomenological, but distinctively different, EOS: the SIII parameter set for the nonrelativistic Skyrme Hartree-Fock theory and the TM1 parameter set in the relativistic mean field theory. The saturation density for a small proton fraction remains almost the same as the normal nuclear matter density for the SIII EOS, but it becomes significantly small for the TM1 EOS. The key EOS parameters used to describe the saturation density are the density derivative of the symmetry energy and the incompressibility of symmetric nuclear matter, while the saturation energy is written using the symmetry energy alone as a good approximation. We conclude that a systematic experimental study of heavy unstable nuclei would enable us to determine the EOS of asymmetric nuclear matter at around the normal nuclear matter density with a fixed proton fraction down to approximately 0.3. Therefore, the answer to the title is yes. (author)

Oyamatsu, K. [Nagoya Univ., Nagoya, Aichi (Japan); Tanihata, I.; Sugahara, Y.; Sumiyoshi, K.; Toki, H.

1999-08-01

41

D mesons and charmonium states in asymmetric nuclear matter at finite temperatures

We investigate the in-medium masses of $D$ and $\\bar{D}$ mesons in the isospin-asymmetric nuclear matter at finite temperatures arising due to the interactions with the nucleons, the scalar isoscalar meson $\\sigma$, and the scalar iso-vector meson $\\delta$ within a SU(4) model. The in-medium masses of $J/\\psi$ and the excited charmonium states ($\\psi(3686)$ and $\\psi(3770)$) are also calculated in the hot isospin asymmetric nuclear matter in the present investigation. These ...

Kumar, Arvind; Mishra, Amruta

2010-01-01

42

Pions in isospin asymmetric matter and nuclear Drell-Yan scattering

Using a self-consistent delta-hole model the pion propagation in isospin asymmetric nuclear matter is studied. In neutron-rich matter, corresponding to heavy nuclei, a significant difference in positive and negative pion light-cone distributions is obtained leading to a nuclear enhancement of up antiquark distribution compared to the down antiquark one. This means that the sea-quark asymmetry in the free nucleon cannot be extracted model independently from an experiment on a neutron-rich nucleus.

Korpa, C L

1999-01-01

43

Thermodynamics of isospin-asymmetric nuclear matter from chiral effective field theory

The density and temperature dependence of the nuclear symmetry free energy is investigated using microscopic two- and three-body nuclear potentials constructed from chiral effective field theory. The nuclear force models and many-body methods are benchmarked to properties of isospin-symmetric nuclear matter in the vicinity of the saturation density as well as the virial expansion of the neutron matter equation of state at low fugacities. The free energy per particle of nuclear matter with varying neutron-to-proton ratio is calculated assuming a quadratic dependence of the interaction contributions on the isospin asymmetry. The thermodynamic equation of state of isospin-asymmetric nuclear matter is examined in detail.

Wellenhofer, Corbinian; Kaiser, Norbert

2015-01-01

44

Phase Transition Of Asymmetric Nuclear Matter Beyond The 4-Nucleon Model

International Nuclear Information System (INIS)

The contribution of the delta meson to asymmetric nuclear matter (ANM) in the four-nucleon model is considered within the Cornwall-Jackiw-Tomboulis (CJT) effective action approach. In the double-bubble approximation the theory provides the nuclear symmetry energy (NSE) consistent with the recent analysis of experimental data and, at the same time, leads to a softer incompressibility, K0 = 240 MeV, without invoking any additional term similar to the Boguta-Bodmer potential. (author)

45

Nucleon Effective Mass in Asymmetric Nuclear Matter within Extended Brueckner Approach

International Nuclear Information System (INIS)

The on-shell properties of the nucleon effective mass in asymmetric nuclear matter are investigated in the framework of an extended Brueckner—Hartree—Fock (BHF) approach. The proton and neutron effective masses in neutron-rich nuclear matter are predicted by including both the effect of ground state correlations and the three-body force (TBF) rearrangement contribution. Within this framework, the neutron effective mass is predicted to be larger than the proton one in neutron-rich nuclear matter, i.e., m*n ? m*p. The effect of ground state correlations turns out to be dominated at low densities and it leads to a strong enhancement of the effective mass. The TBF rearrangement contribution becomes predominant over the effect of ground state correlations at high densities and it reduces remarkably the absolute magnitude of the isospin splitting of the neutron and proton effective masses in neutron-rich matter at high densities. (nuclear physics)

46

Variational Calculation for the Equation of State of Hot Asymmetric Nuclear Matter

International Nuclear Information System (INIS)

We calculate the equation of state (EOS) of asymmetric nuclear matter at finite temperatures with the cluster variational method based on the realistic nuclear Hamiltonian composed of the AV18 and UIX nuclear potentials. The free energy is calculated with an extension of the variational method proposed by Schmidt and Pandharipande. The obtained thermodynamic quantities such as entropy, internal energy, pressure and chemical potential derived from the free energy are reasonable. It is also found that the present variational calculation is self-consistent. These thermodynamic quantities are essential ingredients in our project for constructing a new nuclear EOS applicable to supernova simulations.

47

Landau parameters for asymmetric nuclear matter with a strong magnetic field

The Landau Fermi Liquid parameters are calculated for charge neutral asymmetric nuclear matter in beta equilibrium at zero temperature in the presence of a very strong magnetic field with relativistic mean-field models. Due to the isospin structure of the system, with different populations of protons and neutrons and spin alignment to the field, we find non-vanishing Landau mixing parameters. The existence of quantized Landau levels for the charged sector has some impact on ...

Perez-garcia, M. A.; Providencia, C.; Rabhi, A.

2011-01-01

48

We study the effect of a strong magnetic field on the proton and neutron spin polarization and magnetic susceptibility of asymmetric nuclear matter within a relativistic mean-field approach. It is shown that magnetic fields $B \\sim 10^{16} - 10^{17}$ G have already noticeable effects on the range of densities of interest for the study of the crust of a neutron star. Although the proton susceptibility is larger for weaker fields, the neutron susceptibility becomes of the same...

Rabhi, A.; Pe?rez-garci?a, M. A.; Provide?ncia, C.; Vidan?a, I.

2014-01-01

49

Equation of state for asymmetric nuclear matter with infinite-order summation of ring diagrams

The particle-particle hole-hole ring-diagram summation method is employed to obtain the equation of state of asymmetric nuclear matter over a wide range of asymmetry fraction. Compared with Brueckner Hartree-Fock and model-space Brueckner Hartree-Fock calculations, this approach gives a softer equation of state, increased symmetry energy and a lower value for the incompressibility modulus which agrees quite well with the values used in the hydrodynamical model for the supern...

Shamanna, J.; Kuo, T. T. S.; Bombaci, I.; Ray, Subhankar

2005-01-01

50

Coexistence of phases in asymmetric nuclear matter under strong magnetic fields

The equation of state of nuclear matter is strongly affected by the presence of a magnetic field. Here we study the equilibrium configuration of asymmetric nuclear matter for a wide range of densities, isospin composition, temperatures and magnetic fields. Special attention is paid to the low density and low temperature domain, where a thermodynamical instability exists. Neglecting fluctuations of the Coulomb force, a coexistence of phases is found under such conditions, even for extreme magnetic intensities. We describe the nuclear interaction by using the non--relativistic Skyrme potential model within a Hartree--Fock approach. We found that the coexistence of phases modifies the equilibrium configuration, masking most of the manifestations of the spin polarized matter. However, the compressibility and the magnetic susceptibility show clear signals of this fact. Thermal effects are significative for both quantities, mainly out of the coexistence region.

Aguirre, R

2014-01-01

51

Single particle potentials of asymmetric nuclear matter in different spin-isospin channels

International Nuclear Information System (INIS)

We investigate the neutron and proton single particle (s.p.) potentials of asymmetric nuclear matter and their isospin dependence in various spin-isospin ST channels within the framework of the Brueckner- Hartree-Fock approach. It is shown that in symmetric nuclear matter, the s.p. potentials in both the isospin- singlet T=0 channel and isospin-triplet T=1 channel are essentially attractive, and the magnitudes in the two different channels are roughly the same. In neutron-rich nuclear matter, the isospin-splitting of the proton and neutron s.p. potentials turns out to be mainly determined by the isospin-singlet T=0 channel contribution which becomes more attractive for the proton and more repulsive for the neutron at higher asymmetries. (authors)

52

In existing dark matter models with global symmetries the relic abundance of dark matter is either equal to that of anti-dark matter (thermal WIMP), or vastly larger, with essentially no remaining anti-dark matter (asymmetric dark matter). By exploring the consequences of a primordial asymmetry on the coupled dark matter and anti-dark matter Boltzmann equations we find large regions of parameter space that interpolate between these two extremes. Interestingly, this new asymmetric WIMP framework can accommodate a wide range of dark matter masses and annihilation cross sections. The present-day dark matter population is typically asymmetric, but only weakly so, such that indirect signals of dark matter annihilation are not completely suppressed. We apply our results to existing models, noting that upcoming direct detection experiments will constrain a large region of the relevant parameter space.

Graesser, Michael L; Vecchi, Luca

2011-01-01

53

We present microscopic calculations of light and medium mass nuclei and the equation of state of symmetric and asymmetric nuclear matter using different nucleon-nucleon forces, including a new Argonne version that has the same spin/isospin structure as local chiral forces at next-to-next-to-leading order (N2LO). The calculations are performed using Auxiliary Field Diffusion Monte Carlo (AFDMC) combined with an improved variational wave function. We show that the AFDMC method can now be used to successfully calculate the energies of very light to medium mass nuclei as well as the energy of isospin-asymmetric nuclear matter, demonstrating microscopically the quadratic dependence of the energy on the symmetry energy.

Gandolfi, S; Carlson, J; Schmidt, Kevin E

2014-01-01

54

Variational study of asymmetric nuclear matter and a new term in the mass formula

International Nuclear Information System (INIS)

Asymmetric nuclear matter at zero temperature is studied using a variational method which is an extension of the methods used by the present authors previously for simpler systems. An approximate expression for the energy per nucleon in asymmetric nuclear matter is derived through a combination of two procedures, one used for symmetric nuclear matter and the other for spin-polarized liquid 3He with spin polarization replaced by isospin polarization. The approximate expression for the energy is obtained as a functional of various spin-isospin-dependent radial distribution functions, tensor distribution functions, and spin-orbit distribution functions. The Euler-Lagrange equations are derived to minimize this approximate expression for the energy; they consist of 16 coupled integrodifferential equations for various distribution functions. These equations were solved numerically for several values of the nucleon number density ? and for many degrees of asymmetry ?[?=(?n-?p)/?, where ?n(?p) is the neutron (proton) number density]. Unexpectedly, we find that the energies at a fixed density cannot be represented by a power series in ?2. A new energy term, ?1(?2+?02)1/2, where ?0 is a small number and ?1 is a positive coefficient, is proposed. It is shown that if the power series is supplemented with this new term, it reed with this new term, it reproduces the energies obtained by variational calculations very accurately. This new term is studied in relation to cluster formation in nuclear matter, and some mention is made of a possible similar term in the mass formula for finite nuclei. (author)

55

D mesons and charmonium states in asymmetric nuclear matter at finite temperatures

International Nuclear Information System (INIS)

We investigate the in-medium masses of D and D-bar mesons in the isospin-asymmetric nuclear matter at finite temperatures arising due to the interactions with the nucleons, the scalar-isoscalar meson ?, and the scalar-isovector meson ? within a SU(4) model. However, since the chiral symmetry is explicitly broken for the SU(4) case due to the large charm quark mass, we use the SU(4) symmetry here only to obtain the interactions of the D and D-bar mesons with the light hadron sector but use the observed values of the heavy hadron masses and empirical values of the decay constants. The in-medium masses of J/? and the excited charmonium states [?(3686) and ?(3770)] are also calculated in the hot isospin-asymmetric nuclear matter in the present investigation. These mass modifications arise due to the interaction of the charmonium states with the gluon condensates of QCD, simulated by a scalar dilaton field introduced to incorporate the broken scale invariance of QCD within the effective chiral model. The change in the mass of J/? in the nuclear matter with the density is seen to be rather small, as has been shown in the literature by using various approaches, whereas the masses of the excited states of charmonium [?(3686) and ?(3770)] are seen to have considerable drop at high densities. The present study of the in-medium masses of D (D-bar) mesons as well as of the charmonium states will be of relevance for the observables from the compressed baryonic matter, likee compressed baryonic matter, like the production and collective flow of the D (D-bar) mesons, resulting from the asymmetric heavy-ion collision experiments planned at the future facility of the GSI Facility for Antiproton and Ion Research. The mass modifications of D and D-bar mesons as well as of the charmonium states in hot nuclear medium can modify the decay of the charmonium states (?',?c,J/?) to DD-bar pairs in the hot dense hadronic matter. The small attractive potentials observed for the D-bar mesons may lead to formation of the D-bar mesic nuclei.

56

Thermodynamic instabilities in dense asymmetric nuclear matter and in compact stars

We investigate the presence of thermodynamic instabilities in compressed asymmetric baryonic matter, reachable in high energy heavy ion collisions, and in the cold ?-stable compact stars. To this end we study the relativistic nuclear equation of state with the inclusion of ?-isobars and require the global conservation of baryon and electric charge numbers. Similarly to the low density nuclear liquid-gas phase transition, we show that a phase transition can occur in dense asymmetric nuclear matter and it is characterized by both mechanical instability (fluctuations on the baryon density) and by chemical-diffusive instability (fluctuations on the electric charge concentration). Such thermodynamic instabilities can imply a very different electric charge fraction Z/A in the coexisting phases during the phase transition and favoring an early formation of ?- particles with relevant phenomenological consequences in the physics of the protoneutron stars and compact stars. Finally, we discuss the possible co-existence of very compact and very massive compact stars in terms of two separate families: compact hadronic stars and very massive quark stars.

Lavagno, A.; Drago, A.; Pagliara, G.; Pigato, D.

2014-07-01

57

International Nuclear Information System (INIS)

A phenomenological momentum dependent interaction (MDI) is considered to describe the equation of state (EOS) for isospin asymmetric nuclear matter (ANM), where the density dependence of the nuclear symmetry is the basic input. In this interaction, the symmetry energy shows soft dependence of density. Within the nonrelativistic mean field approach we calculate the nuclear matter fourth-order symmetry energy Esym,4(?). Our result shows that the value of Esym,4(?) at normal nuclear matter density ?0( = 0.161 fm-3) is less than 1 MeV conforming the empirical parabolic approximation to the EOS of ANM at ?0. Then the higher-order effects of the isospin asymmetry on the saturation density ?sat(?), binding energy per nucleon Ksat(?) and isobaric incompressibility Ksat(?) of ANM is being studied, where ? = [?n - ?p]/? is the isospin asymmetry. We have found that the fourth-order isospin asymmetry ? cannot be neglected, while calculating these quantities. Hence the second-order Ksat,2 parameter basically characterizes the isospin dependence of the incompressibility of ANM at saturation density. (author)

58

Energy Technology Data Exchange (ETDEWEB)

Early development of spinodal instabilities and density correlation functions in asymmetric nuclear matter are investigated in the stochastic extension of the Walecka-type relativistic mean field including coupling with rho meson. Calculations are performed under typical conditions encountered in heavy-ion collisions and in the crusts of neutron stars. In general, growth of instabilities occur relatively slower for increasing charge asymmetry of matter. At higher densities around {rho} = 0.4{rho} {sub 0} fluctuations grow relatively faster in the quantal description than those found in the semi-classical limit. Typical sizes of early condensation regions extracted from density correlation functions are consistent with those found from dispersion relations of the unstable collective modes. (orig.)

Yilmaz, O.; Acar, F.; Saatci, S. [Middle East Technical University, Physics Department, Ankara (Turkey); Ayik, S. [Tennessee Technological University, Physics Department, Cookeville, TN (United States); Gokalp, A. [Bilkent University, Department of Physics, Ankara (Turkey)

2013-03-15

59

International Nuclear Information System (INIS)

Early development of spinodal instabilities and density correlation functions in asymmetric nuclear matter are investigated in the stochastic extension of the Walecka-type relativistic mean field including coupling with rho meson. Calculations are performed under typical conditions encountered in heavy-ion collisions and in the crusts of neutron stars. In general, growth of instabilities occur relatively slower for increasing charge asymmetry of matter. At higher densities around ? = 0.4? 0 fluctuations grow relatively faster in the quantal description than those found in the semi-classical limit. Typical sizes of early condensation regions extracted from density correlation functions are consistent with those found from dispersion relations of the unstable collective modes. (orig.)

60

Thermal properties of asymmetric nuclear matter, including the temperature dependence of the symmetry energy, single-particle properties, and differential isospin fractionation, are investigated with different neutron-proton effective mass splittings using an improved isospin- and momentum-dependent interaction. In this improved interaction, the momentum-dependence of the isoscalar single-particle potential at saturation density is well fitted to that extracted from optical model analyses of proton-nucleus scattering data up to nucleon kinetic energy of 1 GeV, and the isovector properties, i.e., the slope of the nuclear symmetry energy, the momentum-dependence of the symmetry potential, and the symmetry energy at saturation density can be flexibly adjusted via three parameters $x$, $y$, and $z$, respectively. Our results indicate that the nucleon phase-space distribution in equilibrium, the temperature dependence of the symmetry energy, and the differential isospin fractionation can be significantly affected ...

Xu, Jun; Li, Bao-An

2014-01-01

61

Examining the energy dependence of symmetry potential in asymmetric nuclear matter

Energy Technology Data Exchange (ETDEWEB)

By using the Hugenholtz–Van Hove (HVH) theorem, the symmetry potential in asymmetric nuclear matter is found to be closely related to symmetry energy E{sub sym}(?) and its density slope L(?). The energy dependence of symmetry potential at saturation density ?{sub 0} is extracted by using recent constraints on both E{sub sym}(?{sub 0}) and L(?{sub 0}) from different methods not only in nuclear structures and reactions but also in astrophysics. The extracted symmetry potentials from different methods are found to be generally consistent with each other. By averaging all extracted symmetry potentials, an energy-dependent form of symmetry potential at the saturation density is obtained, which could be useful to calibrate the single-particle potentials in mean-field models of structures and transport models of reactions.

Xu, Chang, E-mail: cxu@nju.edu.cn [Department of Physics, Nanjing University, Nanjing 210008 (China); CPNPC, Nanjing University, Nanjing 210008 (China); Kavli Institute for Theoretical Physics China, Beijing 100190 (China); Ren, Zhongzhou [Department of Physics, Nanjing University, Nanjing 210008 (China); CPNPC, Nanjing University, Nanjing 210008 (China); Kavli Institute for Theoretical Physics China, Beijing 100190 (China); Center of Theoretical Nuclear Physics, National Laboratory of Heavy-Ion Accelerator, Lanzhou 730000 (China)

2013-09-02

62

Variational study for the equation of state of asymmetric nuclear matter at finite temperatures

An equation of state (EOS) for uniform asymmetric nuclear matter (ANM) is constructed at zero and finite temperatures by the variational method starting from the nuclear Hamiltonian that is composed of the Argonne v18 and Urbana IX potentials. At zero temperature, the two-body energy is calculated with the Jastrow wave function in the two-body cluster approximation which is supplemented by Mayer's condition and the healing-distance condition so as to reproduce the result by Akmal, Pandharipande and Ravenhall. The energy caused by the three-body force is treated somewhat phenomenologically so that the total energy reproduces the empirical saturation conditions. The masses and radii of neutron stars obtained with the EOS are consistent with recent observational data. At finite temperatures, thermodynamic quantities such as free energy, internal energy, entropy, pressure and chemical potentials are calculated with an extension of the method by Schmidt and Pandharipande. The validity of the frozen-correlation app...

Togashi, H; 10.1016/j.nuclphysa.2013.02.014

2013-01-01

63

Effects of the charge symmetry breaking (CSB) in isospin-asymmetric nuclear matter are studied in terms of the $\\rho-\\omega$ meson mixing mediated by nucleon polarizations. Taking into account the rearrangement term neglected previously we evaluate the $\\rho-\\omega$ mixing angle in a novel way within the Relativistic Mean-Field Model with chiral limits. It is found that the symmetry energy is significantly softened at high densities by the CSB. Moreover, the CSB-related rearrangement term plays an important role in determining the pressure and thus also the causality condition in dense isospin-asymmetric nuclear matter.

Jiang, Wei-Zhou

2008-01-01

64

We study the effect of a strong magnetic field on the proton and neutron spin polarization and magnetic susceptibility of asymmetric nuclear matter within a relativistic mean-field approach. It is shown that magnetic fields $B \\sim 10^{16} - 10^{17}$ G have already noticeable effects on the range of densities of interest for the study of the crust of a neutron star. Although the proton susceptibility is larger for weaker fields, the neutron susceptibility becomes of the same order or even larger for small proton fractions and subsaturation densities for $B > 10^{16}$ G. We expect that neutron superfluidity in the crust will be affected by the presence of magnetic fields.

Rabhi, A; Providência, C; Vidaña, I

2014-01-01

65

We study the asymmetric nuclear matter using a holographic QCD model by introducing a baryonic charge in the infrared boundary. We first show that, in the normal hadron phase, the predicted values of the symmetry energy and it's slope parameter are comparable with the empirical values. We find that the phase transition from the normal phase to the pion condensation phase is delayed compared with the pure mesonic matter: The critical chemical potential is larger than the pion...

Nishihara, Hiroki; Harada, Masayasu

2014-01-01

66

Variational study for the equation of state of asymmetric nuclear matter at finite temperatures

International Nuclear Information System (INIS)

An equation of state (EOS) for uniform asymmetric nuclear matter (ANM) is constructed at zero and finite temperatures by the variational method starting from the nuclear Hamiltonian that is composed of the Argonne v18 and Urbana IX potentials. At zero temperature, the two-body energy is calculated with the Jastrow wave function in the two-body cluster approximation which is supplemented by Mayer's condition and the healing-distance condition so as to reproduce the result by Akmal, Pandharipande and Ravenhall. The energy caused by the three-body force is treated somewhat phenomenologically so that the total energy reproduces the empirical saturation conditions. The masses and radii of neutron stars obtained with the EOS are consistent with recent observational data. At finite temperatures, thermodynamic quantities such as free energy, internal energy, entropy, pressure and chemical potentials are calculated with an extension of the method by Schmidt and Pandharipande. The validity of the frozen-correlation approximation employed in this work is confirmed as compared with the result of the fully minimized calculation. The quadratic proton-fraction-dependence of the energy of ANM is confirmed at zero temperature, whereas the free energy of ANM deviates from the quadratic proton-fraction-dependence markedly at finite temperatures. The obtained EOS of ANM will be an important ingredient of a new nuclear EOS for supernova numerical simulations

67

Thermal properties of asymmetric nuclear matter, including the temperature dependence of the symmetry energy, single-particle properties, and differential isospin fractionation, are investigated with different neutron-proton effective mass splittings by using an improved isospin- and momentum-dependent interaction. In this improved interaction, the momentum dependence of the isoscalar single-particle potential at saturation density is well fit to that extracted from optical-model analyses of proton-nucleus scattering data up to the nucleon kinetic energy of 1 GeV, and the isovector properties, i.e., the slope of the nuclear symmetry energy, the momentum dependence of the symmetry potential, and the symmetry energy at saturation density, can be flexibly adjusted via three parameters: x ,y , and z , respectively. Our results indicate that the nucleon phase-space distribution in equilibrium, the temperature dependence of the symmetry energy, and the differential isospin fractionation can be significantly affected by the isospin splitting of the nucleon effective mass.

Xu, Jun; Chen, Lie-Wen; Li, Bao-An

2015-01-01

68

International Nuclear Information System (INIS)

We present an upgraded review of our microscopic investigation on the single-particle properties and the EOS of isospin asymmetric nuclear matter within the framework of the Brueckner theory extended to include a microscopic three-body force. We pay special attention to the discussion of the three-body force effect and the comparison of our results with the predictions by other ab initio approaches. Three-body force is shown to be necessary for reproducing the empirical saturation properties of symmetric nuclear matter within nonrelativistic microscopic frameworks, and also for extending the hole-line expansion to a wide density range. The three-body force effect on nuclear symmetry energy is repulsive, and it leads to a significant stiffening of the density dependence of symmetry energy at supra-saturation densities. Within the Brueckner approach, the three-body force affects the nucleon s.p. potentials primarily via its rearrangement contribution which is strongly repulsive and momentum-dependent at high densities and high momenta. Both the rearrangement contribution induced by the three-body force and the effect of ground-state correlations are crucial for predicting reliably the single-particle properties within the Brueckner framework. (orig.)

69

Landau parameters for asymmetric nuclear matter with a strong magnetic field

International Nuclear Information System (INIS)

The Landau Fermi-liquid parameters are calculated for charge-neutral asymmetric nuclear matter in beta equilibrium at zero temperature in the presence of a very strong magnetic field with relativistic mean-field models. Due to the isospin structure of the system, with different populations of protons and neutrons and spin alignment to the field, we find nonvanishing Landau mixing parameters. The existence of quantized Landau levels for the charged sector has some impact on the Landau parameters with the presence of discretized features in those involving the proton sector. Using the Fermi-liquid formalism singlet and triplet excited quasiparticle states are analyzed, and we find that in-medium effects and magnetic fields are competing; however, the former are more important in the interaction energy range considered. It is found that for magnetic field strengths log10B(G)?17 the relatively low polarization of the system produces mild changes in the generalized Landau parameters with respect to the unmagnetized case, while for larger strengths there is a resolution of the degeneracy of the interaction energies of quasiparticles in the system. As an application we calculate the incompressibility and first sound velocities to illustrate how this formalism can be used to obtain physical information from the system.

70

Asymmetric Higgsino dark matter.

In the supersymmetric framework, prior to the electroweak phase transition, the existence of a baryon asymmetry implies the existence of a Higgsino asymmetry. We investigate whether the Higgsino could be a viable asymmetric dark matter candidate. We find that this is indeed possible. Thus, supersymmetry can provide the observed dark matter abundance and, furthermore, relate it with the baryon asymmetry, in which case the puzzle of why the baryonic and dark matter mass densities are similar would be explained. To accomplish this task, two conditions are required. First, the gauginos, squarks, and sleptons must all be very heavy, such that the only electroweak-scale superpartners are the Higgsinos. With this spectrum, supersymmetry does not solve the fine-tuning problem. Second, the temperature of the electroweak phase transition must be low, in the (1-10) GeV range. This condition requires an extension of the minimal supersymmetric standard model. PMID:23006163

Blum, Kfir; Efrati, Aielet; Grossman, Yuval; Nir, Yosef; Riotto, Antonio

2012-08-01

71

Asymmetric dense matter in holographic QCD

Directory of Open Access Journals (Sweden)

Full Text Available We study asymmetric dense matter in holographic QCD.We construct asymmetric dense matter by considering two quark flavor branes with dierent quark masses in a D4/D6/D6 model. To calculate the symmetry energy in nuclear matter, we consider two quarks with equal masses and observe that the symmetry energy increases with the total charge showing the stiff dependence. This behavior is universal in the sense that the result is independent of parameters in the model. We also study strange (or hyperon matter with one light and one intermediate mass quarks. In addition to the vacuum properties of asymmetric matter, we calculate meson masses in asymmetric dense matter and discuss our results in the light of in-medium kaon masses.

Shin Ik Jae

2012-02-01

72

Annihilating Asymmetric Dark Matter

The relic abundance of particle and antiparticle dark matter (DM) need not be vastly different in thermal asymmetric dark matter (ADM) models. By considering the effect of a primordial asymmetry on the thermal Boltzmann evolution of coupled DM and anti-DM, we derive the requisite annihilation cross section. This is used in conjunction with CMB and Fermi-LAT gamma-ray data to impose a limit on the number density of anti-DM particles surviving thermal freeze-out. When the extended gamma-ray emission from the Galactic Center is reanalyzed in a thermal ADM framework, we find that annihilation into $\\tau$ leptons prefer anti-DM number densities 1-4$\\%$ that of DM while the $b$-quark channel prefers 50-100$\\%$.

Bell, Nicole F; Shoemaker, Ian M

2014-01-01

73

We study the asymmetric nuclear matter using a holographic QCD model by introducing a baryonic charge in the infrared boundary. We first show that, in the normal hadron phase, the predicted values of the symmetry energy and its slope parameter are comparable with the empirical values. We find that the phase transition from the normal phase to the pion condensation phase is delayed compared with the pure mesonic matter: the critical chemical potential is larger than the pion mass which is obtained for the pure mesonic matter. We also show that, in the pion condensation phase, the pion contribution to the isospin number density increases with the chemical potential, while the baryonic contribution is almost constant. Furthermore, the value of chiral condensation implies that the enhancement of the chiral symmetry breaking occurs in the asymmetric nuclear matter as in the pure mesonic matter. We also give a discussion on how to understand the delay in terms of the four-dimensional chiral Lagrangian including the rho and omega mesons based on the hidden local symmetry.

Nishihara, Hiroki; Harada, Masayasu

2014-12-01

74

We study the asymmetric nuclear matter using a holographic QCD model by introducing a baryonic charge in the infrared boundary. We first show that, in the normal hadron phase, the predicted values of the symmetry energy and it's slope parameter are comparable with the empirical values. We find that the phase transition from the normal phase to the pion condensation phase is delayed compared with the pure mesonic matter: The critical chemical potential is larger than the pion mass which is obtained for the pure mesonic matter. We also show that, in the pion condensation phase, the pion contribution to the isospin number density increases with the chemical potential, while the baryonic contribution is almost constant. Furthermore, the value of chiral condensation implies that the enhancement of the chiral symmetry breaking occurs in the asymmetric nuclear matter as in the pure mesonic matter. We also give a discussion on how to understand the delay in terms of the 4-dimensional chiral Lagrangian including the r...

Nishihara, Hiroki

2014-01-01

75

Critical temperature for ?-condensation in asymmetric nuclear matter: the astrophysical context

International Nuclear Information System (INIS)

The critical temperature for ?-particle condensation in nuclear matter with Fermi surface imbalance between protons and neutrons is determined. The in-medium four-body Schroedinger equation, generalizing the Thouless criterion of the BCS transition, is applied using a Hartree-Fock wave function for the quartet projected onto zero total momentum in matter with different chemical potentials for protons and neutrons. (author)

76

Minimal Asymmetric Dark Matter

In the early Universe, any particle carrying a conserved quantum number and in chemical equilibrium with the thermal bath will unavoidably inherit a particle-antiparticle asymmetry. A new particle of this type, if stable, would represent a candidate for asymmetric dark matter (DM) with an asymmetry directly related to the baryon asymmetry. We study this possibility for a minimal DM sector constituted by just one (generic) $SU(2)_L$ multiplet $\\chi$ carrying hypercharge, assuming that at temperatures above the electroweak phase transition an effective operator enforces chemical equilibrium between $\\chi$ and the Higgs boson. We argue that limits from DM direct detection searches severely constrain this scenario, ruling out the possibility of scalar multiplets, and leaving as the only possibilities fermion DM with hypercharge $y = 1/2$ and $y = 1$ with a mass in the few TeV range.

Boucenna, Sofiane M; Nardi, Enrico

2015-01-01

77

Asymmetric dense matter in holographic QCD

We study asymmetric dense matter in holographic QCD.We construct asymmetric dense matter by considering two quark flavor branes with dierent quark masses in a D4/D6/D6 model. To calculate the symmetry energy in nuclear matter, we consider two quarks with equal masses and observe that the symmetry energy increases with the total charge showing the stiff dependence. This behavior is universal in the sense that the result is independent of parameters in the model. We also study strange (or hyper...

Shin Ik Jae; Seo Yunseok; Kim Youngman; Sin Sang-Jin

2012-01-01

78

Cluster formation in asymmetric nuclear matter: semi-classical and quantal approaches

The nuclear-matter liquid-gas phase transition induces instabilities against finite-size density fluctuations. This has implications for both heavy-ion-collision and compact-star physics. In this paper, we study the clusterization properties of nuclear matter in a scenario of spinodal decomposition, comparing three different approaches: the quantal RPA, its semi-classical limit (Vlasov method), and a hydrodynamical framework. The predictions related to clusterization are qualitatively in good agreement varying the approach and the nuclear interaction. Nevertheless, it is shown that i) the quantum effects reduce the instability zone, and disfavor short-wavelength fluctuations; ii) large differences appear bewteen the two semi-classical approaches, which correspond respectively to a collisionless (Vlasov) and local equilibrium description (hydrodynamics); iii) the isospin-distillation effect is stronger in the local equilibrium framework; iv) important variations between the predicted time-scales of cluster for...

Ducoin, C; Chomaz, Ph

2008-01-01

79

We examine short-range correlations in nuclear and neutron matter through the properties of the correlated wave function obtained by solving the Bethe-Goldstone equation. We explore tensor correlations through the dominant tensor-driven transition and central correlations through the singlet and triplet S waves. We compare predictions from a popular meson-theoretic nucleon- nucleon potential employed in the Dirac-Brueckner-Hartree-Fock approach with those from two- and three-body high-quality chiral interactions in Brueckner G-matrix calculations. Short-range correlations in symmetric matter are remarkably stronger than in neutron matter. We find that short-range correlations are very model dependent and have a large impact on the symmetry energy above normal density.

Sammarruca, Francesca

2014-01-01

80

We consider a simple class of models in which the relic density of dark matter is determined by the baryon asymmetry of the universe. In these models a $B - L$ asymmetry generated at high temperatures is transfered to the dark matter, which is charged under $B - L$. The interactions that transfer the asymmetry decouple at temperatures above the dark matter mass, freezing in a dark matter asymmetry of order the baryon asymmetry. This explains the observed relation between the baryon and dark matter densities for dark matter mass in the range 5--15 GeV. The symmetric component of the dark matter can annihilate efficiently to light pseudoscalar Higgs particles $a$, or via $t$-channel exchange of new scalar doublets. The first possibility allows for $h^0 \\to aa$ decays, while the second predicts a light charged Higgs-like scalar decaying to $\\tau\

Kaplan, David E; Zurek, Kathryn M

2009-01-01

81

The study of participant-spectator matter and thermalization for charge asymmetric nuclear collision

International Nuclear Information System (INIS)

Using the isospin-dependent quantum molecular dynamics model, we study the N/Z dependence of participant-spectator matter, anisotropic ratio ?Ra? and relative momentum ?KR?, at different incident energies (E = 100, 200 and 300 MeV per nucleon) and at scaled impact parameters ( b-hat = b/bmax= 0.0-0.4). We have also investigated the effect of isospin-dependent cross-section on these quantities as a function of N/Z of the system. Simulations are carried out for the reactions of 124Pr59 + 124Pr59 (N/Z = 1.101), 124Ba56 + 124Ba56 (N/Z = 1.214), 124I53 + 124I53 (N/Z = 1.33), 124Sn50 + 124Sn50 (N/Z = 1.48) and 124Ag47 + 124Ag47 (N/Z = 1.638). Our results show that the participant matter and anisotropic ratio decrease and the spectator matter and relative momentum increase with an increase in N/Z of the system. (paper)

82

Asymmetric Dark Matter and Effective Operators

In order to annihilate in the early Universe to levels well below the measured dark matter density, asymmetric dark matter must possess large couplings to the Standard Model. In this paper, we consider effective operators which allow asymmetric dark matter to annihilate into quarks. In addition to a bound from requiring sufficient annihilation, the energy scale of such operators can be constrained by limits from direct detection and monojet searches at colliders. We show tha...

Buckley, Matthew R.

2011-01-01

83

Relic abundance of asymmetric Dark Matter

Energy Technology Data Exchange (ETDEWEB)

We investigate the relic abundance of asymmetric Dark Matter particles that were in thermal equilibrium in the early universe. The standard analytic calculation of the symmetric Dark Matter is generalized to the asymmetric case. We calculate the asymmetry required to explain the observed Dark Matter relic abundance as a function of the annihilation cross section. We show that introducing an asymmetry always reduces the indirect detection signal from WIMP annihilation, although it has a larger annihilation cross section than symmetric Dark Matter. This opens new possibilities for the construction of realistic models of MeV Dark Matter.

Iminniyaz, Hoernisa [School of Physics Science and Technology, Xinjiang University, Urumqi 830046 (China); Drees, Manuel [Bethe Center for Theoretical Physics and Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn (Germany); Chen, Xuelei, E-mail: wrns@xju.edu.cn, E-mail: drees@th.physik.uni-bonn.de, E-mail: xuelei@cosmology.bao.ac.cn [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2011-07-01

84

We report on $J/\\psi$ production from asymmetric Cu+Au heavy-ion collisions at $\\sqrt{s_{_{NN}}}$=200 GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of $J/\\psi$ yields in Cu$+$Au collisions in the Au-going direction is found to be comparable to that in Au$+$Au collisions when plotted as a function of the number of participating nucleons. In the Cu-going direction, $J/\\psi$ production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due to stronger low-$x$ gluon suppression in the larger Au nucleus. The relative suppression is opposite to that expected from hot nuclear matter dissociation, since a higher energy density is expected in the Au-going direction.

Aidala, C; Akiba, Y; Akimoto, R; Alexander, J; Aoki, K; Apadula, N; Asano, H; Atomssa, E T; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Bai, X; Bannier, B; Barish, K N; Bathe, S; Baublis, V; Baumann, C; Baumgart, S; Bazilevsky, A; Beaumier, M; Belmont, R; Berdnikov, A; Berdnikov, Y; Bing, X; Black, D; Blau, D S; Bok, J; Boyle, K; Brooks, M L; Bryslawskyj, J; Buesching, H; Bumazhnov, V; Butsyk, S; Campbell, S; Chen, C -H; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choi, S; Christiansen, P; Chujo, T; Cianciolo, V; Cole, B A; Cronin, N; Crossette, N; Csanád, M; Csörg?, T; Datta, A; Daugherity, M S; David, G; Dehmelt, K; Denisov, A; Deshpande, A; Desmond, E J; Ding, L; Do, J H; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; D'Orazio, L; Engelmore, T; Enokizono, A; Esumi, S; Eyser, K O; Fadem, B; Fields, D E; Finger, M; Finger,, M; Fleuret, F; Fokin, S L; Frantz, J E; Franz, A; Frawley, A D; Fukao, Y; Gainey, K; Gal, C; Garg, P; Garishvili, A; Garishvili, I; Giordano, F; Glenn, A; Gong, X; Gonin, M; Goto, Y; de Cassagnac, R Granier; Grau, N; Greene, S V; Perdekamp, M Grosse; Gu, Y; Gunji, T; Guragain, H; Haggerty, J S; Hahn, K I; Hamagaki, H; Hanks, J; Hashimoto, K; Hayano, R; He, X; Hemmick, T K; Hester, T; Hill, J C; Hollis, R S; Homma, K; Hong, B; Hoshino, T; Huang, J; Huang, S; Ichihara, T; Ikeda, Y; Imai, K; Imazu, Y; Inaba, M; Iordanova, A; Isenhower, D; Isinhue, A; Ivanishchev, D; Jacak, B V; Jeon, S J; Jezghani, M; Jia, J; Jiang, X; Johnson, B M; Joo, K S; Jouan, D; Jumper, D S; Kamin, J; Kanda, S; Kang, B H; Kang, J H; Kang, J S; Kapustinsky, J; Kawall, D; Kazantsev, A V; Key, J A; Khachatryan, V; Khandai, P K; Khanzadeev, A; Kijima, K M; Kim, C; Kim, D J; Kim, E -J; Kim, Y -J; Kim, Y K; Kistenev, E; Klatsky, J; Kleinjan, D; Kline, P; Koblesky, T; Kofarago, M; Komkov, B; Koster, J; Kotchetkov, D; Kotov, D; Krizek, F; Kurita, K; Kurosawa, M; Kwon, Y; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, G H; Lee, J; Lee, K B; Lee, K S; Lee, S H; Leitch, M J; Leitgab, M; Lewis, B; Li, X; Lim, S H; Liu, M X; Lynch, D; Maguire, C F; Makdisi, Y I; Makek, M; Manion, A; Manko, V I; Mannel, E; Maruyama, T; McCumber, M; McGaughey, P L; McGlinchey, D; McKinney, C; Meles, A; Mendoza, M; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Milov, A; Mishra, D K; Mitchell, J T; Miyasaka, S; Mizuno, S; Mohanty, A K; Morrison, D P; Moskowitz, M; Moukhanova, T V; Murakami, T; Murata, J; Nagae, T; Nagamiya, S; Nagle, J L; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nattrass, C; Netrakanti, P K; Nihashi, M; Niida, T; Nouicer, R; Novak, T; Novitzky, N; Nyanin, A S; O'Brien, E; Ogilvie, C A; Oide, H; Okada, K; Oskarsson, A; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, I H; Park, S; Park, S K; Pate, S F; Patel, L; Peng, J -C; Perepelitsa, D; Perera, G D N; Peressounko, D Yu; Perry, J; Petti, R; Pinkenburg, C; Pisani, R P; Purschke, M L; Qu, H; Rak, J; Ravinovich, I; Read, K F; Reynolds, D; Riabov, V; Riabov, Y; Richardson, E; Riveli, N; Roach, D; Rolnick, S D; Rosati, M; Ryu, M S; Sahlmueller, B; Saito, N; Sakaguchi, T; Sako, H; Samsonov, V; Sarsour, M; Sato, S; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Sekiguchi, Y; Sen, A; Seto, R; Sett, P; Sharma, D; Shaver, A; Shein, I; Shibata, T -A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Singh, B K; Singh, C P; Singh, V; Skolnik, M; Slune?ka, M; Solano, S; Soltz, R A; Sondheim, W E; Sorensen, S P; Soumya, M; Sourikova, I V; Stankus, P W; Steinberg, P; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Stone, M R; Sugitate, T; Sukhanov, A; Sun, J; Takahara, A; Taketani, A; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tennant, E; Timilsina, A; Todoroki, T; Tomášek, M; Torii, H; Towell, R S; Tserruya, I; van Hecke, H W; Vargyas, M; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Virius, M; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Watanabe, Y S; Wei, F; Whitaker, S; Wolin, S; Woody, C L; Wysocki, M; Yamaguchi, Y L; Yanovich, A; Yokkaichi, S; Yoon, I; You, Z; Younus, I; Yushmanov, I E; Zajc, W A; Zelenski, A; Zhou, S

2014-01-01

85

International Nuclear Information System (INIS)

We investigate the effects of charge independence and charge symmetry breaking in neutron-rich matter. We consider neutron and proton properties in isospin-asymmetric matter at normal densities as well as the high-density neutron matter equation of state and the bulk properties of neutron stars. We find charge symmetry and charge independence breaking effects to be very small. (orig.)

86

We investigate the effects of charge independence and charge symmetry breaking in neutron-rich matter. We consider neutron and proton properties in isospin-asymmetric matter at normal densities as well as the high-density neutron matter equation of state and the bulk properties of neutron stars. We find charge symmetry and charge independence breaking effects to be very small.

Sammarruca, F.; White, L.; Chen, B.

2012-01-01

87

$J/\\psi$ and $\\eta_{c}$ masses in isospin asymmetric hot nuclear matter - a QCD sum rule approach

We study the in-medium masses of the charmonium states $J/\\psi$ and $\\eta_{c}$ in the nuclear medium using QCD sum rule approach. These mass modifications arise due to modifications of the gluon condensates in the hot hadronic matter, which in the present investigation are obtained from the medium modification of a scalar dilaton field within a chiral SU(3) model. The dilaton field is introduced in the effective hadronic model to incorporate the trace anomaly of QCD. The effects of isospin asymmetry, density and temperature of the nuclear medium on the in-medium masses of the lowest charmonium states $J/\\psi$ and $\\eta_{c}$ mesons are investigated in the present work. The results of the present investigation are compared with the existing results on the masses of these states. The medium modifications of the masses of these charmonium states ($J/\\psi$ and $\\eta_c$) seem to be appreciable at high densities and should modify the experimental observables arising from the compressed baryonic matter produced in as...

Kumar, Arvind

2010-01-01

88

Isospin violating dark matter being asymmetric

The isospin violating dark matter (IVDM) scenario offers an interesting possibility to reconcile conflicting results among direct dark matter search experiments for a mass range around 10 GeV. We consider two simple renormalizable IVDM models with a complex scalar dark matter and a Dirac fermion dark matter, respectively, whose stability is ensured by the conservation of "dark matter number". Although both models successfully work as the IVDM scenario with destructive interference between effective couplings to proton and neutron, the dark matter annihilation cross section is found to exceed the cosmological/astrophysical upper bounds. Then, we propose a simple scenario to reconcile the IVDM scenario with the cosmological/astrophysical bounds, namely, the IVDM being asymmetric. Assuming a suitable amount of dark matter asymmetry has been generated in the early Universe, the annihilation cross section beyond the cosmological/astrophysical upper bound nicely works to dramatically reduce the anti-dark matter rel...

Okada, Nobuchika

2013-01-01

89

Solar constraints on asymmetric dark matter

The dark matter content of the Universe is likely to be a mixture of matter and antimatter, perhaps comparable to the measured asymmetric mixture of baryons and antibaryons. During the early stages of the Universe, the dark matter particles are produced in a process similar to baryogenesis, and dark matter freeze-out depends on the dark matter asymmetry and the annihilation cross section (s-wave and p-wave annihilation channels). In these \\eta-parametrised asymmetric dark matter models (\\eta-ADM), the dark matter particles have an annihilation cross section close to the weak interaction cross section, and a value of \\eta-dark matter asymmetry close to the baryon asymmetry \\eta_B. Furthermore, we assume that dark matter scattering of baryons, namely, the spin-independent scattering cross section, is of the same order as the range of values suggested by several theoretical particle physics models used to explain the current unexplained events reported in the DAMA/LIBRA, CoGeNT and CRESST experiments. Here, we c...

Lopes, Ilidio; 10.1088/0004-637X/757/2/130

2012-01-01

90

Asymmetric Inert Scalar Dark Matter

In the quite minimal inert scalar doublet dark matter framework, we analyze what would be the effect of a $B-L$ asymmetry that could have been produced in the Universe thermal bath at high temperature. We show that, unless the "$\\lambda_5$" scalar interaction is tiny, this asymmetry is automatically reprocessed in part into a DM asymmetry that can easily dominate the DM relic density today. This scenario requires the inert DM mass scale to lie in the few-TeV range. Two types of relic density suppressions render this scenario viable: thermalization, from the same "$\\lambda_5$" interaction, of the asymmetries at temperature below the dark matter particle threshold, and DM particle-antiparticle oscillations.

Dhen, Mikael

2015-01-01

91

Asymmetric Dark Matter: Theories, signatures, and constraints

International Nuclear Information System (INIS)

We review theories of Asymmetric Dark Matter (ADM), their cosmological implications and detection. While there are many models of ADM in the literature, our review of existing models will center on highlighting the few common features and important mechanisms for generation and transfer of the matter–anti-matter asymmetry between dark and visible sectors. We also survey ADM hidden sectors, the calculation of the relic abundance for ADM, and how the DM asymmetry may be erased at late times through oscillations. We consider cosmological constraints on ADM from the cosmic microwave background, neutron stars, the Sun, and brown and white dwarves. Lastly, we review indirect and direct detection methods for ADM, collider signatures, and constraints

92

Excluding Light Asymmetric Bosonic Dark Matter

International Nuclear Information System (INIS)

We argue that current neutron star observations exclude asymmetric bosonic noninteracting dark matter in the range from 2 keV to 16 GeV, including the 5-15 GeV range favored by DAMA and CoGeNT. If bosonic weakly interacting massive particles (WIMPs) are composite of fermions, the same limits apply provided the compositeness scale is higher than ?1012 GeV (for WIMP mass ?1 GeV). In the case of repulsive self-interactions, we exclude the large range of WIMP masses and interaction cross sections which complements the constraints imposed by observations of the Bullet Cluster.

93

Warm asymmetric matter in the Quark Meson Coupling Model

In this work we study the warm equation of state of asymmetric nuclear matter in the quark meson coupling model which incorporates explicitly quark degrees of freedom, with quarks coupled to scalar, vector and isovector mesons. Mechanical and chemical instabilities are discussed as a function of density and isospin asymmetry. The binodal section, essential in the study of the liquid-gas phase transition is also constructed and discussed. The main results for the equation of state are compared with two common parametrizations used in the non-linear Walecka model and the differences are outlined.

Panda, P K; Peres-Menezes, D; Providência, C

2003-01-01

94

Asymmetric Dark Matter and Dark Radiation

International Nuclear Information System (INIS)

Asymmetric Dark Matter (ADM) models invoke a particle-antiparticle asymmetry, similar to the one observed in the Baryon sector, to account for the Dark Matter (DM) abundance. Both asymmetries are usually generated by the same mechanism and generally related, thus predicting DM masses around 5 GeV in order to obtain the correct density. The main challenge for successful models is to ensure efficient annihilation of the thermally produced symmetric component of such a light DM candidate without violating constraints from collider or direct searches. A common way to overcome this involves a light mediator, into which DM can efficiently annihilate and which subsequently decays into Standard Model particles. Here we explore the scenario where the light mediator decays instead into lighter degrees of freedom in the dark sector that act as radiation in the early Universe. While this assumption makes indirect DM searches challenging, it leads to signals of extra radiation at BBN and CMB. Under certain conditions, precise measurements of the number of relativistic species, such as those expected from the Planck satellite, can provide information on the structure of the dark sector. We also discuss the constraints of the interactions between DM and Dark Radiation from their imprint in the matter power spectrum

95

Exotic States of Nuclear Matter

pt. A. Theory of nuclear matter EOS and symmetry energy. Constraining the nuclear equation of state from astrophysics and heavy ion reactions / C. Fuchs. In-medium hadronic interactions and the nuclear equation of state / F. Sammarruca. EOS and single-particle properties of isospin-asymmetric nuclear matter within the Brueckner theory / W. Zuo, U. Lombardo & H.-J. Schulze. Thermodynamics of correlated nuclear matter / A. Polls ... [et al.]. The validity of the LOCV formalism and neutron star properties / H. R. Moshfegh ... [et al.]. Ferromagnetic instabilities of neutron matter: microscopic versus phenomenological approaches / I. Vidaã. Sigma meson and nuclear matter saturation / A. B. Santra & U. Lombardo. Ramifications of the nuclear symmetry energy for neutron stars, nuclei and heavy-ion collisions / A. W. Steiner, B.-A. Li & M. Prakash. The symmetry energy in nuclei and nuclear matter / A. E. L. Dieperink. Probing the symmetry energy at supra-saturation densities / M. Di Toro et al. Investigation of low-density symmetry energy via nucleon and fragment observables / H. H. Wolter et al. Instability against cluster formation in nuclear and compact-star matter / C. Ducoin ... [et al.]. Microscopic optical potentials of nucleon-nucleus and nucleus-nucleus scattering / Z.-Y. Ma, J. Rong & Y.-Q. Ma -- pt. B. The neutron star crust: structure, formation and dynamics. Neutron star crust beyond the Wigner-Seitz approximation / N. Chamel. The inner crust of a neutron star within the Wigner-Seitz method with pairing: from drip point to the bottom / E. E. Saperstein, M. Baldo & S. V. Tolokonnikov. Nuclear superfluidity and thermal properties of neutron stars / N. Sandulescu. Collective excitations: from exotic nuclei to the crust of neutron stars / E. Khan, M. Grasso & J. Margueron. Monte Carlo simulation of the nuclear medium: fermi gases, nuclei and the role of Pauli potentials / M. A. Pérez-García. Low-density instabilities in relativistic hadronic models / C. Providência et al. Quartetting in nuclear matter and [symbol] particle condensation in nuclear systems / G. Röpke & P. Schuck et al. -- pt. C. Neutron star structure and dynamics. Shear viscosity of neutron matter from realistic nuclear interactions / O. Benhar & M. Valli. Protoneutron star dynamo: theory and observations / A. Bonanno & V. Urpin. Magnetic field dissipation in neutron stars: from magnetars to isolated neutron stars / J. A. Pons. Gravitational radiation and equations of state in super-dense cores of core-collapse supernovae / K. Kotake. Joule heating in the cooling of magnetized neutron stars / D. N. Aguilera, J. A. Pons & J. A. Miralles. Exotic fermi surface of dense neutron matter / M. V. Zverev, V. A. Khodel & J. W. Clark. Coupling of nuclear and electron modes in relativistic stellar matter / A. M. S. Santos et al. Neutron stars in the relativistic Hartree-Fock theory and hadron-quark phase transition / B. Y. Sun ... [et al.] -- pt. D. Prospects of present and future observations. Measurements of neutron star masses / D. G. Yakovlev. Dense nuclear matter: constraints from neutron stars / J. M. Lattimer. Neutron star versus heavy-ion data: is the nuclear equation of state hard or soft? / J. Schaffner-Bielich ... [et al.]. Surface emission from x-ray dim isolated neutron stars / R. Turolla. High energy neutrino astronomy / E. Migneco. What gravitational waves say about the inner structure of neutron stars / V. Ferrari. Reconciling 2 M[symbol] pulsars and SN1987A: two branches of neutron stars / P. Haensel, M. Bejger & J. L. Zdunik. EOS of dense matter and fast rotation of neutron stars / J. L. Zdunik ... [et al.] -- pt. E. Quark and strange matter in neutron stars. Bulk viscosity of color-superconducting quark matter / M. Alford. Chiral symmetry restoration and quark deconfinement at large densities and temperature / A. Drago, L. Bonanno & A. Lavagno. Color superconducting quark matter in compact stars / D. B. Blaschke, T. Klähn & F. Sandin. Thermal hadronization, Hawking-Unruh radiation and e

Lombardo, Umberto; Baldo, Marcello; Burgio, Fiorella; Schulze, Hans-Josef

2008-02-01

96

Annihilation Signals from Asymmetric Dark Matter

In the simplest models of asymmetric dark matter (ADM) annihilation signals are not expected, since the DM is non-self-conjugate and the relic density of anti-DM is negligible. We investigate a new class of models in which a symmetric DM component, in the `low-mass' 1-10 GeV regime favoured for linking the DM and baryon asymmetries, is repopulated through decays. We find that, in models without significant velocity dependence of the annihilation cross section, observational constraints generally force these decays to be (cosmologically) slow. These late decays can give rise to gamma-ray signal morphologies differing from usual annihilation profiles. A distinctive feature of such models is that signals may be absent from dwarf spheroidal galaxies.

Hardy, Edward; Unwin, James

2014-01-01

97

Annihilation signals from asymmetric dark matter

In the simplest models of asymmetric dark matter (ADM) annihilation signals are not expected, since the DM is non-self-conjugate and the relic density of anti-DM is negligible. We investigate a new class of models in which a symmetric DM component, in the `low-mass' 1-10 GeV regime favoured for linking the DM and baryon asymmetries, is repopulated through decays. We find that, in models without significant velocity dependence of the annihilation cross section, observational constraints generally force these decays to be (cosmologically) slow. These late decays can give rise to gamma-ray signal morphologies differing from usual annihilation profiles. A distinctive feature of such models is that signals may be absent from dwarf spheroidal galaxies.

Hardy, Edward; Lasenby, Robert; Unwin, James

2014-07-01

98

Variational approach to nuclear matter

International Nuclear Information System (INIS)

We calculated the energies of asymmetric nuclear matter at zero and finite temperatures with the cluster variational method. At zero temperature, the expectation value of the two-body Hamiltonian composed of the kinetic energies and the AV18 two-body forces is calculated with the Jastrow wave function in the two-body cluster approximation. The obtained two-body energy is in good agreement with the result with the Fermi Hypernetted Chain (FHNC) calculation by Akmal et al. The energy caused by the UIX three-body forces is treated somewhat phenomenologically so that the total energy reproduces the empirical saturation point. Furthermore, the parameters included in the three-body energy are readjusted so that the Thomas-Fermi (TF) calculations with use of the obtained energy of nuclear matter reproduce the gross feature of the experimental data on atomic nuclei. The nuclear species in the neutron star crust obtained by the TF calculation are reasonable. The free energies of asymmetric nuclear matter at finite temperatures are calculated with an extension of the method proposed by Schmidt and Pandharipande. The obtained free energies are in good agreement with those with the FHNC method, and it is also found that the present variational method is self-consistent. It is remarkable that the symmetry free energy is not proportional to (1 - 2x)2, where x is the proton fraction. With use of the obtained thermodynamic quantities, we are constructing a new nuclear equaes, we are constructing a new nuclear equation of state for supernova simulations. (author)

99

Energy Technology Data Exchange (ETDEWEB)

We review the present statiis of the many-body theory of nuclear and pure neutron matter based on realistic models of nuclear forces, The current models of two- and three-nucleon interactions are discussed along with recent results obtained with the Brueckner and variatioual methods. New initiatives in the variational method and quantuni Monte Carlo nicthods to study pure neutron matter are described, and finally, the analytic behavior of the energy of piire neutron matter at low densities is cliscussed.

Carlson, J. A. (Joseph A.); Cowell, S.; Morales, J.; Ravenhall, D. G.; Pandharipande, V. R. (Vijay R.)

2002-01-01

100

Charge asymmetric cosmic rays as a probe of flavor violating asymmetric dark matter

International Nuclear Information System (INIS)

The recently introduced cosmic sum rules combine the data from PAMELA and Fermi-LAT cosmic ray experiments in a way that permits to neatly investigate whether the experimentally observed lepton excesses violate charge symmetry. One can in a simple way determine universal properties of the unknown component of the cosmic rays. Here we attribute a potential charge asymmetry to the dark sector. In particular we provide models of asymmetric dark matter able to produce charge asymmetric cosmic rays. We consider spin zero, spin one and spin one-half decaying dark matter candidates. We show that lepton flavor violation and asymmetric dark matter are both required to have a charge asymmetry in the cosmic ray lepton excesses. Therefore, an experimental evidence of charge asymmetry in the cosmic ray lepton excesses implies that dark matter is asymmetric

101

Charge Asymmetric Cosmic Rays as a probe of Flavor Violating Asymmetric Dark Matter

DEFF Research Database (Denmark)

The recently introduced cosmic sum rules combine the data from PAMELA and Fermi-LAT cosmic ray experiments in a way that permits to neatly investigate whether the experimentally observed lepton excesses violate charge symmetry. One can in a simple way determine universal properties of the unknown component of the cosmic rays. Here we attribute a potential charge asymmetry to the dark sector. In particular we provide models of asymmetric dark matter able to produce charge asymmetric cosmic rays. We consider spin zero, spin one and spin one-half decaying dark matter candidates. We show that lepton flavor violation and asymmetric dark matter are both required to have a charge asymmetry in the cosmic ray lepton excesses. Therefore, an experimental evidence of charge asymmetry in the cosmic ray lepton excesses implies that dark matter is asymmetric.

Masina, Isabella; Sannino, Francesco

2011-01-01

102

Isospin violating dark matter being asymmetric

The isospin violating dark matter (IVDM) scenario offers an interesting possibility to reconcile conflicting results among direct dark matter search experiments for a mass range around 10 GeV. We consider two simple renormalizable IVDM models with a complex scalar dark matter and a Dirac fermion dark matter, respectively, whose stability is ensured by the conservation of "dark matter number". Although both models successfully work as the IVDM scenario with destructive interf...

Okada, Nobuchika; Seto, Osamu

2013-01-01

103

The possibility for occurrence of a Bose condensate of dibaryons in nuclear matter is investigated within the framework of the Walecka model in the mean-field approximation. Constraints for the omega - and sigma - meson coupling constants with dibaryons following from the requirement of stability of dibaryon matter against compression are derived and the effect of sigma - and pi - meson exchange current contributions to the sigma - dibaryon coupling constant is discussed. Th...

Faessler, Amand; Buchmann, A. J.; Krivoruchenko, M. I.; Martemyanov, B. V.

1997-01-01

104

Multifragmentation of charge asymmetric nuclear systems

The multifragmentation of excited spherical nuclear sources with various N/Z ratios and fixed mass number is studied within dynamical and statistical models. The dynamical model treats the multifragmentation process as a final stage of the growth of density fluctuations in unstable expanding nuclear matter. The statistical model makes a choice of the final multifragment configuration according to its statistical weight at a global thermal equilibrium. Similarities and differ...

Larionov, A. B.; Botvina, A. S.; Colonna, M.; Di Toro, M.

1999-01-01

105

International Nuclear Information System (INIS)

Instead of discussing finite hypernuclei, we consider the theoretically simpler problem of a hyperon in nuclear matter. Most of the talk is devoted to the much better known case of the ? hyperon. The problem of a ? hyperon in NM is considered at the end. (orig./HSI)

106

We study the behavior of cold nuclear matter near saturation density (\\rho 0) and very low temperature using classical molecular dynamics. We used three different (classical) nuclear interaction models that yield `medium' or `stiff' compressibilities. For high densities and for every model the ground state is a classical crystalline solid, but each one with a different structure. At subsaturation densities, we found that for every model the transition from uniform (crystal) to non-uniform matter occurs at \\rho ~ 0.12 fm^(-3) = 0.75 \\rho 0. Surprisingly, at the non-uniform phase, the three models produce `pasta-like' structures as those allegedly present in neutron star matter but without the long-range Coulomb interaction and with different length scales.

Dorso, C O; Nichols, J I; López, J A

2012-01-01

107

Continuous flavor symmetries and the stability of asymmetric dark matter

Generically, the asymmetric interactions in asymmetric dark matter (ADM) models could lead to decaying DM. We show that, for ADM that carries nonzero baryon number, the continuous flavor symmetries that generate the flavor structure in the quark sector also imply a looser lower bound on the mass scale of the asymmetric mediators between the dark and visible sectors. The mediators for B = 2 ADM that can produce a signal in the future indirect dark matter searches can thus also be searched for at the LHC. For two examples of the mediator models, with either the MFV or Froggatt-Nielsen flavor breaking pattern, we derive the FCNC constraints and discuss the search strategies at the LHC.

Bishara, Fady; Zupan, Jure

2015-01-01

108

Continuous Flavor Symmetries and the Stability of Asymmetric Dark Matter

Generically, the asymmetric interactions in asymmetric dark matter (ADM) models lead to decaying DM. We show that, for ADM that carries nonzero baryon number, the continuous flavor symmetries that generate the flavor structure in the quark sector also imply a looser lower bound on the mass scale of the asymmetric mediators between the dark and visible sectors. The mediators for $B=2$ ADM that can produce a signal in the future indirect dark matter searches can thus also be searched for at the LHC. For two examples of the mediator models, with either the MFV or Froggatt-Nielsen flavor breaking pattern, we derive the FCNC constraints and discuss the search strategies at the LHC.

Bishara, Fady

2014-01-01

109

Asymmetric dark matter and the Sun

DEFF Research Database (Denmark)

Cold dark matter particles with an intrinsic matter-antimatter asymmetry do not annihilate after gravitational capture by the Sun and can affect its interior structure. The rate of capture is exponentially enhanced when such particles have self-interactions of the right order to explain structure formation on galactic scales. A `dark baryon' of mass 5 GeV is a natural candidate and has the required relic abundance if its asymmetry is similar to that of ordinary baryons. We show that such particles can solve the `solar composition problem'. The predicted small decrease in the low energy neutrino fluxes may be measurable by the Borexino and SNO+ experiments.

Frandsen, Mads Toudal; Sarkar, Subir

2010-01-01

110

Gamma ray constraints on flavor violating asymmetric dark matter

International Nuclear Information System (INIS)

We show how cosmic gamma rays can be used to constrain models of asymmetric Dark Matter decaying into lepton pairs by violating flavor. First of all we require the models to explain the anomalies in the charged cosmic rays measured by PAMELA, Fermi and HESS performing combined fits we determine the allowed values of the Dark Matter mass and lifetime. For these models, we then determine the constraints coming from the measurement of the isotropic ?-ray background by Fermi for a complete set of lepton flavor violating primary modes and over a range of DM masses from 100 GeV to 10 TeV. We find that the Fermi constraints rule out the flavor violating asymmetric Dark Matter interpretation of the charged cosmic ray anomalies

111

Gamma ray constraints on flavor violating asymmetric dark matter

DEFF Research Database (Denmark)

We show how cosmic gamma rays can be used to constrain models of asymmetric Dark Matter decaying into lepton pairs by violating flavor. First of all we require the models to explain the anomalies in the charged cosmic rays measured by PAMELA, Fermi and H.E.S.S.; performing combined fits we determine the allowed values of the Dark Matter mass and lifetime. For these models, we then determine the constraints coming from the measurement of the isotropic gamma-ray background by Fermi for a complete set of lepton flavor violating primary modes and over a range of DM masses from 100 GeV to 10 TeV. We find that the Fermi constraints rule out the flavor violating asymmetric Dark Matter interpretation of the charged cosmic ray anomalies.

Masina, I.; Panci, P.

2012-01-01

112

Seismic signals from asymmetric underground nuclear explosions

Energy Technology Data Exchange (ETDEWEB)

The methods discussed to estimate the effect on the seismic signals from asymmetric underground nuclear explosions, depends on the use of large-scale numerical codes and high-speed computers. The use of a two-dimensional (2D) radiation diffusion coupled Eulerian hydrodynamic code (SOIL) for the early time phenomenology is discussed. The results from this calculation are then coupled into a 2D Lagrangian code that treats the strength of the materials and the effects of fractures, ground reflections and spells. The final step in the simulation is the use of a seismic code (which uses the representation theory) to develop the actual far field seismic signals. These calculations were run on the CRAY YMP computers at the Los Alamos National Laboratory.

Davis, C.G.

1993-09-01

113

Correlations in Nuclear Matter

We analyze the nuclear matter correlation properties in terms of the pair correlation function. To this aim we systematically compare the results for the variational method in the Lowest Order Constrained Variational (LOCV) approximation and for the Bruekner-Hartree-Fock (BHF) scheme. A formal link between the Jastrow correlation factor of LOCV and the Defect Function (DF) of BHF is established and it is shown under which conditions and approximations the two approaches are equivalent. From the numerical comparison it turns out that the two correlation functions are quite close, which indicates in particular that the DF is approximately local and momentum independent. The Equations of State (EOS) of Nuclear Matter in the two approaches are also compared. It is found that once the three-body forces (TBF) are introduced the two EOS are fairly close, while the agreement between the correlation functions holds with or without TBF.

Baldo, M

2012-01-01

114

D mesons in isospin asymmetric strange hadronic matter

We study the in-medium properties of $D$ and $\\bar{D}$ mesons in isospin asymmetric hyperonic matter arising due to their interactions with the light hadrons. The interactions of $D$ and $\\bar{D}$ mesons with these light hadrons are derived by generalizing the chiral SU(3) model used for the study of hyperonic matter to SU(4). The nucleons, the scalar isoscalar meson, $\\sigma$ and the scalar-isovector meson, $\\delta$ as modified in the strange hadronic matter, modify the mas...

Kumar, Arvind; Mishra, Amruta

2010-01-01

115

Correlations in Nuclear Matter

We analyze the nuclear matter correlation properties in terms of the pair correlation function. To this aim we systematically compare the results for the variational method in the Lowest Order Constrained Variational (LOCV) approximation and for the Bruekner-Hartree-Fock (BHF) scheme. A formal link between the Jastrow correlation factor of LOCV and the Defect Function (DF) of BHF is established and it is shown under which conditions and approximations the two approaches are ...

Baldo, M.; Moshfegh, H. R.

2012-01-01

116

Nucleon properties in nuclear matter

We present recent studies on the effective mass of the nucleon in infinite and homogeneous nuclear matter and its relation to nuclear matter properties within the framework of the in-medium modified Skyrme model. Medium modifications are achieved by introducing optical potential for pion fields and parametrization of the Skyrme parameter in nuclear medium. The present approach is phenomenologically well justified by pion physics in nuclear matter and describe successfully bu...

Yakhshiev, Ulugbek; Kim, Hyun-chul

2011-01-01

117

Charge Asymmetric Cosmic Rays as a probe of Flavor Violating Asymmetric Dark Matter

The recently introduced cosmic sum rules combine the data from PAMELA and Fermi-LAT cosmic ray experiments in a way that permits to neatly investigate whether the experimentally observed lepton excesses violate charge symmetry. One can in a simple way determine universal properties of the unknown component of the cosmic rays. Here we attribute a potential charge asymmetry to the dark sector. In particular we provide models of asymmetric dark matter able to produce charge asy...

Masina, Isabella; Sannino, Francesco

2011-01-01

118

Asymmetric dark matter via spontaneous co-genesis

International Nuclear Information System (INIS)

We investigate, in the context of asymmetric dark matter (DM), a new mechanism of spontaneous co-genesis of linked DM and baryon asymmetries, explaining the observed relation between the baryon and DM densities, ?DM?/?B ? 5. The co-genesis mechanism requires a light scalar field, ?, with mass below 5 eV which couples derivatively to DM, much like a 'dark axion'. The field ? can itself provide a final state into which the residual symmetric DM component can annihilate away

119

Constraining Asymmetric Dark Matter through observations of compact stars

DEFF Research Database (Denmark)

We put constraints on asymmetric dark matter candidates with spin-dependent interactions based on the simple existence of white dwarfs and neutron stars in globular clusters. For a wide range of the parameters (WIMP mass and WIMP-nucleon cross section), WIMPs can be trapped in progenitors in large numbers and once the original star collapses to a white dwarf or a neutron star, these WIMPs might self-gravitate and eventually collapse forming a mini-black hole that eventually destroys the star. We impose constraints competitive to direct dark matter search experiments, for WIMPs with masses down to the TeV scale.

Kouvaris, Christoforos; Tinyakov, Peter

2011-01-01

120

Nuclear Matter Equation of State and Three body Forces

The energy per particle, symmetry energy, pressure, Free energy are calculated for asymmetric nuclear matter using BHF approach and modern nucleon-nucleon CD-Bonn, Nijm1, Argonnev18 and Reid93 potentials. To obtain saturation in nuclear matter we add three-body interaction terms which are equivalent a la Skyrme to a density-dependent two-nucleon interaction. Good agreement is obtained in comparison with previous theoretical estimates and experimental data.

Mansour, Hesham M. M.; Gamoudi, Abdelsalam

2011-01-01

121

Spectral properties of nuclear matter

We review self-consistent spectral methods for nuclear matter calculations. The in-medium T-matrix approach is conserving and thermodynamically consistent. It gives both the global and the single-particle properties the system. The T-matrix approximation allows to address the pairing phenomenon in cold nuclear matter. A generalization of nuclear matter calculations to the superfluid phase is discussed and numerical results are presented for this case. The linear response of ...

Bozek, P.

2005-01-01

122

Matter induced charge symmetry breaking and pion form factor in nuclear medium

Medium modification of pion form factor has been evaluated in asymmetric nuclear matter. It is shown that both the shape and the pole position of the pion form factor in dense asymmetric nuclear matter is different from its vacuum counterpart with $\\rho$-$\\omega$ mixing. This is due to the density and asymmetry dependent $\\rho$-$\\omega$ mixing which could even dominate over its vacuum counterpart in matter. Effect of the in-medium pion factor on experimental observables {\\it...

Roy, Pradip; Dutt-mazumder, Abhee K.; Sarkar, Sourav; Alam, Jan-e

2006-01-01

123

A Model of Asymmetric Hadronic Dark Matter and Leptogenesis

The paper suggests a model to account for the common origins of the asymmetric dark matter (ADM) and matter-antimatter asymmetry. The ADM nature is a stable hadronic particle consisting of a heavy color scalar and a light $u$ quark, which is formed after the QCD phase transition. At the early stage the ADM are in thermal equilibrium through collisions with the nucleons, moreover, they can emit the $\\gamma$ photons with $0.32$ MeV energy. However they are decoupling and become the dark matter at the temperature about $130$ MeV. The mass upper limit of the ADM is predicted as $M_{D}<1207$ GeV. It is feasible and promising to test the model in future experiments.

Yang, Wei-Min

2015-01-01

124

Possible implications of asymmetric fermionic dark matter for neutron stars

International Nuclear Information System (INIS)

We consider the implications of fermionic asymmetric dark matter (ADM) for a “mixed neutron star” composed of ordinary baryons and dark fermions. We find examples, where for a certain range of dark fermion mass – when it is less than that of ordinary baryons – such systems can reach higher masses than the maximal values allowed for ordinary (“pure”) neutron stars. This is shown both within a simplified, heuristic Newtonian analytic framework with non-interacting particles and via a general relativistic numerical calculation, under certain assumptions for the dark matter equation of state. Our work applies to various dark fermion models such as mirror matter models and to other models where the dark fermions have self-interactions

125

Functional renormalization group study of nuclear and neutron matter

A chiral model based on nucleons interacting via boson exchange is investigated. Fluctuation effects are included consistently beyond the mean-field approximation in the framework of the functional renormalization group. The liquid-gas phase transition of symmetric nuclear matter is studied in detail. No sign of a chiral restoration transition is found up to temperatures of about 100 MeV and densities of at least three times the density of normal nuclear matter. Moreover, the model is extended to asymmetric nuclear matter and the constraints from neutron star observations are discussed.

Drews, Matthias

2014-01-01

126

Propagation of neutrinos in nuclear matter

International Nuclear Information System (INIS)

We study the elementary interactions between neutrinos and dense matter in a proto-neutron star. Equations of state obtained with different nuclear effective interactions (Skyrme, Gogny, Relativistic Lagrangians) are first discussed. Then, we characterize their stability in spin and isospin. We derive magnetic susceptibilities for all isospin asymmetry values as a function of Landau parameters G??'0 (where ?, ?' = proton or neutron). From this work, we select a parametrization for each of the 3 effective forces: Sly230b,D1P,NL3. We calculate the pure neutron matter and asymmetric nuclear matter response functions with and without charge exchange, describing nuclear correlations in both approaches: non-relativistic (Hartree-Fock with Skyrme forces, then complete RPA) and relativistic (in the Hartree approximation). At the end, we calculate neutrino mean free paths neutral current and charged current reactions. Comparisons between relativistic and non-relativistic approaches allow us to identify relativistic effects in nuclear matter at densities as low as twice the saturation density. RPA correlations make the medium more transparent to neutrinos compared to free Fermi gas. The importance of the effective mass in mean free path calculations is also shown. (author)

127

Covariant density functional theory for nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The present thesis is organized as follows. In Chapter 2 we study the Nucleon-Nucleon (NN) interaction in Dirac-Brueckner (DB) approach. We start by considering the NN interaction in free-space in terms of the Bethe-Salpeter (BS) equation to the meson exchange potential model. Then we present the DB approach for nuclear matter by extending the BS equation for the in-medium NN interaction. From the solution of the three-dimensional in-medium BS equation, we derive the DB self-energies and total binding energy which are the main results of the DB approach, which we later incorporate in the field theoretical calculation of the nuclear equation of state. In Chapter 3, we introduce the basic concepts of density functional theory in the context of Quantum Hadrodynamics (QHD-I). We reach the main point of this work in Chapter 4 where we introduce the DDRH approach. In the DDRH theory, the medium dependence of the meson-nucleon vertices is expressed as functionals of the baryon field operators. Because of the complexities of the operator-valued functionals we decide to use the mean-field approximation. In Chapter 5, we contrast microscopic and phenomenological approaches to extracting density dependent meson-baryon vertices. Chapter 6 gives the results of our studies of the EOS of infinite nuclear matter in detail. Using formulas derived in Chapters 4 and 5 we calculate the properties of symmetric and asymmetric nuclear matter and pure neutron matter. (orig.)

Badarch, U.

2007-07-01

128

The possibility for the occurrence of a Bose condensate of dibaryons in nuclear matter is investigated within the framework of the Walecka model in the mean-field approximation. The effect of 0954-3899/24/4/011/img8- and 0954-3899/24/4/011/img9-meson exchange current contributions on the 0954-3899/24/4/011/img8-dibaryon coupling constant is discussed. The mean-field solutions of the model are constructed. The effective nucleon mass 0954-3899/24/4/011/img11 vanishes when the density of dibaryons approaches a critical value 0954-3899/24/4/011/img12. The Green functions of the equilibrium binary mixture of nucleons and dibaryons are constructed by solving the Gorkov-Dyson system of equations in the no-loop approximation. We find that when the square of the sound velocity is positive, the dispersion laws for all elementary excitations of the system are real functions.

Faessler, Amand; Buchmann, A. J.; Krivoruchenko, M. I.; Martemyanov, B. V.

1998-04-01

129

International Nuclear Information System (INIS)

The possibility for the occurrence of a Bose condensate of dibaryons in nuclear matter is investigated within the framework of the Walecka model in the mean-field approximation. The effect of ?- and ?-meson exchange current contributions on the ?-dibaryon coupling constant is discussed. The mean-field solutions of the model are constructed. The effective nucleon mass mN* vanishes when the density of dibaryons approaches a critical value ?DVc,max approx.= 0.15 fm-3. The Green functions of the equilibrium binary mixture of nucleons and dibaryons are constructed by solving the Gorkov-Dyson system of equations in the no-loop approximation. We find that when the square of the sound velocity is positive, the dispersion laws for all elementary excitations of the system are real functions. (author)

130

Energy Technology Data Exchange (ETDEWEB)

The possibility for the occurrence of a Bose condensate of dibaryons in nuclear matter is investigated within the framework of the Walecka model in the mean-field approximation. The effect of {sigma}- and {pi}-meson exchange current contributions on the {sigma}-dibaryon coupling constant is discussed. The mean-field solutions of the model are constructed. The effective nucleon mass m{sub N}* vanishes when the density of dibaryons approaches a critical value {rho}{sub DV}{sup c,max} approx.= 0.15 fm{sup -3}. The Green functions of the equilibrium binary mixture of nucleons and dibaryons are constructed by solving the Gorkov-Dyson system of equations in the no-loop approximation. We find that when the square of the sound velocity is positive, the dispersion laws for all elementary excitations of the system are real functions. (author)

Faessler, Amand; Buchmann, A.J. [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany); Krivoruchenko, M.I. [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany); Institute for Theoretical and Experimental Physics, B Cheremushkinskaya 25, 117259 Moscow (Russian Federation); Martemyanov, B.V. [Institute for Theoretical and Experimental Physics, B Cheremushkinskaya 25, 117259 Moscow (Russian Federation)

1998-04-01

131

Nuclear matter and electron scattering

International Nuclear Information System (INIS)

We show that inclusive electron scattering at large momentum transfer allows a measurement of short-range properties of nuclear matter. This provides a very valuable constraint in selecting the calculations appropriate for predicting nuclear matter properties at the densities of astrophysical interest. (orig.)

132

The possibility for occurrence of a Bose condensate of dibaryons in nuclear matter is investigated within the framework of the Walecka model in the mean-field approximation. Constraints for the omega - and sigma - meson coupling constants with dibaryons following from the requirement of stability of dibaryon matter against compression are derived and the effect of sigma - and pi - meson exchange current contributions to the sigma - dibaryon coupling constant is discussed. The mean-field solutions of the model are constructed. The effective nucleon mass vanishes when the density of dibaryons approaches a critical value about 0.15/fm^3. The Green's functions of the equilibrium binary mixture of nucleons and dibaryons are constructed by solving the Gorkov-Dyson system of equations in the no-loop approximation. We find that when the square of the sound velocity is positive, the dispersion laws for all elementary excitations of the system are real functions. This indicates stability of the ground state of the hete...

Faessler, A; Krivoruchenko, M I; Martemyanov, B V; Faessler, Amand

1998-01-01

133

Pion correlations in nuclear matter

International Nuclear Information System (INIS)

The saturation properties of the nuclear matter taking pion correlations into account are studied. We construct a Bogoliubov transformation for the pion pair operators and calculate the energy associated with the pion pairs. The pion dispersion relation is investigated. The correlation energy due to one-pion exchange in nuclear matter and neutron matter at random phase approximation using the generator coordinate method is also studied. The techniques of the charged pion correlations are discussed in the neutron matter calculations. We observe that there is no sign of the pion condensation in this model. (author)

134

Monte Carlo approach to nuclei and nuclear matter

International Nuclear Information System (INIS)

We report on the most recent applications of the Auxiliary Field Diffusion Monte Carlo (AFDMC) method. The equation of state (EOS) for pure neutron matter in both normal and BCS phase and the superfluid gap in the low-density regime are computed, using a realistic Hamiltonian containing the Argonne AV8' plus Urbana IX three-nucleon interaction. Preliminary results for the EOS of isospin-asymmetric nuclear matter are also presented.

135

Discovering asymmetric dark matter with anti-neutrinos

International Nuclear Information System (INIS)

We discuss possible signatures of Asymmetric Dark Matter (ADM) through dark matter decays to neutrinos. We specifically focus on scenarios in which the Standard Model (SM) baryon asymmetry is transferred to the dark sector (DS) through higher dimensional operators in chemical equilibrium. In such cases, the dark matter (DM) carries lepton and/or baryon number, and we point out that for a wide range of quantum number assignments, by far the strongest constraints on dark matter decays come from decays to neutrinos through the ''neutrino portal'' operator HL. Together with the facts that ADM favors lighter DM masses ? a few GeV and that the decays would lead only to anti-neutrinos and no neutrinos (or vice versa), the detection of such decays at neutrino telescopes would provide compelling evidence for ADM. We discuss current and future bounds on models where the DM decays to neutrinos through operators of dimension ? 6. For dimension 6 operators, the scale suppressing the decay is bounded to be ?>1012–1013 GeV

136

Soliton formation in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The propagation of a density disturbance in nuclear fluid is considered for the case when the nuclear equation of state is derived from a Skyrme-type effective nucleon-nucleon potential. It is shown that the velocity-dependent terms of this potential are responsible for the possible formation of solitary waves in nuclear matter. These solitons are rarefaction waves and not compressional as previously suggested. Their amplitudes increase with increasing temperature, which makes them a possible mechanism for nuclear multifragmentation.

Abul-Magd, A.Y.; El-Taher, I.; Khaliel, F.M. (Department of Mathematics, Faculty of Science, Zagazig University, Zagazig (Egypt))

1992-01-01

137

Soliton formation in nuclear matter

International Nuclear Information System (INIS)

The propagation of a density disturbance in nuclear fluid is considered for the case when the nuclear equation of state is derived from a Skyrme-type effective nucleon-nucleon potential. It is shown that the velocity-dependent terms of this potential are responsible for the possible formation of solitary waves in nuclear matter. These solitons are rarefaction waves and not compressional as previously suggested. Their amplitudes increase with increasing temperature, which makes them a possible mechanism for nuclear multifragmentation

138

Shear viscosity of nuclear matter

In this talk I report my recent study on the shear viscosity of neutron-rich nuclear matter from a relaxation time approach. An isospin- and momentum-dependent interaction is used in the study. Effects of density, temperature, and isospin asymmetry of nuclear matter on its shear viscosity have been discussed. Similar to the symmetry energy, the symmetry shear viscosity is defined and its density and temperature dependence are studied.

Xu, Jun

2013-01-01

139

Deuteron distribution in nuclear matter

We analyze the properties of deuteron-like structures in infinite, correlated nuclear matter, described by a realistic hamiltonian containing the Urbana $v_{14}$ two-nucleon and the Urbana TNI many-body potentials. The distribution of neutron-proton pairs, carrying the deuteron quantum numbers, is obtained as a function of the total momentum by computing the overlap between the nuclear matter in its ground state and the deuteron wave functions in correlated basis functions t...

Benhar, O.; Fabrocini, A.; Fantoni, S.; Illarionov, A. Yu; Lykasov, G. I.

2001-01-01

140

Phase transitions in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The rather general circumstances under which a phase transition in hadronic matter at finite temperature to an abnormal phase in which baryon effective masses become small and in which copious baryon-antibaryon pairs appear is emphasized. A preview is also given of a soliton model of dense matter, in which at a density of about seven times nuclear density, matter ceases to be a color insulator and becomes increasingly color conducting. 22 references.

Glendenning, N.K.

1984-11-01

141

Bottomonium states in hot asymmetric strange hadronic matter

We calculate the in-medium masses of the bottomonium states [?(1S),?(2S),?(3S), and ? (4S)] in isospin asymmetric strange hadronic matter at finite temperatures. The medium modifications of the masses arise due to the interaction of these heavy quarkonium states with the gluon condensates of QCD. The gluon condensates in the hot hadronic matter are computed from the medium modification of a scalar dilaton field within a chiral SU(3) model, introduced in the hadronic model to incorporate the broken scale invariance of QCD. There is seen to be a drop in the masses of the bottomonium states and mass shifts are observed to be quite considerable at high densities for the excited states. The effects of density, isospin asymmetry, strangeness, as well as temperature of the medium on the masses of the ? states are investigated. The effects of the isospin asymmetry as well as strangeness fraction of the medium are seen to be appreciable at high densities and small temperatures. The density effects are the most dominant medium effects which should have observable consequences in the compressed baryonic matter (CBM) in the heavy ion collision experiments in the future facility at FAIR, GSI. The study of the ? states will, however, require access to energies higher than the energy regime planned at CBM experiment. The density effects on the bottomonium masses should also show up in the dilepton spectra at the Super Proton Synchrotron (SPS) energies, especially for the excited states for which the mass drop is observed to quite appreciable.

Mishra, Amruta; Pathak, Divakar

2014-08-01

142

Chiral thermodynamics of nuclear matter

International Nuclear Information System (INIS)

We present a calculation of the equation of state of nuclear matter in the frame of in-medium chiral perturbation theory. The calculations are performed up to three-loop order in the free energy density. The contributions to the free energy per particle originate from one- and two-pion exchange diagrams; the effects from two-pion exchange with ?-isobar excitation are also included, as well as three-body forces. The equation of state and the corresponding phase diagram, displaying the liquid-gas phase transition, is investigated for different proton-to-neutron ratios, from isospin-symmetric nuclear matter to the limiting case of pure neutron matter.

143

Asymmetric inelastic inert doublet dark matter from triplet scalar leptogenesis

International Nuclear Information System (INIS)

The nature of dark matter (DM) particles and the mechanism that provides their measured relic abundance are currently unknown. In this paper we investigate inert scalar and vector like fermion doublet DM candidates with a charge asymmetry in the dark sector, which is generated by the same mechanism that provides the baryon asymmetry, namely baryogenesis-via-leptogenesis induced by decays of scalar triplets. At the same time the model gives rise to neutrino masses in the ballpark of oscillation experiments via type II seesaw. We discuss possible sources of depletion of asymmetry in the DM and visible sectors and solve the relevant Boltzmann equations for quasi-equilibrium decay of triplet scalars. A Monte-Carlo-Markov-Chain analysis is performed for the whole parameter space. The survival of the asymmetry in the dark sector leads to inelastic scattering off nuclei. We then apply Bayesian statistic to infer the model parameters favoured by the current experimental data, in particular the DAMA annual modulation and XENON100 exclusion limit. The latter strongly disfavours asymmetric scalar doublet DM of mass O(TeV) as required by DM-DM-bar oscillations, while an asymmetric vector like fermion doublet DM with mass around 100 GeV is a good candidate for DAMA annual modulation yet satisfying the constraints from XENON100 data.

144

Anatomy of nuclear matter fundamentals

The bridge between finite and infinite nuclear system is analyzed for the fundamental quantities like binding energy, density, compressibility, giant monopole excitation energy and effective mass of both nuclear matter and finite nuclei systems. It is shown quantitatively that by knowing one of the fundamental property of one system one can estimate the same in its counter part, only approximately

Patra, S K; Singh, S K; Bhuyan, M

2014-01-01

145

Constraints on light asymmetric dark matter from solar neutrinos

International Nuclear Information System (INIS)

We study the effect of dark matter (DM) particles in the Sun, focusing in particular on the possible reduction of the solar neutrinos flux due to the energy carried away by DM particles from the innermost regions of the Sun, and to the consequent reduction of the temperature of the solar core. In the very low-mass range between 4 and 10 GeV, recently advocated to explain the findings of the DAMA and CoGent experiments, the effects on neutrino fluxes are detectable only for DM models with very small, or vanishing, self-annihilation cross section, such as the so-called asymmetric DM models, and we study the combination of DM masses and Spin Dependent cross sections which can be excluded with current solar neutrino data.

146

A Dirac description of ¹S0+³ S1-³ D1 pairing in nuclear matter

Scientific Electronic Library Online (English)

Full Text Available We develop a Dirac-Hartree-Fock-Bogoliubov description of nuclear matter pairing in ¹S0 and ³S¹-³ D¹ channels. Here we investigate the density dependence ot the ¹S0 and ³S¹-³ D¹ pairing fields in asymmetric nuclear matter, using a Bonn meson-exchange interaction between Dirac nucleons. In this work, [...] we present preliminary results.

B. Funke, Haas; B. V., Carlson; Tobias, Frederico.

2004-09-01

147

Deuteron distribution in nuclear matter

We analyze the properties of deuteron-like structures in infinite, correlated nuclear matter, described by a realistic hamiltonian containing the Urbana $v_{14}$ two-nucleon and the Urbana TNI many-body potentials. The distribution of neutron-proton pairs, carrying the deuteron quantum numbers, is obtained as a function of the total momentum by computing the overlap between the nuclear matter in its ground state and the deuteron wave functions in correlated basis functions theory. We study the differences between the S- and D-wave components of the deuteron and those of the deuteron-like pair in the nuclear medium. The total number of deuteron type pairs is computed and compared with the predictions of Levinger's quasideuteron model. The resulting Levinger's factor in nuclear matter at equilibrium densityis 11.63. We use the local density approximation to estimate the Levinger's factor for heavy nuclei, obtaining results which are consistent with the available experimental data from photoreactions.

Benhar, O; Fantoni, S; Illarionov, A Yu; Lykasov, G I

2002-01-01

148

Deuteron distribution in nuclear matter

We analyze the properties of deuteron-like structures in infinite, correlated nuclear matter, described by a realistic hamiltonian containing the Urbana v14 two-nucleon and the Urbana TNI many-body potentials. The distribution of neutron-proton pairs, carrying the deuteron quantum numbers, is obtained as a function of the total momentum by computing the overlap between the nuclear matter in its ground state and the deuteron wave functions in correlated basis functions theory. We study the differences between the S- and D-wave components of the deuteron and those of the deuteron-like pair in the nuclear medium. The total number of deuteron type pairs is computed and compared with the predictions of Levinger's quasideuteron model. The resulting Levinger's factor in nuclear matter at equilibrium density is 11.63. We use the local density approximation to estimate the Levinger's factor for heavy nuclei, obtaining results which are consistent with the available experimental data from photoreactions.

Benhar, O.; Fabrocini, A.; Fantoni, S.; Illarionov, A. Yu.; Lykasov, G. I.

2002-05-01

149

Bottomonium states in hot asymmetric strange hadronic matter

We calculate the in-medium masses of the bottomonium states ($\\Upsilon(1S)$, $\\Upsilon(2S)$, $\\Upsilon(3S)$ and $\\Upsilon(4S)$) in isospin asymmetric strange hadronic matter at finite temperatures. The medium modifications of the masses arise due to the interaction of these heavy quarkonium states with the gluon condensates of QCD. The gluon condensates in the hot hadronic matter are computed from the medium modification of a scalar dilaton field within a chiral SU(3) model, introduced in the hadronic model to incorporate the broken scale invariance of QCD. There is seen to be drop in the masses of the bottomonium states and the mass shifts are observed to be quite considerable at high densities for the excited states. The effects of density, isospin asymmetry, strangeness as well as temperature of the medium on the masses of the $\\Upsilon$-states are investigated. The effects of the isopsin asymmetry as well as strangeness fraction of the medium are seen to be appreciable at high densities and small temperat...

Mishra, Amruta

2014-01-01

150

International Nuclear Information System (INIS)

The goal in this thesis is thus twofold: The first is to investigate the feasibility of using heavy ion collisions to create conditions in the laboratory which are ripe for the formation of a quark-gluon plasma. The second is to develop a technique for studying some of the many non-perturbative features of this novel phase of matter

151

Directory of Open Access Journals (Sweden)

Full Text Available The modification of the properties of nucleon in nuclear medium has been investigated in the context of flux tube model. A nucleon has been described as diquark-quark system connected by flux tube and quasi particle diquark model has been used to describe the diquak constituting the nucleon. The modification of incompressiblity, the Roper resonance etc in the nuclear medium have been investigated. The results are compared with recent experimental and theoretical predictions. Some interesting observations are made.

Aparajita Bhattacharya

2011-02-01

152

Electron scattering from nuclear matter

International Nuclear Information System (INIS)

We use inclusive electron scattering to study the short-range aspects of nuclear matter wave functions. Comparison to data at large momentum transfer allows detailed studies of P(k, E) at large momenta, N-N correlations and colour transparency. (orig.)

153

The kaon energy in a nuclear medium and its dependence on kaon-nucleon and nucleon-nucleon correlations is discussed. The transition from the Lenz potential at low densities to the Hartree potential at high densities can be calculated analytically by making a Wigner-Seitz cell approximation and employing a square well potential. As the Hartree potential is less attractive than the Lenz one, kaon condensation inside cores of neutron stars appears to be less likely than previo...

Heiselberg, Henning

1998-01-01

154

Sound modes in hot nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The propagation of the isoscalar and isovector sound modes in a hot nuclear matter is considered. The approach is based on the collisional kinetic theory and takes into account the temperature and memory effects. It is shown that the sound velocity and the attenuation coefficient are significantly influenced by the Fermi surface distortion (FSD). The corresponding influence is much stronger for the isoscalar mode than for the isovector one. The memory effects cause a nonmonotonous behavior of the attenuation coefficient as a function of the relaxation time leading to a zero-to-first sound transition with increasing temperature. The mixing of both the isoscalar and the isovector sound modes in an asymmetric nuclear matter is evaluated. The condition for the bulk instability and the instability growth rate in the presence of the memory effects is studied. It is shown that both the FSD and the relaxation processes lead to a shift of the maximum of the instability growth rate to the longer-wavelength region.

Kolomietz, V. M.; Shlomo, S.

2001-10-01

155

Sound modes in hot nuclear matter

International Nuclear Information System (INIS)

The propagation of the isoscalar and isovector sound modes in a hot nuclear matter is considered. The approach is based on the collisional kinetic theory and takes into account the temperature and memory effects. It is shown that the sound velocity and the attenuation coefficient are significantly influenced by the Fermi surface distortion (FSD). The corresponding influence is much stronger for the isoscalar mode than for the isovector one. The memory effects cause a nonmonotonous behavior of the attenuation coefficient as a function of the relaxation time leading to a zero-to-first sound transition with increasing temperature. The mixing of both the isoscalar and the isovector sound modes in an asymmetric nuclear matter is evaluated. The condition for the bulk instability and the instability growth rate in the presence of the memory effects is studied. It is shown that both the FSD and the relaxation processes lead to a shift of the maximum of the instability growth rate to the longer-wavelength region

156

Isospin dependence of nuclear matter symmetry energy coefficients

Generalized symmetry energy coefficients of asymmetric nuclear matter are obtained as screening functions. The dependence of the isospin symmetry energy coefficient on the neutron proton (n-p) asymmetry may be determined unless by a constant (exponent) $Z$ which depend on microscopic properties. The dependence of the generalized symmetry energy coefficients with Skyrme forces on the n-p asymmetry and on the density, only from .5 up to 1.5 $\\rho_0$, are investigated in the is...

Braghin, Fabio L.

2001-01-01

157

Symmetry energy: from nuclear matter to finite nuclei

We suggest a particular procedure of derivation of the beta-stability line and isotopic symmetry energy. The behavior of the symmetry energy coefficient $b(A,N-Z)$ is analyzed. We redefine the surface tension coefficient and the surface symmetry energy for an asymmetric nuclear Fermi-liquid drop with a finite diffuse layer. Following Gibbs-Tolman concept, we introduce the equimolar radius at which the surface tension is applied. The relation of the nuclear macroscopic characteristics like surface and symmetry energies, Tolman length, etc. to the bulk properties of nuclear matter is considered. The surface-to-volume symmetry energy ratio for several Skyrme-force parametrizations is obtained.

Kolomietz, V M

2014-01-01

158

Dynamical simulation of expanding nuclear matter

International Nuclear Information System (INIS)

We study the properties of nuclear matter expanding dynamically using QMD model. For this purpose we developed an extended periodic boundary condition prescription. To calculate EOS of the expanding nuclear matter, the liquid-gas phase transition is discussed. (author)

159

Nuclear matter in the crust of neutron stars derived from realistic NN interactions

Properties of inhomogeneous nuclear matter are evaluated within a relativistic mean field approximation using density dependent coupling constants. A parameterization for these coupling constants is presented, which reproduces the properties of the nucleon self-energy obtained in Dirac Brueckner Hartree Fock calculations of asymmetric nuclear matter but also provides a good description for bulk properties of finite nuclei. The inhomogeneous infinite matter is described in te...

Go?gelein, P.; Dalen, E. N. E.; Fuchs, C.; Mu?ther, H.

2007-01-01

160

Chemical and mechanical instability in warm and dense nuclear matter

We investigate the possible thermodynamic instability in a warm and dense nuclear medium (T<50 MeV and \\rho_0<\\rho_B< 3\\rho_0) where a phase transition from nucleonic matter to resonance-dominated Delta-matter can take place. The analysis is performed by requiring the global conservation of baryon and electric charge numbers in the framework of a relativistic equation of state. Similarly to the liquid-gas phase transition, we show that the nucleon-Delta matter phase transition is characterized by both mechanical instability (fluctuations on the baryon density) and by chemical-diffusive instability (fluctuations on the charge concentration) in asymmetric nuclear matter. We then perform an investigation and a comparative study on the different nature of such instabilities and phase transitions.

Lavagno, A; 10.1103/PhysRevC.86.024917

2012-01-01

161

Matter induced charge symmetry breaking and pion form factor in nuclear medium

Medium modification of pion form factor has been evaluated in asymmetric nuclear matter. It is shown that both the shape and the pole position of the pion form factor in dense asymmetric nuclear matter is different from its vacuum counterpart with $\\rho$-$\\omega$ mixing. This is due to the density and asymmetry dependent $\\rho$-$\\omega$ mixing which could even dominate over its vacuum counterpart in matter. Effect of the in-medium pion factor on experimental observables {\\it e.g.}, invariant mass distribution of lepton pairs has been demonstrated.

Roy, P; Sarkar, S; Alam, J; Roy, Pradip; Dutt-Mazumder, Abhee K.; Sarkar, Sourav; Alam, Jan-e

2006-01-01

162

Deuteron distribution in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

We analyze the properties of deuteron-like structures in infinite, correlated nuclear matter, described by a realistic hamiltonian containing the Urbana v{sub 14} two-nucleon and the Urbana TNI many-body potentials. The distribution of neutron-proton pairs, carrying the deuteron quantum numbers, is obtained as a function of the total momentum by computing the overlap between the nuclear matter in its ground state and the deuteron wave functions in correlated basis functions theory. We study the differences between the S- and D-wave components of the deuteron and those of the deuteron-like pair in the nuclear medium. The total number of deuteron type pairs is computed and compared with the predictions of Levinger's quasideuteron model. The resulting Levinger's factor in nuclear matter at equilibrium density is 11.63. We use the local density approximation to estimate the Levinger's factor for heavy nuclei, obtaining results which are consistent with the available experimental data from photoreactions.

Benhar, O.; Fabrocini, A. E-mail: adelchi.fabrocini@pi.infn.it; Fantoni, S.; Illarionov, A.Y.; Lykasov, G.I

2002-05-20

163

Constraining Asymmetric Bosonic Non-interacting Dark Matter with Neutron Stars

The Hawking evaporation of small black holes formed by the collapse of dark matter at the center of neutron stars plays a key role in loosing the constraint on the mass of asymmetric bosonic non-interacting dark matter particles. Different from previous works we show that such a kind of dark matter is viable in the mass range from 3.3 GeV to ~ 10 TeV, which covers the most attractive regions, including the preferred asymmetric dark matter mass ~ 5.7 GeV as well as the 5-15 GeV range favored by DAMA and CoGeNT.

Fan, Yi-zhong; Chang, Jin

2012-01-01

164

Relic Abundance of Asymmetric Dark Matter in Scalar--Tensor Model

The relic abundance of asymmetric Dark Matter particles in the scalar--tensor model is analysized in this article. We extend the numeric and analytic calculation of the relic density of the asymmetric Dark Matter in the standard cosmological scenario to the nonstandard cosmological scenario. We focus on the scalar--tensor model. Hubble expansion rate is changed in the nonstandard cosmological scenario. This leaves its imprint on the relic density of Dark Matter particles. In this article we investigate to what extent the asymmetric Dark Matter particle's relic density is changed in the scalar--tensor model. We use the observed present day Dark Matter abundance to find the constraints on the parameter space in this model.

Wang, Shun-zhi; Mamat, Mamatrishat

2015-01-01

165

Expanding nuclear matter by QMD

International Nuclear Information System (INIS)

We study the properties of dynamically expanding nuclear matter. For this purpose, we apply quantum molecular dynamics (QMD) model to homogeneously expanding 3-dimensional system with periodic boundary condition. Simulation is performed for given initial temperatures and expanding velocities. The calculated fragment mass distribution for slow expansion obeys the power law predicted by Fisher's droplet model, while that for rapid expansion exhibits the exponential shape. (author)

166

Expanding nuclear matter by QMD

Energy Technology Data Exchange (ETDEWEB)

We study the properties of dynamically expanding nuclear matter. For this purpose, we apply quantum molecular dynamics (QMD) model to homogeneously expanding 3-dimensional system with periodic boundary condition. Simulation is performed for given initial temperatures and expanding velocities. The calculated fragment mass distribution for slow expansion obeys the power law predicted by Fisher's droplet model, while that for rapid expansion exhibits the exponential shape. (author)

Chikazumi, Shinpei [Tsukuba Univ., Tsukuba, Ibaraki (Japan); Maruyama, Toshiki; Chiba, Satoshi; Iwamoto, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Niida, Koji [Research Organization for Information Science and Technology, Tokai, Ibaraki (Japan)

2000-08-01

167

Main Achievements 2003-2004 - Theoretical hadronic physics - Nuclear matter

International Nuclear Information System (INIS)

In the fundamental field of the many-body problem of strongly interacting particles major successes were achieved. We have performed a fully consistent description of the dynamical response functions in strongly correlated fermionic systems and carried out a new self-consistent and symmetry-conserving calculation of the nucleon spectral function in asymmetric nuclear medium, connected to the analysis of vertex functions and self-energy corrections in medium. These studies have applications to studies of the nuclear medium as well as condensed matter

168

BCS-BEC crossovers and unconventional phases in dilute nuclear matter. II

We study the phase diagram of isospin-asymmetrical nuclear matter in the density-temperature plane, allowing for four competing phases of nuclear matter: (i) the unpaired phase, (ii) the translationally and rotationally symmetric, but isospin-asymmetrical BCS condensate, (iii) the current-carrying Larkin-Ovchinnikov-Fulde-Ferrell phase, and (iv) the heterogeneous phase-separated phase. The phase diagram of nuclear matter composed of these phases features two tri-critical points in general, as well as crossovers from the asymmetrical BCS phase to a BEC of deuterons plus a neutron gas, both for the homogeneous superfluid phase (at high temperatures) and for the heterogeneous phase (at low temperatures). The BCS-BEC type crossover in the condensate occurs as the density is reduced. We analyze in detail some intrinsic properties of these phases, including the Cooper-pair wave function, the coherence length, the occupation numbers of majority and minority nucleonic components, and the dispersion relations of quasi...

Stein, Martin; Huang, Xu-Guang; Clark, John W

2014-01-01

169

Low densities in nuclear and neutron matters and in the nuclear surface

International Nuclear Information System (INIS)

Nuclear and neutron matters are investigated in the low density region, well below the nuclear saturation density. Microscopic calculations, based on the Bethe-Brueckner approach with a few realistic nucleon-nucleon potentials, are compared with the predictions of a set of phenomenological effective interactions, mostly employed in nuclear structure studies. An energy functional is constructed on the basis of the microscopic bulk EoS and applied to a selection of nuclei throughout the mass table. The results provide a microscopic basis for a link between nuclear surface behaviour and neutron EoS previously observed with phenomenological effective forces. Possible effects of pairing on asymmetric nuclear matter are also analyzed in detail. The results are expected to illuminate the physical mechanisms which determine the behaviour of the surface density tail in exotic nuclei

170

Quasiparticle interaction in nuclear matter

International Nuclear Information System (INIS)

A microscopic calculation of the quasiparticle interaction in nuclear matter is detailed. In order to take especial care of the contributions from the low momentum states, a model space is introduced. Excluded from the model space, the high momentum states are absorbed into the model interaction. Brueckner theory suggests the choice of a truncated G-matrix as a good approximation for this model interaction. A simple perturbative approach is attempted within the model space. The calculated quasiparticle interaction is consistent with experimental results. (11 tables, 14 figures)

171

Light clusters in nuclear matter

International Nuclear Information System (INIS)

Within a quantum statistical approach, a in-medium Schroedinger equation is derived for a few-nucleon system embedded in nuclear matter. Medium modifications of the cluster quasiparticles are described by self-energy and Pauli blocking effects. Benchmarks such as the nuclear statistical equilibrium, virial expansion and the relativistic mean field approximation are considered. An interesting effect is the formation of a four- or two-nucleon quantum condensate, showing the crossover from Cooper pairing to Bose-Einstein condensation. The resulting thermodynamic properties are of interest for heavy-ion collisions and astrophysical applications. Quantum condensates and the Mott effect are also of relevance for the structure of finite nuclei, specially dilute excited states like the Hoyle state of 12C. (author)

172

Quantum hadrodynamic and nuclear matter

International Nuclear Information System (INIS)

The properties of infinite nuclear matter are studied in the model relativistic quantum field theory of Walecka. Neutral scalar and vector meson exchange reproduces the basic Lorentz structure of the observed nucleon-nucleon interaction, and the consequences of this structure are studied in detail. In the mean-field approximation, nuclear saturation involves a cancellation between large attractive and repulsive components in the average potential energy. The attractive scalar field decreases the nucleon mass significantly, and the strong vector repulsion implies a stiff high-density equation of state. Corrections to the mean-field approach arising from vacuum fluctuations, self-consistent nucleon exchange, and two-nucleon correlations are examined. These have a small effect on the condensed meson fields but may produce significant changes in the binding energy. Corrections to the mean-field equation of state are small at high density

173

Lepton-flavored asymmetric dark matter and interference in direct detection

In flavored dark matter models, dark matter can scatter off of nuclei through Higgs and photon exchange, both of which can arise from renormalizable interactions and individually lead to strong constraints from direct detection. While these two interaction channels can destructively interfere in the scattering amplitude, for a thermal relic with equal abundances for the dark matter particle and its antiparticle, this produces no effect on the total event rate. Focusing on lepton-flavored dark matter, we show that it is quite natural for dark matter to have become asymmetric during high-scale leptogenesis, and that in this case the direct detection bounds can be significantly weakened due to interference. We quantify this by mapping out and comparing the regions of parameter space that are excluded by direct detection for the symmetric and asymmetric cases of lepton-flavored dark matter. In particular, we show that the entire parameter region except for a narrow Higgs resonance window is ruled out in the symmetric case for fermion dark matter when the coupling to the Higgs dominates over the coupling to leptons, while large portions of parameter space are still allowed for the asymmetric case. The same is also true for a dark matter mass above 8 GeV for scalar dark matter when the coupling to leptons dominates over the coupling to the Higgs.

Hamze, Ali; Kilic, Can; Koeller, Jason; Trendafilova, Cynthia; Yu, Jiang-Hao

2015-02-01

174

Big Bang Synthesis of Nuclear Dark Matter

We investigate the physics of dark matter models featuring composite bound states carrying a large conserved dark "nucleon" number. The properties of sufficiently large dark nuclei may obey simple scaling laws, and we find that this scaling can determine the number distribution of nuclei resulting from Big Bang Dark Nucleosynthesis. For plausible models of asymmetric dark matter, dark nuclei of large nucleon number, e.g. > 10^8, may be synthesised, with the number distributi...

Hardy, Edward; Lasenby, Robert; March-russell, John; West, Stephen M.

2014-01-01

175

Asymmetric dark matter annihilation as a test of non-standard cosmologies

International Nuclear Information System (INIS)

We show that the relic abundance of the minority component of asymmetric dark matter can be very sensitive to the expansion rate of the Universe and the temperature of transition between a non-standard pre-Big Bang Nucleosynthesis cosmological phase and the standard radiation dominated phase, if chemical decoupling happens before this transition. In particular, because the annihilation cross section of asymmetric dark matter is typically larger than that of symmetric dark matter in the standard cosmology, the decrease in relic density of the minority component in non-standard cosmologies with respect to the majority component may be compensated by the increase in annihilation cross section, so that the annihilation rate at present of asymmetric dark matter, contrary to general belief, could be larger than that of symmetric dark matter in the standard cosmology. Thus, if the annihilation cross section of the asymmetric dark matter candidate is known, the annihilation rate at present, if detectable, could be used to test the Universe before Big Bang Nucleosynthesis, an epoch from which we do not yet have any data

176

Combustion of nuclear matter into strange matter

International Nuclear Information System (INIS)

We study the properties of the combustion of pure neutron matter into strange matter in the framework of relativistic hydrodynamical theory of combustion. Because of the uncertainties in the actual properties of neutron matter, we employ the free neutron, Bethe-Johnson, Lattimer-Ravenhall, and Walecka equations of state and for strange matter we adopt the MIT bag model approximation. We find that combustion is possible for free neutron, Bethe-Johnson, and Lattimer-Ravenhall neutron matter but not for Walecka neutron matter. We interpret these results using a simple polytropic approximation showing that there exists a general flammability condition. We also study the burning of neutron matter into strange matter in a pipe showing that hydrodynamics demands flames faster than predicted by kinetics by several orders of magnitude, implying that the flame must be turbulent. Also the conditions for the deflagration to detonation transition are addressed, showing that in a pipe some of them are satisfied, strongly suggesting that the actual combustion mode should be detonation

177

Asymmetric capture of Dirac dark matter by the Sun

Current problems with the solar model may be alleviated if a significant amount of dark matter from the galactic halo is captured in the Sun. We discuss the capture process in the case where the dark matter is a Dirac fermion and the background halo consists of equal amounts of dark matter and anti-dark matter. By considering the case where dark matter and anti-dark matter have different cross sections on solar nuclei as well as the case where the capture process is considered to be a Poisson process, we find that a significant asymmetry between the captured dark particles and anti-particles is possible. Such an asymmetry puts a lower bound on the total amount of captured dark matter and could be a possible solution to the solar composition problem.

Blennow, Mattias

2015-01-01

178

Asymmetric Dark Matter May Alter the Evolution of Low-mass Stars and Brown Dwarfs

We study energy transport by asymmetric dark matter in the interiors of very low-mass stars and brown dwarfs. Our motivation is to explore astrophysical signatures of asymmetric dark matter, which otherwise may not be amenable to conventional indirect dark matter searches. In viable models, the additional cooling of very-low mass stellar cores can alter stellar properties. Asymmetric dark matter with mass 4 < Mx/GeV < 10 and either spin-dependent (spin-independent) cross sections of sigma \\sim 10^{-37} cm^2 (sigma \\sim 10^{-40} cm^2) can increase the minimum mass of main sequence hydrogen burning, partly determining whether or not the object is a star at all. Similar dark matter candidates reduce the luminosities of low-mass stars and accelerate the cooling of brown dwarfs. Such light dark matter is of particular interest given results from the DAMA, CoGeNT, and CRESST dark matter searches. We discuss possibilities for observing dark matter effects in stars in the solar neighborhood, globular clusters, ...

Zentner, Andrew R

2011-01-01

179

D-mesons and charmonium states in hot isospin asymmetric strange hadronic matter

We study the properties of $D$ and $\\bar{D}$ mesons in hot isospin asymmetric strange hadronic matter, arising due to their interactions with the hadrons in the hyperonic medium. The interactions of $D$ and $\\bar{D}$ mesons with these light hadrons are derived by generalizing the chiral SU(3) model used for the study of hyperonic matter to SU(4). We also study the mass modifications of the charmonium states $J/\\psi$, $\\psi(3686)$ and $\\psi(3770)$ in the isospin asymmetric st...

Kumar, Arvind; Mishra, Amruta

2011-01-01

180

Light Front Theory Of Nuclear Matter

A relativistic light front formulation of nuclear dynamics is applied to infinite nuclear matter. A hadronic meson-baryon Lagrangian, consistent with chiral symmetry, leads to a nuclear eigenvalue problem which is solved, including nucleon-nucleon (NN) correlations, in the one-boson-exchange approximation for the NN potential. The nuclear matter saturation properties are reasonably well reproduced, with a compression modulus of 180 MeV. We find that there are about 0.05 exce...

Miller, G. A.; Machleidt, R.

1998-01-01

181

Nuclear matter in relativistic mean field theory with isovector scalar meson

International Nuclear Information System (INIS)

Relativistic mean field (RMF) theory of nuclear matter with the isovector scalar mean field corresponding to the ?-meson [a0(980)] is studied. While the ?-meson field vanishes in symmetric nuclear matter, it can influence properties of asymmetric nuclear matter in neutron stars. The RMF contribution due to ?-field to the nuclear symmetry energy is negative. To fit the empirical value, Es?30 MeV, a stronger ?-meson coupling is required than in absence of the ?-field. The energy per particle of neutron star matter is than larger at high densities than the one with no ?-field included. Also, the proton fraction of ?-stable matter increases. Splitting of proton and neutron effective masses due to the ?-field can affect transport properties of neutron star matter. (author). 4 refs, 6 figs

182

Structure of the subsaturated nuclear matter

Energy Technology Data Exchange (ETDEWEB)

Quantum molecular dynamics is applied to study the ground state and excited state properties of nuclear matter at subsaturation densities. The structure of nuclear matter at subsaturation density shows some exotic shapes with variation of the density. However, the structure in our result is rather irregular compared to those of previous works due to the existence of local minimum configurations. (author)

Maruyama, Toshiki; Maruyama, Tomoyuki; Chiba, Satoshi; Iwamoto, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Niita, Koji; Oyamatsu, Kazuhiro

1998-07-01

183

Quasiparticle pole strength in nuclear matter

International Nuclear Information System (INIS)

It is argued that single-particle-like behavior in nuclear matter is much less probable than Brueckner theory suggests. In particular, the quasiparticle pole strength is evaluated for nuclear matter and it is shown that, contrary to the spirit of Brueckner theory, low momentum states play a crucial role in determining the magnitude of z/sub k/sub F/. (auth)

184

Holographic Symmetry Energy of the Nuclear Matter

We calculate the symmetry energy of the nuclear matter by using the bottom-up approach, so called hard wall model. To consider the nuclear matter, we introduce the isospin for u- and d-quarks. We find that in the hard wall model, the symmetry energy of the nuclear matter is proportional to the square of nucleon density. We also study the symmetry energy of the quark matter in the deconfining phase. Finally, we investigate the effect of the symmetry energy on the Hawking-Page...

Park, Chanyong

2011-01-01

185

Simple effective interaction: Infinite nuclear matter and finite nuclei

The mean field properties and equation of state for asymmetric nuclear matter are studied by using a simple effective interaction which has a single finite range Gaussian term. The study of finite nuclei with this effective interaction is done by means of constructing a quasilocal energy density functional for which the single particle equations take the form of Skryme-Hartree-Fock equations. The predictions of binding energies and charge radii of spherical nuclei are found to be compatible with the results of standard models as well as experimental data.

Behera, B; Bhuyan, M; Routray, T R; Sharma, B K; Patra, S K

2013-01-01

186

Light Asymmetric Dark Matter on the Lattice: SU(2) Technicolor with Two Fundamental Flavors

The SU(2) gauge theory with two massless Dirac flavors constitutes the building block of several models of Technicolor. Furthermore it has also been used as a template for the construction of a natural light asymmetric, or mixed type, dark matter candidate. We use explicit lattice simulations to confirm the pattern of chiral symmetry breaking by determining the Goldstone spectrum and therefore show that the dark matter candidate can, de facto, be constituted by a complex Gol...

Lewis, Randy; Pica, Claudio; Sannino, Francesco

2011-01-01

187

Interfering composite asymmetric dark matter as explanation for DAMA and CoGeNT results

International Nuclear Information System (INIS)

We provide a simple mechanism for reconciling the direct dark matter experimental results. We consider light asymmetric composite dark matter which scatters off nuclei via Higgs and photon exchange. We demonstrate that the interference between these two channels naturally accommodates the experimental results. We discover that this happens for a compositeness scale of the order of the electroweak. We also provide a model realization based on strong dynamics at the electroweak scale.

188

Interfering Composite Asymmetric Dark Matter for DAMA and CoGeNT

We provide a simple mechanism for reconciling the direct dark matter experimental results. We consider light asymmetric composite dark matter which scatters off nuclei via Higgs and photon exchange. We demonstrate that the interference between these two channels naturally accommodates the experimental results. We discover that this happens for a compositeness scale of the order of the electroweak. We also provide a model realization based on strong dynamics at the electrowea...

Del Nobile, Eugenio; Kouvaris, Chris; Sannino, Francesco

2011-01-01

189

Charge Asymmetric Cosmic Ray Signals From Dark Matter Decay

The PAMELA and Fermi measurements of the cosmic-ray electron and positron spectra have generated much interest over the past two years, because they are consistent with a significant component of the electron and positron fluxes between 20 GeV and 1 TeV being produced through dark matter annihilation or decay. However, since the measurements are also consistent with astrophysical interpretations, the message is unclear. In this paper, we point out that dark matter can have a...

Chang, Spencer; Goodenough, Lisa

2011-01-01

190

Leptonic Indirect Detection Signals from Strongly Interacting Asymmetric Dark Matter

Particles with TeV mass and strong self-interactions generically have the right annihilation cross section to explain an observed excess of cosmic electrons and positrons if the end-product of the annihilation is charged leptons. We present an explicit model of strongly-coupled TeV-scale dark matter whose relic abundance related to the matter-antimatter asymmetry of the observed universe. The B - L asymmetry of the standard model is transfered to the dark sector by an operator carrying standard model lepton number. Lepton number violation naturally induces dark matter particle-antiparticle oscillations at late times, allowing dark matter-antimatter annihilations today. The dark matter annihilates into lighter strongly-interacting particles in the dark sector that decay to leptons via the transfer operator. The strong dynamics in the dark sector is at the weak scale due to supersymmetry breaking. The correct dark matter abundance is automatically obtained for natural values of dimensionless parameters, analogo...

Cai, Yi; Luty, Markus A

2009-01-01

191

Nuclear matter in neutron star crust

International Nuclear Information System (INIS)

Properties of nuclear matter below the nuclear saturation density is analyzed by numerical simulations with the periodic boundary condition. The equation of state at these densities is softened by the formation of cluster(s) internal density of which is nearly equal to the saturation density. The structure of nuclear matter shows some exotic shapes with variation of the density. Furthermore, it is found that the symmetry parameter asym(?) is not a linear function of density at low density region. (author)

192

Unifying Asymmetric Inert Fermion Doublet Dark Matter and Leptogenesis with Neutrino Mass

We propose a scalar Triplet extension of the standard model (SM) to unify the origin of neutrino mass with the visible and dark matter component of the Universe. We assume that the scalar triplet is super heavy, so that its CP-violating out-of-equilibrium decay in the early Universe not only produce asymmetric dark matter which is the neutral component of an additional vector like fermion doublet, but also give rise to lepton asymmetry. The latter gets converted to observed baryon asymmetry via B+L violating sphaleron processes. Below electroweak phase transition the scalar triplet acquires a vacuum expectation value and give rise to sub-eV Majorana masses to three flavors of active neutrinos. Thus an unification of the origin of neutrino mass, lepton asymmetry and asymmetric dark matter is achieved within a scalar triplet extension of the SM.

Sahu, Narendra

2012-01-01

193

Charge asymmetric cosmic ray signals from dark matter decay

International Nuclear Information System (INIS)

The PAMELA and Fermi measurements of the cosmic ray electron and positron spectra have generated much interest over the past two years, because they are consistent with a significant component of the electron and positron fluxes between 20 GeV and 1 TeV being produced through dark matter annihilation or decay. However, since the measurements are also consistent with astrophysical interpretations, the message is unclear. In this paper, we point out that dark matter can have a more distinct signal in cosmic rays, that of a charge asymmetry. Such charge asymmetry can result if the dark matter's abundance is due to a relic asymmetry, allowing its decay to generate an asymmetry in positrons and electrons. This is analogous to the baryon asymmetry, where decaying neutrons produce electrons and not positrons. We explore benchmark scenarios where the dark matter decays into a leptophilic charged Higgs boson or electroweak gauge bosons. These models have observable signals in gamma rays and neutrinos, which can be tested by Fermi and IceCube. The most powerful test will be at AMS-02, given its ability to distinguish electron and positron charge above 100 GeV. Specifically, an asymmetry favoring positrons typically predicts a larger positron ratio and a harder (softer) high energy spectrum for positrons (electrons) than charge symmetric sources. We end with a brief discussion on how such scenarios differ from the leading astrophysical explanations.xplanations.

194

Light asymmetric dark matter from new strong dynamics

DEFF Research Database (Denmark)

A ~5 GeV `dark baryon' with a cosmic asymmetry similar to that of baryons is a natural candidate for the dark matter. We study the possibility of generating such a state through dynamical electroweak symmetry breaking, and show that it can share the relic baryon asymmetry via sphaleron interactions, even though it has no electroweak interactions. The scattering cross-section on nucleons, estimated in analogy to QCD, is within reach of underground direct detection experiments.

Frandsen, Mads Toudal; Sarkar, Subir

2011-01-01

195

On heterogeneous states in nuclear matter

International Nuclear Information System (INIS)

A model for description of heterogeneous states in quark matter and phase transitions from nucleon to 6-quark state is considered. A possibility of nucleon-multiquark heterophase mixture occurrence in nuclear matter is discussed. Behaviour of thermodynamic functions for ground and heterophase states of nuclear matter is investigated. Dependence of phase concentration Wsub(h) (h=3q, 6q, 12q dusters) on the parameters of the whole system of nuclear matter is determined. Phase transitions from hadron matter to 6-quark, which are phase transition of the first order, are considered. The calculated values are presente as diagrams of concentration dependences of nucleon and 6-quark components on density in the system and behaviour of specific free energies of phase states of the system at density vaiation. It is shown, that consideration in the suggested model with hamiltonian permits to disclose thermodynamic efficiency of heterophase state +6 g bags. The structural function for heterophase mixture is determined

196

Skyrmions, dense matter and nuclear forces

International Nuclear Information System (INIS)

A simple introduction to a number of properties of Skyrme's chiral soliton model of baryons is given. Some implications of the model for dense matter and for nuclear interactions are discussed. (orig.)

197

Photon Production from Charge-Asymmetric Hot and Dense Matter

A new channel of direct photon production from a quark gluon plasma (QGP) is explored. This process appears at Next-to-Leading-Order in the presence of a charge asymmetry in the heated matter and may be effectively described as the bremsstrahlung of a real photon from a thermal gluon. The photon production from this new mechanism is calculated in the effective theory of QCD at high temperature. The results show that the photon production rate may not as big as the annihilati...

Qin, Guang-you; Majumder, Abhijit; Gale, Charles

2007-01-01

198

Pion condensation in symmetric nuclear matter

International Nuclear Information System (INIS)

Using a model which is based essentially on the chiral SU(2)xSU(2) symmetry of the pion-nucleon interaction, we examine the possibility of pion condensation in symmetric nucleon matter. We find that the pion condensation is not likely to occur in symmetric nuclear matter for any finite value of the nuclear density. Consequently, no critical opalescence phenomenon is expected to be seen in the pion-nucleus interaction. (author). 20 refs

199

Pion condensation in symmetric nuclear matter

Using a model which is based essentially on the chiral SU(2)×SU(2) symmetry of the pion-nucleon interaction, we examine the possibility of pion condensation in symmetric nucleon matter. We find that the pion condensation is not likely to occur in symmetric nuclear matter for any finite value of the nuclear density. Consequently, no critical opalescence phenomenom is expected to be seen in the pion-nucleus interaction.

Kabir, K.; Saha, S.; Nath, L. M.

1988-01-01

200

Dark Matter Studies Entrain Nuclear Physics

We review theoretically well-motivated dark-matter candidates, and pathways to their discovery, in the light of recent results from collider physics, astrophysics, and cosmology. Taken in aggregate, these encourage broader thinking in regards to possible dark-matter candidates --- dark-matter need not be made of "WIMPs," i.e., elementary particles with weak-scale masses and interactions. Facilities dedicated to nuclear physics are well-poised to investigate certain non-WIMP ...

Gardner, Susan; Fuller, George

2013-01-01

201

Heavy Mesons in Nuclear Matter and Nuclei

Heavy mesons in nuclear matter and nuclei are analyzed within different frameworks, paying a special attention to unitarized coupled-channel approaches. Possible experimental signatures of the properties of these mesons in matter are addressed, in particular in connection with the future FAIR facility at GSI.

Tolos, Laura; Garcia-Recio, Carmen; Molina, Raquel; Nieves, Juan; Oset, Eulogio; Ramos, Angels; Romanets, Olena; Salcedo, Lorenzo Luis; Torres-Rincon, Juan M

2014-01-01

202

Dense nuclear matter and symmetry energy in strong magnetic fields

International Nuclear Information System (INIS)

The properties of nuclear matter in the presence of a strong magnetic field, including the density-dependent symmetry energy, the chemical composition and spin polarizations, are investigated in the framework of the relativistic mean field models FSUGold. The anomalous magnetic moments (AMM) of the particles and the nonlinear isoscalar–isovector coupling are included. It is found that the parabolic isospin dependence of the energy per nucleon of asymmetric nuclear matter remains valid for the values of magnetic field below 105Bce, Bce=4.414×1013 G being the electron critical field. Accordingly, the symmetry energy can be obtained by the difference of the energy per nucleon in pure neutron matter and that in symmetric matter. The symmetry energy, which is enhanced by the presence of the magnetic field, significantly affects the chemical composition and the proton polarization. The effects of the AMM of each component on the energy per nucleon, symmetry energy, chemical composition and spin polarization are discussed in detail

203

Asymmetric WIMP Dark Matter in the presence of DM/anti-DM oscillations

International Nuclear Information System (INIS)

The general class of 'Asymmetric Dark Matter (DM)' scenarios assumes the existence of a primordial particle/anti-particle asymmetry in the dark matter sector related to the asymmetry in the baryonic one, as a way to achieve the observed similarity between the baryonic and dark matter energy densities today. Focusing on this framework we study the effect of oscillations between dark matter and its anti-particle on the re-equilibration of the initial asymmetry. We calculate the evolution of the dark matter relic abundance and show how oscillations re-open the parameter space of asymmetric dark matter models, in particular in the direction of allowing large (WIMP-scale) DM masses. We found in particular that a typical WIMP with a mass at the EW scale (about 1 TeV) having a primordial asymmetry of the same order as the baryon asymmetry, naturally gets the correct relic abundance if the ?m mass term is in the ? meV range. This turns out to be a natural value for fermionic DM arising from the higher dimensional operator H2DM2/? where H is the Higgs field and ? ? MPl. Finally, we constrain the parameter space in this framework by applying up-to-date bounds from indirect detection signals on annihilating DM

204

On phase transitions of nuclear matter in the Nambu-Jona-Lasinio model

International Nuclear Information System (INIS)

Within the Cornwall-Jackiw-Tomboulis (CJT) approach a general formalism is established for the study of asymmetric nuclear matter (ANM) described by Nambu-Jona-Lasinio (NJL) model. Restricting to the double-bubble approximation (DBA) we determine the bulk properties of ANM. Restricting to the double-bubble approximation (DBA) we determine the bulk properties of ANM, in particular, the density dependence of the nuclear symmetry energy, which is in good agreement with data of recent analyses. (author)

205

Soliton matter as a model of dense nuclear matter

International Nuclear Information System (INIS)

We employ the hybrid soliton model of the nucleon consisting of a topological meson field and deeply bound quarks to investigate the behavior of the quarks in soliton matter as a function of density. To organize the calculation, we place the solitons on a spatial lattice. The model suggests the transition of matter from a color insulator to a color conductor above a critical density of a few times normal nuclear density. There is no latent heat associated with the transition

206

Cosmic ray-dark matter scattering: a new signature of (asymmetric) dark matter in the gamma ray sky

International Nuclear Information System (INIS)

We consider the process of scattering of Galactic cosmic-ray electrons and protons off of dark matter with the radiation of a final-state photon. This process provides a novel way to search for Galactic dark matter with gamma rays. We argue that for a generic weakly interacting massive particle, barring effects such as co-annihilation or a velocity-dependent cross section, the gamma-ray emission from cosmic-ray scattering off of dark matter is typically smaller than that from dark matter pair-annihilation. However, if dark matter particles cannot pair-annihilate, as is the case for example in asymmetric dark matter scenarios, cosmic-ray scattering with final state photon emission provides a unique window to detect a signal from dark matter with gamma rays. We estimate the expected flux level and its spectral features for a generic supersymmetric setup, and we also discuss dipolar and luminous dark matter. We show that in some cases the gamma-ray emission might be large enough to be detectable with the Fermi Large Area Telescope

207

Clusters in nuclear matter and Mott points

Light clusters (mass number $A \\leq 4$) in nuclear matter at subsaturation densities are described using a quantum statistical approach. In addition to self-energy and Pauli-blocking, effects of continuum correlations are taken into account to calculate the quasiparticle properties and abundances of light elements. Medium-modified quasiparticle properties are important ingredients to derive a nuclear matter equation of state applicable in the entire region of warm dense matter below saturation density. The influence of the nucleon-nucleon interaction on the quasiparticle shift is discussed.

Röpke, G

2015-01-01

208

Past and present of nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The subject of nuclear matter is interesting for many fields of physics ranging from condensed matter to lattice QCD. Knowing its properties is important for our understanding of neutron stars, supernovae and cosmology. Experimentally, we have the most precise information on ground state nuclear matter from the mass formula and from the systematics of monopole vibrations. This gives us the ground state density, binding energy and the compression modulus k at ground state density. However, those methods can not be extended towards the regime we are most interested in, the regime of high density and high temperature. Additional information can be obtained from the observation of neutron stars and of supernova explosions. In both cases information is limited by the rare events that nature provides for us. High energy heavy ion collisions, on the other hand, allow us to perform controlled experiments in the laboratory. For a very short period in time we can create a system that lets us study nuclear matter properties. Density and temperature of the system depend on the mass of the colliding nuclei, on their energy and on the impact parameter. The system created in nuclear collisions has at best about 200 constituents not even close to infinite nuclear matter, and it lasts only for collision times of {approx} 10{sup {minus}22}sec, not an ideal condition for establishing any kind of equilibrium. Extended size and thermal and chemical equilibrium, however, axe a priori conditions of nuclear matter. As a consequence we need realistic models that describe the collision dynamics and non-equilibrium effects in order to relate experimental observables to properties of nuclear matter. The study of high energy nuclear collisions started at the Bevalac. I will try to summarize the results from the Bevalac studies, the highlights of the continuing program, and extension to higher energies without claiming to be complete.

Ritter, H.G.

1994-05-01

209

Nuclear matter - quark matter phase diagram with strangeness

International Nuclear Information System (INIS)

A phenomenological equation of state of strongly interacting matter, including strange degrees of freedom is presented. It is shown that the hyperon and kaon interactions must be included, in order to obtain a reasonable description of the deconfinement transition at high baryon densities. The consequences of kaon condensation on the nuclear matter - quark matter phase diagram are explored. The relative particle abundances obtained in an isentropic expansion of a blob of quark-gluon plasma are presented for different initial conditions. Implications for ultra-relativistic heavy-ion collisions are briefly discussed. (orig.)

210

Light Asymmetric Dark Matter on the Lattice: SU(2) Technicolor with Two Fundamental Flavors

DEFF Research Database (Denmark)

The SU(2) gauge theory with two massless Dirac flavors constitutes the building block of several models of Technicolor. Furthermore it has also been used as a template for the construction of a natural light asymmetric, or mixed type, dark matter candidate. We use explicit lattice simulations to confirm the pattern of chiral symmetry breaking by determining the Goldstone spectrum and therefore show that the dark matter candidate can, de facto, be constituted by a complex Goldstone boson. We also determine the phenomenologically relevant spin one and spin zero isovector spectrum and demonstrate that it is well separated from the Goldstone spectrum.

Lewis, Randy; Pica, Claudio

2012-01-01

211

Nuclear matter in all its states

International Nuclear Information System (INIS)

This report includes the nine lectures which have been presented at the Joliot-Curie School of Nuclear Physics in 1985. The subjects covered are the following: thermodynamic description of excited nuclei; heavy ion reactions at high energy (theoretical approach); heavy ion reactions at high energy (experimental approach); relativistic nuclear physics and quark effects in nuclei; quark matter; nuclear compressibility and its experimental determinations; hot nuclei; anti p-nucleus interaction; geant resonances at finite temperature

212

Quark and gluon condensates in nuclear matter

International Nuclear Information System (INIS)

Quark and gluon condensates in nuclear matter are studied. These in-medium condensates may be linked to a wide range of nuclear phenomena and are important inputs to QCD sum-rule calculations at finite density. The Hellmann-Feynman theorem yields a prediction of the quark condensate that is model independent to first order in the nucleon density. This linear density dependence, with slope determined by the nucleon ? term, implies that the quark condensate is reduced considerably at nuclear matter saturation density---it is roughly 25--50 % smaller than the vacuum value. The trace anomaly and the Hellmann-Feynman theorem lead to a prediction of the gluon condensate that is model independent to first order in the nucleon density. At nuclear matter saturation density, the gluon condensate is about 5% smaller than the vacuum value. Contributions to the in-medium quark condensate that are of higher order in the nucleon density are estimated with mean-field quark-matter calculations using the Nambu--Jona-Lasinio and Gell-Mann--Levy models. Treatments of nuclear matter based on hadronic degrees of freedom are also considered, and the uncertainties are discussed

213

D-mesons and charmonium states in hot isospin asymmetric strange hadronic matter

We study the properties of $D$ and $\\bar{D}$ mesons in hot isospin asymmetric strange hadronic matter, arising due to their interactions with the hadrons in the hyperonic medium. The interactions of $D$ and $\\bar{D}$ mesons with these light hadrons are derived by generalizing the chiral SU(3) model used for the study of hyperonic matter to SU(4). The nucleons, hyperons, the scalar isoscalar meson, $\\sigma$ and the scalar-isovector meson, $\\delta$ as modified in the strange hadronic matter, modify the masses of $D$ and $\\bar{D}$ mesons. It is found that as compared to the ${D}$ mesons, the $\\bar{D}$ meson properties are more sensitive to the isospin asymmetry at high densities. The effects of strangeness in the medium on the properties of $D$ and $\\bar{D}$ mesons are studied in the present investigation. We also investigate the mass modifications of the charmonium states $J/\\psi$, $\\psi(3686)$ and $\\psi(3770)$ in the isospin asymmetric strange hadronic matter at finite temperatures. The mass modifications of t...

Kumar, Arvind

2011-01-01

214

Big Bang Synthesis of Nuclear Dark Matter

We investigate the physics of dark matter models featuring composite bound states carrying a large conserved dark "nucleon" number. The properties of sufficiently large dark nuclei may obey simple scaling laws, and we find that this scaling can determine the number distribution of nuclei resulting from Big Bang Dark Nucleosynthesis. For plausible models of asymmetric dark matter, dark nuclei of large nucleon number, e.g. > 10^8, may be synthesised, with the number distribution taking one of two characteristic forms. If small-nucleon-number fusions are sufficiently fast, the distribution of dark nuclei takes on a logarithmically-peaked, universal form, independent of many details of the initial conditions and small-number interactions. In the case of a substantial bottleneck to nucleosynthesis for small dark nuclei, we find the surprising result that even larger nuclei, with size >> 10^8, are often finally synthesised, again with a simple number distribution. We briefly discuss the constraints arising from the...

Hardy, Edward; March-Russell, John; West, Stephen M

2014-01-01

215

Nuclear Pasta Matter for Different Proton Fractions

Nuclear matter under astrophysical conditions is explored with time-dependent and static Hartree-Fock calculations. The focus is in a regime of densities where matter segregates into liquid and gaseous phases unfolding a rich scenario of geometries, often called nuclear pasta shapes (e.g. spaghetti, lasagna). Particularly the appearance of the different phases depending on the proton fraction and the transition to uniform matter are investigated. In this context the neutron background density is of special interest, because it plays a crucial role for the type of pasta shape which is built. The study is performed in two dynamical ranges, one for hot matter and one at temperature zero to investigate the effect of cooling.

Schütrumpf, B; Maruhn, J A; Reinhard, P -G

2014-01-01

216

Chiral Quark Dynamics in Dense Nuclear Matter

We consider a new approach to the description of dense nuclear matter in the framework of chirally symmetric, quark-based hadron models. As previously in the Skyrme model, the dense environment is described in terms of hyperspherical cells of unit baryon number. The intrinsic curvature of these cells generates a new gauge interaction for the quark fields which mediates interactions with the ambient matter. We apply this approach to the Nambu-Jona-Lasinio (NJL) model, constru...

Forkel, Hilmar

1994-01-01

217

Ambiguities about infinite nuclear matter

International Nuclear Information System (INIS)

Exact solutions of the harmonic-oscillator and infinite hyperspherical well are given for the ground state of a infinitely heavy (N=Z) nucleus. The density of matter is a steadily decreasing function. The kinetic energy per particle is 12% smaller than the one predicted by the Fermi sea

218

Nuclear matter in the crust of neutron stars derived from realistic NN interactions

International Nuclear Information System (INIS)

Properties of inhomogeneous nuclear matter are evaluated within a relativistic mean-field approximation by using density-dependent coupling constants. A parametrization for these coupling constants is presented that reproduces the properties of the nucleon self-energy obtained in Dirac-Brueckner-Hartree-Fock calculations of asymmetric nuclear matter but also provides a good description for bulk properties of finite nuclei. The inhomogeneous infinite matter is described in terms of cubic Wigner-Seitz cells, which allows for a microscopic description of the structures in the so-called pasta-phase of nuclear configurations and provides a smooth transition to the limit of homogeneous matter. The effects of pairing properties and finite temperature are considered. A comparison is made to corresponding results by employing the phenomenological Skyrme Hartree-Fock approach, and the consequences for the Thomas-Fermi approximation are discussed

219

Holographic cold nuclear matter and neutron star

We have previously found a new phase of cold nuclear matter based on a holographic gauge theory, where baryons are introduced as instanton gas in the probe D8/$\\overline{\\rm D8}$ branes. In our model, we could obtain the equation of state (EOS) of our nuclear matter by introducing fermi momentum. Then, here we apply this model to the neutron star and study its mass and radius by solving the Tolman-Oppenheimer-Volkoff (TOV) equations in terms of the EOS given here. We give so...

Ghoroku, Kazuo; Kubo, Kouki; Tachibana, Motoi; Toyoda, Fumihiko

2013-01-01

220

Holographic cold nuclear matter and neutron star

We have previously found a new phase of cold nuclear matter based on a holographic gauge theory, where baryons are introduced as instanton gas in the probe D8//lineD8 branes. In our model, we could obtain the equation of state (EOS) of our nuclear matter by introducing Fermi momentum. Then, here we apply this model to the neutron star and study its mass and radius by solving the Tolman-Oppenheimer-Volkoff (TOV) equations in terms of the EOS given here. We give some comments for our holographic model from a viewpoint of the other field theoretical approaches.

Ghoroku, Kazuo; Kubo, Kouki; Tachibana, Motoi; Toyoda, Fumihiko

2014-04-01

221

Holographic cold nuclear matter and neutron star

We have previously found a new phase of cold nuclear matter based on a holographic gauge theory, where baryons are introduced as instanton gas in the probe D8/$\\overline{\\rm D8}$ branes. In our model, we could obtain the equation of state (EOS) of our nuclear matter by introducing fermi momentum. Then, here we apply this model to the neutron star and study its mass and radius by solving the Tolman-Oppenheimer-Volkoff (TOV) equations in terms of the EOS given here. We give some comments for our holographic model from a viewpoint of the other field theoretical approaches.

Ghoroku, Kazuo; Tachibana, Motoi; Toyoda, Fumihiko

2013-01-01

222

Transport properties of ?-stable nuclear matter

International Nuclear Information System (INIS)

The transport properties of matter in the interior of rotating neutron stars play a critical role in determining the evolution of these compact objects. In this brief report we discuss a study of the shear viscosity of stellar matter composed by neutrons, protons and electrons in equilibrium with respect to ? decay and electronic capture. The aim of this work is calculate in a fully consistent manner the equation of state and the transport properties of nuclear matter, in particular the shear viscosity coefficient, using the same dynamical model.

223

Wanted! Nuclear Data for Dark Matter Astrophysics

Astronomical observations from small galaxies to the largest scales in the universe can be consistently explained by the simple idea of dark matter. The nature of dark matter is however still unknown. Empirically it cannot be any of the known particles, and many theories postulate it as a new elementary particle. Searches for dark matter particles are under way: production at high-energy accelerators, direct detection through dark matter-nucleus scattering, indirect detection through cosmic rays, gamma rays, or effects on stars. Particle dark matter searches rely on observing an excess of events above background, and a lot of controversies have arisen over the origin of observed excesses. With the new high-quality cosmic ray measurements from the AMS-02 experiment, the major uncertainty in modeling cosmic ray fluxes is in the nuclear physics cross sections for spallation and fragmentation of cosmic rays off interstellar hydrogen and helium. The understanding of direct detection backgrounds is limited by poor ...

Gondolo, Paolo

2013-01-01

224

Two-body correlation functions in dilute nuclear matter

International Nuclear Information System (INIS)

Finding the distinct features of the crossover from the regime of large overlapping Cooper pairs to the limit of non-overlapping pairs of fermions (Shafroth pairs) in multicomponent Fermi systems remains one of the actual problems in a quantum many-body theory. Here this transition is studied by calculating the two-body density, spin and isospin correlation functions in dilute asymmetric nuclear matter. It is shown that criterion of the crossover (Phys. Rev. Lett. 95, 090402 (2005)), consisting in the change of the sign of the density correlation function at low momentum transfer, fails to describe correctly the density-driven BEC-BCS transition at finite isospin asymmetry or finite temperature. As an unambiguous signature of the BEC-BCS transition, there can be used the presence (BCS regime) or absence (BEC regime) of the singularity in the momentum distribution of the quasiparticle density of states

225

Skyrme interaction and nuclear matter constraints

This paper presents a detailed assessment of the ability of the 240 Skyrme interaction parameter sets in the literature to satisfy a series of criteria derived from macroscopic properties of nuclear matter in the vicinity of nuclear saturation density at zero temperature and their density dependence, derived by the liquid-drop model, in experiments with giant resonances and heavy-ion collisions. The objective is to identify those parametrizations which best satisfy the current understanding o...

Dutra, M.; Lourenc?o, O.; Sa? Martins, Js; Delfino, A.; Stone, Jr; Stevenson, Pd

2012-01-01

226

Analogies between nuclear physics and Dark Matter

A fermionic description of dark matter using analogies with nuclear physics is developed. At tree level, scalar and vector processes are considered and the two-body potential are explicitly calculated using the Breit approximation. We show that the total cross sections in both cases exhibit Sommerfeld enhancement.

Carcamo, Dante; Gamboa, Jorge

2014-01-01

227

Shock waves in relativistic nuclear matter, I

International Nuclear Information System (INIS)

The relativistic Rankine-Hugoniot relations are developed for a 3-dimensional plane shock and a 3-dimensional oblique shock. Using these discontinuity relations together with various equations of state for nuclear matter, the temperatures and the compressibilities attainable by shock compression for a wide range of laboratory kinetic energy of the projectile are calculated. 12 references

228

Nuclear physics of hot dense matter

International Nuclear Information System (INIS)

The equation of state of hot dense matter is an essential ingredient to describe the gravitational contraction of massive stars. Some of the nuclear physics problems occurring in the determination of the equation of state of hot dense matter are discussed. This particularly rich domain of nuclear physics deals with very unusual nuclei, whose mass numbers can be sometimes as large as a thousand, whose existence becomes possible in dense matter because of the screening of Coulomb forces. A calculation of the properties of hot nuclear matter in the mean field approximation is presented. It is shown that a useful approximation to study the phase equilibrium equations is to consider low temperature expansions for the nucleus expansions for the vapor. A simple formula is derived for the limiting temperature TL beyond which nuclei no longer exist. The equation of state is discussed at subnuclear density and in the domain densities greater than the nuclear saturation density. The standard methods of non relativistic many-body theory as well as relativistic mean-field and Dirac-Brueckner approaches are also discussed. (K.A.) 70 refs., 9 figs

229

Condensed matter studies by nuclear methods

International Nuclear Information System (INIS)

The separate abstract was prepared for 1 of the papers in this volume. The remaining 13 papers dealing with the use but not with advances in the use of nuclear methods in studies of condensed matter, were considered outside the subject scope of INIS. (M.F.W.)

230

Asymmetric optical nuclear spin pumping in a single uncharged quantum dot

A highly asymmetric dynamic nuclear spin pumping is observed in a single self assembled InGaAs quantum dot subject to resonant optical pumping of the neutral exciton transition leading to a large maximum polarization of 54%. This dynamic nuclear polarization is found to be much stronger following pumping of the higher energy Zeeman state. Time-resolved measurements allow us to directly monitor the buildup of the nuclear spin polarization in real time and to quantitatively st...

Klotz, F.; Jovanov, V.; Kierig, J.; Clark, E. C.; Bichler, M.; Abstreiter, G.; Brandt, M. S.; Finley, J. J.; Schwager, H.; Giedke, G.

2010-01-01

231

The public and nuclear matters

International Nuclear Information System (INIS)

The nuclear industry has an image problem and is facing a major crisis of public confidence. The solution lies not merely in better public relations and advertising campaigns, but in a fundamental reassessment of electricity management, a comprehensive re-examination of the economics of electricity use and generation and, in all probability, a shift towards more public-friendly reactor designs. Over the next decade the industry faces two great forces: the power of public opinion and the momentum of inherent technological advance. Somehow these two elements have to be guided so that they complement each other. This article aims to show how this might be achieved. (author)

232

Probing Cold Dense Nuclear Matter

Energy Technology Data Exchange (ETDEWEB)

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

Subedi, Ramesh; Shneor, R.; Monaghan, Peter; Anderson, Bryon; Aniol, Konrad; Annand, John; Arrington, John; Benaoum, Hachemi; Benmokhtar, Fatiha; Bertozzi, William; Boeglin, Werner; Chen, Jian-Ping; Choi, Seonho; Cisbani, Evaristo; Craver, Brandon; Frullani, Salvatore; Garibaldi, Franco; Gilad, Shalev; Gilman, Ronald; Glamazdin, Oleksandr; Hansen, Jens-Ole; Higinbotham, Douglas; Holmstrom, Timothy; Ibrahim, Hassan; Igarashi, Ryuichi; De Jager, Cornelis; Jans, Eddy; Jiang, Xiaodong; Kaufman, Lisa; Kelleher, Aidan; Kolarkar, Ameya; Kumbartzki, Gerfried; LeRose, John; Lindgren, Richard; Liyanage, Nilanga; Margaziotis, Demetrius; Markowitz, Pete; Marrone, Stefano; Mazouz, Malek; Meekins, David; Michaels, Robert; Moffit, Bryan; Perdrisat, Charles; Piasetzky, Eliazer; Potokar, Milan; Punjabi, Vina; Qiang, Yi; Reinhold, Joerg; Ron, Guy; Rosner, Guenther; Saha, Arunava; Sawatzky, Bradley; Shahinyan, Albert; Sirca, Simon; Slifer, Karl; Solvignon, Patricia; Sulkosky, Vince; Sulkosky, Vincent; Sulkosky, Vince; Sulkosky, Vincent; Urciuoli, Guido; Voutier, Eric; Watson, John; Weinstein, Lawrence; Wojtsekhowski, Bogdan; Wood, Stephen; Zheng, Xiaochao; Zhu, Lingyan

2008-06-01

233

Probing Cold Dense Nuclear Matter

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, where a proton is knocked-out of the nucleus with high momentum transfer and high missing momentum, show that in 12C the neutron-proton pairs are nearly twenty times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

Subedi, R; Monaghan, P; Anderson, B D; Aniol, K; Annand, J; Arrington, J; Benaoum, H; Benmokhtar, F; Bertozzi, W; Boeglin, W; Chen, J -P; Choi, Seonho; Cisbani, E; Craver, B; Frullani, S; Garibaldi, F; Gilad, S; Gilman, R; Glamazdin, O; Hansen, J -O; Higinbotham, D W; Holmstrom, T; Ibrahim, H; Igarashi, R; De Jager, C W; Jans, E; Jiang, X; Kaufman, L; Kelleher, A; Kolarkar, A; Kumbartzki, G; LeRose, J J; Lindgren, R; Liyanage, N; Margaziotis, D J; Markowitz, P; Marrone, S; Mazouz, M; Meekins, D; Michaels, R; Moffit, B; Perdrisat, C F; Piasetzky, E; Potokar, M; Punjabi, V; Qiang, Y; Reinhold, J; Ron, G; Rosner, G; Saha, A; Sawatzky, B; Shahinyan, A; Širca, S; Slifer, K; Solvignon, P; Sulkosky, V; Urciuoli, G; Voutier, E; Watson, J W; Weinstein, L B; Wojtsekhowski, B; Wood, S; Zheng, X -C; Zhu, L; 10.1126/science.1156675

2009-01-01

234

Probing Cold Dense Nuclear Matter

International Nuclear Information System (INIS)

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

235

Probing cold dense nuclear matter.

Energy Technology Data Exchange (ETDEWEB)

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

Subedi, R.; Monaghan, P.; Shneor, R.; Anderson, B. D.; Aniol, K.; Arrington, J.; Physics; Kent State Univ.; Tel Aviv Univ.; California State Univ. Los Angeles

2008-06-13

236

Hadron-quark phase transition in asymmetric matter with boson condensation

International Nuclear Information System (INIS)

In the present work we study the hadron-quark phase transition with boson condensation in asymmetric matter by investigating the binodal surface and extending it to finite temperature to mimic the QCD phase diagram. We consider a system with two conserved charges (isospin and baryon densities) using the Gibbs' criteria for phase equilibrium. To obtain these conditions we use two different models for the two possible phases, namely, the nonlinear Walecka model (NLWM) for the hadron matter (also including hyperons) and the MIT bag model for the quark phase. It is shown that the phase transition is very sensitive to the density dependence of the equation of state and the symmetry energy. For an isospin asymmetry of 0.2 and a mixed phase with a fraction of 20% of quarks, a transition density in the interval 2?0t0 was obtained for temperatures 30< T<65 MeV.

237

Possible Indication of Momentum-Dependent Asymmetric Dark Matter in the Sun

Broad disagreement persists between helioseismological observables and predictions of solar models computed with the latest surface abundances. Here we show that most of these problems can be solved by the presence of asymmetric dark matter coupling to nucleons as the square of the momentum q exchanged in the collision. We compute neutrino fluxes, small frequency separations, surface helium abundances, sound speed profiles, and convective zone depths for a number of models, showing more than a 6 ? preference for q2 models over others, and over the standard solar model. The preferred mass (3 GeV) and reference dark matter-nucleon cross section (10-37 cm2 at q0=40 MeV ) are within the region of parameter space allowed by both direct detection and collider searches.

Vincent, Aaron C.; Scott, Pat; Serenelli, Aldo

2015-02-01

238

Possible indication of momentum-dependent asymmetric dark matter in the sun.

Broad disagreement persists between helioseismological observables and predictions of solar models computed with the latest surface abundances. Here we show that most of these problems can be solved by the presence of asymmetric dark matter coupling to nucleons as the square of the momentum q exchanged in the collision. We compute neutrino fluxes, small frequency separations, surface helium abundances, sound speed profiles, and convective zone depths for a number of models, showing more than a 6? preference for q^{2} models over others, and over the standard solar model. The preferred mass (3 GeV) and reference dark matter-nucleon cross section (10^{-37}??cm^{2} at q_{0}=40??MeV) are within the region of parameter space allowed by both direct detection and collider searches. PMID:25768751

Vincent, Aaron C; Scott, Pat; Serenelli, Aldo

2015-02-27

239

BCS-BEC crossovers and unconventional phases in dilute nuclear matter

We study the phase diagram of isospin-asymmetrical nuclear matter in the density-temperature plane, allowing for four competing phases of nuclear matter: (i) the unpaired phase; (ii) the translationally and rotationally symmetric, but isospin-asymmetrical BCS condensate; (iii) the current-carrying Larkin-Ovchinnikov-Fulde-Ferrell phase; and (iv) the heterogeneous phase-separated phase. The phase diagram of nuclear matter composed of these phases features two tricritical points, in general, as well as crossovers from the asymmetrical BCS phase to a Bose-Einstein condensate (BEC) of deuterons plus a neutron gas, for both the homogeneous superfluid phase (at high temperatures) and the heterogeneous phase (at low temperatures). The BCS-BEC-type crossover in the condensate occurs as the density is reduced. We analyze in detail some intrinsic properties of these phases, including the Cooper-pair wave function, the coherence length, the occupation numbers of majority and minority nucleonic components, and the dispersion relations of quasiparticle excitations about the ground state. We show by explicit examples that the physics of the individual phases and the transition from weak to strong coupling can be well understood by tracing the behavior of these quantities.

Stein, Martin; Sedrakian, Armen; Huang, Xu-Guang; Clark, John W.

2014-12-01

240

Towards Nuclear Physics of OHe Dark Matter

The nonbaryonic dark matter of the Universe can consist of new stable charged particles, bound in heavy "atoms" by ordinary Coulomb interaction. If stable particles $O^{--}$ with charge -2 are in excess over their antiparticles (with charge +2), the primordial helium, formed in Big Bang Nucleosynthesis, captures all $O^{--}$ in neutral "atoms" of O-helium (OHe). Interaction with nuclei plays crucial role in the cosmological evolution of OHe and in the effects of these dark atoms as nuclear interacting dark matter. Slowed down in terrestrial matter OHe atoms cause negligible effects of nuclear recoil in underground detectors, but can experience radiative capture by nuclei. Local concentration of OHe in the matter of detectors is rapidly adjusted to the incoming flux of cosmic OHe and possess annual modulation due to Earth's orbital motion around the Sun. The potential of OHe-nucleus interaction is determined by polarization of OHe by the Coulomb and nuclear force of the approaching nucleus. Stark-like effect b...

Khlopov, Maxim Yu; Soldatov, Evgeny Yu

2011-01-01

241

The Microscopic Approach to Nuclear Matter and Neutron Star Matter

We review a variety of theoretical and experimental investigations aimed at improving our knowledge of the nuclear matter equation of state. Of particular interest are nuclear matter extreme states in terms of density and/or isospin asymmetry. The equation of state of matter with unequal concentrations of protons and neutrons has numerous applications. These include heavy-ion collisions, the physics of rare, short-lived nuclei and, on a dramatically different scale, the physics of neutron stars. The "common denominator" among these (seemingly) very different systems is the symmetry energy, which plays a crucial role in both the formation of the neutron skin in neutron-rich nuclei and the radius of a neutron star (a system 18 orders of magnitude larger and 55 orders of magnitude heavier). The details of the density dependence of the symmetry energy are not yet sufficiently constrained. Throughout this article, our emphasis will be on the importance of adopting a microscopic approach to the many-body problem, w...

Sammarruca, Francesca

2010-01-01

242

Probing nuclear matter with jet conversions

International Nuclear Information System (INIS)

We discuss the flavor of leading jet partons as a valuable probe of nuclear matter. We point out that the coupling of jets to nuclear matter naturally leads to an alteration of jet chemistry even at high transverse momentum pT. In particular, quantum chromodynamics (QCD) jets coupling to a chemically equilibrated quark gluon plasma in nuclear collisions will lead to hadron ratios at high transverse momentum pT that can differ significantly from their counterparts in p+p collisions. Flavor measurements could complement energy loss as a way to study interactions of hard QCD jets with nuclear matter. Roughly speaking they probe the inverse mean free path 1/? while energy loss probes the average squared momentum transfer ?2/?. We present some estimates for the rate of jet conversions in a consistent Fokker-Planck framework and their impact on future high-pT identified hadron measurements at RHIC and LHC. We also suggest some novel observables to test flavor effects

243

Probing nuclear matter with jet conversions

We discuss the flavor of leading jet partons as a valuable probe of nuclear matter. We point out that the coupling of jets to nuclear matter naturally leads to an alteration of jet chemistry even at high transverse momentum pT. In particular, quantum chromodynamics (QCD) jets coupling to a chemically equilibrated quark gluon plasma in nuclear collisions will lead to hadron ratios at high transverse momentum pT that can differ significantly from their counterparts in p+p collisions. Flavor measurements could complement energy loss as a way to study interactions of hard QCD jets with nuclear matter. Roughly speaking they probe the inverse mean free path 1/? while energy loss probes the average squared momentum transfer ?2/?. We present some estimates for the rate of jet conversions in a consistent Fokker-Planck framework and their impact on future high-pT identified hadron measurements at RHIC and LHC. We also suggest some novel observables to test flavor effects.

Liu, W.; Fries, R. J.

2008-05-01

244

Probing Nuclear Matter with Jet Conversions

We discuss the flavor of leading jet partons as a valuable probe of nuclear matter. We point out that the coupling of jets to nuclear matter naturally leads to an alteration of jet chemistry even at high transverse momentum $p_T$. In particular, QCD jets coupling to a chemically equilibrated quark gluon plasma in nuclear collisions, will lead to hadron ratios at high transverse momentum $p_T$ that can differ significantly from their counterparts in $p+p$ collisions. Flavor measurements could complement energy loss as a way to study interactions of hard QCD jets with nuclear matter. Roughly speaking they probe the inverse mean free path $1/\\lambda$, while energy loss probes the average momentum transfer $\\mu^2/\\lambda$. We present some estimates for the rate of jet conversions in a consistent Fokker-Planck framework and their impact on future high-$p_T$ identified hadron measurements at RHIC and LHC. We also suggest some novel observables to test flavor effects.

Liu, W

2008-01-01

245

Quartic isospin asymmetry energy of nuclear matter from chiral pion-nucleon dynamics

Based on a chiral approach to nuclear matter, we calculate the quartic term in the expansion of the equation of state of isospin-asymmetric nuclear matter. The contributions to the quartic isospin asymmetry energy $A_4(k_f)$ arising from $1\\pi$-exchange and chiral $2\\pi$-exchange in nuclear matter are calculated analytically together with three-body terms involving virtual $\\Delta(1232)$-isobars. From these interaction terms one obtains at saturation density $\\rho_0 = 0.16\\,$fm$^{-3}$ the value $A_4(k_{f0})= 1.5\\,$MeV, more than three times as large as the kinetic energy part. Moreover, iterated $1\\pi$-exchange exhibits components for which the fourth derivative with the respect to the isospin asymmetry parameter $\\delta$ becomes singular at $\\delta =0$. The genuine presence of a non-analytical term $\\delta^4 \\ln|\\delta|$ in the expansion of the energy per particle of isospin-asymmetric nuclear matter is demonstrated by evaluating a s-wave contact interaction at second order.

Kaiser, N

2015-01-01

246

Sub-saturation phases of nuclear matter

International Nuclear Information System (INIS)

We study the zero-temperature equation of state of isospin-symmetric nuclear matter below saturation density by minimizing the energy of the nucleons in a periodic cubic cell at each mean density. We take the energy per nucleon to be the Thomas-Fermi approximation to the Skyrme III functional and include the Coulomb energy. We find several phase transitions between different topologies of matter, going from spheres to rods to slabs to tubes to bubbles with increasing density, and discuss their implications for models of supernova core collapse. (orig.)

247

D-mesons and charmonium states in hot isospin asymmetric strange hadronic matter

International Nuclear Information System (INIS)

The study of the medium modifications of hadrons is an important topic of research in strong interaction physics, which is of relevance in the heavy-ion collision experiments as well as in nuclear astrophysics. The study of the mass modifications of D mesons is relevant in understanding their production as well as collective flow in the heavy-ion collision experiments. The present paper is devoted to the study of medium modifications of D mesons in isospin asymmetric strange hadronic medium at finite temperatures

248

Wanted! Nuclear Data for Dark Matter Astrophysics

Astronomical observations from small galaxies to the largest scales in the universe can be consistently explained by the simple idea of dark matter. The nature of dark matter is however still unknown. Empirically it cannot be any of the known particles, and many theories postulate it as a new elementary particle. Searches for dark matter particles are under way: production at high-energy accelerators, direct detection through dark matter-nucleus scattering, indirect detection through cosmic rays, gamma rays, or effects on stars. Particle dark matter searches rely on observing an excess of events above background, and a lot of controversies have arisen over the origin of observed excesses. With the new high-quality cosmic ray measurements from the AMS-02 experiment, the major uncertainty in modeling cosmic ray fluxes is in the nuclear physics cross sections for spallation and fragmentation of cosmic rays off interstellar hydrogen and helium. The understanding of direct detection backgrounds is limited by poor knowledge of cosmic ray activation in detector materials, with order of magnitude differences between simulation codes. A scarcity of data on nucleon spin densities blurs the connection between dark matter theory and experiments. What is needed, ideally, are more and better measurements of spallation cross sections relevant to cosmic rays and cosmogenic activation, and data on the nucleon spin densities in nuclei.

Gondolo, P.

2014-06-01

249

Charge-dependent directed flow in asymmetric nuclear collisions

The directed flow of identified hadrons is studied within the parton-hadron-string-dynamics (PHSD) approach for the asymmetric system Cu+Au in non-central collisions at $\\sqrt{s_{NN}}$ = 200 GeV. It is emphasized that due to the difference in the number of protons of the colliding nuclei an electric field emerges which is directed from the heavy to the light nucleus. This strong electric field is only present for about 0.25 fm/c at $\\sqrt{s_{NN}}$ = 200 GeV and leads to a sp...

Voronyuk, V.; Toneev, V. D.; Voloshin, S. A.; Cassing, W.

2014-01-01

250

Nucleon properties inside compressed nuclear matter

Our model calculations performed in the frame of the Bag Model (BM) approach show the modifications of nucleon mass, nucleon radius and a Parton Distribution Function (PDF) in Nuclear Matter (NM) above the saturation point. They originated from the pressure correction to the nucleon rest energy. Similar correction leads to conservation of a nuclear longitudinal momenta - essential in the explanation of the EMC effect at the saturation point of NM. Presented finite pressure corrections are generalization of the Hugenholtz-van Hove theorem valid for finite nucleon sizes inside NM.

Rozynek, Jacek

2014-01-01

251

Friedel oscillations in relativistic nuclear matter

We calculate the low-momentum N-N effective potential obtained in the OBE approximation, inside a nuclear plasma at finite temperature, as described by the relativistic \\sigma - \\omega model. We analyze the screening effects on the attractive part of the potential in the intermediate range as density or temperature increase. In the long range the potential shows Friedel-like oscillations instead of the usual exponential damping. These oscillations arise from the sharp edge of the Fermi surface and should be encountered in any realistic model of nuclear matter.

Alonso, J D; Pérez, A

1994-01-01

252

D-mesons and charmonium states in hot isospin asymmetric strange hadronic matter

International Nuclear Information System (INIS)

We study the properties of D and anti D mesons in hot isospin asymmetric strange hadronic matter, arising due to their interactions with the hadrons in the hyperonic medium. The interactions of D and anti D mesons with these light hadrons are derived by generalizing the chiral SU(3) model used for the study of hyperonic matter to SU(4). The nucleons, hyperons, the scalar isoscalar meson, ? and the scalar-isovector meson, ? as modified in the strange hadronic matter, modify the masses of D and anti D mesons. It is found that, as compared to the anti D mesons (anti D0, D-), the properties of the D mesons (D0, D +) are more sensitive to the isospin asymmetry at high densities. On the other hand, the effects of strangeness fraction are found to be more dominant for the anti D mesons as compared to the D mesons and these modifications are observed to be particularly appreciable at high densities. We also study the mass modifications of the charmonium states J/?, ?(3686) and ?(3770) in the isospin asymmetric strange hadronic matter at finite temperatures and investigate the possibility of the decay of the charmonium states into D anti D pairs in the hot hadronic medium. The mass modifications of these charmonium states arise due to their interaction with the gluon condensates of QCD, simulated by a scalar dilaton field introduced to incorporate the broken scale invariance of QCD within the effective chiral model. The effects effective chiral model. The effects of finite quark masses are taken into account in the trace of the energy momentum tensor in QCD, while investigating the medium modification of the charmonium masses through the modification of the gluon condensate in the medium. We also compute the partial decay widths of the charmonium states to the D anti D pairs in the hadronic medium. The strong dependence on density of the in-medium properties of the D, anti D and the charmonium states, as well as the partial decay widths of charmonium states to D anti D pairs, found in the present investigation, will be of direct relevance in observables like open charm enhancement as well as J/? suppression in the compressed baryonic matter (CBM) experiments at the future Facility for Antiproton and Ion Research, GSI, where the baryonic matter at high densities is planned to be produced. (orig.)

253

Nucleons interacting with excited nuclear matter

International Nuclear Information System (INIS)

Full text: In microscopic approaches of precompound reactions the dependence of the optical potential on the excitation is still an open question, which might heal some deficiencies of present day calculations. For the interesting energy regime the nuclear matter approach is well suited, which is based on the g-matrix obtained from Bethe-Goldstone equation. In order to account for the excitation of nuclear matter a simple model of excitation has been developed and a correspondingly refined Pauli-operator has been formulated. The dependence of the g-matrix on the excitation as well as on the incident energy is studied. In addition, the impact of excitation on optical potentials and cross sections is discussed. (author)

254

Collective modes of infinite nuclear matter

International Nuclear Information System (INIS)

In this paper we study the longitudinal collective vibrations of infinite nuclear matter in the long wavelength limit. We present an alternative method for solving the Landau equations which allows analytical expression for the response function, the odd sum rules and the strength of the modes. We solve the theory for a selection of Skyrme interactions and we also consider the properties of the ground state of the system specifically associated with the four collective states which exist in nuclear matter. The relationship between the quantum mechanical response function and the corresponding classical hydrodynamical quantity is explored and the approximate results obtained through sum rules are compared with the exact solutions of the RPA equations. Finally the Landau parameters obtained with the Skyrme forces are tested against the antisymmetry property of the foward particle-hole scattering amplitude on the Fermi surface and the enhancement factor in the photonuclear dipole sum rule

255

A variational theory of nuclear matter. III

International Nuclear Information System (INIS)

Developments in a variational theory of nuclear matter for treating v6 homework potentials that include central, spin, isospin and tensor operators are reported. The central, spin, isospin and tensor correlations are parametrized by their range d, and the magnitudes of the non-central correlations. Integral equations are used to sum Fermi hypernetted chain, and single operator chain diagrams. All commutators required to evaluate the energy from the operator chain functions are treated exactly, and the energy is found to have a minimum with respect to variations in all parameters. Results of calculations with v6 models based on the Reid and Bethe-Johnson potentials are reported. A crude estimate of the effect of the spin-orbit potentials on nuclear matter binding energy indicates that it could be significant. (Auth.)

256

We present a relativistic chiral effective theory for symmetric and asymmetric nuclear matter taken in the Hartree-Fock scheme. The nuclear binding is insured by a background chiral invariant scalar field associated with the radial fluctuations of the chiral quark condensate. Nuclear matter saturation is obtained once the scalar response of the nucleon generating three-body repulsive forces is incorporated. For these parameters related to the scalar sector and quark confinement mechanism inside the nucleon we make use of an analysis of lattice results on the nucleon mass evolution with the quark mass. The other parameters are constrained as most as possible by standard hadron and nuclear phenomenology. Special attention is paid to the treatment of the propagation of the scalar fluctuations. The rearrangement terms associated with in-medium modified mass and coupling constants are explicitly included to satisfy the Hugenholtz -Van Hove theorem. We point out the important role of the tensor piece of the rho exc...

Massot, E

2008-01-01

257

The inclusive transverse response of nuclear matter

The electromagnetic inclusive transverse response of nuclear matter at saturation density is studied within the correlated basis function perturbation theory for momentum transfers q from 300 to 550 MeV/c. The correlation operator includes a Jastrow component, accounting for the short range repulsion, as well as longer range spin, tensor and isospin ones. The Schiavilla- Pandharipande-Riska model for the two-body electromagnetic currents, satisfying the continuity equation w...

Fabrocini, A.

1996-01-01

258

Spin responses in correlated nuclear matter

Correlated Basis Function theory is used to compute the longitudinal and transverse dynamical spin responses in nuclear matter. The effect of the tensor correlations, induced by realistic nucleon-nucleon interactions, is studied in the isoscalar and isovector channels. Their inclusion brings the values of the ratio between the longitudinal and transverse responses close to unity and to the experimental estimates in medium-heavy nuclei.

Fabrocini, Adelchi

1994-02-01

259

Nuclear matter and its equation of state

International Nuclear Information System (INIS)

We can estimate the nuclear bulk compressibility from the excitation energy of the monopole vibration mode, which represents a density oscillation about rho0, of extremely small magnitude (a few percent) only. A description of the monopole excitation energy systematics has been obtained by assuming a parabolic shape about rho0 for the energy-density relation of cold nuclear matter. This implies a linear pressure response to small density changes inside nuclear matter. It enables one to define a nuclear 'sound' mode and the sound velocity turns out to be vsub(s)proportional0.2 c. All of this could be known only for small excursions from rho0 as long as we were unable to subject nuclei to extreme stresses. The study of head-on collisions of heavy nuclei at high energy has removed this limitation. In these reactions we are reproducing under laboratory conditions the extremely violent transformations of matter occuring in the cosmic and stellar evolution. From the quark-gluon stage of the Big Bang, prior to hadronic freeze-out, to the supernova these cosmic events require an understanding of matter bulk properties over an enormous range of density, from about 10 times rho0 down to about 10-3 rho0. We will approach them through the compression-expansion-freeze-out cycle of central nucleus-nucleus collisions in the energy range from 50 MeV per projectile nucleon, corresponding to the compression barrier, upwards to 225 GeV/A (the top energy of the CERN SPS), and further into the TeV/A range by observation of events induced by cosmic ray nuclei. In this article I describe some of the results recently obtained at the BEVALAC, i.e. in the GeV/A domain. (orig./HSI)

260

Nuclear matter with off-shell propagation

Symmetric nuclear matter is studied within the conserving, self-consistent T-matrix approximation. This approach involves off-shell propagation of nucleons in the ladder diagrams. The binding energy receives contributions from the background part of the spectral function, away form the quasiparticle peak. The Fermi energy at the saturation point fulfills the Hugenholz-Van Hove relation. In comparison to the Brueckner-Hartree-Fock approach, the binding energy is reduced and the equation of state is harder

Bozek, P

2002-01-01

261

Nuclear matter with off-shell propagation

Symmetric nuclear matter is studied within the conserving, self-consistent T-matrix approximation. This approach involves off-shell propagation of nucleons in the ladder diagrams. The binding energy receives contributions from the background part of the spectral function, away form the quasiparticle peak. The Fermi energy at the saturation point fulfills the Hugenholz-Van Hove relation. In comparison to the Brueckner-Hartree-Fock approach, the binding energy is reduced and t...

Bozek, P.

2002-01-01

262

Equation of state of dense nuclear matter

International Nuclear Information System (INIS)

An equation of state for cold nuclear matter for the region of densities pnm-4pnm, where pnm is empirical nuclear-matter density, is constructed. We begin from the detailed calculation of Day and Wiringa for the two-body interactions; these give a saturation density of ? 2 pnm. This density is brought down to pnm by the addition of relativistic corrections. Additional binding is obtained from three-body forces. A reasonable picture is obtained with the Day-Wiringa compression modules for the two-body calculation, but the picture can be further improved by choosing this to be smaller. Analysis shows that hot nuclear matter formed in heavy ion collisions demands a very stiff equation of state. We understand this as arising from the strong velocity dependence in the real part of the optical model potential which follows chiefly from the Lorentz character of the interactions, the vector mean field growing with increasing density and the scalar one decreasing. This gives a substantial repulsive contribution to the energy per particle and produces a stiff effective equation of state for several hundred MeV heavy-ion collisions. With increasing degree of equilibration the magnitude of the repulsive energy decreases since equilibration decreases the effective momentum. Given the strong velocity dependence in the interaction, the hot equation of state can be reconciled with the cool one. (orig./HSI)l one. (orig./HSI)

263

Nuclear matter theory: a status report

International Nuclear Information System (INIS)

Recent years have brought considerable improvement in the quality of both diagrammatic and variational many-body techniques. There appears to be general agreement that realistic NN potentials give a reasonable binding energy but an equilibrium density that is some 75% larger than the empirical value. Both conventional and chiral models of genuine manybody forces offer mechanisms for removing this discrepancy with each providing a simple picture for the required additional attraction for /rho/ 0. Neither approach is presently able to make a priori estimates of the magnitude of this effect with the delicacy required by the nuclear matter problem. Nor is it clear how to merge these pictures. We should not anticipate quick answers to these questions. One suitable interim strategy is to assume that many-body forces of the form suggested by either conventional or chiral pictures are responsible for the remaining discrepancy and to adjust parameters in such model many-body forces to restore agreement between theory and experiment. This might seem to be a summary dismissal of the standard nuclear matter problem. It should rather be regarded as revealing the next and richer layer of the nuclear matter problem

264

Reactions of nuclear fusion in condensed matter

International Nuclear Information System (INIS)

Analysis of energy losses of fast particles indicates that the most probable energy range for reactions of nuclear fusion in condensed matter lies within the limits from ?0 to ?2 of normalized energy. During interaction of accelerated deuterium ions from plasma glow discharge with various elements, the dependence of nuclear fusion rate on ion bombardment parameters is of threshold character. Four-fold increase of specific power results in growth of tritium yield rate by four order of magnitude, up to 109 at./s, neutron-to-tritium yield ratio being equal to 10-7 to 10-9. The ion energy was estimated to be in the range (40...80) · 1.6 · 10-19 J. The measurements of thermal effects, isotopic composition of the target and the radiography show that nuclear fusion reactions between deuterium and target atoms may occur at comparatively low energies

265

A Naturally Light Sterile neutrino in an Asymmetric Dark Matter Model

A recently proposed asymmetric mirror dark matter model where the mirror sector is connected with the visible one by a right handed neutrino portal, is shown to lead naturally to a 3+1 active-sterile neutrino spectrum, if the portal consists only of two right handed neutrinos. At the tree level the model has four massless neutrino states, three active and one sterile. The active neutrinos pick up tiny masses via the minimal radiative inverse seesaw mechanism at the one loop level. The loop effects also generate the large solar and atmospheric mixings, as well as the observed reactor mixing for certain range of parameters of the model. The dominant contribution to the sterile neutrino mass ($\\sim$ eV) arises from the gravitationally induced dimension-5 operators. Generating active-sterile mixing requires a two Higgs doublet extension of SM and a small mixing between the ordinary and mirror Higgs fields, which occurs naturally in mirror models.

Zhang, Yongchao; Mohapatra, Rabindra N

2013-01-01

266

Transport of nucleons in nuclear matter

International Nuclear Information System (INIS)

Full text: Earlier we have developed the unified calculation method based on expansion of a nuclear matter distribution function over complete system of basis functions from discrete and continual parts. It is shown that the developed theory can be applied to description of nucleon gas thermalization in highly excited nucleus after completion of fast stage of intranuclear cascade caused by nucleons with the energies of 100 - 1000 MeV [1-3]. Using non-linear kinetic equations, which take into account the Pauli principles, the transport of nucleons in nuclear matter was solved by using linearization. In accordance with the unified description methodology and selecting the weighing functions to be equal to the Fermi distribution, the effective and fast-converging algorithm for solution of non-linear equation of nucleon gas thermalization in excited nucleus was developed. Approximated equations depending on geometric parameter of nuclear system ? ?(B2) for the eigenvalues are derived. Formula for parameters characterizing thermalization ?ij(t), ?(t) and diffusion Dij(t) properties of nuclear matter and, in contrary to the linearized case, depending on time as well as those for time-dependence of thermalization on non-linear terms are derived by taking into account the non-linear effects in the closed form. It is shown that the spectrum of nucleons in the remnant excited nucleus progresses to equilibrium (Fermi) state as a result of sequential local pair collisions. But, because of finite sizes and transparency of nucleus, with hot nucleons emitting from the remnant nucleus its temperature decreases to T = 0oK, nucleons cool down to equilibrium at T = 0oK, the spectrum of nucleons stayed in the nucleus will be a step-like function ?(PF-P)

267

Charge-dependent directed flow in asymmetric nuclear collisions

The directed flow of identified hadrons is studied within the parton-hadron-string-dynamics (PHSD) approach for the asymmetric system Cu+Au in non-central collisions at $\\sqrt{s_{NN}}$ = 200 GeV. It is emphasized that due to the difference in the number of protons of the colliding nuclei an electric field emerges which is directed from the heavy to the light nucleus. This strong electric field is only present for about 0.25 fm/c at $\\sqrt{s_{NN}}$ = 200 GeV and leads to a splitting of the directed flow $v_1$ for particles with the same mass but opposite electric charges in case of an early presence of charged quarks and antiquarks. The microscopic calculations of the directed flow for $\\pi^\\pm, K^\\pm, p$ and $\\bar{p}$ are carried out in the PHSD by taking into account the electromagnetic field induced by the spectators as well as its influence on the hadronic and partonic quasiparticle trajectories. It is shown that the splitting of the directed flow as a function of pseudorapidity $\\eta$ and in particular as...

Voronyuk, V; Voloshin, S A; Cassing, W

2014-01-01

268

Chiral quark dynamics in dense nuclear matter

International Nuclear Information System (INIS)

We consider a new approach to the description of dense nuclear matter in the framework of chirally symmetric, quark-based hadron models. As previously in the Skyrme model, the dense environment is described in terms of hyperspherical cells of unit baryon number. The intrinsic curvature of these cells generates a new gauge interaction for the quark fields which mediates interactions with the ambient matter. We apply this approach to the Nambu-Jona-Lasinio (NJL) model, construct its curved-space quark propagator and solve the ladder Bethe-Salpeter equation for the pion. We find a high-density phase transition to chiral restoration, discuss the density dependence of the chiral order parameter and of the pion properties, and compare with results of the conventional chemical-potential approach. The new approach can additionally describe baryon-density-free cavities in the dense medium. ((orig.))

269

Elementary diagrams in nuclear and neutron matter

International Nuclear Information System (INIS)

Variational calculations of nuclear and neutron matter are currently performed using a diagrammatic cluster expansion with the aid of nonlinear integral equations for evaluating expectation values. These are the Fermi hypernetted chain (FHNC) and single-operator chain (SOC) equations, which are a way of doing partial diagram summations to infinite order. A more complete summation can be made by adding elementary diagrams to the procedure. The simplest elementary diagrams appear at the four-body cluster level; there is one such E4 diagram in Bose systems, but 35 diagrams in Fermi systems, which gives a level of approximation called FHNC/4. We developed a novel technique for evaluating these diagrams, by computing and storing 6 three-point functions, Sxyz(r12, r13, r23), where xyz (= ccd, cce, ddd, dde, dee, or eee) denotes the exchange character at the vertices 1, 2, and 3. All 35 Fermi E4 diagrams can be constructed from these 6 functions and other two-point functions that are already calculated. The elementary diagrams are known to be important in some systems like liquid 3He. We expect them to be small in nuclear matter at normal density, but they might become significant at higher densities appropriate for neutron star calculations. This year we programmed the FHNC/4 contributions to the energy and tested them in a number of simple model cases, including liquid 3He and Bethe's hluding liquid 3He and Bethe's homework problem. We get reasonable, but not exact agreement with earlier published work. In nuclear and neutron matter with the Argonne v14 interaction these contributions are indeed small corrections at normal density and grow to only 5-10 MeV/nucleon at 5 times normal density

270

Spin-asymmetry energy of nuclear matter

We calculate the density-dependent spin-asymmetry energy $S(k_f)$ of isospin-symmetric nuclear matter in the three-loop approximation of chiral perturbation theory. The interaction contributions to $S(k_f)$ originate from one-pion exchange, iterated one-pion exchange, and (irreducible) two-pion exchange with no, single, and double virtual $\\Delta$-isobar excitation. We find that the truncation to $1\\pi$-exchange and iterated $1\\pi$-exchange terms (which leads already to a go...

Kaiser, N.

2004-01-01

271

Brueckner-Bethe calculations of nuclear matter

International Nuclear Information System (INIS)

The calculations described here are based on the following model. The nucleus is treated as a collection of point nucleons that obey the nonrelativistic Schroedinger equation and interact through a 2-body potential. The potential has a one-pion-exchange tail, and in some cases additional constraints based on theory are imposed. Typical potentials of interest are Hamada-Johnston, Reid, Paris, and Bonn. The basic question is whether these potentials can account for the saturation properties of nuclei and nuclear matter. (orig./HSI)

272

Pion condensation in symmetric nuclear matter

International Nuclear Information System (INIS)

We have investigated the possibility of pion condensation in symmetric nuclear matter using a model of pion-nucleon interaction based essentially on chiral SU(2) x SU(2) symmetry. We have found that pion condensation is not possible for any finite value of the density. Consequently, no critical opalescence phenomenon is likely to be seen in pion-nucleus scattering nor is it likely to be possible to explain the EMC effect in terms of an increased number of pions in the nucleus. (author)

273

Strange mesons in dense nuclear matter

International Nuclear Information System (INIS)

Experimental data on the production of kaons and antikaons in heavy ion collisions at relativistic energies are reviewed with respect to in-medium effects. The K-/K+ ratios measured in nucleus-nucleus collisions are 1-2 orders of magnitude larger than in proton-proton collisions. The azimuthal angle distributions of K+ mesons indicate a repulsive kaon-nucleon potential. Microscopic transport calculations consistently explain both the yields and the emission patterns of kaons and antikaons when assuming that their properties are modified in dense nuclear matter. The K+ production excitation functions measured in light and heavy collision systems provide evidence for a soft nuclear equation-of-state. (orig.)

274

Pions in nuclear matter and nuclei

International Nuclear Information System (INIS)

The Fermi-averaged pion-nuclear matter scattering matrix in the region of the N*(1232) resonance is calculated by use of two models, one incorporating a single-channel (l = 1) potential separable in the pion-nucleon relative coordinate and a realistic nucleon pseudopotential to investigate the effects of the Pauli principle and nucleon recoil and binding, and the other fixing the positions of the nucleons to investigate the effects of two-nucleon scattering and correlations. The main results are that nucleon recoil and the Pauli principle can combine in a manner that significantly enhances the averaged scattering matrix element by allowing the trajectory of the pole in that matrix element to intersect the real axis, an effect extended to higher incident pion momentum by the binding due to the pseudopotential; that two-nucleon correlations in the Fermi sea ground state introduce only a small effect (approximately ten percent) to the scattering; and that two-nucleon encounters drastically change the size and shape of the resulting pion-nuclear matter optical potential and thus, invalidate the application of a lowest-order optical potential in this energy regime. An estimate utilizing the exact model wave functions is made of the matrix elements describing pion-two-nucleon scattering and pion absorption and re-emission on two nucleons; these two processes are found to be approximately of equal importance

275

Inclusive transverse response of nuclear matter

The electromagnetic inclusive transverse response of nuclear matter at saturation density is studied within the correlated basis function perturbation theory for momentum transfers q from 300 to 550 MeV/c. The correlation operator includes a Jastrow component, accounting for the short range repulsion, as well as longer range spin, tensor, and isospin ones. Up to correlated one-particle-one-hole intermediate states are considered. The spreading due to the decay of particle (hole) states into two-particle-one-hole (two-hole-one-particle) states is considered via a realistic optical potential model. The Schiavilla-Pandharipande-Riska model for the two-body electromagnetic currents, constructed so as to satisfy the continuity equation with realistic v14 potentials, is adopted. Currents due to intermediate ?-isobar excitations are also included. The global contribution of the two-body currents turns out to be positive and provides an enhancement of the one-body transverse response ranging from ~20% for the lower momenta to ~10% for the higher ones. This finding is in agreement with the Green's function Monte Carlo studies of the transverse Euclidean response in A=3,4 nuclei and contradicts previous results obtained within the Fermi gas and shell models. The tensor-isospin component of the correlation is found to be the leading factor responsible for such a behavior. The nuclear matter response is compared to recent experimental data on 40Ca and 56Fe.

Fabrocini, Adelchi

1997-01-01

276

Incomprehensibility in finite nuclei and nuclear matter

The incompressibility (compression modulus) $K_{\\rm 0}$ of infinite symmetric nuclear matter at saturation density has become one of the major constraints on mean-field models of nuclear many-body systems as well as of models of high density matter in astrophysical objects and heavy-ion collisions. We present a comprehensive re-analysis of recent data on GMR energies in even-even $^{\\rm 112-124}$Sn and $^{\\rm 106,100-116}$Cd and earlier data on 58 $\\le$ A $\\le$ 208 nuclei. The incompressibility of finite nuclei $K_{\\rm A}$ is expressed as a leptodermous expansion with volume, surface, isospin and Coulomb coefficients $K_{\\rm vol}$, $K_{\\rm surf}$, $K_\\tau$ and $K_{\\rm coul}$. \\textit{Assuming} that the volume coefficient $K_{\\rm vol}$ is identified with $K_{\\rm 0}$, the $K_{\\rm coul}$ = -(5.2 $\\pm$ 0.7) MeV and the contribution from the curvature term K$_{\\rm curv}$A$^{\\rm -2/3}$ in the expansion is neglected, compelling evidence is found for $K_{\\rm 0}$ to be in the range 250 $ < K_{\\rm 0} < $ 315 MeV,...

Stone, J R; Moszkowski, S A

2014-01-01

277

Recent Advances in Microscopic Approaches to Nuclear Matter and Symmetry Energy

Directory of Open Access Journals (Sweden)

Full Text Available Nuclear matter is a convenient theoretical laboratory to test many-body theories. When neutron and proton densities are different, the isospin dependence of the nuclear force gives rise to the symmetry energy term in the equation of state. This quantity is a crucial mechanism in the formation of the neutron skin in nuclei, as well as in other systems and phenomena involved in the dynamics of neutrons and protons in neutron-rich systems, such as isospin-asymmetric heavy-ion collisions. In this article, we will review phenomenological facts about the symmetry energy and recent experimental efforts to constrain its density dependence and related quantities. We will then review our microscopic approach to the equation of state of symmetric and asymmetric nuclear matter and present a corresponding set of predictions. Our calculations utilize the Dirac–Brueckner–Hartree–Fock method and realistic meson-theoretic nucleon-nucleon potentials. Chiral perturbation theory is an alternative approach, based on a well-defined scheme, which allows one to develop nuclear forces at each order of the chiral expansion. We will present and discuss predictions based on chiral perturbation theory, where we employ consistent two- and three-body chiral interactions. Throughout the article, one of the focal points is the importance of pursuing ab initio methods towards a deeper understanding of the many-body system.

Francesca Sammarruca

2014-10-01

278

Reflection asymmetric nuclear shapes obtained by solving a differential equation

International Nuclear Information System (INIS)

The equilibrium nuclear shapes in fission theory are usually obtained by minimizing the deformation energy for a given surface equation. In the following we present a method allowing to obtain a very general equilibrium (saddle-point) shape as a solution of a differential equation without an a priori introduction of a shape parametrization. In the approach based on a pure liquid drop model (LDM), saddle-point shapes are always reflection symmetric: the deformation energy increases with the mass-asymmetry parameter ? = (A1 - A2)/(A1 + A2), where ? is replaced by an almost linear dependent quantity (dL-dR)/R0. In this way the well established experimentally fission fragment mass asymmetry can not be explained. By adding the shell corrections ?E to the LDM deformation energy, Edef ELDM + ? E, we succeeded to obtain minima as shown. The nuclear surface equation of an axially symmetric body u(x) is a solution of the following differential equation: u'' = 2 + 1/u[u'2 + (x - d + Vs)(4u + u'2)3/2], where d is an input parameter which determines the deformation. In our present approach we included in the deformation energy E(R)=ELD(R) + ?E(R) - ?E0 a phenomenological shell correction ?E, and the above written differential equation is solved iteratively by using Runge-Kutta method. The procedure is repeated umethod. The procedure is repeated until the solution of the variational problem leads to the minimum of the deformation energy which is the sum of the surface and Coulomb energies plus shell corrections. At a given deformation we find the fragment volumes and the corresponding number of protons and neutrons Zi(R), Ni(R) (i=1,2).For every fragment we add contributions from protons and neutrons ?E(R) = ?i ?Ei(R) = ?i [?Epi(R) + ?Eni(R)] given by ?Epi Cs(Zi) ; ?Eni = Cs(Ni), where s(Z) = F(Z)/[(Z-2/3] - cZ1/3 and a similar equation for s(N), where F(n) = 3/5 [((Ni5/3 - Ni-15/3)/(Ni - Ni-1))(n - Ni-1) - n5/3+ Ni-15/3] in which n in (Ni-1, Ni) is the actual number of protons or neutrons Z or N, and Ni-1, Ni are the neighbouring magic numbers. The parameters c = 0.2, C = 6.2 MeV were determined by fit with experimental masses and deformations. By introducing shell corrections we obtained minima of deformation energy for parent nuclei 238 U, 232,228 Th at a finite mass asymmetry giving for the three nuclei the same mass number of the heavy fragment A1 = 125. (authors)

279

Hadron-quark phase transition in asymmetric matter with dynamical quark masses

International Nuclear Information System (INIS)

The two-equation-of-state model is used to describe the hadron-quark phase transition in asymmetric matter formed at high density in heavy-ion collisions. For the quark phase, the three-flavor Nambu-Jona-Lasinio effective theory is used to investigate the influence of dynamical quark mass effects on the phase transition. At variance to the MIT-Bag results, with fixed-current quark masses, the main important effect of the chiral dynamics is the appearance of an end point for the coexistence zone. We show that a first-order hadron-quark phase transition may take place in the region T subset of (50-80) MeV and ?B subset of (2-4)?0, which is possible to be probed in the new planned facilities, such as FAIR at GSI-Darmstadt and NICA at JINR-Dubna. From the isospin properties of the mixed phase, some possible signals are suggested. The importance of chiral symmetry and dynamical quark mass on the hadron-quark phase transition is stressed. The difficulty of an exact location of a critical end point comes from its appearance in a region of competition between chiral symmetry breaking and confinement, where our knowledge of effective QCD theories is still rather uncertain.

280

Self-interacting asymmetric dark matter coupled to a light massive dark photon

Dark matter (DM) with sizeable self-interactions mediated by a light species offers a compelling explanation of the observed galactic substructure; furthermore, the direct coupling between DM and a light particle contributes to the DM annihilation in the early universe. If the DM abundance is due to a dark particle-antiparticle asymmetry, the DM annihilation cross-section can be arbitrarily large, and the coupling of DM to the light species can be significant. We consider the case of asymmetric DM interacting via a light (but not necessarily massless) Abelian gauge vector boson, a dark photon. In the massless dark photon limit, gauge invariance mandates that DM be multicomponent, consisting of positive and negative dark ions of different species which partially bind in neutral dark atoms. We argue that a similar conclusion holds for light dark photons; in particular, we establish that the multi-component and atomic character of DM persists in much of the parameter space where the dark photon is sufficiently l...

Petraki, Kalliopi; Kusenko, Alexander

2014-01-01

281

Inclusive transverse response of nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The electromagnetic inclusive transverse response of nuclear matter at saturation density is studied within the correlated basis function perturbation theory for momentum transfers q from 300 to 550 MeV/c. The correlation operator includes a Jastrow component, accounting for the short range repulsion, as well as longer range spin, tensor, and isospin ones. Up to correlated one-particle{endash}one-hole intermediate states are considered. The spreading due to the decay of particle (hole) states into two-particle{endash}one-hole (two-hole{endash}one-particle) states is considered via a realistic optical potential model. The Schiavilla-Pandharipande-Riska model for the two-body electromagnetic currents, constructed so as to satisfy the continuity equation with realistic v{sub 14} potentials, is adopted. Currents due to intermediate {Delta}-isobar excitations are also included. The global contribution of the two-body currents turns out to be positive and provides an enhancement of the one-body transverse response ranging from {approximately}20{percent} for the lower momenta to {approximately}10{percent} for the higher ones. This finding is in agreement with the Green{close_quote}s function Monte Carlo studies of the transverse Euclidean response in A=3,4 nuclei and contradicts previous results obtained within the Fermi gas and shell models. The tensor-isospin component of the correlation is found to be the leading factor responsible for such a behavior. The nuclear matter response is compared to recent experimental data on {sup 40}Ca and {sup 56}Fe. {copyright} {ital 1997} {ital The American Physical Society}

Fabrocini, A. [Department of Physics, University of Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56100 Pisa (Italy)

1997-01-01

282

On the spin saturation and thermal properties of nuclear matter

International Nuclear Information System (INIS)

The binding energy and the incompressibility of nuclear matter with degree of spin saturation D is calculated using the Skyrme interaction and two forms of a velocity dependent effective potential. The effect of the degree of spin saturation D on the thermal properties of nuclear matter is also discussed. It is found that generally the pressure decreases with increasing D. (author)

283

Cluster virial expansion for quark and nuclear matter

We employ the $\\Phi-$ derivable approach to many particle systems with strong correlations that can lead to the formation of bound states (clusters) of different size. We define a generic form of $\\Phi-$ functionals that is fully equivalent to a selfconsistent cluster virial expansion up to the second virial coefficient for interactions among the clusters. As examples we consider nuclei in nuclear matter and hadrons in quark matter, with particular attention to the case of the deuterons in nuclear matter and mesons in quark matter. We derive a generalized Beth-Uhlenbeck equation of state, where the quasiparticle virial expansion is extended to include arbitrary clusters. The approach is applicable to nonrelativistic potential models of nuclear matter as well as to relativistic field theoretic models of quark matter. It is particularly suited for a description of cluster formation and dissociation in hot, dense matter.

Blaschke, David

2015-01-01

284

Nuclear Matter from Effective Quark-Quark Interaction

We study neutron matter and symmetric nuclear matter with the quark-meson model for the two-nucleon interaction. The Bethe-Bruckner-Goldstone many-body theory is used to describe the correlations up to the three hole-line approximation with no extra parameters. At variance with other non-relativistic realistic interactions, the three hole-line contribution turns out to be non-negligible and to have a substantial saturation effect. The saturation point of nuclear matter, the ...

Baldo, M.; Fukukawa, K.

2014-01-01

285

Nuclear stopping power in warm and hot dense matter

International Nuclear Information System (INIS)

We present a method to estimate the nuclear component of the stopping power of ions propagating in dense matter. Three kinds of effective pair potentials are proposed. Results from the warm dense matter regime and the domain of high energy density physics are presented and discussed for proton and helium. The role of ionic temperature is examined. The nuclear stopping power can play a noticeable role in hot dense matter.

286

Cold Nuclear Matter Effects at PHENIX

Energy Technology Data Exchange (ETDEWEB)

While the study of the quark-gluon plasma has been the primary focus of the RHIC experiments, much work has also been done to understand so-called cold nuclear matter (CNM) eects through d+Au collisions where no hot plasma is produced. Eects such as nuclear shadowing, Cronin enhancement, and initial-state parton energy loss, among others, are not only interesting in their own right, but have direct implications on QGP-related measurements in A+A collisions. Recently PHENIX has measured CNM eects at midrapidity in s_NN = 200 GeV d+Au collisions. Measurements of reconstructed jets reveal the centrality dependence of both jet suppression and broadening of the away-side jet. Meanwhile, single electrons from heavy flavor decays exhibit enhancement, increasing with centrality, over a broad p_T range. J/psi and psi' modification have also been measured and are quite dierent in magnitude, in contrast with our expectations. The above results are presented here and compared to our present understanding of CNM effects.

Wysocki, Matthew G [ORNL; PHENIX, Collaboration [The

2013-01-01

287

Cold Nuclear Matter Effects at PHENIX

Energy Technology Data Exchange (ETDEWEB)

While the study of the quark-gluon plasma has been the primary focus of the RHIC experiments, much work has also been done to understand so-called cold nuclear matter (CNM) effects through d + Au collisions where no hot plasma is produced. Effects such as nuclear shadowing, Cronin enhancement, and initial-state parton energy loss, among others, are not only interesting in their own right, but have direct implications on QGP-related measurements in A + A collisions. Recently PHENIX has measured CNM effects at midrapidity in ?(s{sub NN})=200 GeVd + Au collisions. Measurements of reconstructed jets reveal the centrality dependence of both jet suppression and broadening of the away-side jet. Meanwhile, single electrons from heavy flavor decays exhibit enhancement, increasing with centrality, over a broad p{sub T} range. J/? and ?? modification have also been measured and are quite different in magnitude, in contrast with our expectations. The above results are presented here and compared to our present understanding of CNM effects.

Wysocki, Matthew G.

2013-05-02

288

Cold Nuclear Matter Effects at PHENIX

International Nuclear Information System (INIS)

While the study of the quark-gluon plasma has been the primary focus of the RHIC experiments, much work has also been done to understand so-called cold nuclear matter (CNM) effects through d + Au collisions where no hot plasma is produced. Effects such as nuclear shadowing, Cronin enhancement, and initial-state parton energy loss, among others, are not only interesting in their own right, but have direct implications on QGP-related measurements in A + A collisions. Recently PHENIX has measured CNM effects at midrapidity in ?(sNN)=200 GeVd + Au collisions. Measurements of reconstructed jets reveal the centrality dependence of both jet suppression and broadening of the away-side jet. Meanwhile, single electrons from heavy flavor decays exhibit enhancement, increasing with centrality, over a broad pT range. J/? and ?? modification have also been measured and are quite different in magnitude, in contrast with our expectations. The above results are presented here and compared to our present understanding of CNM effects

289

Width of the ? meson in nuclear matter

International Nuclear Information System (INIS)

The ratios of the cross sections for ?-meson production induced by 2.83-GeV protons on Cu, Ag, and Au nuclei to the respective cross section for C nuclei were measured at the ANKE-COSY facility in the momentum range of 0.6-1.6 GeV/c and the angular range of 0°-8°. The product ? mesons were identified by their decay ? ? K+K-. The procedure used to separate kaon pairs was described in detail, and all sources of the background and their contribution to the resulting error in the values found for the above cross-section ratios were analyzed. The A dependence of the cross section for ?-meson production was shown to obey the A0.56±0.03 law. The total width of the ? meson at a normal nuclear density was extracted from a comparison of the measured cross-section ratios with the results of calculations based on two theoretical models. The resulting width value exceeds substantially both the vacuum width and the width expected in the absence of the nuclear-matter effect on the properties of the ? meson.

290

A fermionic molecular dynamics technique to model nuclear matter

International Nuclear Information System (INIS)

Full text: At sub-nuclear densities of about 1014 g/cm3, nuclear matter arranges itself in a variety of complex shapes. This can be the case in the crust of neutron stars and in core-collapse supernovae. These slab like and rod like structures, designated as nuclear pasta, have been modelled with classical molecular dynamics techniques. We present a technique, based on fermionic molecular dynamics, to model nuclear matter at sub-nuclear densities in a semi classical framework. The dynamical evolution of an antisymmetric ground state is described making the assumption of periodic boundary conditions. Adding the concepts of antisymmetry, spin and probability distributions to classical molecular dynamics, brings the dynamical description of nuclear matter to a quantum mechanical level. Applications of this model vary from investigation of macroscopic observables and the equation of state to the study of fundamental interactions on the microscopic structure of the matter. (author)

291

An equation of state of nuclear matter at high temperatures

International Nuclear Information System (INIS)

The exciting development in the recent past of the possible discovery of the quark-gluon plasma formation in ultra high energy heavy-ion collisions has given impetus to study the nuclear matter at very high temperatures. The properties of nuclear matter are explored at high nuclear temperatures by taking up the quantum statistical mechanical approach to the equation of state which is expressed in the form of virial expansion

292

Strangeness and charm in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The properties of strange (K, K{sup ¯} and K{sup ¯?}) and open-charm (D, D{sup ¯} and D{sup ?}) mesons in dense matter are studied using a unitary approach in coupled channels for meson–baryon scattering. In the strangeness sector, the interaction with nucleons always comes through vector-meson exchange, which is evaluated by chiral and hidden gauge Lagrangians. For the interaction of charmed mesons with nucleons we extend the SU(3) Weinberg–Tomozawa Lagrangian to incorporate spin–flavor symmetry and implement a suitable flavor symmetry breaking. The in-medium solution for the scattering amplitude accounts for Pauli blocking effects and meson self-energies. On one hand, we obtain the K, K{sup ¯} and K{sup ¯?} spectral functions in the nuclear medium and study their behaviour at finite density, temperature and momentum. We also make an estimate of the transparency ratio of the ?A?K{sup +}K{sup ??}A{sup ?} reaction, which we propose as a tool to detect in-medium modifications of the K{sup ¯?} meson. On the other hand, in the charm sector, several resonances with negative parity are generated dynamically by the s-wave interaction between pseudoscalar and vector meson multiplets with 1/2{sup +} and 3/2{sup +} baryons. The properties of these states in matter are analyzed and their influence on the open-charm meson spectral functions is studied. We finally discuss the possible formation of D-mesic nuclei at FAIR energies.

Tolos, Laura, E-mail: tolos@ice.csic.es [Instituto de Ciencias del Espacio (IEEC/CSIC), Campus Universitat Autònoma de Barcelona, Facultat de Ciències, Torre C5, E-08193 Bellaterra (Barcelona) (Spain); Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe University, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Cabrera, Daniel [Departamento de Física Teórica II, Universidad Complutense, 28040 Madrid (Spain); Garcia-Recio, Carmen [Departamento de Física Atómica, Molecular y Nuclear, and Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, E-18071 Granada (Spain); Molina, Raquel [Research Center for Nuclear Physics (RCNP), Mihogaoka 10-1, Ibaraki 567-0047 (Japan); Nieves, Juan; Oset, Eulogio [Instituto de Física Corpuscular (Centro Mixto CSIC-UV), Institutos de Investigación de Paterna, Aptdo. 22085, 46071 Valencia (Spain); Ramos, Angels [Departament d' Estructura i Constituents de la Matèria, Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain); Romanets, Olena [Theory Group, KVI, University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); Salcedo, Lorenzo Luis [Departamento de Física Atómica, Molecular y Nuclear, and Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, E-18071 Granada (Spain)

2013-09-20

293

Coherent scattering of neutrinos by 'nuclear pasta' in dense matter

International Nuclear Information System (INIS)

We examine coherent scattering cross section of neutrino and nucleon systems via weak-neutral current at subnuclear densities, which will be important in supernova cores. Below melting density and temparature of nuclei, nuclear shape becomes rodlike and slablike; this is called nuclear 'pasta'. Transition of structure will greatly influence coherent effects which can not easily be predicted. We calculate static structure factor of nuclear matter using data of several nuclear models, and discuss the effects of existence of nuclear pasta on neutrino opacity in hot dense matter

294

QMD application of sub-saturated nuclear matter

Energy Technology Data Exchange (ETDEWEB)

QMD (quantum molecular dynamics) has not been applied to supernova and neutron star matter. We begun to apply QMD, microscopic simulation of nuclear reaction, to the infinite system of nuclear matter. The infinite system was simulated by N particles system under the periodic boundary condition. Pauli potential introduced repulsive force which the same kinds of particles could not approach at phase space, instead of antisymmetrization of the system. Supernova matter was appropriate to the symmetric nuclear matter, the inhomogeneous structure was observed less than 0.8 {rho}{sub 0} of density, but homogeneous more than it. Each nucleus was seen to separate from others less than 0.2 {rho}{sub 0}. Neutron star matter attains {beta} equilibrium and not symmetric matter and the lowest energy was obtained at about 0.03-0.08 of proton content. (S.Y.)

Maruyama, Toshiki; Maruyama, Tomoyuki; Iwamoto, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Niita, Koji; Chikamatsu, Kazuhiro

1997-05-01

295

Nuclear security matters [electronic resource] : analysis on reducing the risk of nuclear terrorism.

International Nuclear Information System (INIS)

Nuclear Security Matters provides accessible analysis from the world's leading experts on nuclear security and nuclear terrorism. This website is intended to help inform researchers, reporters, government officials, and the interested public on policy options for strengthening nuclear security and reducing the risk of nuclear terrorism.

296

International Nuclear Information System (INIS)

Nuclear matter and ground state properties for (proton and neutron) semi-closed shell nuclei are described in relativistic mean field theory with coupling constants which depend on the vector density. The parametrization of the density dependence for ?-, ?- and ?-mesons is obtained by fitting to properties of nuclear matter and some finite nuclei. The equation of state for symmetric and asymmetric nuclear matter is discussed. Finite nuclei are described in Hartree approximation, including a charge and an improved center-of-mass correction. Pairing is considered in the BCS approximation. Special attention is directed to the predictions for properties at the neutron and proton driplines, e.g. for separation energies, spin-orbit splittings and density distributions. (orig.)

297

Antikaons in infinite nuclear matter and nuclei

Energy Technology Data Exchange (ETDEWEB)

In this work we studied the properties of antikaons and hyperons in infinite cold nuclear matter. The in-medium antikaon-nucleon scattering amplitude and self-energy has been calculated within a covariant many-body framework in the first part. Nuclear saturation effects have been taken into account in terms of scalar and vector nucleon mean-fields. In the second part of the work we introduced a non-local method for the description of kaonic atoms. The many-body approach of anti KN scattering can be tested by the application to kaonic atoms. A self-consistent and covariant many-body approach has been used for the determination of the antikaon spectral function and anti KN scattering amplitudes. It considers s-, p- and d-waves and the application of an in-medium projector algebra accounts for proper mixing of partial waves in the medium. The on-shell reduction scheme is also implemented by means of the projector algebra. The Bethe-Salpeter equation has been rewritten, so that the free-space anti KN scattering can be used as the interaction kernel for the in-medium scattering equation. The latter free-space scattering is based on a realistic coupled-channel dynamics and chiral SU(3) Lagrangian. Our many-body approach is generalized for the presence of large scalar and vector nucleon mean-fields. It is supplemented by an improved renormalization scheme, that systematically avoids the occurrence of medium-induced power-divergent structures and kinematical singularities. A modified projector basis has been introduced, that allows for a convenient inclusion of nucleon mean-fields. The description of the results in terms of the 'physical' basis is done with the help of a recoupling scheme based on the projector algebra properties. (orig.)

Moeller, M.

2007-12-10

298

Antikaons in infinite nuclear matter and nuclei

International Nuclear Information System (INIS)

In this work we studied the properties of antikaons and hyperons in infinite cold nuclear matter. The in-medium antikaon-nucleon scattering amplitude and self-energy has been calculated within a covariant many-body framework in the first part. Nuclear saturation effects have been taken into account in terms of scalar and vector nucleon mean-fields. In the second part of the work we introduced a non-local method for the description of kaonic atoms. The many-body approach of anti KN scattering can be tested by the application to kaonic atoms. A self-consistent and covariant many-body approach has been used for the determination of the antikaon spectral function and anti KN scattering amplitudes. It considers s-, p- and d-waves and the application of an in-medium projector algebra accounts for proper mixing of partial waves in the medium. The on-shell reduction scheme is also implemented by means of the projector algebra. The Bethe-Salpeter equation has been rewritten, so that the free-space anti KN scattering can be used as the interaction kernel for the in-medium scattering equation. The latter free-space scattering is based on a realistic coupled-channel dynamics and chiral SU(3) Lagrangian. Our many-body approach is generalized for the presence of large scalar and vector nucleon mean-fields. It is supplemented by an improved renormalization scheme, that systematically avoids the occurrence of medium-induced power-divergent structures and kinematical singularities. A modified projector basis has been introduced, that allows for a convenient inclusion of nucleon mean-fields. The description of the results in terms of the 'physical' basis is done with the help of a recoupling scheme based on the projector algebra properties. (orig.)

299

Compressibility of nuclear matter from the chiral soliton model

International Nuclear Information System (INIS)

The compressibility of isospin symmetric nuclear matter is studied in the framework of the in-medium modified chiral soliton model. On one hand, in the mesonic sector, the model is related to pion physics in nuclear matter while on the other hand, in the many baryonic sector, it reproduces the volume term coefficient aV of the semi-empirical binding energy formula. Within our framework, we found an interesting result that aV became density independent in the region 0.35?0 ? ? ? 1.08?0 . The model reproduces well the compression modulus, K ? 300 MeV, of isospin symmetric and infinite nuclear matter.

300

Strangeness and Charm in Nuclear Matter

The properties of strange ($K$, $\\bar K$ and $\\bar K^*$) and open-charm ($D$, $\\bar D$ and $D^*$) mesons in dense matter are studied using a unitary approach in coupled channels for meson-baryon scattering. In the strangeness sector, the interaction with nucleons always comes through vector-meson exchange, which is evaluated by chiral and hidden gauge Lagrangians. For the interaction of charmed mesons with nucleons we extend the SU(3) Weinberg-Tomozawa Lagrangian to incorporate spin-flavor symmetry and implement a suitable flavor symmetry breaking. The in-medium solution for the scattering amplitude accounts for Pauli blocking effects and meson self-energies. On one hand, we obtain the $K$, $\\bar K$ and $\\bar K^*$ spectral functions in the nuclear medium and study their behaviour at finite density, temperature and momentum. We also make an estimate of the transparency ratio of the $\\gamma A \\to K^+ K^{*-} A^\\prime$ reaction, which we propose as a tool to detect in-medium modifications of the $\\bar K^*$ meson....

Tolos, Laura; Garcia-Recio, Carmen; Molina, Raquel; Nieves, Juan; Oset, Eulogio; Ramos, Angels; Romanets, Olena; Salcedo, Lorenzo Luis

2012-01-01

301

The inclusive transverse response of nuclear matter

The electromagnetic inclusive transverse response of nuclear matter at saturation density is studied within the correlated basis function perturbation theory for momentum transfers q from 300 to 550 MeV/c. The correlation operator includes a Jastrow component, accounting for the short range repulsion, as well as longer range spin, tensor and isospin ones. The Schiavilla- Pandharipande-Riska model for the two-body electromagnetic currents, satisfying the continuity equation with realistic v_14 potentials, is adopted. Currents due to intermediate Delta-isobar excitations, are also included. The global contribution of the two-body currents turns out to be positive and provides an enhancement of the one-body transverse response ranging from about 20% for the lower momenta to about 10% for the higher ones. This finding is in agreement with the Green's Function Monte Carlo studies of the transverse Euclidean response in A=3,4 nuclei and contradicts previous results obtained within the Fermi gas and shell models. Th...

Fabrocini, A

1997-01-01

302

The nucleon spectral function in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

A microscopic theory based on orthogonal correlated basis functions is developed for the single-particle spectral function of an infinite Fermi system. The nucleon spectral function P(k,E) has been calculated for a realistic model of nuclear matter in which spin-isospin and tensor correlations are fully taken into account. P(k,E) is analyzed in terms of a single-particle strength, which turns out to be completely determined by two-body breakup processes, and a background which is mainly furnished by three-body breakup processes. The strength of single-particle states close to the Fermi surface can be measured by (e,e'p) reactions in kinematical conditions corresponding to low missing energy E, whereas the background requires a wide range of E values, extended up to several hundreds of MeV. The relations between P(k,E), the momentum distribution and the response function are discussed in connection with the analysis of inclusive (e,e') data at high momentum transfer. (orig.).

Benhar, O. (Istituto Nazionale di Fisica Nucleare, Rome (Italy). Sezione Sanita Istituto Superiore di Sanita, Rome (Italy). Lab. di Fisica); Fabrocini, A. (Pisa Univ. (Italy). Dipt. di Fisica Istituto Nazionale di Fisica Nucleare, Pisa (Italy)); Fantoni, S. (Istituto Nazionale di Fisica Nucleare, Lecce (Italy) Lecce Univ. (Italy). Dipt. di Fisica)

1989-12-11

303

The nucleon spectral function in nuclear matter

A microscopic theory based on orthogonal correlated basis functions is developed for the single-particle spectral function of an infinite Fermi system. The nucleon spectral function P( k, E) has been calculated for a realistic model of nuclear matter in which spin-isospin and tensor correlations are fully taken into account. P( k, E) is analyzed in terms of a single-particle strength, which turns out to be completely determined by two-body breakup processes, and a background which is mainly furnished by three-body breakup processes. The strength of single-particle states close to the Fermi surface can be measured by (e, e'p) reactions in kinematical conditions corresponding to low missing energy E, whereas the background requires a wide range of E values, extended up to several hundreds of MeV. The relations between P( k, E), the momentum distribution and the response function are discussed in connection with the analysis of inclusive (e,e') data at high momentum transfer.

Benhar, Omar; Fabrocini, Adelchi; Fantoni, Stefano

1989-12-01

304

Kaons in nuclear matter; Kaonen in Kernmaterie

Energy Technology Data Exchange (ETDEWEB)

The subject of the doctoral thesis is examination of the properties of kaons in nuclear matter. A specific method is explained that has been developed for the scientific objectives of the thesis and permits description of the kaon-nucleon interactions and kaon-nucleon scattering in a vacuum. The main challenge involved was to find approaches that would enable application of the derived relations out of the kaon mass shell, connected with the second objective, namely to possibly find methods which are independent of models. The way chosen to achieve this goal relied on application of reduction formulas as well as current algebra relations and the PCAC hypothesis. (orig./CB) [Deutsch] Die Arbeit befasst sich mit der Untersuchung der Eigenschaften von Kao nen in Kernmaterie. Zu diesem Zweck wurde ein Verfahren entwickelt, di e Kaon- Nukleon- Wechselwirkung und Kaon- Nukleon- Streuung im Vakuumzu beschreiben. Die Hauptherausforderung bestand darin, dass die abgel eiteten Relationen ausserhalb der Kaonen- Massenschale anwendbar werde n. Eine Nebenforderung war, dass die vorgeschlagenen Verfahren moeglic hst modell- unabhaengig sind. Um dieses Ziel zu erreichen, wurden Redu ktionsformeln, Stromalgebra- Relationen und die PCAC- Hypothese angewe ndet.

Kolomeitsev, E.E.

1997-02-01

305

Dielectron spectroscopy in cold nuclear matter

International Nuclear Information System (INIS)

The subject of this thesis is the production of light mesons and baryonic resonances in p+Nb collisions at Ekin=3.5 GeV via their decay in e+e- pairs and their kinematic observables. This reaction system in particular allows for the production of vector mesons in approximately cold nuclear matter and the study of expected in-medium effects. The experiment was conducted at the dielectron spectrometer HADES at GSI Helmholtzzentrum fuer Schwerionenforschung GmbH. In total, 64827±294 signal pairs with an pair opening angle ?ee>9 and e+/e- momenta 80e(MeV/c)ee(MeV/c2)ee> 550 MeV/c2). Inclusive e+e- production cross sections inside the HADES acceptance were calculated by analyzing the simultaneously measured charged pions and by comparing the obtained ?- yields to an independent data set. For the vector mesons one obtains ??,acc=(65.8±4.6(stat)±18.4(sys)) nb and ??,acc=(7.8±1.7(stat)±2.2 (sys)) nb. A comparison with cross sections in free p+p collisions at Ekin=3.5 GeV results in the nuclear modification factors RpA as well as their scaling ? with the nuclear mass number A and their dependence on the pair lab momenta pee. While absorption is not important for the ? meson (?? ?1), scaling factors ? ?0.7 are established for the quasi free decay (pee>800 MeV/c) of all other hadrons. From an adapted Glauber model calculation a minimal absorption >or similar 35% of all contributing hadrons in nuclei can be deduced. At smaller pair momenta different scaling factors are obtained. The ? meson is absorbed with a higher probability (??=0.62), but for all other sources above the ?0 mass, dominantly ?, ?, and ? with ?=0.82-0.86, production in secondary reactions exceeds the absorption inside the nucleus. Measured e+e- distributions were compared with different transport model calculations. Within the uncertainties the cross section of the ?0 Dalitz decay is reproduced in all models. However differences arise in the high mass region and the distributions of transverse momenta and rapidities. Additionally the GiBUU calculations describe the behaviour of slow and fast e+e- sources due to a momentum dependent in medium decay width. In the experiment no signal of the direct decay ??e+e- was measured. The existing upper level for the branching ratio BR=2.7 x 10-5 has to be reduced by at least a factor of 3. (orig.)

306

Energy Technology Data Exchange (ETDEWEB)

Nuclear matter presents a phase transition of the liquid-gas type. This well-known feature is due to the nuclear interaction profile (mean-range attractive, short-range repulsive). Symmetric-nuclear-matter thermodynamics is thus analogous to that of a Van der Waals fluid. The study shows up to be more complex in the case of asymmetric matter, composed of neutrons and protons in an arbitrary proportion. Isospin, which distinguishes both constituents, gives a measure of this proportion. Studying asymmetric matter, isospin is an additional degree of freedom, which means one more dimension to consider in the space of observables. The nuclear liquid-gas transition is associated with the multi-fragmentation phenomenon observed in heavy-ion collisions, and to compact-star physics: the involved systems are neutron rich, so they are affected by the isospin degree of freedom. The present work is a theoretical study of isospin effects which appear in the asymmetric nuclear matter liquid-gas phase transition. A mean-field approach is used, with a Skyrme nuclear effective interaction. We demonstrate the presence of a first-order phase transition for asymmetric matter, and study the isospin distillation phenomenon associated with this transition. The case of phase separation at thermodynamic equilibrium is compared to spinodal decomposition. Finite size effects are addressed, as well as the influence of the electron gas which is present in the astrophysical context. (author)

Ducoin, C

2006-10-15

307

Effective field theory: a complete relativistic nuclear model

International Nuclear Information System (INIS)

Recent applications of the models based on effective field theory include studies of pion-nucleus scattering, the nuclear spin-orbit force, asymmetric nuclear matter at finite temperature, the properties of the drip-line nuclei as well as the symmetric and asymmetric infinite nuclear matter including the neutron star

308

The response function of a slab of noninteracting nuclear matter

International Nuclear Information System (INIS)

Analytic expressions of the density and of the particle-hole polarization propagator are derived for a slab of noninteracting nuclear matter. The nondiagonal behaviour of the polarization propagator in the momentum components perpendicular to the slab is explored

309

Transverse charge densities in the nucleon in nuclear matter

We investigated the transverse charge densities in the nucleon in nuclear matter within the framework of the in-medium modified Skyrme model. The medium modification of the nucleon electromagnetic form factors are first discussed. The results show that the form factors in nuclear matter fall off faster than those in free space, as the momentum transfer increases. As a result, the charge radii of the nucleon become larger, as the nuclear matter density increases. The transverse charge densities in the nucleon indicate that the size of the nucleon tends to bulge out in nuclear matter. This salient feature of the swelling is more clearly observed in the neutron case. When the proton is transversely polarized, the transverse charge densities exhibit the distortion due to the effects of the magnetization.

Yakhshiev, Ulugbek

2013-01-01

310

K meson-nucleus interactions: strangeness and nuclear matter

International Nuclear Information System (INIS)

A brief review is provided of some straightforward K-nuclear and ?-hypernuclear systems. A discussion of less straightforward speculations on H-dibaryons and strange quark matter by many authors, is also given. 28 refs., 6 figs

311

A contribution to phenomenology of phase transitions in nuclear matter

International Nuclear Information System (INIS)

A review is given on the phenomenology of phase transitions in nuclear matter and neutron matter. We deal with (1) the liquid-gas transition in expanding nuclear systems and collapsing stellar cores, (2) the pion condensation in neutron stars and the direct pion emission in relativistic heavy ion collisions and (3) the deconfinement transition in neutron stars, in the early universe and in the compression/expansion stage of heavy ion reactions. (author)

312

Monotonous braking of high energy hadrons in nuclear matter

International Nuclear Information System (INIS)

Propagation of high energy hadrons in nuclear matter is discussed. The possibility of the existence of the monotonous energy losses of hadrons in nuclear matter is considered. In favour of this hypothesis experimental facts such as pion-nucleus interactions (proton emission spectra, proton multiplicity distributions in these interactions) and other data are presented. The investigated phenomenon in the framework of the hypothesis is characterized in more detail

313

Hot Nuclear Matter in the Quark Meson Coupling Model

We study here hot nuclear matter in the quark meson coupling (QMC) model which incorporates explicitly quark degrees of freedom, with quarks coupled to scalar and vector mesons. The equation of state of nuclear matter including the composite nature of the nucleons is calculated at finite temperatures. The calculations are done taking into account the medium-dependent bag constant. Nucleon properties at finite temperatures as calculated here are found to be appreciably different from the value at $T=0.$

Panda, P K; Eisenberg, J M; Greiner, W

1997-01-01

314

Investigations of instabilities in nuclear matter in stochastic relativistic models

Energy Technology Data Exchange (ETDEWEB)

The spinodal instabilities for symmetric nuclear matter at finite temperature are studied within different relativistic mean-field models in the semi-classical approximation and the relativistic results are compared with Skyrme type non-relativistic calculations. Qualitatively similar results appear in the unstable response of the system in both non-relativistic and relativistic descriptions. Furthermore, the early growth of baryon, scalar and current density correlation functions are calculated for hot symmetric nuclear matter.

Ayik, S., E-mail: ayik@tntech.edu [Physics Department, Tennessee Technological University, Cookeville, TN 38505 (United States); Yilmaz, O.; Acar, F.; Danisman, B. [Physics Department, Middle East Technical University, 06531 Ankara (Turkey); Er, N. [Physics Department, Abant Izzet Baysal University, Bolu (Turkey); Gokalp, A. [Physics Department, Middle East Technical University, 06531 Ankara (Turkey)

2011-06-01

315

Investigations of instabilities in nuclear matter in stochastic relativistic models

International Nuclear Information System (INIS)

The spinodal instabilities for symmetric nuclear matter at finite temperature are studied within different relativistic mean-field models in the semi-classical approximation and the relativistic results are compared with Skyrme type non-relativistic calculations. Qualitatively similar results appear in the unstable response of the system in both non-relativistic and relativistic descriptions. Furthermore, the early growth of baryon, scalar and current density correlation functions are calculated for hot symmetric nuclear matter.

316

Many-body theory of nuclear and neutron star matter

International Nuclear Information System (INIS)

We present results obtained for nuclei, nuclear and neutron star matter, and neutron star structure obtained with the recent Argonne v18 two- nucleon and Urbana IX three-nucleon interactions including relativistic boost corrections. These interactions predict that matter will undergo a transition to a spin layered phase with neutral pion condensation. We also consider the possibility of a transition to quark matter. (orig.)

317

Longitudinal spin-dependent correlations in nuclear matter

A Jastrow-type wave function, with the two-body correlation factor depending on the spin-isospin state of the particles, is used for variational calculations of the energy per particle of infinite Fermi systems. Results are presented for nuclear matter and neutron matter using two semi-realistic potentials.

Fabrocini, A.; Fantoni, S.

1981-04-01

318

Nuclear incompressibility: From finite nuclei to nuclear matter

International Nuclear Information System (INIS)

The recent increase of experimental data concerning the giant monopole resonance energy Esub(M) gives information on the incompressibility modulus of nuclear matter, provided one can extrapolate the incompressibility of a nucleus Ksub(A), defined by Esub(M) = [h/2?2Ksub(A)/m2>]sup(1/2), to the infinite medium. We discuss the theoretical interpretation of the coefficients of an Asup(-1/3) expansion of Ksub(A) by studying the asymptotic behaviour of two RPA sum rules (corresponding to the scaling and the constrained model), evaluated using self-consistent Thomas-Fermi calculations. We show that the scaling model is the most suitable one as it leads to a rapidly converging Asup(-1/3) expansion of the corresponding incompressibility Ksup(S)sub(A), whereas this is not the case with the constrained model. Some semi-empirical relations between the coefficients of the expansion of Ksup(S)sub(A) are established, which reduce to one the number of free parameters in a best-fit analysis of the experimental data. This reduction is essential due to the still limited number and accuracy of experimental data. We then show the compatibility of the data given by the various experimental groups with this parametrization and obtain a value of Ksub(n.m.) = 220 +- 20 MeV, in good agreement with more microscopic analyses. (orig.)

319

Effects of Brown-Rho scalings in nuclear matter, neutron stars and finite nuclei

International Nuclear Information System (INIS)

We have carried out calculations for nuclear matter, neutron stars and finite nuclei using NN potentials with and without the medium-dependent modifications based on the Brown-Rho (BR) scalings. Using the Vlow-k low-momentum interactions derived from such potentials, the equations of state (EOS) for symmetric and asymmetric nuclear matter, for densities up to ? 5?0, are calculated using a RPA method where the particle-particle hole-hole ring diagrams are summed to all orders. The medium effects from both a linear BR scaling (BR1) and a non-linear one (BR2) are considered, and they both are essential for our EOSs to reproduce the nuclear matter saturation properties. For densities ? below ?0, results from BR1 and BR2 are close to each other. For higher densities, the EOS given by BR2 is more desirable and is well reproduced by that given by the interaction (Vlow-k+TBF) where Vlow-k is the unsealed low-momentum interaction and TBF is an empirical Skyrme three-body force. The moment of inertia of neutron stars is ? 60 and ? 25Mo-dotkm2 respectively with and without the inclusion of the above BR2 medium effects. Effects from the BR scaling are important for the long half-life, ? 5000yrs, of the 14C - 14N ?-decay.

320

Higher-order symmetry energy of nuclear matter and the inner edge of neutron star crusts

The parabolic approximation to the equation of state of the isospin asymmetric nuclear matter (ANM) is widely used in the literature to make predictions for the nuclear structure and the neutron star properties. Based on the realistic M3Y-Paris and M3Y-Reid nucleon-nucleon interactions, we investigate the effects of the higher-order symmetry energy on the proton fraction in neutron stars and the location of the inner edge of their crusts and their core-crust transition density and pressure, thermodynamically. Analytical expressions for different-order symmetry energy coefficients of ANM are derived using the realistic interactions mentioned above. It is found that the higher-order terms of the symmetry energy coefficients up to its eighth-order (E$_{sym8}$) contributes substantially to the proton fraction in $\\beta$ stable neutron star matter at different nuclear matter densities, the core-crust transition density and pressure. Even by considering the symmetry energy coefficients up to E$_{sym8}$, we obtain a...

Seif, W M

2014-01-01

321

The role of meson dynamics in nuclear matter saturation

International Nuclear Information System (INIS)

The problem of the saturation of nuclea matter in the non-relativistic limit of the model proposed by J.D. Walecka is studied. In the original context nuclear matter saturation is obtained as a direct consequence of relativistic effects and both scalar and vector mesons are treated statically. In the present work we investigate the effect of the meson dynamics for the saturation using a Born-Oppenheimer approximation for the ground state. An upper limit for the saturation curve of nuclear matter and are able to decide now essential is the relativistic treatment of the nucleons for this problem, is obtained. (author)

322

Isovector Response of Nuclear Matter at Finite Temperature

International Nuclear Information System (INIS)

The dipole response function of nuclear matter at zero and finite temperatures is investigated in an extended RPA approach by including collisional damping mechanism and coherent damping due to particle-phonon coupling. Calculations are carried out for nuclear dipole vibrations by employing the Steinwedel-Jensen model and compared with experimental results for 120Sn and 208Pb. (author)

323

Relativistic Mean-Field Hadronic Models under Nuclear Matter Constraints

Relativistic mean-field (RMF) models have been widely used in the study of many hadronic frameworks because of several important aspects not always present in nonrelativistic models, such as intrinsic Lorentz covariance, automatic inclusion of spin, appropriate saturation mechanism for nuclear matter, causality and, therefore, no problems related to superluminal speed of sound. With the aim of identifying the models which best satisfy well known properties of nuclear matter, we have analyzed 263 parameterizations of seven different types of RMF models under three different sets of constraints related to symmetric nuclear matter, pure neutron matter, symmetry energy, and its derivatives. One of these (SET1) is formed of the same constraints used in a recent work in which we analyzed 240 Skyrme parameterizations. The results pointed to 2 models consistent with all constraints. Using another set of constraints, namely, SET2a, formed by the updated versions of the previous one, we found 4 models approved simultan...

Dutra, M; Avancini, S S; Carlson, B V; Delfino, A; Menezes, D P; Providência, C; Typel, S; Stone, J R

2014-01-01

324

Inex - NEA's programme on nuclear emergency matters

International Nuclear Information System (INIS)

The OECD Nuclear Energy Agency has a long tradition of expertise in the area of nuclear emergency policy, planing, preparedness and management. A major mechanism for the latter has been the development, preparation and organization of the International Nuclear Exercise (INEX) series. These international exercises have provided a valuable and unique forum for testing and verifying existing as well as new arrangements and concepts for international nuclear emergency management. This document presents the different INEX over the last 15 years and their contribution in the nuclear emergency management in an international context. (A.L.B.)

325

Experimental signals of the first phase transition of nuclear matter

Vaporized and multifragmenting sources produced in heavy ion collisions at intermediate energies are good candidates to investigate the phase diagram of nuclear matter. The properties of highly excited nuclear sources which undergo a simultaneous disassembly into particles are found to sign the presence of a gas phase. For heavy nuclear sources produced in the Fermi energy domain, which undergo a simultaneous disassembly into particles and fragments, a fossil signal (fragmen...

Borderie, B.

2001-01-01

326

Attenuation of high-energy particles leptoproduced in nuclear matter

International Nuclear Information System (INIS)

It is shown that the difference in nuclear attenuation of different hadrons produced in deep inelastic scattering of leptons from nuclear targets is sensitive to the composition of the intermediate state in nuclear matter. Measurements of attenuation should not only allow to determine if the high-energy component of this state is a quark or a hadron, but also give information on quark absorption cross-section and on time scale of hadronization. (author)

327

From nuclear matter to finite nuclei. Pt. 1

International Nuclear Information System (INIS)

In this paper we develop various parametrizations of the nuclear matter Dirac-Brueckner G-matrix, which are suitable for application in relativistic Hartree-Fock calculations of finite nuclei. The relativistic one boson exchange model forms the basis of this effective interaction. The parameters, which are obtained from a least squares fit, explicitly depend on the density. We also require the interaction to reproduce the self-energies and the binding energy of nuclear matter very accurately. It is shown that for densities up to 1.5 times normal nuclear density the saturation curve virtually coincides with the original Dirac-Brueckner result and yields a good prediction of the nuclear matter compressibility. (orig.)

328

From quantum to semiclassical kinetic equations: Nuclear matter estimates

International Nuclear Information System (INIS)

Starting from the exact microscopic time evolution of the quantum one body density associated with a many fermion system semiclassical approximations are derived to it. In the limit where small momentum transfer two body collisions are dominant we get a Fokker-Planck equation and work out friction and diffusion tensors explicitly for nuclear matter. If arbitrary momentum transfers are considered a Boltzmann equation is derived and used to calculate the viscosity coefficient of nuclear matter. A derivation is given of the collision term used by Landau to describe the damping of zero sound waves at low temperature in Plasmas. Memory effects are essential for this. The damping of zero sound waves in nuclear matter is also calculated and the value so obtained associated with the bulk value of the damping of giant resonances in finite nuclei. The bulk value is estimated to be quite small indicating the importance of the nuclear surface for the damping. (Author)

329

Equation of state for $\\beta$-stable hot nuclear matter

We provide an equation of state for hot nuclear matter in $\\beta$-equilibrium by applying a momentum-dependent effective interaction. We focus on the study of the equation of state of high-density and high-temperature nuclear matter, containing leptons (electrons and muons) under the chemical equilibrium condition in which neutrinos have left the system. The conditions of charge neutrality and equilibrium under $\\beta$-decay process lead first to the evaluation of proton and lepton fractions and afterwards the evaluation of internal energy, free energy, pressure and in total to the equation of state of hot nuclear matter. Thermal effects on the properties and equation of state of nuclear matter are evaluated and analyzed in the framework of the proposed effective interaction model. Special attention is dedicated to the study of the contribution of the components of $\\beta$-stable nuclear matter to the entropy per particle, a quantity of great interest for the study of structure and collapse of supernova.

Moustakidis, Ch C

2008-01-01

330

On the influence of the nuclear medium on the new nuclear matter states

International Nuclear Information System (INIS)

In many nucleus-nucleus collisions at high energies an increase of the particle production below the free nucleon-nucleon threshold has been observed. This increase can be related to the effects of the nuclear medium on the properties of the elementary particles, as well as on the new states of the nuclear matter, as resonance matter, for example. The present work takes into account the previous predictions on the rest mass particle modifications and resonance matter formation to discuss the influences of the nuclear medium on this new nuclear matter state. Experimental results on neutron-proton collisions at momenta between 1.25 GeV/c and 5.1 GeV/c, as well as on nucleus-nucleus collisions at energies between 1 A GeV and 15 A GeV are considered. Nuclear density and temperature determinations mainly at the pion emission, and the effective mass are used to establish the rest mass modification and the resonance weights in the considered collisions. A significant increase of the resonance matter formation is observed in nucleus-nucleus collisions, as compared with nucleon-nucleon collisions, at the same energy. The behaviour of the resonance matter formation in nucleus-nucleus collisions is also discussed. A like-saturation behaviour with energy increase can be considered. The major conclusion is that the nuclear medium has an important influence on the new states of nuclear matter. (authors)

331

Nuclear physics: the core of matter, the fuel of stars

International Nuclear Information System (INIS)

Dramatic progress has been made in all branches of physics since the National Research Council's 1986 decadal survey of the field. The Physics in a New Era series explores these advances and looks ahead to future goals. The series includes assessments of the major subfields and reports on several smaller subfields, and preparation has begun on an overview volume on the unity of physics, its relationships to other fields, and its contributions to national needs. Nuclear Physics is the latest volume of the series. The book describes current activity in understanding nuclear structure and symmetries, the behavior of matter at extreme densities, the role of nuclear physics in astrophysics and cosmology, and the instrumentation and facilities used by the field. It makes recommendations on the resources needed for experimental and theoretical advances in the coming decade. Nuclear physics addresses the nature of matter making up 99.9 percent of the mass of our everyday world. It explores the nuclear reactions that fuel the stars, including our Sun, which provides the energy for all life on Earth. The field of nuclear physics encompasses some 3,000 experimental and theoretical researchers who work at universities and national laboratories across the United States, as well as the experimental facilities and infrastructure that allow these researchers to address the outstanding scientific questions facing us. This report provides an overview of the frontiers of nuclear physicserview of the frontiers of nuclear physics as we enter the next millennium, with special attention to the state of the science in the United States.The current frontiers of nuclear physics involve fundamental and rapidly evolving issues. One is understanding the structure and behavior of strongly interacting matter in terms of its basic constituents, quarks and gluons, over a wide range of conditions - from normal nuclear matter to the dense cores of neutron stars, and to the Big Bang that was the birth of the universe. Another is to describe quantitatively the properties of nuclei, which are at the centers of all atoms in our world, in terms of models derived from the properties of the strong interaction. These properties include the nuclear processes that fuel the stars and produce the chemical elements. A third active frontier addresses fundamental symmetries of nature that manifest themselves in the nuclear processes in the cosmos, such as the behavior of neutrinos from the Sun and cosmic rays, and in low-energy laboratory tests of these symmetries. With recent developments on the rapidly changing frontiers of nuclear physics the Committee on Nuclear Physics is greatly optimistic about the next ten years. Important steps have been taken in a program to understand the structure of matter in terms of quarks and gluons

332

Constraints on the skewness coefficient of symmetric nuclear matter

Within the nonlinear relativistic mean field model, we show that both the pressure of symmetric nuclear matter at supra-saturation densities and the maximum mass of neutron stars are sensitive to the skewness coefficient $J_0$ of symmetric nuclear matter. Using experimental constraints on the pressure of symmetric nuclear matter at supra-saturation densities from flow data in heavy ion collisions and the astrophysical observation of a large mass neutron star PSR J0348+0432, with the former favoring a smaller $J_0$ while the latter a larger $J_0$, we extract a constraint of $-494 MeV \\leq J_0 \\leq -10 MeV$. This constraint is compared with the results obtained in other analyses.

Cai, Bao-Jun

2014-01-01

333

On growth of spinodal instabilities in nuclear matter

Early growth of density fluctuations of nuclear matter in spinodal region is investigated employing the stochastic mean-field approach. In contrast to the earlier treatments in which only collective modes were included in the calculations, in the present work non-collective modes are also included, thus providing a complete treatment of the density correlation functions. Calculations are carried out for symmetric matter in non-relativistic framework using a semi-classical approximation.

Yilmaz, O; Acar, F; Gokalp, A

2015-01-01

334

Pion absorption in excited nuclear matter

International Nuclear Information System (INIS)

The target dependence and azimuthal correlations of protons and plons are investigated for pA reactions at 4.9, 60 and 200 GeV. The experimental observations can be understood qualitatively under the assumption that pions are absorbed in excited target spectator matter. (orig.)

335

Nuclear-like states of quark matter

International Nuclear Information System (INIS)

In a world with only one flavor of light quark, QCD suggests that the low energy states of quark matter are similar to nuclei, but are not well represented as collections of baryons. Except for the existence of open nucleon channels, the same would be true for the actual, two-light-flavor world. 3 refs

336

Nuclear power - a matter of confidence

International Nuclear Information System (INIS)

It is the Central Electricity Generating Board's view that nuclear power is a safe technology and, on reasonable hypotheses, a sound economic investment of national resources. This booklet, based on a talk to members of Parliament in October 1981, sets out the reasons for this. The proposal to build a pressurized water reactor at Sizewell (Sizewell-B) is set in the historical and economic context of the overall energy policy. It acknowledges that public acceptability and the strategy for developing nuclear power in this country are the main problems facing the CEGB's nuclear policy. The Sizewell-B public enquiry is seen as a chance of gaining public confidence in the decision-making process associated with nuclear power. (U.K.)

337

Lectures notes on phase transformations in nuclear matter

The atomic nucleus, despite of being one of the smallest objects found in nature, appears to be large enough to experience phase transitions. The book deals with the liquid and gaseous phases of nuclear matter, as well as with the experimental routes to achieve transformation between them.Theoretical models are introduced from the ground up and with increasing complexity to describe nuclear matter from a statistical and thermodynamical point of view. Modern critical phenomena, heavy ion collisions and computational techniques are presented while establishing a linkage to experimental data.The

López, Jorge A

2000-01-01

338

Polarized nuclear matter using extended Seyler-Blanchard potentials

International Nuclear Information System (INIS)

In the present work the equation of state (EOS) is derived using three types of potentials for polarized nuclear matter. The potentials used are the extended Seyler-Blanchard (SB), modified Seyler-Blanchard (MSB) and the generalized Seyler-Blanchard (GSB) potentials. It is found that the equation of state derived using SB potential is a stiff EOS whereas the equations of state derived using MSB and GSB potentials are soft ones. The phase diagram for nuclear matter is also studied. The shapes are similar for the three potentials used but the critical temperatures are slightly different. copyright 1997 The American Physical Society

339

Polarized nuclear matter using extended Seyler-Blanchard potentials

In the present work the equation of state (EOS) is derived using three types of potentials for polarized nuclear matter. The potentials used are the extended Seyler-Blanchard (SB), modified Seyler-Blanchard (MSB) and the generalized Seyler-Blanchard (GSB) potentials. It is found that the equation of state derived using SB potential is a stiff EOS whereas the equations of state derived using MSB and GSB potentials are soft ones. The phase diagram for nuclear matter is also studied. The shapes are similar for the three potentials used but the critical temperatures are slightly different.

Mansour, H. M. M.; Hammad, M.; Hassan, M. Y. M.

1997-09-01

340

Nuclear Matter EOS with a Three-body Force

The effect of a microscopic three-body force on the saturation properties of nuclear matter is studied within the Brueckner-Hartree-Fock approach. The calculations show a decisive improvement of the saturation density along with an overall agreement with the empirical saturation point. With the three-body force the symmetry energy turns more rapidly increasing with density, which allows for the direct URCA process to occur in $\\beta$-stable neutron star matter. The influence of the three-body force on the nuclear mean field does not diminish the role of the ground state correlations.

Lejeune, A; Zuo, W

2000-01-01

341

Describing hot and dense nuclear matter with gauged linear ?-model

International Nuclear Information System (INIS)

To describe nuclear matter at high temperature and high baryon density appropriate for RHIC and LHC, an effective theory is proposed. Three developments underlie the effective theory: (1) relativistic mean field theory description of nuclear matter with mesons mediating interactions; (2) topological soliton description of the nucleon with hidden local symmetry; (3) phenomenological knowledge of nucleon-nucleon interaction and nucleon structure obtained from elastic NN scattering at c.m.energies of hundreds of GeV. When these developments are combined together, a gauged linear a-model with anomalous action and condensed quark-antiquark ground state emerges as the effective theory. (author)

342

? particles and the ''pasta'' phase in nuclear matter

International Nuclear Information System (INIS)

The effects of the ? particles in nuclear matter at low densities are investigated within three different parametrizations of relativistic models at finite temperature. Both homogeneous and inhomogeneous matter (pasta phase) are described for neutral nuclear matter with fixed proton fractions and stellar matter subject to ? equilibrium and trapped neutrinos. In homogeneous matter, ? particles are present only at densities below 0.02 fm-3 and their presence decreases with increase of the temperature and, for a fixed temperature, the ? particle fraction decreases for smaller proton fractions. A repulsive interaction is important to mimic the dissolution of the clusters in homogeneous matter. The effect of the ? particles on the pasta structure is very small except close to the critical temperatures and/or proton fractions, when it may still predict a pasta phase while no pasta phase would occur in the absence of light clusters. It is shown that for densities above 0.01 fm3 the ?-particle fraction in the pasta phase is much larger than that in homogeneous matter.

343

Quantum Monte Carlo Calculations of Symmetric Nuclear Matter

International Nuclear Information System (INIS)

We present an accurate numerical study of the equation of state of nuclear matter based on realistic nucleon-nucleon interactions by means of auxiliary field diffusion Monte Carlo (AFDMC) calculations. The AFDMC method samples the spin and isospin degrees of freedom allowing for quantum simulations of large nucleonic systems and represents an important step forward towards a quantitative understanding of problems in nuclear structure and astrophysics

344

Continued fraction approximation for the nuclear matter response function

International Nuclear Information System (INIS)

A continued fraction approximation is used to calculate the Random Phase Approximation (RPA) response function of nuclear matter. The convergence of the approximation is assessed by comparing it with the numerically exact response function obtained with a typical effective finite-range interaction used in nuclear physics. It is shown that just the first order term of the expansion can give reliable results at densities up to the saturation density value

345

Nuclear matter equation of state with effects of excluded volume

International Nuclear Information System (INIS)

Phenomenological mean field models of nuclear interactions are generalized to the case where the mean fields depend not only on density but also on temperature. As an application of general formalism we extend the Walecka model to account for hard core nuclear repulsion. The effects of this modification on the phase boundary between the hadron matter and the quark-gluon plasma and on main thermodynamic functions are considered

346

Energy Technology Data Exchange (ETDEWEB)

We study the elementary interactions between neutrinos and dense matter in a proto-neutron star. Equations of state obtained with different nuclear effective interactions (Skyrme, Gogny, Relativistic Lagrangians) are first discussed. Then, we characterize their stability in spin and isospin. We derive magnetic susceptibilities for all isospin asymmetry values as a function of Landau parameters G{sup {pi}}{sup {pi}}{sup '}{sub 0} (where {pi}, {pi}' = proton or neutron). From this work, we select a parametrization for each of the 3 effective forces: Sly230b,D1P,NL3. We calculate the pure neutron matter and asymmetric nuclear matter response functions with and without charge exchange, describing nuclear correlations in both approaches: non-relativistic (Hartree-Fock with Skyrme forces, then complete RPA) and relativistic (in the Hartree approximation). At the end, we calculate neutrino mean free paths neutral current and charged current reactions. Comparisons between relativistic and non-relativistic approaches allow us to identify relativistic effects in nuclear matter at densities as low as twice the saturation density. RPA correlations make the medium more transparent to neutrinos compared to free Fermi gas. The importance of the effective mass in mean free path calculations is also shown. (author)

Margueron, J

2001-07-01

347

A new improved quark mass density-dependent model including u, d quarks, $\\sigma$ mesons, $\\omega$ mesons and $\\rho$ mesons is presented. Employing this model, the properties of nuclear matter, neutron matter and neutron star are studied. We find that it can describe above properties successfully. The results given by the new improved quark mass density- dependent model and by the quark meson coupling model are compared.

Wu, Chen; Su, Ru-keng

2008-01-01

348

The Modification of the Scalar Field in dense Nuclear Matter

Directory of Open Access Journals (Sweden)

Full Text Available We show the possible evolution of the nuclear deep inelastic structure function with nuclear density ?. The nucleon deep inelastic structure function represents distribution of quarks as function of Björken variable x which measures the longitudinal fraction of momentum carried by them during the Deep Inelastic Scattering (DIS of electrons on nuclear targets. Starting with small density and negative pressure in Nuclear Matter (NM we have relatively large inter-nucleon distances and increasing role of nuclear interaction mediated by virtual mesons.When the density approaches the saturation point, ? = ?0, we have no longer separate mesons and nucleons but eventually modified nucleon Structure Function (SF in medium. The ratio of nuclear to nucleon SF measured at saturation point is well known as “EMC effect”. For larger density, ? > ?0, when the localization of quarks is smaller then 0.3 fm, the nucleons overlap. We argue that nucleon mass should start to decrease in order to satisfy the Momentum Sum Rule (MSR of DIS. These modifications of the nucleon Structure Function (SF are calculated in the frame of the nuclear Relativistic Mean Field (RMF convolution model. The correction to the Fermi energy from term proportional to the pressure is very important and its inclusion modifies the Equation of State (EoS for nuclear matter.

Ro?ynek J.

2011-04-01

349

Nuclear condensation and symmetry energy of dilute nuclear matter: an S-matrix approach

Based on the general analysis of the grand canonical partition function in the S-matrix framework, the calculated results on symmetry energy, free energy and entropy of dilute warm nuclear matter are presented. At a given temperature and density, the symmetry energy or symmetry free energy of the clusterized nuclear matter in the S-matrix formulation deviates, particularly at low temperature and relatively higher density, in a subtle way, from the linear dependence on the sq...

De, J. N.; Samaddar, S. K.

2008-01-01

350

Nuclear "pasta" structures in low-density nuclear matter and neutron star crust

In neutron star crust, non-uniform structure of nuclear matter is expected, which is called the "pasta" structure. From the recent studies of giant flares in magnetars, these structures might be related to some observables and physical quantities of the neutron star crust. To investigate the above quantities, we numerically explore the pasta structures with a fully threedimensional geometry and study the properties of low-density nuclear matter, based on the relativistic mea...

Okamoto, Minoru; Maruyama, Toshiki; Yabana, Kazuhiro; Tatsumi, Toshitaka

2013-01-01

351

Phase transitions in nuclear matter. Formation conditions and experimental signals

International Nuclear Information System (INIS)

The nuclear collisions at different energies offer conditions to excite fundamental nuclear matter and some phase transitions could appear. The phase transition type is related to the collision energy, as well as to the collision geometry. The two aspects involve associated de Broglie wavelength and the mean free path. Depending on the relationships of the two quantities with the nuclear radius and the internucleonic distance different excitation mechanisms can be supposed. Diverse phase transition can be considered in connection with these excitation mechanisms. Therefore, a discussion on the correlation between phase transition type and excitation mechanisms is useful to establish formation conditions and experimental signatures. An important stage in this discussion is related to the energy range where different phase transitions are more or less probable. The energy dependencies for some interesting physical quantities could reflect such energy ranges for a few phase transitions. The aspects related to the influences of effectiveness of the nuclear structure are important, too. The present work discusses all these aspects of the phase transitions in nuclear matter. They are reviewed and analysed in the terms of the present experimental results. The formation conditions and experimental signals for four phase transitions - nuclear liquid-vapour, resonance matter, hadronic plasma and quark-gluon plasma - are presented in the paper. Some new aspects related to the qu paper. Some new aspects related to the quark-gluon plasma formation in Au-Au collisions at the energies available at RHIC-BNL(USA) are included, too. A special attention will be done to the antiproton regeneration mechanisms in highly excited nuclear matter as signals of a phase transition. These considerations include mainly the author results obtained in different collaborations (SKM 200 - JINR Dubna, MULTI - KEK Tsukuba, UB - RIKEN Tokyo, BRAHMS - BNL Upton, New York). (author)

352

Three-dimensional structure of low-density nuclear matter

International Nuclear Information System (INIS)

We numerically explore the pasta structures and properties of low-density nuclear matter without any assumption on the geometry. We observe conventional pasta structures, while a mixture of the pasta structures appears as a metastable state at some transient densities. We also discuss the lattice structure of droplets.

353

Inequalities for low-energy symmetric nuclear matter

Using effective field theory we prove inequalities for the correlations of two-nucleon operators in low-energy symmetric nuclear matter. For physical values of operator coefficients in the effective Lagrangian, the S = 1, I = 0 channel correlations must have the lowest energy and longest correlation length in the two-nucleon sector. This result is valid at nonzero density and temperature.

Lee, Dean

2004-01-01

354

Role of Hyperon Negative Energy Sea in Nuclear Matter

We have examined the contribution of the filled negative energy sea of hyperons to the energy/particle in nuclear matter at the one and two loop levels. While this has the potential to be significant, we find a strong cancellation between the one and two loop contributions for our chosen parameters so that hyperon effects can be justifiably neglected.

Ellis, P. J.; Parendo, S. B.; Prakash, M.

1995-01-01

355

Revisiting the Hugenholtz-Van Hove theorem in nuclear matter

An assessment of the magnitude of the rearrangement contribution to the Fermi energy and to the binding energy per particle is carried out in symmetric nuclear matter by extending the G-matrix framework. The restoration of the thermodynamic consistency or, equivalently, the fulfillment of the Hugenholtz-Van Hove theorem, is discussed.

Czerski, P; Molinari, A

2002-01-01

356

Chiral Phase Structure of Hot and Dense Nuclear Matter

The description of nuclear matter bulk properties in the framework of quark-based hadron models in curved unit cells is extended to finite temperature. We discuss the analogy and interplay of density and temperature effects in this formulation and study, as an application, the temperature and density dependence of chiral vacuum properties in the Nambu-Jona-Lasinio (NJL) model.

Forkel, Hilmar; Jackson, A. D.

1995-01-01

357

The coexistence curve of finite charged nuclear matter

International Nuclear Information System (INIS)

The multifragmentation data of the ISiS Collaboration and the EOS Collaboration are examined. Fisher's droplet formalism, modified to account for Coulomb energy, is used to determine the critical exponents ? and ?, the surface energy coefficient c0, the pressure-temperature-density coexistence curve of finite nuclear matter and the location of the critical point

358

The nucleon spectral function in infinite nuclear matter

A perturbadve calculation of the nucleon spectral function in infinite nuclear matter has been carried out using a complete set of orthonormal correlated states. Correlation effects, giving rise to a quenching of the single particle strengths and to a sizeable background contribution are discussed.

Benhar, Omar; Fabrocini, Adelchi; Fantoni, Stefano

1989-06-01

359

The nucleon spectral function in infinite nuclear matter

Energy Technology Data Exchange (ETDEWEB)

A perturbative calculation of the nucleon spectral function in infinite nuclear matter has been carried out using a complete set of orthonormal correlated states. Correlation effects, giving rise to a quenching of the single particle strengths and to a sizeable background contribution are discussed. (orig.).

Benhar, O. (Istituto Nazionale di Fisica Nucleare, Rome (Italy). Ist. Superiore di Sanita); Fabrocini, A. (Pisa Univ. (Italy). Dipt. di Fisica; Istituto Nazionale di Fisica Nucleare, Pisa (Italy)); Fantoni, S. (Lecce Univ. (Italy). Dipt. di Fisica; Istituto Nazionale di Fisica Nucleare, Lecce (Italy))

1989-06-26

360

Radiative energy loss of jets in hot / cold nuclear matter

International Nuclear Information System (INIS)

The radiative energy loss encountered by a high energy quark or gluon propagating in a nuclear medium is estimated. Under reasonable assumptions it is found to be larger by at least an order of magnitude in hot compared to cold matter. (author)

361

Revisiting the Hugenholtz-Van Hove theorem in nuclear matter

International Nuclear Information System (INIS)

An assessment of the magnitude of the rearrangement contribution to the Fermi energy and to the binding energy per particle is carried out in symmetric nuclear matter by extending the G-matrix framework. The restoration of the thermodynamic consistency or, equivalently, the fulfillment of the Hugenholtz-Van Hove theorem, is discussed

362

Phase transitions of nuclear matter beyond mean field theory

International Nuclear Information System (INIS)

The Cornwall-Jackiw-Tomboulis (CJT) effective action approach is applied to study the phase transition of nuclear matter modeled by the four-nucleon interaction. It is shown that in the Hartree-Fock approximation (HFA) a first-order phase transition takes place at low temperature, whereas the phase transition is of second order at higher temperature

363

Three-dimensional calculation of inhomogeneous nuclear matter

Energy Technology Data Exchange (ETDEWEB)

We numerically explore the pasta structures and properties of low-density symmetric nuclear matter without any assumption on the geometry. We observe conventional pasta structures, while a mixture of the pasta appears as a meta-stable state at some transient densities. We also analyze the lattice structure of droplets.

Okamoto, Minoru; Maruyama, Toshiki; Yabana, Kazuhiro; Tatsumi, Toshitaka [Graduate School of Pure and Applied Science, University of Tsukuba (Japan); Advanced Science Research Center, Japan Atomic Energy Agency (Japan); Graduate School of Pure and Applied Science, University of Tsukuba (Japan); Department of Physics, Kyoto University (Japan)

2012-11-12

364

Three-dimensional calculation of inhomogeneous nuclear matter

International Nuclear Information System (INIS)

We numerically explore the pasta structures and properties of low-density symmetric nuclear matter without any assumption on the geometry. We observe conventional pasta structures, while a mixture of the pasta appears as a meta-stable state at some transient densities. We also analyze the lattice structure of droplets.

365

Three dimensional structure of low-density nuclear matter

We numerically explore the pasta structures and properties of low-density nuclear matter without any assumption on the geometry. We observe conventional pasta structures, while a mixture of the pasta structures appears as a metastable state at some transient densities. We also discuss the lattice structure of droplets.

Okamoto, Minoru; Yabana, Kazuhiro; Tatsumi, Toshitaka

2011-01-01

366

Three-dimensional structure of low-density nuclear matter

Energy Technology Data Exchange (ETDEWEB)

We numerically explore the pasta structures and properties of low-density nuclear matter without any assumption on the geometry. We observe conventional pasta structures, while a mixture of the pasta structures appears as a metastable state at some transient densities. We also discuss the lattice structure of droplets.

Okamoto, Minoru, E-mail: okamoto@nucl.ph.tsukuba.ac.jp [Graduate School of Pure and Applied Science, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8571 (Japan); Advanced Science Research Center, Japan Atomic Energy Agency, Shirakata Shirane 2-4, Tokai, Ibaraki 319-1195 (Japan); Maruyama, Toshiki, E-mail: maruyama.toshiki@jaea.go.jp [Advanced Science Research Center, Japan Atomic Energy Agency, Shirakata Shirane 2-4, Tokai, Ibaraki 319-1195 (Japan); Graduate School of Pure and Applied Science, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8571 (Japan); Yabana, Kazuhiro, E-mail: yabana@nucl.ph.tsukuba.ac.jp [Graduate School of Pure and Applied Science, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8571 (Japan); Center of Computational Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8571 (Japan); Tatsumi, Toshitaka, E-mail: tatsumi@ruby.scphys.kyoto-u.ac.jp [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

2012-07-09

367

The strangeness and charm of dense nuclear matter

The creation of strangeness and charm in nucleus-nucleus collisions at threshold beam energies is discussed as a probe for compressed baryonic matter. Experimental data on strangeness production at SIS energies indicate that the properties of kaons and antikaons are modified in dense nuclear matter. The yield of K/sup +/ mesons emitted in heavy-ion collisions at beam energies below 1.5 AGeV is found to be sensitive to the nuclear equation-of-state. An experiment is proposed at the future GSI facility to explore the QCD phase diagram in the region of highest baryon densities. This approach is complementary to the studies of matter at high temperatures performed at the CERN-SPS, RHIC and the future LHC. Experimental observables and the proposed detector system will be discussed. (35 refs).

Senger, P

2003-01-01

368

Nuclear reactor operation monitoring and dark matter searches

International Nuclear Information System (INIS)

Most of the Dark Matter and high energy astrophysics experiments have developed advanced technologies that may have also application to nuclear detection. These technologies sharing many characteristics such as energy scales, particle type, time structures and combination of high and low background signal levels. We demonstrated high flux of electron neutrino (?e) can be produced at nuclear power reactors via electron capture or inverse beta decay of the fission products and neutron activation on the fuel rods and the construction materials at the reactor core and can be enhanced by loading selected isotopes to the reactor core, and the potential applications and achievable statistical accuracies were examined. In addition, many facets of the detector science overlap with needs for next generation dark matter and neutrino experiments. I will discuss results of our several successful deployments of prototype high purity germanium detectors. I will also discuss reactor operation monitory and shed light on the dark matter searches results. (author)

369

Nuclear matter from effective quark-quark interaction

We study neutron matter and symmetric nuclear matter with the quark-meson model for the two-nucleon interaction. The Bethe-Bruckner-Goldstone many-body theory is used to describe the correlations up to the three hole-line approximation with no extra parameters. At variance with other non-relativistic realistic interactions, the three hole-line contribution turns out to be non-negligible and to have a substantial saturation effect. The saturation point of nuclear matter, the compressibility, the symmetry energy and its slope are within the phenomenological constraints. Since the interaction also reproduces fairly well the properties of three nucleons system, these results indicate that the explicit introduction of the quark degrees of freedom for the construction of the nucleon-nucleon interaction strongly reduces the possible role of three-body forces

Baldo, M

2014-01-01

370

Nuclear matter from effective quark-quark interaction.

We study neutron matter and symmetric nuclear matter with the quark-meson model for the two-nucleon interaction. The Bethe-Bruckner-Goldstone many-body theory is used to describe the correlations up to the three hole-line approximation with no extra parameters. At variance with other nonrelativistic realistic interactions, the three hole-line contribution turns out to be non-negligible and to have a substantial saturation effect. The saturation point of nuclear matter, the compressibility, the symmetry energy, and its slope are within the phenomenological constraints. Since the interaction also reproduces fairly well the properties of the three-nucleon system, these results indicate that the explicit introduction of the quark degrees of freedom within the considered constituent quark model is expected to reduce the role of three-body forces. PMID:25541769

Baldo, M; Fukukawa, K

2014-12-12

371

Nuclear Matter from Effective Quark-Quark Interaction

We study neutron matter and symmetric nuclear matter with the quark-meson model for the two-nucleon interaction. The Bethe-Bruckner-Goldstone many-body theory is used to describe the correlations up to the three hole-line approximation with no extra parameters. At variance with other nonrelativistic realistic interactions, the three hole-line contribution turns out to be non-negligible and to have a substantial saturation effect. The saturation point of nuclear matter, the compressibility, the symmetry energy, and its slope are within the phenomenological constraints. Since the interaction also reproduces fairly well the properties of the three-nucleon system, these results indicate that the explicit introduction of the quark degrees of freedom within the considered constituent quark model is expected to reduce the role of three-body forces.

Baldo, M.; Fukukawa, K.

2014-12-01

372

Nuclear "pasta" structures in low-density nuclear matter and neutron star crust

In neutron star crust, non-uniform structure of nuclear matter is expected, which is called the "pasta" structure. From the recent studies of giant flares in magnetars, these structures might be related to some observables and physical quantities of the neutron star crust. To investigate the above quantities, we numerically explore the pasta structures with a fully threedimensional geometry and study the properties of low-density nuclear matter, based on the relativistic mean-field model and the Thomas-Fermi approximation. We observe typical pasta structures for fixed proton number-fraction and two of them for cold catalyzed matter. We also discuss the crystalline configuration of "pasta".

Okamoto, Minoru; Yabana, Kazuhiro; Tatsumi, Toshitaka

2013-01-01

373

A Phase-Space Noncommutative Picture of Nuclear Matter

Noncommutative features are introduced into a relativistic quantum field theory model of nuclear matter, the quantum hadrodynamics-I nuclear model (QHD-I). It is shown that the nuclear matter equation of state (NMEoS) depends on the fundamental momentum scale, $\\eta$, introduced by the phase-space noncommutativity (NC). Although it is found that NC geometry does not affect the nucleon fields up to $O(\\eta^2)$, it affects the energy density, the pressure and other derivable quantities of the NMEoS, such as the nucleon \\textit{effective mass}. Under the conditions of saturation of the symmetric NM, the estimated value for the noncommutative parameter is $\\sqrt{\\eta}=0.014 MeV/c$.

Bertolami, Orfeu

2015-01-01

374

Deuteron Distribution in Nuclei and in Correlated Nuclear Matter

We compute the distribution of quasideuterons in doubly closed shell nuclei and infinite correlated nuclear matter. The ground states of $^{16}$O and $^{40}$Ca are described in $ls$ coupling using a realistic hamiltonian including the Argonne $v_{8}^\\prime$ and the Urbana IX models of two-- and three--nucleon potentials, respectively. The nuclear wave function contains central and tensor correlations, and correlated basis functions theory is used to evaluate the distribution of neutron-proton pairs, having the deuteron quantum numbers, as a function of their total momentum. By computing the number of deuteron--like pairs we are able to extract the Levinger's factor and compare to both the available experimental data and the predictions of the local density approximation, based on nuclear matter estimates. The agreement with the experiments is excellent, whereas the local density approximation is shown to sizably overestimate the Levinger's factor in the region of the medium nuclei.

Illarionov, A Yu

2003-01-01

375

Pairing in bulk nuclear matter beyond BCS

The influence of short-range correlations on the spectral distribution of neutrons is incorporated in the solution of the gap equation for the ${}^3P_2-{}^3F_2$ coupled channel in pure neutron matter. This effect is studied for different realistic interactions including one based on chiral perturbation theory. The gap in this channel vanishes at all relevant densities due to the treatment of these correlations. We also consider the effect of long-range correlations by including polarization terms in addition to the bare interaction which allow the neutrons to exchange density and spin fluctuations governed by the strength of Landau parameters allowed to have reasonable values consistent with the available literature. Preliminary results indicate that reasonable values of these parameters do not generate a gap in the ${}^3P_2-{}^3F_2$ coupled channel either for all three realistic interactions although the pairing interaction becomes slightly more attractive.

Ding, D; Dickhoff, W H; Dussan, H; Rios, A; Polls, A

2014-01-01

376

Probing dense matter with strangeness production in nuclear collisions

International Nuclear Information System (INIS)

Experiments on strangeness production in nucleus-nucleus collisions at SIS energies address fundamental questions of modern nuclear physics: the determination of the nuclear equation-of-state at high baryon densities and the properties of hadrons in dense nuclear matter. From the yields of K+ mesons measured in heavy-ion collisions a value for the nuclear compressibility of ??200MeV is extracted for nuclear densities around twice saturation density using different microscopic transport models. Both the yield of K+ mesons and their anisotropic azimuthal angular distribution (elliptic flow) exhibit strong evidence for a repulsive K+N potential. The yields of K+ and K- mesons measured in proton-nucleus collisions can be reproduced by transport calculations assuming at saturation density a repulsive K+N potential of U=25MeV and an attractive K-N potential of U=-80±20MeV

377

Nonlinear mean field theory for nuclear matter and surface properties

International Nuclear Information System (INIS)

Nuclear matter properties are studied in a nonlinear relativistic mean field theory. We determine the parameters of the model from bulk properties of symmetric nuclear matter and a reasonable value of the effective mass. In this work, we stress the nonrelativistic limit of the theory which is essentially equivalent to a Skyrme hamiltonian, and we show that most of the results can be obtained, to a good approximation, analytically. The strength of the required parameters is determined from the binding energy and density of nuclear matter and the effective nucleon mass. For realistic values of the parameters, the nonrelativistic approximation turns out to be quite satisfactory. Using reasonable values of the parameters, we can account for other key properties of nuclei, such as the spin-orbit coupling, surface energy, and diffuseness of the nuclear surface. Also the energy dependence of the nucleon-nucleus optical model is accounted for reasonably well except near the Fermi surface. It is found, in agreement with empirical results, that the Landau parameter F0 is quite small in normal nuclear matter. Both density dependence and momentum dependence of the NN interaction, but especially the former, are important for nuclear saturation. The required scalar and vector coupling constants agree fairly well with those obtained from analyses of NN scattering phase shifts with one-boson-exchange models. The mean field theory provides a semiquantitative justification frovides a semiquantitative justification for the weak Skyrme interaction in odd states. The strength of the required nonlinear term is roughly consistent with that derived using a new version of the chiral mean field theory in which the vector mass as well as the nucleon mass is generated by the sigma-field. (orig.)

378

Meson production in dense nuclear matter

International Nuclear Information System (INIS)

Pion and Kaon production has been studied in symmetric nucleus-nucleus collisions at beam energies between 0.8 and 1.8 AGeV. The anisotropic azimuthal emission of pions in semi-central collisions can be explained by the emission of high-energy pions in early stage of the collision and a late ''freeze-out'' of low energy pions. In nucleus-nucleus collisions at 1 AGeV, the K+ multiplicity increases more than linearly both with A (in A + A collisions) and with Apart (i.e. the number of participating nucleons in Au + Au collisions). This nonlinear behaviour is due to collective effects such as multiple hadron-hadron encounters. According to transport calculations, the large K+ cross section observed for Au + Au collisions at 1 AGeV is a consequence of a soft nuclear equation of state. The large K-/K+ ratio measured in Ni + Ni collisions at equivalent beam energies (compared to p+p collisions) is a signature for an enhanced in-medium K- production. In order to reproduce the data, transport models have to consider a reduction of the K- mass in the dense nuclear medium. (author)

379

Open charm tomography of cold nuclear matter

International Nuclear Information System (INIS)

We study the relative contribution of partonic subprocesses to D meson production and D meson-triggered inclusive di-hadrons to lowest order in perturbative QCD. While gluon fusion dominates the creation of large angle DD pairs, charm on light parton scattering determines the yield of single inclusive D mesons. The distinctly different nonperturbative fragmentation of c quarks into D mesons versus the fragmentation of quarks and gluons into light hadrons results in a strong transverse momentum dependence of anticharm content of the away side charm-triggered jet. In p+A reactions, we calculate and resum the coherent nuclear-enhanced power corrections from the final-state partonic scattering in the medium. We find that single and double inclusive open charm production can be suppressed as much as the yield of neutral pions from dynamical high-twist shadowing. Effects of energy loss in p+A collisions are also investigated phenomenologically and may lead to significantly weaker transverse momentum dependence of the nuclear attenuation

380

Open charm tomography of cold nuclear matter

We study the relative contribution of partonic subprocesses to D meson production and D meson-triggered inclusive di-hadrons to lowest order in perturbative QCD. While gluon fusion dominates the creation of large angle DD¯ pairs, charm on light parton scattering determines the yield of single inclusive D mesons. The distinctly different nonperturbative fragmentation of c quarks into D mesons versus the fragmentation of quarks and gluons into light hadrons results in a strong transverse momentum dependence of anticharm content of the away side charm-triggered jet. In p+A reactions, we calculate and resum the coherent nuclear-enhanced power corrections from the final-state partonic scattering in the medium. We find that single and double inclusive open charm production can be suppressed as much as the yield of neutral pions from dynamical high-twist shadowing. Effects of energy loss in p+A collisions are also investigated phenomenologically and may lead to significantly weaker transverse momentum dependence of the nuclear attenuation.

Vitev, I.; Goldman, T.; Johnson, M. B.; Qiu, J. W.

2006-09-01

381

Pion condensation in a theory consistent with bulk properties of nuclear matter

International Nuclear Information System (INIS)

A relativistic field theory of nuclear matter is solved for the self-consistent field strengths inthe mean-field approximation. The theory is constrained to reproduce the bulk properties of nuclear matter. A weak pion condensate is compatible with this constraint. At least this is encouraging as concerns the possible existence of a new phase of nuclear matter. In contrast, the Lee-Wick density isomer is probably not compatible with the properties of nuclear matter. 3 figures

382

Climate Change, Nuclear Power and Nuclear Proliferation: Magnitude Matters

International Nuclear Information System (INIS)

Integrated energy, environment and economics modeling suggests electrical energy use will increase from 2.4 TWe today to 12 TWe in 2100. It will be challenging to provide 40% of this electrical power from combustion with carbon sequestration, as it will be challenging to provide 30% from renewable energy sources. Thus nuclear power may be needed to provide ?30% by 2100. Calculations of the associated stocks and flows of uranium, plutonium and minor actinides indicate that the proliferation risks at mid-century, using current light-water reactor technology, are daunting. There are institutional arrangements that may be able to provide an acceptable level of risk mitigation, but they will be difficult to implement. If a transition is begun to fast-spectrum reactors at mid-century, without a dramatic change in the proliferation risks of such systems, at the end of the century proliferation risks are much greater, and more resistant to mitigation. The risks of nuclear power should be compared with the risks of the estimated 0.64 C long-term global surface-average temperature rise predicted if nuclear power were replaced with coal-fired power plants without carbon sequestration. Fusion energy, if developed, would provide a source of nuclear power with much lower proliferation risks than fission.

383

Pairing in bulk nuclear matter beyond BCS

Energy Technology Data Exchange (ETDEWEB)

The influence of short-range correlations on the spectral distribution of neutrons is incorporated in the solution of the gap equation for the {sup 3}P{sub 2}?{sup 3}F{sub 2} coupled channel in pure neutron matter. This effect is studied for different realistic interactions including one based on chiral perturbation theory. The gap in this channel vanishes at all relevant densities due to the treatment of these correlations. We also consider the effect of long-range correlations by including polarization terms in addition to the bare interaction which allow the neutrons to exchange density and spin fluctuations governed by the strength of Landau parameters allowed to have reasonable values consistent with the available literature. Preliminary results indicate that reasonable values of these parameters do not generate a gap in the {sup 3}P{sub 2}?{sup 3}F{sub 2} coupled channel either for all three realistic interactions although the pairing interaction becomes slightly more attractive.

Ding, D.; Dickhoff, W. H.; Dussan, H. [Department of Physics, Washington University, St. Louis, Missouri 63130 (United States); Witte, S. J. [Department of Physics, Washington University, St. Louis, Missouri 63130, USA and Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Rios, A. [Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Polls, A. [Departament d' Estructura i Constituents de la Matèria, Universitat de Barcelona, E-08028 Barcelona (Spain)

2014-10-15

384

Nuclear matter descriptions including quark structure of the hadrons

International Nuclear Information System (INIS)

It is nowadays well established that nucleons are composite objects made of quarks and gluons, whose interactions are described by Quantum chromodynamics (QCD). However, because of the non-perturbative character of QCD at the energies of nuclear physics, a description of atomic nuclei starting from quarks and gluons is still not available. A possible alternative is to construct effective field theories based on hadronic degrees of freedom, in which the interaction is constrained by QCD. In this framework, we have constructed descriptions of infinite nuclear matter in relativistic mean field theories taking into account the quark structure of hadrons. In a first approach, the in medium modifications of mesons properties is dynamically obtained in a Nambu-Jona-Lasinio (NJL) quark model. This modification is taken into account in a relativistic mean field theory based on a meson exchange interaction between nucleons. The in-medium modification of mesons masses and the properties of infinite nuclear matter have been studied. In a second approach, the long and short range contributions to the in-medium modification of the nucleon are determined. The short range part is obtained in a NJL quark model of the nucleon. The long range part, related to pions exchanges between nucleons, has been determined in the framework of Chiral Perturbation theory. These modifications have been used to constrain the couplings of a point coupling relativistic mean field model. A realistic description of the saturation properties of nuclear matter is obtained. (author)

385

The ?? cloud contribution to the ? width in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The width of the ? meson in cold nuclear matter is computed in a hadronic many-body approach, focusing on a detailed treatment of the medium modifications of intermediate ?? states. The ? and ? propagators are dressed by their self-energies in nuclear matter taken from previously constrained many-body calculations. The pion self-energy includes Nh and ?h excitations with short-range correlations, while the ? self-energy incorporates the same dressing of its 2? cloud with a full 3-momentum dependence and vertex corrections, as well as direct resonance-hole excitations; both contributions were quantitatively fit to total photo-absorption spectra and ?N??N scattering. Our calculations account for in-medium decays of type ?N??N{sup (?)},??N(?), and 2-body absorptions ?NN?NN{sup (?)},?NN. This causes deviations of the in-medium ? width from a linear behavior in density, with important contributions from spacelike ? propagators. The ? width from the ?? cloud may reach up to 200 MeV at normal nuclear matter density, with a moderate 3-momentum dependence. This largely resolves the discrepancy of linear T–? approximations with the values deduced from nuclear photoproduction measurements.

Cabrera, D. [Institute for Theoretical Physics, Frankfurt University, 60438 Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies, Frankfurt University, 60438 Frankfurt am Main (Germany); Rapp, R. [Cyclotron Institute and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843-3366 (United States)

2014-02-05

386

On the calculation of correlation functions in nuclear matter

International Nuclear Information System (INIS)

A new three-parameter set of nuclear matter correlation functions is generated by two-body Euler-Lagrange equations. The parameters include two correlation ranges, d for central, sigma1 x sigma2, tau1 x tau2 and (sigma1 x sigma2)(tau1 x tau2) correlations, and dsub(t) for tensor correlations. A new parameter ? that simulates the quenching of noncentral interactions in matter is introduced. Simple physical arguments indicate that this parameterization is more appropriate. The new correlation functions give 2-3 MeV lower energies for the semirealistic ?6 models at equilibrium density. (orig.)

387

Gluon condensation and deconfinement critical density in nuclear matter

International Nuclear Information System (INIS)

An upper limit to the critical density for the transition to the deconfined phase, at zero temperature, has been evaluated by analyzing the behavior of the gluon condensate in nuclear matter. Due to the non-linear baryon density effects, the upper limit to the critical density, ?c turns out about nine times the saturation density, ?0 for the value of the gluon condensate in vacuum =0.012 GeV4. For neutron matter ?c?8.5?0. The dependence of the critical density on the value of the gluon condensate in vacuum is studied

388

Review of the theory of infinite nuclear matter

International Nuclear Information System (INIS)

Given a two-body force, there seems to be two distinct starting points in the many-body perturbation-theoretic problem of computing the energy per nucleon of infinite (as well as finite) nuclear matter: ordinary Hartree-Fock theory and the Brueckner theory. The former theory, treated almost exclusively with plane-wave solutions, has long-ago fallen into disuse, to yield to the latter, apparently more sophisticated, theory. After a brief outline of many-fermion diagramatic techniques, the Brueckner-Bethe-Goldstone series expansion in terms of the density is discussed as a low density, non-ideal Fermi gas theory, whose convergence is analyzed. A calculation based on particle-hole Green's function techniques shows that a nucleon gas condenses to the liquid phase at about 3% of the empirical nuclear matter saturation density. The analogy between the BBG expansion and the virial expansion for a classical or quantum gas is studied with special emphasis on the apparent impossibility of analytical-continuing the latter gas theory to densities in the liquid regime, as first elucidated by Lee and Yang. It is finally argued that ordinary HF theory may provide a good starting point for the eventual understanding of nuclear matter as it gives (in the finite nuclear problem, at any rate) not only the basic liquid properties of a definite density and a surface but also provides independent-particle aspects, avoiding at the same time the idea of n-body clusters appropriate only for d of n-body clusters appropriate only for dilute gases. This program has to date not been carried out for infinite nuclear matter, mainly because of insufficient knowledge regarding low-energy, non-plane-wave solutions of the HF equations, in the thermodynamic limit

389

Climate Change, Nuclear Power and Nuclear Proliferation: Magnitude Matters

Energy Technology Data Exchange (ETDEWEB)

Integrated energy, environment and economics modeling suggests that worldwide electrical energy use will increase from 2.4 TWe today to ~12 TWe in 2100. It will be challenging to provide 40% of this electrical power from combustion with carbon sequestration, as it will be challenging to provide 30% from renewable energy sources derived from natural energy flows. Thus nuclear power may be needed to provide ~30%, 3600 GWe, by 2100. Calculations of the associated stocks and flows of uranium, plutonium and minor actinides indicate that the proliferation risks at mid-century, using current light-water reactor technology, are daunting. There are institutional arrangements that may be able to provide an acceptable level of risk mitigation, but they will be difficult to implement. If a transition is begun to fast-spectrum reactors at mid-century, without a dramatic change in the proliferation risks of such systems, at the end of the century global nuclear proliferation risks are much greater, and more resistant to mitigation. Fusion energy, if successfully demonstrated to be economically competitive, would provide a source of nuclear power with much lower proliferation risks than fission.

Robert J. Goldston

2011-04-28

390

Climate Change, Nuclear Power and Nuclear Proliferation: Magnitude Matters

International Nuclear Information System (INIS)

Integrated energy, environment and economics modeling suggests that worldwide electrical energy use will increase from 2.4 TWe today to ?12 TWe in 2100. It will be challenging to provide 40% of this electrical power from combustion with carbon sequestration, as it will be challenging to provide 30% from renewable energy sources derived from natural energy flows. Thus nuclear power may be needed to provide ?30%, 3600 GWe, by 2100. Calculations of the associated stocks and flows of uranium, plutonium and minor actinides indicate that the proliferation risks at mid-century, using current light-water reactor technology, are daunting. There are institutional arrangements that may be able to provide an acceptable level of risk mitigation, but they will be difficult to implement. If a transition is begun to fast-spectrum reactors at mid-century, without a dramatic change in the proliferation risks of such systems, at the end of the century global nuclear proliferation risks are much greater, and more resistant to mitigation. Fusion energy, if successfully demonstrated to be economically competitive, would provide a source of nuclear power with much lower proliferation risks than fission.

391

Open charm tomography of cold nuclear matter

We study the relative contribution of partonic sub-processes to D meson production and D meson-triggered inclusive di-hadrons to lowest order in perturbative QCD. While gluon fusion dominates the creation of large angle DD-bar pairs, charm on light parton scattering determines the yield of single inclusive D mesons. The distinctly different non-perturbative fragmentation of c quarks into D mesons versus the fragmentation of quarks and gluons into light hadrons results in a strong transverse momentum dependence of anticharm content of the away-side charm-triggered jet. In p+A reactions, we calculate and resum the coherent nuclear-enhanced power corrections from the final state partonic scattering in the medium. We find that single and double inclusive open charm production can be suppressed as much as the yield of neutral pions from dynamical high-twist shadowing. Effects of energy loss in p+A collisions are also investigated phenomenologically and may lead to significantly weaker transverse momentum dependenc...

Vitev, I; Johnson, M B; Qiu, J W

2006-01-01

392

Appearance of the Gyroid Network Phase in Nuclear Pasta Matter

Nuclear matter under the conditions of a supernova explosion unfolds into a rich variety of spatially structured phases, called nuclear pasta. We investigate the role of periodic networklike structures with negatively curved interfaces in nuclear pasta structures, by static and dynamic Hartree-Fock simulations in periodic lattices. We investigate particularly the role of minimal surfaces in that context. As the most prominent result, we identify the single gyroid network structure of cubic chiral symmetry, a well known configuration in nanostructured softmatter systems, both as a dynamical state and as a cooled static solution. While most observed gyroids are only meta-stable, the very small energy differences to the ground state indicate its relevance for structures in nuclear pasta.

Schuetrumpf, B; Iida, K; Schroeder-Turk, G E; Maruhn, J A; Mecke, K; Reinhard, P -G

2014-01-01

393

Spinodal decomposition of expanding nuclear matter and multifragmentation

Density fluctuations of expanding nuclear matter are studied within a mean-field model in which fluctuations are generated by an external stochastic field. Fluctuations develop about a mean one-body phase-space density corresponding to a hydrodinamic motion that describes a slow expansion of the system. A fluctuation-dissipation relation suitable for a uniformly expanding medium is obtained and used to constrain the strength of the stochastic field. The distribution of the liquid domains in the spinodal decomposition is derived. Comparison of the related distribution of the fragment size with experimental data on the nuclear multifragmentation is quite satisfactory.

Matera, F; Fabbri, G

2003-01-01

394

Phase structure in a chiral model of nuclear matter

International Nuclear Information System (INIS)

The phase structure of symmetric nuclear matter in the extended Nambu-Jona-Lasinio (ENJL) model is studied by means of the effective potential in the one-loop approximation. It is found that chiral symmetry gets restored at high nuclear density and a typical first-order phase transition of the liquid-gas transition occurs at zero temperature, T=0, which weakens as T grows and eventually ends up with a second-order critical point at T=20 MeV. This phase transition scenario is confirmed by investigating the evolution of the effective potential versus the effective nucleon mass and the equation of state.

395

Correlation effects on the weak response of nuclear matter

International Nuclear Information System (INIS)

The consistent description of the nuclear response at low and high momentum transfer requires a unified dynamical model, suitable to account for both short- and long-range correlation effects. We report the results of a study of the charged current weak response of symmetric nuclear matter, carried out using an effective interaction obtained from a realistic model of the nucleon-nucleon force within the formalism of correlated basis functions. Our approach allows for a clear identification of the kinematical regions in which different interaction effects dominate.

396

The Coester line in relativistic mean field nuclear matter

Scientific Electronic Library Online (English)

Full Text Available The Walecka model contains essentially two parameters that are associated with the Lorentz scalar (S) and vector (V) interactions. These parameters are related to a two-body interaction consisting of S and V, imposing the condition that the two-body binding energy is fixed. We have obtained a set of [...] different values for the nuclear matter binding energies (B N) at equilibrium densities (rhoo). We investigated the existence of a linear correlation between B N and rhoo, claimed to be universal for nonrelativistic systems and usually known as the Coester line, and found an approximate linear correlation only if V - S remains constant. It is shown that the relativistic content of the model, which is related to the strength of V - S, is responsible for the shift of the Coester line to the empirical region of nuclear matter saturation.

A., Delfino; M., Malheiro; V. S., Timóteo; J. S. Sá, Martins.

2005-03-01

397

Electric-dipole sum rule in nuclear matter

The enhancement factor K in the electric-dipole sum rule for some realistic models of symmetrical nuclear matter is calculated using variational theory. The nuclear-matter wave function used contains central, spin, isospin, tensor and spin-orbit pair correlations. The non-central correlations, particularly the tensor one, give the major contribution to K. At experimental equilibrium density K. turns out to be ? 1.8, of which 65% comes from OPEP and 30% from the short-range part of the interaction. The two-pion-exchange three-nucleon interaction contributes ? 0.2% and is cancelled, to a large extent, by the contribution due to the intermediate-range two-body potential. The relationship of the summed oscillator strength with the effective mass is also discussed.

Fabrocini, A.; Fantoni, S.

1985-03-01

398

Electric-dipole sum rule in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The enhancement factor K in the electric-dipole sum rule for some realistic models of symmetrical nuclear matter is calculated using variational theory. The nuclear-matter wave function used contains central, spin, isospin, tensor and spin-orbit pair correlations. The non-central correlations, particularly the tensor one, give the major contribution of K. At experimental equilibrium density K turns out to be proportional 1.8 of which 65% comes from OPEP and 30% from the short-range part of the interaction. The two-pion-exchange three-nucleon interaction contributes proportional0.2% and is cancelled, to a large extent, by the contribution due to the intermediate-range two-body potential. The relationship of the summed oscillator strength with the effective mass is also discussed.

Fabrocini, A.; Fantoni, S.

1985-03-11

399

From nuclear matter to finite nuclei. Pt. 2

International Nuclear Information System (INIS)

We discuss various relativistic models describing ground-state properties of spherical nuclei, are discussed. Relativistic mean-field and Hartree-Fock theories, which serve as a startingpoint for subsequent models, are reviewed. Using a density-dependent parametrization of the Dirac-Brueckner G-matrix in nuclear matter, we achieve an effective Dirac-Brueckner-Hartree-Fock model for finite nuclei. Finite nuclei results obtained with this model are compared with the less advanced Density-Dependent Mean-Field model, which simulates Dirac-Brueckner calculations for nuclear matter as well. It is shown that the effective Dirac-Brueckner-Hartree-Fock approach most successfully reproduces experimental data concerning spherical nuclei. (orig.)

400

Finite size effects in Neutron Star and Nuclear matter simulations

In this work we study molecular dynamics simulations of symmetric nuclear matter using a semi-classical nucleon interaction model. We show that, at sub-saturation densities and low temperatures, the solutions are non-homogeneous structures reminiscent of the ``nuclear pasta'' phases expected in Neutron Star Matter simulations, but shaped by artificial aspects of the simulations. We explore different geometries for the periodic boundary conditions imposed on the simulation cell: cube, hexagonal prism and truncated octahedron. We find that different cells may yield different solutions for the same physical conditions (i.e. density and temperature). The particular shape of the solution at a given density can be predicted analytically by energy minimization. We also show that even if this behavior is due to finite size effects, it does not mean that it vanishes for very large systems and it actually is independent of the system size: The system size sets the only characteristic length scale for the inhomogeneitie...

Molinelli, P A Giménez

2014-01-01

401

Investigation of the organic matter in inactive nuclear tank liquids

International Nuclear Information System (INIS)

Environmental Protection Agency (EPA) methodology for regulatory organics fails to account for the organic matter that is suggested by total organic carbon (TOC) analysis in the Oak Ridge National Laboratory (ORNL) inactive nuclear waste-tank liquids and sludges. Identification and measurement of the total organics are needed to select appropriate waste treatment technologies. An initial investigation was made of the nature of the organics in several waste-tank liquids. This report details the analysis of ORNL wastes

402

Radial densities of nuclear matter and charge via moment methods

International Nuclear Information System (INIS)

In this report I will discuss some initial efforts in our program to describe radial densities of nuclear matter and charge with the use of moment methods. A brief introduction to trace reduction formulas and computation problems along with proposed methods to overcome them will be given. This will be followed by a general discussion on computation of expectation values using moment methods with particular emphasis on formulation for the radial density applications

403

Heating of nuclear matter and multifragmentation : antiprotons vs. pions.

Energy Technology Data Exchange (ETDEWEB)

Heating of nuclear matter with 8 GeV/c {bar p} and {pi}{sup {minus}} beams has been investigated in an experiment conducted at BNL AGS accelerator. All charged particles from protons to Z {approx_equal} 16 were detected using the Indiana Silicon Sphere 4{pi} array. Significant enhancement of energy deposition in high multiplicity events is observed for antiprotons compared to other hadron beams. The experimental trends are qualitatively consistent with predictions from an intranuclear cascade code.

Back, B.; Beaulieu, L.; Breuer, H.; Gushue, S.; Hsi, W.-C.; Korteling, R. G.; Kwiatkowski, K.; Laforest, R.; Lefort, T.; Martin, E.; Pienkowski, L.; Ramakrishnan, E.; Remsberg, L. P.; Rowland, D.; Ruangma, A.; Viola, V. E.; Winchester, E.; Yennello, S. J.

1999-05-03

404

Two-Nucleon Spectral Function in Infinite Nuclear Matter

The two-nucleon spectral function in nuclear matter is studied using Correlated Basis Function perturbation theory, including central and tensor correlations produceded by a realistic hamiltonian. The factorization property of the two-nucleon momentum distribution into the product of the two single nucleon distributions shows up in an analogous property of the spectral function. The correlated model yields a two-hole contribution quenched whith respect to Fermi gas model, wh...

Benhar, Omar; Fabrocini, Adelchi

1999-01-01

405

Final-state interactions in the response of nuclear matter

Final-state interactions in the response of a many-body system to an external probe delivering large momentum are normally described using the eikonal approximation, for the trajectory of the struck particle, and the frozen approximation, for the positions of the spectators. We propose a generalization of this scheme, in which the initial momentum of the struck particle is explicitly taken into account. Numerical calculations of the nuclear matter response at 1 $< |{\\bf q}|

Petraki, M.; Mavrommatis, E.; Benhar, O.; Clark, J. W.; Fabrocini, A.; Fantoni, S.

2002-01-01

406

The ? potential in nuclear matter from a realistic interaction

International Nuclear Information System (INIS)

Previous studies on the nuclear matter properties have shown the relevance of the ? isobar degrees of freedom, as well as the need of an accurate estimate of the corresponding ? potential. Motivated by this result, we have calculated the potential energy of the ? isobar in nuclear matter with the same model nucleon-nucleon interaction, the Argonne v28, which was previously used in the study of nuclear matter. This potential includes all possible transitions from NN states to N? and ?? ones, and give an excellent fit to nucleon-nucleon phenomenological phase shifts and deuteron properties. All diagrams with one nucleon hole-line are summed up in the framework of a G-matrix approach. The ? potential so obtained was found to be weakly attractive at low density, becoming repulsive at increasing density with a value of 50 MeV at saturation. The repulsive potential receives the main contribution from the isotopic spin T=2 channels and it appears to be in contradiction with the phenomenology on ? production in nuclei. The sensitivity to possible simple modifications of the potential is explored and it is concluded that complete refitting of the parameters would be necessary in order to remove the contradiction with phenomenology, while keeping the agreement with nucleon-nucleon data. This result indicates the strong constraints that the phenomenology on the ? isobar imposes on any realistic nucleon-nucleon potential, to be used in self-consistent calculat used in self-consistent calculations of nuclear matter properties, which include ? degrees of freedom. Possible improvements of the interaction are briefly indicated. ((orig.))

407

Transport coefficients of nuclear matter in neutron star cores

We calculate thermal conductivity and shear viscosity of nucleons in dense nuclear matter of neutron star cores in the non-relativistic Brueckner-Hartree-Fock framework. Nucleon-nucleon interaction is described by the Argonne v18 potential with addition of the Urbana IX effective three-body forces. We find that this three body force leads to decrease of the kinetic coefficients with respect to the two-body case. The results of calculations are compared with electron and muon...

Shternin, P. S.; Baldo, M.; Haensel, P.

2013-01-01

408

Single particle spectrum and binding energy of nuclear matter

In non-relativistic Brueckner calculations of nuclear matter, the self-consistent single particle potential is strongly momentum dependent. To simplify the calculations, a parabolic approximation is often used in the literature. The variation in the binding energy value introduced by the parabolic approximation is quantitatively analyzed in detail. It is found that the approximation can introduce an uncertainty of 1-2 MeV near the saturation density.

Baldo, M.; Fiasconaro, A.

2000-01-01

409

Self-Energy of Decuplet Baryons in Nuclear Matter

We calculate, in chiral perturbation theory, the change in the self-energy of decuplet baryons in nuclear matter. These self-energy shifts are relevant in studies of meson-nucleus scattering and of neutron stars. Our results are leading order in an expansion in powers of the ratio of characteristic momenta to the chiral symmetry-breaking scale (or the nucleon mass). Included are contact diagrams generated by 4-baryon operators, which were neglected in earlier studies for the...

Ouellette, Stephen M.; Seki, Ryoichi

1997-01-01

410

?NN correlations and the ?-particle binding in nuclear matter

International Nuclear Information System (INIS)

The ? particle energy in nuclear matter is calculated with separable S state ?N and NN potentials of Puff's type. By solving the Bethe-Faddeev equations, the three-body ?NN cluster energy Esub(?3) is calculated with the repulsive result Esub(?3) approximately equal to 3-4 MeV, which is less than 10% of the magnitude of the two-body ?N cluster energy. The result suggests a satisfactory convergence of the reaction matrix method of calculating Bsub(?). (author)

411

Cold Nuclear Matter Effects and Heavy Quark Production in PHENIX

International Nuclear Information System (INIS)

The PHENIX experiment uses semileptonic and leptonic decay channels, respectively, to measure open and closed heavy flavor cross sections across the rapidity range ?2.2NN)=200GeV, and for Au + Au collisions at ?(SNN)=62GeV. We discuss recent d + Au results for open heavy flavor and J/? production, and discuss their implications for the cold nuclear matter contributions to heavy flavor production in heavy ion collisions

412

Diagrammatic calculation of thermodynamical quantities in nuclear matter

In medium T-matrix calculations for symmetric nuclear matter at zero and finite temperatures are presented. The internal energy is calculated from the Galitskii-Koltun's sum rule and from the summation of the diagrams for the interaction energy. The pressure at finite temperature is obtained from the generating functional form of the thermodynamic potential. The entropy at high temperature is estimated and compared to expressions corresponding to a quasiparticle gas.

Soma, V

2006-01-01

413

Heating of nuclear matter and multifragmentation: antiprotons vs. pions

International Nuclear Information System (INIS)

Heating of nuclear matter with 8 GeV/c bar p and ?- beams has been investigated in an experiment conducted at BNL AGS accelerator. All charged particles from protons to Z ? 16 were detected using the Indiana Silicon Sphere 4? array. Significant enhancement of energy deposition in high multiplicity events is observed for antiprotons compared to other hadron beams. The experimental trends are qualitatively consistent with predictions from an intranuclear cascade code

414

Theory of superfluid states with singlet and triplet types of pairing in nuclear matter

International Nuclear Information System (INIS)

The paper presents the results of investigation of superfluid states in a two-component Fermi liquid in the framework of the Fermi liquid approach. Particular attention is paid to superfluid states in nuclear matter which are characterized by the superposition of singlet and triplet types of pairing in spin and isospin spaces. The authors have formulated the basic points of the Fermi liquid approach which are used in the study of superfluidity in nuclear matter with the superposition of singlet and triplet types of pairing. Derivation of the system of self-consistency equations and their solution are presented. For concrete calculations the interaction in the Skyrme model is taken. Using this model the conditions for the existence of the considered states are determined. These conditions impose certain constraints on the potential of interaction and on the density of particles in the system. It is shown that the states with a complete set of nonzero order parameters are realized only in a narrow density range, whose width and position in the density scale depend on the choice of a particular Skyrme force. Considered are 18 different parameterizations, and indicated is for which of them the studied types of superfluid states may appear The problem of stability of the states with superposition of singlet and triplet types of pairing is studied. It is shown that the lowest value of the thermodynamic potential corresponds to purely triplet states, then in order of increasing there are the thermodynamic potential of purely singlet states, and mixed singlet-triplet states. The case of unitary states is considered separately. For these states the solutions of the self-consistency equations are analyzed too. The density range for these states is defined and it is shown that this range is different than from that which corresponds to the nonunitary states. In addition, studied is the problem of the existence of unitary superfluid states with the superposition of singlet and triplet superfluidity in the case of asymmetrical nuclear matter. It is shown that the appearance of asymmetry causes the unitarity of superfluid states in nuclear matter to be broken.

415

Variational calculations of realistic models of nuclear matter

International Nuclear Information System (INIS)

We report variational calculations of nuclear matter with a semi-realistic Reid v14 model of the two-nucleon interaction operator. The v14 model fits the available nucleon-nucleon scattering data up to 425 MeV lab energy, and has relatively weak L2 and (L x S)2 interactions in additon to the standard central, tensor and (L x S). The L2 an (L x S)2 interactions are treated semiperturbatively; their contribution reduces the overbinding of nuclear matter. However, the equilibrium ksub(F) = 1.7 fm-1 and E0 = -17.5MeV obtained with the v14 model are both higher than their empirical values ksub(F) = 1.33 fm -1 and E0 = -16 MeV. We assume that the difference between the calculated and empirical E(p) is entirely due to three-nucleon interactions (TNI). The TNI contributions are phenomenologically added to the nuclear matter energy, and their parameters are adjusted to obtain the correct equilibrium energy, density and compressibility. The required TNI contributions appear to be of reasonable magnitude. (orig.)

416

Nuclear spin resonances in double beta decays and dark matters

International Nuclear Information System (INIS)

In this paper, as the experiment using the spin in atomic nuclei as the experimental means, the double data decay and the experiment for searching for dark matters by Ejiri group of Osaka University are reported. Double beta decay is the phenomenon in which beta decay occurs twice successively in atomic nuclei, and theoretically a number of decay modes are considered. In double beta decay, two beta rays (electrons) and two neutrinos are emitted, therefore, the energy spectra of beta ray become continuous. The probability of decay, the effect of neutrino emission and others are discussed. The detector (ELEGANTS V) that the group of Osaka University uses for the measurement is introduced. The thin film specimens of Mo are used. The spectrum is shown, and the half life was obtained. The results are reported. The existence of space dark matters was predicted, but it has not been found. The application of NaI detector to the search for dark matters has been investigated. NaI consists of the nuclei having finite nuclear spin, and is suitable to the search for the dark matters of spin coupling type. The limit for the existence of dark matters was determined. (K.I.)

417

Finite size effects in neutron star and nuclear matter simulations

In this work we study molecular dynamics simulations of symmetric nuclear and neutron star matter using a semi-classical nucleon interaction model. Our aim is to gain insight on the nature of the so-called 'finite size effects', unavoidable in this kind of simulations, and to understand what they actually affect. To do so, we explore different geometries for the periodic boundary conditions imposed on the simulation cell: cube, hexagonal prism and truncated octahedron. For nuclear matter simulations we show that, at sub-saturation densities and low temperatures, the solutions are non-homogeneous structures reminiscent of the 'nuclear pasta' phases expected in neutron star matter simulations, but only one structure per cell and shaped by specific artificial aspects of the simulations-for the same physical conditions (i.e. number density and temperature) different cells yield different solutions. The particular shape of the solution at low enough temperature and a given density can be predicted analytically by surface minimization. We also show that even if this behavior is due to the imposition of periodic boundary conditions on finite systems, this does not mean that it vanishes for very large systems, and it is actually independent of the system size. We conclude that, for nuclear matter simulations, the cells' size sets the only characteristic length scale for the inhomogeneities, and the geometry of the periodic cell determines the shape of those inhomogeneities. To model neutron star matter we add a screened Coulomb interaction between protons, and perform simulations in the three cell geometries. Our simulations indeed produce the well known nuclear pasta, with (in most cases) several structures per cell. However, we find that for systems not too large results are affected by finite size in different ways depending on the geometry of the cell. In particular, at the same certain physical conditions and system size, the hexagonal prism yields a single structure per cell while the cubic and truncated octahedron show consistent results, with more than one structure per cell. For systems of the size studied in this work these effects are still noticeable, but we find evidence to support that the dependence of the results on the cell geometry becomes smaller as the system size is increased. When the Coulomb interaction is present, the competition between opposing interactions of different range results in a proper, physically meaningful length scale that is independent of the system size and periodic cell of choice. Only under these conditions 'finite size effects' will vanish for large enough systems (i.e. cells much larger than this characteristic length). Larger simulations are in order, but our computational capabilities forbid it for the time being.

Giménez Molinelli, P. A.; Dorso, C. O.

2015-01-01

418

Covariant description of dynamical processes in relativistic nuclear matter

International Nuclear Information System (INIS)

We report results of covariant calculations of density-dependent polarization processes in relativistic nuclear matter. We consider the polarization induced by those mesons that play an important role in the boson-exchange model of nuclear forces (?,?,?,?). After obtaining the polarization operators, we construct the propagators for these mesons. The covariant nature of the calculation greatly clarifies the structure of the polarization operators and associated Green's functions. (In addition to the meson momentum, these quantities depend upon another four-vector, ??, that describes the uniform motion of the medium.) In the case of the pion, we show that the same results are obtained for pseudovector or pseudoscalar coupling to the nucleon, if the associated Lagrangians are related by chiral transformations. Of particular interest are the extremely large values found for the polarization operators of the omega and sigma mesons. It is also found that the coupling of the sigma and omega fields through the polarization process is also extremely large. (Because of these results one cannot usefully consider the sigma and omega fields as independent degrees of freedom in nuclear matter.) We describe methods for reorganizing the calculation of ring diagrams in which we group those diagrams that exhibit strong cancellations. We also comment on the implication of our results for nuclear structure studies

419

The effective action approach applied to nuclear matter (1)

International Nuclear Information System (INIS)

Within the framework of the Walecka model (QHD-I) the application of the Cornwall-Jackiw-Tomboulis (CJT) effective action to nuclear matter is presented. The main feature is the treating of the meson condensates for the system of finite nuclear density. The system of couple Schwinger-Dyson (SD) equations is derived. It is shown that SD equations for sigma-omega mixings are absent in this formalism. Instead, the energy density of the nuclear ground state does explicitly contain the contributions from the ring diagrams, amongst others. In the bare-vertex approximation, the expression for energy density is written down for numerical computation in the next paper. (author). 14 refs, 3 figs

420

More about the B and D mesons in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

We calculate the shifts in decay constants of the pseudoscalar B and D mesons in nuclear medium in the frame work of QCD sum rules. We write those shifts in terms of the B - N and D - N scattering lengths and an extra phenomenological parameter entered to calculations. Computing an appreciate forward scattering correlation function, we derive the QCD sum rules for the B - N and D - N scattering lengths and the extra phenomenological parameter in terms of various operators in nuclear medium. We numerically find the values of the shifts in the decay constants compared to their vacuum values. Using the sum rules obtained, we also determine the shifts in the masses of these particles due to nuclear matter and compare the results obtained with the previous predictions in the literature. (orig.)

Azizi, K. [Dogus University, Department of Physics, Istanbul (Turkey); Er, N. [Abant Izzet Baysal University, Department of Physics, Bolu (Turkey); Sundu, H. [Kocaeli University, Department of Physics, Izmit (Turkey)

2014-08-15

421

More about the B and D mesons in nuclear matter

International Nuclear Information System (INIS)

We calculate the shifts in decay constants of the pseudoscalar B and D mesons in nuclear medium in the frame work of QCD sum rules. We write those shifts in terms of the B - N and D - N scattering lengths and an extra phenomenological parameter entered to calculations. Computing an appreciate forward scattering correlation function, we derive the QCD sum rules for the B - N and D - N scattering lengths and the extra phenomenological parameter in terms of various operators in nuclear medium. We numerically find the values of the shifts in the decay constants compared to their vacuum values. Using the sum rules obtained, we also determine the shifts in the masses of these particles due to nuclear matter and compare the results obtained with the previous predictions in the literature. (orig.)

422

Nuclear Transparency Effect in the Strongly Interacting Matter

We discuss that the results of study of the nuclear transparency effect in nuclear-nuclear collisions at relativistic and ultrarelativistic energies could help to extract the information on new phases of the strongly interacting matter as well as the QCD critical point. The results could provide further confirmation of the existence of the "horn" effect which had initially been obtained for the ratio of average values of K+ to pi+ -mesons' multiplicity as a function of the initial energies in the NA49 SPS CERN experiment. To observe the "horn" as a function of centrality, the new more enriched experimental data are required. The data which are expected from NICA/MPD JINR and CBM GSI setups could fulfill the requirement.

Ajaz, M; Abdinov, O B; Zaman, Ali; Khan, K H; Wazir, Z; Khalilova, Sh

2012-01-01

423

Application of effective field theory on nuclear matter and neutron matter

International Nuclear Information System (INIS)

In the thesis the effective field theory in NLO and NNLO order is applied. The order NLO still knows no three-particle forces. The theory yields however already in this order the saturation behaviour of nuclear matter. This is due to the fact that in the NLO order the scattering phases are qualitatively correctly reproduced, especially the scattering phases 1S0 and 3S1 are for energies above 200 MeV negative, which is in all potentials by a so called hard core represented. In the NNLO orde three-particle forces occur, which lead to a larger improvement of the saturation curve, however the saturation point lies still at too high densities. A correction of the low-energy constants by scarcely three percent of the value in the vacuum generates however a saturation curve, which reproduces the empirical binding energy per particle, the density and the compressibility of nuclear matter. About the equation of state of neutron matter is empirically few known. At small densities of neutron matter (kf-1) the NLO and NNLO orders scarcely differ, but indeed from the free Fermi gas. For applications in finite nuclei a simplified parametrization of the nucleon-nucleon interactions was developed, which reproduces both the known scattering phases with an NLO-comparable accuracy and the empirical saturation behaviour

424

Triplet seesaw model: from inflation to asymmetric dark matter and leptogenesis

The nature of dark matter (DM) particles and the mechanism that provides their measured relic abundance are currently unknown. Likewise, the nature of the inflaton is unknown as well. We investigate the triplet seesaw model in an unified picture. At high energy scale, we consider Higgs inflation driven by an admixture of standard model and triplet Higgs fields, both coupled non-minimally to gravity. At intermediate and low energies we investigate vector like fermion doublet DM candidates with a charge asymmetry in the dark sector, which is generated by the same mechanism that provides the baryon asymmetry, namely baryogenesis-via-leptogenesis induced by the decay of scalar triplets. At the same time the model gives rise to neutrino masses in the ballpark of oscillation experiments via type-II seesaw. We then apply Bayesian statistics to infer the model parameters giving rise to the observed baryon asymmetry and DM density, compatibly with inflationary and DM direct detection constraints, updated with the CRESST-II excess, the new XENON100 data release and KIMS exclusion limit.

Arina, Chiara

2014-03-01

425

Triplet seesaw model: from inflation to asymmetric dark matter and leptogenesis

The nature of dark matter (DM) particles and the mechanism that provides their measured relic abundance are currently unknown. Likewise, the nature of the inflaton is unknown as well. We investigate the triplet seesaw model in an unified picture. At high energy scale, we consider Higgs inflation driven by an admixture of standard model and triplet Higgs fields, both coupled non-minimally to gravity. At intermediate and low energies we investigate vector like fermion doublet DM candidates with a charge asymmetry in the dark sector, which is generated by the same mechanism that provides the baryon asymmetry, namely baryogenesis-via-leptogenesis induced by the decay of scalar triplets. At the same time the model gives rise to neutrino masses in the ballpark of oscillation experiments via type-II seesaw. We then apply Bayesian statistics to infer the model parameters giving rise to the observed baryon asymmetry and DM density, compatibly with inflationary and DM direct detection constraints, updated with the CRES...

Arina, Chiara

2012-01-01

426

The understanding of the interaction of nucleons in nuclear and neutron-rich matter at non-zero temperature is important for a variety of applications ranging from heavy-ion collisions to nuclear astrophysics. In this papre we apply the Dirac-Brueckner-Hartree-Fock method along with the Bonn B potential to predict single-particle properties in symmetric nuclear matter and neutron-rich matter at finite temperature. It is found that temperature effects are generally small but can be significant at low density and momentum.

Sammarruca, Francesca

2010-01-01

427

Open charm in nuclear matter at finite temperature

We study the properties of open-charm mesons ($D$ and $\\bar {D}$) in nuclear matter at finite temperature within a self-consistent coupled-channel approach. The meson-baryon interactions are adopted from a type of broken SU(4) s-wave Tomozawa-Weinberg terms supplemented by an attractive scalar-isoscalar attraction. The in-medium solution at finite temperature incorporates Pauli blocking effects, mean-field binding on all the baryons involved, and $\\pi$ and open-charm meson self-energies in a self-consistent manner. In the $DN$ sector, the $\\Lambda_c$ and $\\Sigma_c$ resonances, generated dynamically at 2593 MeV and 2770 MeV in free space, remain close to their free-space position while acquiring a remarkable width due to the thermal smearing of Pauli blocking as well as from the nuclear matter density effects. As a result, the $D$ meson spectral density shows a single pronounced peak for energies close to the $D$ meson free-space mass that broadens with increasing matter density with an extended tail particula...

Tolos, Laura; Mizutani, Tetsuro

2007-01-01

428

In-medium modified ?–?–? mesonic Lagrangian and properties of nuclear matter

International Nuclear Information System (INIS)

We investigate the bulk properties of symmetric nuclear matter within the framework of an in-medium modified chiral solitonic model with ?, ? and ? mesons. We consider the modification of meson degrees of freedom in nuclear matter, based on phenomenology of pion–nucleus scattering and the empirical nuclear mass formula. We discuss the results of the density dependence of the volume term in the mass formula and the incompressibility of symmetric nuclear matter, comparing them with relativistic mean-field models. The mass dropping of the ? meson in nuclear matter is also obtained and discussed

429

Microscopic calculation of the longitudinal response of nuclear matter

The orthogonalized version of correlated basis theory is used to evaluate the longitudinal response of nuclear matter from realistic nuclear interaction. The correlated 1plh excited states have been fully retained in the calculation. The 2p2h correlated states entering the self-energy insertions, have also been treated exactly. The calculated response results to be in good agreement with previous similar calculations of the density response of symmetrical nuclear matter which included the effect of 2p2h correlated states approximately via the optical potential. Its comparison with the response calculated along the Brueckner theory in the y-scaling region is also discussed. At moderately high values of the momentum transfer, the longitudinal response is compared with the available experimental data from quasi-free electron scattering off medium-heavy nuclei. Our theoretical estimates are in fair agreement with the data on 40Ca, 48Ca, 56Fe and 238U, except at the highest values of both the momentum transfer and missing energy.

Fabrocini, A.; Fantoni, S.

1989-10-01

430

Converting of Matter to Nuclear Energy by AB-Generator

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: Researcher offered a new nuclear generator which allowed to convert any matter to nuclear energy in accordance with Einstein equation E = mc2. The method was based upon tapping the energy potential of a Micro Black Hole (MBH and Hawking radiation created by this MBH. Researcher did not meet the idea and its research in literature to develop the method for getting a cheap energy. Approach: As is well-known, vacuum continuously produced virtual pairs of particles and antiparticles, in particular, photons and anti-photons. MBH event horizon allowed separating them. Anti-photons can be moved to MBH and be annihilated, decreasing mass of MBH, resulting photons leave the MBH neighborhood as Hawking radiation. The offered nuclear generator (named by Researcher as AB-generator utilized Hawking radiation and injected the matter into MBH and kept MBH in a stable state with near-constant mass. Results: AB-generator can be produced gigantic energy outputs and should be cheaper than a conventional electric station by a factor of hundreds of times. One also may be used in aerospace as a photon rocket or as a power source for many vehicles. Conclusion: Many scientists expect Large Hadron Collider at CERN may be produced one MBH every second. A technology to capture them may be developed; than they may be used for the AB-generator.

Alexander Bolonkin

2009-01-01

431

Extraction of nuclear matter properties from nuclear masses by a model of equation of state

The extraction of nuclear matter properties from measured nuclear masses is investigated in the energy density functional formalism of nuclei. It is shown that the volume energy $a_1$ and the nuclear incompressibility $K_0$ depend essentially on $\\mu_n N+\\bar{\\mu}_p Z-2E_N$, whereas the symmetry energy $J$ and the density symmetry coefficient $L$ as well as symmetry incompressibility $K_s$ depend essentially on $\\mu_n-\\bar{\\mu}_p$, where $\\bar{\\mu}_p=\\mu_p-\\partial E_C/\\part...

Chung, K. C.; Wang, C. S.; Santiago, A. J.

2001-01-01

432

$D_S$ Mesons in Asymmetric Hot and Dense Hadronic Matter

The in-medium properties of $D_S$ mesons are investigated within the framework of a chiral effective model. These are observed to experience net attractive interactions in a dense hadronic medium, hence reducing the masses of the $D_S^+$ and $D_S^-$ mesons from the vacuum values. While this conclusion holds in both nuclear and hyperonic media, the magnitude of the mass drop is observed to intensify with the inclusion of strangeness in the medium. Additionally, in hyperonic medium, the mass degeneracy of the $D_S$ mesons is observed to be broken, due to opposite signs of the Weinberg-Tomozawa interaction term in the Lagrangian density. Along with the magnitude of the mass drops, the mass splitting between $D_S^+$ and $D_S^-$ mesons is also observed to grow with an increase in baryonic density and strangeness content of the medium. However, all medium effects analyzed are found to be weakly dependent on isospin asymmetry and temperature. We discuss the possible implications emanating from this analysis, which a...

Pathak, Divakar

2014-01-01

433

The concept of physical surface in nuclear matter

The main point of a physical definition of surface forces in the matter in general, especially in the nuclear matter, is that the curvature of surfaces and its variation should be physically defined. The forces are therefore just the vehicles of introducing physics. The problem of mathematical definition of a surface in term of the curvature parameters thus naturally occurs. The present work addresses this problem in terms of the asymptotic directions of a surface in a point. A physical meaning of these parameters is given, first in terms of inertial forces, then in terms of a differential theory of colors, whereby the space of curvature parameters is identified with the color space. The work concludes with an image of the evolution of a local portion of a surface.

Mazilu, Nicolae; Agop, Maricel

2015-02-01

434

Nucleon-nucleon correlations in dense nuclear matter

International Nuclear Information System (INIS)

In this thesis new results on the problematics of the formation of nucleon-nucleon correlations in nuclear matter could be presented. Starting from a general study of the two-particle problem in matter we studied the occurrence of a suprafluid phase (pair condensate of nucleons). The Gorkov decoupling by means of anomalous Green functions was generalized, so that also Cooper pairs with spin 1 (triplet pairing) can be described. A generalized gap equation resulted, which permits to determine the order parameters of the suprafluied phase in arbitrary channels of the nucleon-nucleon scattering states. This equation was solvd in the 1S0-, in the 3P2-3F2, and in the 3S1-3D1 channel under application of realistic nucleon-nucleon potentials. The behaviour of the resulting gap parameters in the single channels was studied as function of density and temperature. (orig.)

435

Strange mesons in nuclear matter at finite temperature

We study the properties of $K$ and $\\bar K$ mesons in nuclear matter at finite temperature from a chiral unitary approach in coupled channels which incorporates the $s$- and p-waves of the kaon-nucleon interaction. The in-medium solution accounts for Pauli blocking effects, mean-field binding on all the baryons involved, and $\\pi$ and kaon self-energies. We calculate $K$ and $\\bar K$ (off-shell) spectral functions and single particle properties. The $\\bar K$ effective mass g...

Tolo?s Rigueiro, Laura; Cabrera, D.; Ramos Go?mez, A?ngels

2008-01-01

436

Final-state interactions in the response of nuclear matter

Final-state interactions in the response of a many-body system to an external probe delivering large momentum are normally described using the eikonal approximation, for the trajectory of the struck particle, and the frozen approximation, for the positions of the spectators. We propose a generalization of this scheme, in which the initial momentum of the struck particle is explicitly taken into account. Numerical calculations of the nuclear matter response at 1 $< |{\\bf q}| <$ 2 GeV/c show that the inclusion of this momentum dependence leads to a sizable effect in the low energy tail. Possible implications for the analysis of existing electron-nucleus scattering data are discussed.

Petraki, M; Benhar, O; Clark, J W; Fabrocini, A; Fantoni, S

2003-01-01

437

Nuclear-matter Green functions in correlated-basis theory

Energy Technology Data Exchange (ETDEWEB)

A microscopic calculation of the one-body Green function for a realistic model of nuclear matter, including spin and tensor correlations, is presented. The calculation, based on the theory of orthogonal correlated basis functions, takes into account up to two-particle (hole) one-hole (particle) correlated basis-function states in the particle (hole) spectral function. The zeroth order of the ladder approximation for the density response is analysed in both the low- and high-momentum transfer regions. The single-particle strengths are compared with other theoretical estimates and experimental data from (e, e'p) experiments. (orig.).

Benhar, O. (Dept. of Physics, Illinois Univ., Urbana-Champaign, Urbana, IL (United States)); Fabrocini, A. (Dept. of Physics, INFN, Pisa (Italy)); Fantoni, S. (Interdisciplinary Lab. for Advanced Studies (ILAS), INFN, Trieste (Italy))

1992-12-07

438

Nuclear-matter green functions in correlated-basis theory

A microscopic calculation of the one-body Green function for a realistic model of nuclear matter, including spin and tensor correlations, is presented. The calculation, based on the theory of orthogonal correlated basis functions, takes into account up to two-particle (hole) one-hole (particle) correlated bsiss-function states in the particle (hole) spectral function. The zeroth order of the ladder approximation for the density response is analysed in both the low- and high- momentum transfer regions. The single-particle strengths are compared with other theoretical estimates and experimental data from (e, e'p) experiments.

Benhar, O.; Fabrocini, A.; Fantoni, S.

1992-12-01

439

Final-state interactions in the response of nuclear matter

Final-state interactions in the response of a many-body system to an external probe delivering large momentum are normally described using the eikonal approximation, for the trajectory of the struck particle, and the frozen approximation, for the positions of the spectators. We propose a generalization of this scheme, in which the initial momentum of the struck particle is explicitly taken into account. Numerical calculations of the nuclear matter response at 1<|q|<2 GeV/c show that the inclusion of this momentum dependence leads to a sizable effect in the low-energy tail. Possible implications for the analysis of existing electron-nucleus scattering data are discussed.

Petraki, M.; Mavrommatis, E.; Benhar, O.; Clark, J. W.; Fabrocini, A.; Fantoni, S.

2003-01-01

440

Transport coefficients of nuclear matter in neutron star cores

We calculate thermal conductivity and shear viscosity of nucleons in dense nuclear matter of neutron star cores in the non-relativistic Brueckner-Hartree-Fock framework. Nucleon-nucleon interaction is described by the Argonne v18 potential with addition of the Urbana IX effective three-body forces. We find that this three body force leads to decrease of the kinetic coefficients with respect to the two-body case. The results of calculations are compared with electron and muon transport coefficients as well as with the results of other authors.

Shternin, P S; Haensel, P

2013-01-01

441

Effect of pairing on breathing mode and nuclear matter compressibility

International Nuclear Information System (INIS)

The systematics of the giant monopole resonance in even-mass Sn isotopes have been studied in the framework of the quasiparticle random-phase approximation. The effect of the inclusion of pairing correlations on the properties of the giant monopole and giant quadrupole resonances in superfluid Sn nuclei has been evaluated. A shift in the monopole energies of these nuclei by about 100--150 keV has been observed. It is shown that the shift in the energy of the breathing mode of finite superfluid nuclei influences the extraction of the nuclear matter compressibility from empirical data only minimally

442

Time-Varying Nuclear Decay Parameters and Dark Matter

Recently published data suggest a possible solar influence on some nuclear decay rates, including evidence for an annual variation attributed to the varying Earth-Sun distance. Here, we consider the possibility that the annual signal seen by the DAMA collaboration, and interpreted by them as evidence for dark matter, may in fact be due to the radioactive contaminant 40K, which is known to be present in their detector. We also consider the possibility that part of the DAMA signal may arise from relic big-bang neutrinos.

Nistor, J.; Fischbach, E.; Gruenwald, J. T.; Javorsek, D.; Jenkins, J. H.; Lee, R. H.

2014-01-01

443

Time-Varying Nuclear Decay Parameters and Dark Matter

Recently published data suggest a possible solar influence on some nuclear decay rates, including evidence for an annual variation attributed to the varying Earth-Sun distance. Here, we consider the possibility that the annual signal seen by the DAMA collaboration, and interpreted by them as evidence for dark matter, may in fact be due to the radioactive contaminant K-40, which is known to be present in their detector. We also consider the possibility that part of the DAMA signal may arise from relic big-bang neutrinos.

Nistor, Jonathan; Gruenwald, John T; Javorsek, Daniel; Jenkins, Jere H; Lee, Robert H

2013-01-01

444

Nucleon-nucleon cross sections in isospin symmetric nuclear matter

International Nuclear Information System (INIS)

The nucleon-nucleon cross sections in symmetric nuclear matter were investigated in the frame- work of the extended Brueckner-Hartree-Fock (BHF) approach with Argonne V14 two body interaction.The influences of the ground state correlation and the rearrangement contribution of the three-body force (TBF) on the cross section have been obtained and discussed separately for identical and non-identical nucleon collisions. It is shown that the magnitudes of the cross section are increased by the effects of the ground state correlation in low momentum transfers, and are suppressed in medium with increasing density when the rearrangement contribution of the TBF force is considered. (authors)

445

From pion production to the nuclear matter equation of state

International Nuclear Information System (INIS)

Equilibrium rate calculations are used to show that thermal and chemical equilibrium are approached during the high density stage in central nucleus-nucleus collisions. The total pion multiplicity is established as a probe of the high density stage. The observed pion multiplicities are compared to predictions of a hadrochemical model with Rankine-Hugoniot compression. Assuming a partition of the internal energy per nucleon into thermal and compressional energy fractions, a nuclear matter equation of state is found which is very similar to that derived using an independent intranuclear cascade approach. 20 references

446

Hot nuclei and liquid - gas phase transition in nuclear matter

International Nuclear Information System (INIS)

The paper gives a popular presentation of the problem of the liquid-gas phase transition in nuclear matter. According to the models, in nucleus, as in ordinary liquid, peculiar condition can be created (high temperature and reduced density), when the system enters the region of the phase instability in respect to the liquid-gas transition (spinodal region). This state may disintegrate into ensemble of small drops (fragments), surrounded by a nuclear gas. The 'thermal' multifragmentation takes place, which is a new (multibody) decay mode of highly excited nuclei. The evidences of this scenario are considered, which have been obtained by the experiments with the FASA setup. This 4?-device is installed on the beam of relativistic light projectiles, which give the possibility to heat nucleus without the excitation of the collective degrees of freedom. (author)

447

Scattering of GeV electrons by nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The cross section for inclusive electron scattering by nuclear matter is calculated at high momentum transfers using a microscopic spectral function, and compared with that extrapolated from data on laboratory nuclei. It is found that the cross section obtained with the plane-wave impulse approximation is close to the observed data at large values of the energy loss, but too small at low values. In this regime final-state interactions are important; after including their effects theory and data are in fair agreement. It is necessary to treat nucleon-nucleon correlations consistently in estimating the final-state interactions. The effects of possible time dependence of the nucleon-nucleon cross section, giving rise to nuclear transparency, are also investigated. The {ital y} scaling of the response function is discussed to further elucidate the role of final-state interactions.

Benhar, O. (Istituto Nazionale di Fisica Nucleare, Sezione Sanita, I-00161 Roma (Italy)); Fabrocini, A. (Department of Physics, University of Pisa, I-56100 Pisa (Italy)); Fantoni, S. (International School for Advanced Studies, I-34014 Trieste (Italy)); Miller, G.A. (Department of Physics, University of Washington, Seattle, Washington 98195 (United States)); Pandharipande, V.R. (Department of Physics, University of Illinois, Urbana, Illinois 61801 (United States)); Sick, I. (Department of Physics, University of Basel, CH-4056, Basel (Switzerland))

1991-12-01

448

Scattering of GeV electrons by nuclear matter

The cross section for inclusive electron scattering by nuclear matter is calculated at high momentum transfers using a microscopic spectral function, and compared with that extrapolated from data on laboratory nuclei. It is found that the cross section obtained with the plane-wave impulse approximation is close to the observed data at large values of the energy loss, but too small at low values. In this regime final-state interactions are important; after including their effects theory and data are in fair agreement. It is necessary to treat nucleon-nucleon correlations consistently in estimating the final-state interactions. The effects of possible time dependence of the nucleon-nucleon cross section, giving rise to nuclear transparency, are also investigated. The y scaling of the response function is discussed to further elucidate the role of final-state interactions.

Benhar, O.; Fabrocini, A.; Fantoni, S.; Miller, G. A.; Pandharipande, V. R.; Sick, I.

1991-12-01

449

The rho meson in nuclear matter - a chiral unitary approach

International Nuclear Information System (INIS)

In this work, the properties of the ? meson at rest in cold symmetric nuclear matter are studied. We make use of a chiral unitary approach to pion-pion scattering in the vector-isovector channel, calculated from the lowest order Chiral Perturbation Theory (?PT) lagrangian including explicit resonance fields. Low energy chiral constraints are considered by matching our expressions to those of one loop ?PT. To account for the medium corrections, the ? couples to ?? pairs which are properly renormalized in the nuclear medium, accounting for both p-h and ?-h excitations. The terms where the ? couples directly to the hadrons in the p-h or ?-h excitations are also accounted for. In addition, the ? is also allowed to couple to N*(1520)-h components

450

Chiral approach to the rho meson in nuclear matter

International Nuclear Information System (INIS)

In this work, the properties of the ? meson at rest in cold symmetric nuclear matter are studied. We make use of a chiral unitary approach to pion-pion scattering in the vector-isovector channel, calculated from the lowest-order Chiral Perturbation Theory (?PT) Lagrangian including explicit resonance fields. Low-energy chiral constraints are considered by matching our expressions to those of one-loop ?PT. To account for the medium corrections, the ? couples to ?? pairs which are properly renormalized in the nuclear medium, accounting for both p-h and ?-h excitations. The terms where the ? couples directly to the hadrons in the p-h or ?-h excitations are also accounted for. In addition, the ? is also allowed to couple to N*(1520)-h components

451

QCD sum rules for ? isobar in nuclear matter

International Nuclear Information System (INIS)

The self-energies of ? isobar propagating in nuclear matter are calculated using the finite-density QCD sum-rule methods. The calculations show that the Lorentz vector self-energy for the ? is significantly smaller than the nucleon vector self-energy. The magnitude of the ? scalar self-energy is larger than the corresponding value for the nucleon, which suggests a strong attractive net self-energy for the ?; however, the prediction for the scalar self-energy is very sensitive to the density dependence of certain in-medium four-quark condensate. Phenomenological implications for the couplings of the ? to the nuclear scalar and vector fields are briefly discussed. (author). 28 refs., 1 fig

452

Nuclear matter symmetry energy from polarizabilities at low density

The nuclear matter polarizability had been proposed as a suitable framework to investigate the symmetry energy [F.L. Braghin, Nucl. Phys. A 665 (2000) 13; 696 (2001) 413; Err709 (2002) 487; F.L. Braghin, Phys. Rev. C 71 064303 (2005); Phys. Rev. C 79 069902(E) (2009); Proc. of XXX Braz. Meeting on Nucl. Phys. 2007, ed. by A. Suaide, Braz. Phys. Soc. (2008)]. It provides an original and rich conceptual framework yielding the simultaneous dependences of the symmetry energy on diverse variables. We present few different results for the symmetry energy dependence mainly on: temperature and momentum at low nuclear densities (?=0.1?). Based on the form of the polarizability we present an argument supporting that, due to the behavior of the density fluctuations, a third order term in the n-p asymmetry can yield a more reasonable result than a linear term.

Braghin, Fábio L.

2010-03-01

453

Quantum teleportation of nuclear matter and its investigation

International Nuclear Information System (INIS)

Since its discovery in 1993, quantum teleportation (QT) is a subject for intense theoretical and experimental studies. Experimental demonstration of QT has so far been limited to teleportation of light. In this paper, we propose a new experimental scheme for QT of nuclear matter. We show that the standard technique of nuclear physics experiment could be successfully applied for teleportation of spin states of atomic nuclei. We claim that there are no theoretical prohibitions upon a possibility of a complete Bell measurement, therefore, the implementation of all the four quantum communication channels is at least theoretically possible. A general expression for scattering amplitude of two 1/2-spin particles is given in the Bell operator basis, and the peculiarities of Bell states registration are briefly discussed

454

Cold nuclear matter effects in J/(psi) production

International Nuclear Information System (INIS)

Lattice QCD predicts that, above a certain critical energy density or temperature, strongly interacting matter undergoes a phase transition from the hadronic world to a quark-gluon plasma state, where the coloured quarks and gluons are no longer bound to colourless hadrons. The suppression of quarkonium production in high-energy nuclear collisions is one of the most interesting signatures of QGP formation, for two reasons: due to their large masses, charm and beauty quarks are created only in the initial hard scattering processes, before the QGP is formed; and the Q(bar Q) binding potential should be screened in the deconfined colour medium. Until the LHC starts colliding Pb nuclei, charm is the heaviest quark that can check the validity of the finite temperature QCD predictions, given the much smaller beauty production cross sections. However, the interpretation of the presently available results on charmonium suppression in heavy-ion collisions, obtained at the SPS and RHIC, is hampered by a multitude of other 'nuclear effects', which exist even in the absence of QGP formation, such as the badly understood nuclear modifications of the gluon distribution functions, the level of energy lost by the partons traversing the nuclei before producing the Q(bar Q) pair, the rate at which the nascent quarkonium state is broken up by the surrounding nuclear matter, etc. Fortunately, most of these 'cold nuclear matter' effects can be studied on the basis of proton-nucleus measurdied on the basis of proton-nucleus measurements. However, care must be taken when converting the p-A observations into a reference baseline that can be used in the analysis of the heavy-ion data. In particular, it has recently been shown (1) that it is wrong to assume that the rate of final-state Glauber-like J/? absorption, usually called the 'J/? absorption cross section', ?absJ/?, is independent of the collision energy and of the charmonium kinematics, as was previously assumed in the analysis of the SPS heavy-ion data.

455

Off-Fermi Shell Nucleons in Superdense Nuclear Matter

Based on recent progress in understanding the nature of two-nucleon (2N) short range correlations (SRCs) we performed world data analysis on inclusive electro-nuclear reactions at large momentum transfer to extract the probabilities of 2N SRCs for 3He, 4H, 12C, 27Al, 56Fe and 197Au nuclei. Using recent observations on strong dominance of proton-neutron SRCs as compared to proton-proton and neutron-neutron correlations we parameterized the obtained probabilities as a function of nuclear density and asymmetry. Using the obtained functional form of the probabilities we estimated the fractions of the off-Fermi shell protons and neutrons in the superdense nuclear matter relevant to neutron stars. Our results indicate that starting at 3-4 nuclear saturation densities the protons with fractional densities x_p={1\\over 9} will populate mostly the high momentum (off-Fermi shell) tail of the momentum distribution while only 20% of the neutrons will be in the high momentum tail. We discuss the implication of our observat...

McGauley, Michael

2011-01-01

456

Nuclear matter at finite temperature and density: theory and experiment

International Nuclear Information System (INIS)

The consequences of a phase transition associated with symmetry restoration to SU(2) x SU(2) in nuclear matter are investigated. The changes in the mass spectrum due to the phase transition (a) at zero temperature and high density, and (b) at high temperature with zero chemical potential are evaluated in the sigma model of particle physics. The experimentally observable effects necessitate the measurement of current correlation functions. In this thesis, the Vector-Vector-Axial vector (VVA) and the Vector-Vector-Pseudoscalar (VVP) current correlation functions are evaluated. The VVP correlation function is related to the neutral-pion decay amplitude. The changes in the decay rate of ?0 ? 2? in the nuclear medium are evaluated by including the effects of changes in the mass spectrum of particles, and by using the cutting rules of many-body field theory for the real and imaginary parts of the amplitude. The changes in the mass spectrum due to symmetry restoration affect the decay rate of ?0 ? 2? by at least two orders of magnitude and these results are tabulated. The Primakoff effect (? + '?' ? ?0) is proposed as a means of providing the signal for the abnormal phase. An expression for the Primakoff differential cross section is derived taking into account nuclear absorption effects, the nonuniform nuclear density, and a background contribution arising from strong coherent nuclear processes. Finally, the new field of relativlly, the new field of relativistic nuclear fragmentation is introduced. A phenomenological analysis of recent FNAL data involving proton-nucleus collisions (E591) is carried out

457

Nuclear matter with a Bose condensate of dibaryons in relativistic mean-field theory

If sufficiently light dibaryon resonances exist, a Bose condensate of dibaryons can occur in nuclear matter before the quark-hadron phase transition. Within a relativistic mean-field model we show that heterophase nuclear-dibaryon matter is for a wide set of parameters energetically more favorable than normal nuclear matter. Production of dibaryons is, however, relatively suppressed as compared to estimates based on the model of non-interacting nucleons and dibaryons.

Faessler, Amand; Buchmann, A. J.; Krivoruchenko, M. I.; Martemyanov, B. V.

1997-02-01

458

Nuclear Matter with a Bose Condensate of Dibaryons in Relativistic Mean-Field Theory

If sufficiently light dibaryon resonances exist, a Bose condensate of dibaryons can occur in nuclear matter before the quark-hadron phase transition. Within a relativistic mean-field model we show that heterophase nuclear-dibaryon matter is for a wide set of parameters energetically more favorable than normal nuclear matter. Production of dibaryons is, however, relatively suppressed as compared to estimates based on the model of non-interacting nucleons and dibaryons.

Faessler, A; Krivoruchenko, M I; Martemyanov, B V; Faessler, Amand

1997-01-01

459

Nuclear Matter with a Bose Condensate of Dibaryons in Relativistic Mean-Field Theory

If sufficiently light dibaryon resonances exist, a Bose condensate of dibaryons can occur in nuclear matter before the quark-hadron phase transition. Within a relativistic mean-field model we show that heterophase nuclear-dibaryon matter is for a wide set of parameters energetically more favorable than normal nuclear matter. Production of dibaryons is, however, relatively suppressed as compared to estimates based on the model of non-interacting nucleons and dibaryons.

Faessler, Amand; Buchmann, A. J.; Krivoruchenko, M. I.; Martemyanov, B. V.

1996-01-01

460

Non-Abelian energy loss in cold nuclear matter

International Nuclear Information System (INIS)

We use a formal recurrence relation approach to multiple parton scattering to find the complete solution to the problem of medium-induced gluon emission from partons propagating in cold nuclear matter. The differential bremsstrahlung spectrum, where Landau-Pomeranchuk-Migdal destructive interference effects are fully accounted for, is calculated for three different cases: (i) a generalization of the incoherent Bertsch-Gunion solution for asymptotic on-shell jets (ii) initial-state energy loss of incoming jets that undergo hard scattering, and (iii) final-state energy loss of jets that emerge out of a hard scatter. Our analytic solutions are given as an infinite opacity series, which represents a cluster expansion of the sequential multiple scattering. These new solutions allow, for the first time, direct comparison between initial- and final-state energy loss in cold nuclei. We demonstrate that, contrary to the naive assumption, energy loss in cold nuclear matter can be large. Numerical results to first order in opacity show that, in the limit of large jet energies, initial- and final-state energy losses exhibit different path length dependences, linear versus quadratic, in contrast to earlier findings. In addition, in this asymptotic limit, initial-state energy loss is considerably larger than final-state energy loss. These new results have significant implications for heavy-ion phenomenology in both p+A and A+A reactions

461

Nuclear matter calculations with a recent N-isobar potential

International Nuclear Information System (INIS)

The effect of N33(1236) isobar in nuclei has been investigated in detail by Prof. A.M. Green and his group with a NN to NN33 transition potential used in a coupled channel calculation. The effect of this N33 virtual state is to decrease the binding in nuclear matter at normal density by 5-7 Mev/A. The coupled channel formalism is closely related to the two-pion exchange potential being a dynamic component of the intermediate state. It was shown by Durso et al (1977) that the transition potential employed before 1977 when twice iterated did not agree with the two-pion box diagram. Since then Green et al (1978) have given a new potential which is in better agreement with the dispersion theoretic two-pion potential. This new potential has been used with the Reid and the Tourreil-Rouben Sprung potential in a full nuclear matter calculation to show that the extra repulsion is now only about 2 Mev from virtual isobar states. This result is in agreement with a model for estimating the extra repulsion. (auth.)

462

The Hypothesis of Nuclear Fusion in Condensed Matter: An Update

In our 1986 and1989 papers, we discussed the hypothesis of nuclear fusion in condensed matter and particularly in the planets and provided supporting evidence.[1,2] We continue to assert that non-thermonuclear d-Z fusion (including but not limited to d-d fusion) may occur in the core-region of the earth, and generally in hydrogen-bearing metals and minerals which are subjected to extreme off-equilibrium conditions. This hypothesis can be tested by measuring tritium and helium-3 in magmatic fluids from hot-spot volcanoes which tap plumes arising from the core-mantle boundary. In particular, magmatic waters of Kilauea, Loihi, and Icelandic volcanoes are predicted to contain significant tritium. Magmatic emissions of Kilauea demonstrated anomalous tritium content over twelve years ago[3], and a re-test of Kilauea emissions is urged along with further laboratory experiments. [1] C. DeW. Van Siclen and S. E. Jones, "Piezonuclear fusion in isotopic hydrogen molecules," J. Phys. G: Nucl. Phys. 12: 213-221 (March 1986). [2] S. E. Jones, et al., Observation of Cold Nuclear Fusion in Condensed Matter, Nature 338: 737-740 (April 1989). [4] F. Goff and G. M. McMurtry, "Tritium and stable isotopes of magmatic waters," J. Volcanology and Geothermal Research, 97: 347-396 (2000)

Jones, Steven; Ellsworth, John; Rees, Lawrence

2004-05-01

463

Nuclear matter calculations with a pseudoscalar-pseudovector chiral model

International Nuclear Information System (INIS)

A mixed pseudoscalar-pseudovector ?N coupling relativistic Lagrangian is obtained from a pure pseudoscalar chiral one, by transforming the nucleon field according to a generalized Weinberg transformation, which depends on a mixing parameter. The interaction is generated by the ?, ? and ? meson exchanges. Within the Hartree-Fock context, pion polarization effects, including the ? isobar, are considered in the random phase approximation in nuclear matter. These effects are interpreted, in a non-relativistic framework, as a modification of the range and intensity of a Yukawa-type potential by means of a simple function which takes into account the nucleon-hole and ?-hole excitations. Results show stability of relativistic nuclear matter against pion condensation. Compression modulus is diminished by the combined effects of the nucleon and ? polarization towards the usually accepted experimental values. The ?N interaction strength used in this paper is less than the conventional one to ensure the viability of the model. The fitting parameters of the model are the scalar meson mass m? and the ?-N coupling constant g?. (author)

464

Nuclear matter calculations with a pseudoscalar-pseudovector chiral model

Energy Technology Data Exchange (ETDEWEB)

A mixed pseudoscalar-pseudovector {pi}N coupling relativistic Lagrangian is obtained from a pure pseudoscalar chiral one, by transforming the nucleon field according to a generalized Weinberg transformation, which depends on a mixing parameter. The interaction is generated by the {sigma}, {omega} and {pi} meson exchanges. Within the Hartree-Fock context, pion polarization effects, including the {delta} isobar, are considered in the random phase approximation in nuclear matter. These effects are interpreted, in a non-relativistic framework, as a modification of the range and intensity of a Yukawa-type potential by means of a simple function which takes into account the nucleon-hole and {delta}-hole excitations. Results show stability of relativistic nuclear matter against pion condensation. Compression modulus is diminished by the combined effects of the nucleon and {delta} polarization towards the usually accepted experimental values. The {pi}N interaction strength used in this paper is less than the conventional one to ensure the viability of the model. The fitting parameters of the model are the scalar meson mass m{sub {sigma}} and the {omega}-N coupling constant g{sub {omega}}. (author)

Niembro, R.; Marcos, S.; Bernardos, P. [University of Cantabria, Faculty of Sciences, Department of Modern Physics, 39005 Santander (Spain); Fomenko, V.N. [St Petersburg University for Railway Engineering, Department of Mathematics, 197341 St Petersburg (Russian Federation); Savushkin, L.N. [St Petersburg University for Telecomunications, Department of Physics, 191065 St Petersburg (Russian Federation); Lopez-Quelle, M. [University of Cantabria, Faculty of Sciences, Department of Applied Physics, 39005 Santander, Spain (Spain)

1998-10-01

465

Pure Neutron Matter Constraints and Nuclear Symmetry Energy

In this review, we will discuss the results of our recent work to study the general optimization of the pure isovector parameters of the popular relativistic mean-field (RMF) and Skyrme-Hartree-Fock (SHF) nuclear energy-density functionals (EDFs), using constraints on the pure neutron matter (PNM) equation of state (EoS) from recent {\\sl ab initio} calculations. By using RMF and SHF parameterizations that give equivalent predictions for ground-state properties of doubly magic nuclei and properties of symmetric nuclear matter (SNM) and PNM, we found that such optimization leads to broadly consistent symmetry energy $J$ and its slope parameter $L$ at saturation density within a tight range of $\\sigma(J) < 2$ MeV and $\\sigma(L) < 6$ MeV. We demonstrate that a clear model dependence shows up (a) in the curvature parameter of the symmetry energy $K_{\\rm sym}$, (b) the symmetry energy at supra-saturation densities, and (c) the radius of neutron stars.

Fattoyev, F J; Xu, Jun; Li, Bao-An

2012-01-01

466

Strange quark matter in the Universe and accelerator nuclear beams

International Nuclear Information System (INIS)

An almost symmetric mixture of u, d and s-quarks - Strange Quark Matter (SQM) is strongly argued to be the ground and absolutely stable of the matter. Astrophysical objects, supposed to be the SQM states, could be formed as the result of the Big Bang (in the early Universe) and the conversion of neutron stars into strange ones. Such objects are considered to be favourable candidates as black holes. The unique possibility to produce the SQM under terrestrial conditions (at accelerator laboratories) are violent relativistic nucleus-nucleus collisions so called 'little big bang'. The expected singulares of SQM are reviewed which could be revealed from astrophysical observations of peculiarities of large SQM objects as well as from accelerator experiments with searching smaller SQM states including the simplest one - metastable six-quark H dihyperon. The first results of the Dubna search experiments, with considerable heating of matter and formation a dense strangeness abundant fireball (mixed phase?) in central nuclear collisions, is presented. Under these favourable conditions a candidate for H dihyperon is observed and an upper limit of production cross sections of this SQM state is estimated. Some prospects and advantages of further searches for light SQM states, using the JINR new superconducting accelerator - Nuclotron with energy 5-6 GeV per nucleon, are briefly outlined. 19 refs., 7 figs

467

Effect of nuclear response functions in dark matter direct detection

We examine the effect of nuclear response functions, as laid out by Fitzpatrick et al. [J. Cosmol. Astropart. Phys. 02 (2013) 004], on dark matter (DM) direct detection in the context of well-motivated UV completions, including electric and magnetic dipoles, anapole, spin-orbit, and pseudoscalar-mediated DM. Together, these encompass five of the six nuclear responses extracted from the nonrelativistic effective theory of Fitzpatrick et al. [J. Cosmol. Astropart. Phys. 02 (2013) 004] (with the sixth difficult to UV complete), with two of the six combinations corresponding to standard spin-independent and spin-dependent responses. For constraints from existing direct detection experiments, we find that only the COUPP constraint, due to its heavy iodine target with large angular momentum and an unpaired spin, and its large energy range sensitivity, is substantially modified by the new responses compared to what would be inferred using the standard form factors to model the energy dependence of the response. For heavy targets such as xenon and germanium, the behavior of the new nuclear responses as recoil energy increases can be substantially different from that of the standard responses, but this has almost no impact on the constraints derived from experiments such as LUX, XENON100, and CDMS since the maximum nuclear recoil energy detected in these experiments is relatively low. We simulate mock data for 80 and 250 GeV DM candidates utilizing the new nuclear responses to highlight how they might affect a putative signal, and find the new responses are most important for highly momentum-suppressed interactions such as the magnetic dipole or pseudoscalar-mediated interaction when the target is relatively heavy (such as xenon and iodine).

Gresham, Moira I.; Zurek, Kathryn M.

2014-06-01

468

Nucleon mean free path in nuclear matter based on nuclear Schwinger-Dyson formalism

A mean free path of nucleon moving through nuclear matter with kinetic energy of more than 100MeV is formulated based on the bare vertex nuclear Schwinger-Dyson (BNSD) method in the Walecka model. The self-energy which is derived from the higher order diagrams more than the forth order includes the Feynman part of propagator of energetic nucleon and grows up rapidly as an increase of kinetic energy. To avoid too large growth of these diagrams, meson propagators are modified ...

Mitsumori, Tomohiro; Noda, Nobuo; Koide, Kazuharu; Kouno, Hiroaki; Hasegawa, Akira; Nakano, Masahiro

1995-01-01

469

Three-dimensional calculation of inhomogeneous structure in low-density nuclear matter

In low-density nuclear matter which is relevant to the crust region of neutron stars and collapsing stage of supernovae, non-uniform structures called "nuclear pasta" are expected. So far, most works on nuclear pasta have used the Wigner-Seitz cell approximation with anzats about the geometrical structures like droplet, rod, slab and so on. We perform fully three-dimensional calculation of non-uniform nuclear matter for some cases with fixed proton ratios and in beta-equilib...

Okamoto, Minoru; Maruyama, Toshiki; Yabana, Kazuhiro; Tatsumi, Toshitaka

2011-01-01

470

Modification of the omega-meson lifetime in nuclear matter.

Information on hadron properties in the nuclear medium has been derived from the photoproduction of omega mesons on the nuclei C, Ca, Nb, and Pb using the Crystal Barrel/TAPS detector at the ELSA tagged photon facility in Bonn. The dependence of the omega-meson cross section on the nuclear mass number has been compared with three different types of models: a Glauber analysis, a Boltzmann-Uehling-Uhlenbeck analysis of the Giessen theory group, and a calculation by the Valencia theory group. In all three cases, the inelastic omega width is found to be 130-150 MeV/c(2) at normal nuclear matter density for an average 3-momentum of 1.1 GeV/c. In the rest frame of the omega meson, this inelastic omega width corresponds to a reduction of the omega lifetime by a factor approximately 30. For the first time, the momentum dependent omegaN cross section has been extracted from the experiment and is in the range of 70 mb. PMID:18518443

Kotulla, M; Trnka, D; Mühlich, P; Anton, G; Bacelar, J C S; Bartholomy, O; Bayadilov, D; Beloglazov, Y A; Bogendörfer, R; Castelijns, R; Crede, V; Dutz, H; Ehmanns, A; Elsner, D; Ewald, R; Fabry, I; Fuchs, M; Essig, K; Funke, Ch; Gothe, R; Gregor, R; Gridnev, A B; Gutz, E; Höffgen, S; Hoffmeister, P; Horn, I; Hössl, J; Jaegle, I; Junkersfeld, J; Kalinowsky, H; Klein, Frank; Klein, Fritz; Klempt, E; Konrad, M; Kopf, B; Krusche, B; Langheinrich, J; Löhner, H; Lopatin, I V; Lotz, J; Lugert, S; Menze, D; Messchendorp, J G; Mertens, T; Metag, V; Mosel, U; Nanova, M; Novotny, R; Ostrick, M; Pant, L M; van Pee, H; Pfeiffer, M; Roy, A; Radkov, A; Schadmand, S; Schmidt, Ch; Schmieden, H; Schoch, B; Shende, S; Suft, G; Sumachev, V V; Szczepanek, T; Süle, A; Thoma, U; Varma, R; Walther, D; Weinheimer, Ch; Wendel, Ch

2008-05-16

471