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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 author finally poses. (author)

2

Instabilities in asymmetric nuclear matter

The existence of phase transitions from liquid to gas phases in asymmetric nuclear matter (ANM) is related with the instability regions which are limited by the spinodals. In this work we investigate the instabilities in ANM described within relativistic mean field hadron models, both with constant and density dependent couplings at zero and finite temperatures. In calculating the proton and neutron chemical potentials we have used an expansion in terms of Bessel functions that is convenient at low densities. The role of the isovector scalar $\\delta$-meson is also investigated in the framework of relativistic mean field models and density dependent hadronic models. It is shown that the main differences occur at finite temperature and large isospin asymmetry close to the boundary of the instability regions.

Avancini, S S; Peres-Menezes, D; Providęncia, C

2004-01-01

3

Quasideuteron pairing in asymmetric nuclear matter

International Nuclear Information System (INIS)

We study the standard 1 S 0 and the quasideuteron 3 S 1-3 D 1 pairing fields in asymmetric nuclear matter, using a Bonn meson-exchange interaction in a Dirac-Hartree-Fock-Bogoliubov approximation. We obtain a quasideuteron field very similar to those found in nonrelativistic calculations at densities below saturation, both in symmetric and asymmetric nuclear matter. This field has the properties of a Bose-Einstein condensate at low densities and those of a BCS condensate at high densities. The quasideuteron pairing field in asymmetric nuclear matter is stable only when accompanied by standard 1 S 0 neutron-neutron and proton-proton pairing fields

4

Kaons and antikaons in asymmetric nuclear matter

The properties of kaons and antikaons and their modification in isospin asymmetric nuclear matter are investigated using a chiral SU(3) model. These isospin dependent medium effects are important for asymmetric heavy ion collision experiments. In the present work, the medium modifications of the energies of the kaons and antikaons, within the asymmetric nuclear matter, arise due to the interactions of kaons and antikaons with the nucleons and scalar mesons. The values of the parameters in the model are obtained by fitting the saturation properties of nuclear matter and kaon-nucleon scattering lengths. The pion-nucleon scattering lengths are also calculated within the chiral effective model and compared with earlier results from the literature. The density dependence of the isospin asymmetry is seen to be appreciable for the kaon and antikaon optical potentials. This can be particularly relevant for the future accelerator facility FAIR at GSI, where experiments using neutron rich beams are planned to be used i...

Mishra, A; Greiner, W

2008-01-01

5

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 NN-interactions and derive in-medium self-energies by Dirac-Brueckner theory. By the DDRH 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 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, Andreas

2014-01-01

6

Hot and Flowing, Asymmetric Nuclear Matter

We develop a consistent treatment for hot and flowing asymmetric nuclear matter. Using the mean-field theory (MFT), predictions of the ? - ? Walecka model at finite temperature are compared with the corresponding results of the Zimanyi-Moszkowski and the non-linear models. The statistical theory of grand-canonical potentials is incorporated to the formalism. We also describe the behavior, at finite temperature, of the asymmetric and flowing nuclear matter. As an application, we describe bulk properties of neutron and protoneutron stars by considering the Tolman-Oppenheimer-Volkoff (TOV) equations.

Marranghello, G. F.; Vasconcellos, C. A. Z.

2001-04-01

7

Asymmetric Nuclear Matter with Pion Dressing

Digital Repository Infrastructure Vision for European Research (DRIVER)

We discuss a self-consistent method to calculate the properties of cold asymmetric nuclear matter which is dressed with isoscalar scalar pion condensates. The nucleon-nucleon interaction is mediated by these pion pairs, omega- and rho- mesons. The parameters of these interactions are evaluated self-consistently using the saturation properties of nuclear matter like binding energy, pressure, compressibility and symmetry energy. The computed equation of state of pure neutron m...

Sarangi, S.; Panda, P. K.; Sahu, S. K.; Maharana, L.

2007-01-01

8

Asymmetric nuclear matter : a variational approach

Digital Repository Infrastructure Vision for European Research (DRIVER)

We discuss here a self-consistent method to calculate the properties of the cold asymmetric nuclear matter. In this model, the nuclear matter is dressed with s-wave pion pairs and the nucleon-nucleon (N-N) interaction is mediated by these pion pairs, $\\omega$ and $\\rho$ mesons. The parameters of these interactions are calculated self-consistently to obtain the saturation properties like equilibrium binding energy, pressure, compressibility and symmetry energy. The computed e...

Sarangi, S.; Panda, P. K.; Sahu, S. K.; Maharana, L.

2008-01-01

9

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)

10

Asymmetric Nuclear Matter:. a Variational Approach

We discuss here a self-consistent method to calculate the properties of the cold asymmetric nuclear matter. In this model, the nuclear matter is dressed with s-wave pion pairs and the nucleon-nucleon (N-N) interaction is mediated by these pion pairs, ? and ? mesons. The parameters of these interactions are calculated self-consistently to obtain the saturation properties like equilibrium binding energy, pressure, compressibility and symmetry energy. The computed equation of state is then used in the Tolman-Oppenheimer-Volkoff (TOV) equation to study the mass and radius of a neutron star in the pure neutron matter limit.

Sarangi, S.; Panda, P. K.; Sahu, S. K.; Maharana, L.

2009-12-01

11

Asymmetric Nuclear Matter with Pion Dressing

We discuss a self-consistent method to calculate the properties of cold asymmetric nuclear matter which is dressed with isoscalar scalar pion condensates. The nucleon-nucleon interaction is mediated by these pion pairs, omega- and rho- mesons. The parameters of these interactions are evaluated self-consistently using the saturation properties of nuclear matter like binding energy, pressure, compressibility and symmetry energy. The computed equation of state of pure neutron matter (PNM) is used to calculate mass and radius of a pure neutron star.

Sarangi, S; Sahu, S K; Maharana, L

2007-01-01

12

Asymmetric nuclear matter : a variational approach

We discuss here a self-consistent method to calculate the properties of the cold asymmetric nuclear matter. In this model, the nuclear matter is dressed with s-wave pion pairs and the nucleon-nucleon (N-N) interaction is mediated by these pion pairs, $\\omega$ and $\\rho$ mesons. The parameters of these interactions are calculated self-consistently to obtain the saturation properties like equilibrium binding energy, pressure, compressibility and symmetry energy. The computed equation of state is then used in the Tolman- Oppenheimer-Volkoff (TOV) equation to study the mass and radius of a neutron star in the pure neutron matter limit.

Sarangi, S; Sahu, S K; Maharana, L

2008-01-01

13

Asymmetric nuclear matter and its instabilities

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english In order to investigate the instabilities in asymmetric nuclear matter described within relativistic mean field hadron models, we build the spinodals. We have used relativistic models both with constant and density dependent couplings at zero and finite temperatures. We have seen that the main diffe [...] rences in the spinodals occur at finite temperature and large isospin asymmetry close to the boundary of the instability regions.

S. S., Avancini; D. P., Menezes; L., Brito; C., Providęncia.

2005-09-01

14

Correlated momentum distribution in asymmetric nuclear matter

The understanding of the variation of microscopic nuclear properties with isospin asymmetry is an important issude for both nuclear experiments and theory. The recent results on nucleon knock-out reactions seem to indicate that there is a strong dependence of spectroscopic factor on isospin [1]. This could indicate that the occupation numbers of low-lying nuclear states are changing with asymmetry [2]. We perform realistic many-body calculations of asymmetric nuclear matter within the Self-Consistent Green's Functions method to study the impact of isospin asymmetry on the correlated momentum distributions of asymmetric nuclear matter [2,3]. Using different internucleon potentials, we assess the model dependence of these calculations and conclude that the change of n(k) with isospin is well constrained from realistic calculations. [1] A. Gade et al., Phys. Rev. C 77, 044306 (2008). [2] T. Frick et al., Phys. Rev. C 71, 014313 (2005). [3] W. Dickhoff and C. Barbieri, Prog. Part. Nucl. Phys 52, 377 (2004).

Rios Huguet, Arnau

2008-10-01

15

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)

16

Topological phase transition in asymmetric nuclear matter

Starting from an effective model of asymmetric nuclear matter we show that at finite temperature T and baryon chemical potential ?B there exists a topological phase transition from state of non-Fermi liquid to that of Fermi liquid which is protected by winding numbers. At low ?B the transition is first-order, then extends to a second-order phase transition at larger ?B through a tri-critical point. The isospin dependences of the tri-critical point and the phase diagram in the (T, ?B)-plane are established. The distinction between this type of phase transition and the similar phenomenon caused by the Silver Blaze property (SBP) at T = 0 is confirmed for isospin varying from 0 to 1. We reveal that the topological phase transition could emerge in a large class of nuclear theories.

Phat, Tran Huu; Thu, Nguyen Van

2014-05-01

17

Saturation properties of isospin asymmetric nuclear matter

The saturation properties of the isospin asymmetric nuclear matter, ANM, are studied microscopically using the density dependent M3Y-Paris and M3Y-Reid effective interactions in their CDM3Y-K versions. To do so, two-dimensional expansion of the energy per nucleon of ANM with respect to its density, ?, and isospin asymmetry, I?(?-?)/?, has been used within a suitable density range. Within this framework, the ANM saturation density, energy per nucleon and incompressibility as functions of the isospin asymmetry, I, up to its eighth order are derived in simple analytical formulas. These formulas link explicitly the ANM saturation properties to the CDM3Y-K density dependence forms through 24 characteristic quantities and coefficients which represent the different order partial derivatives of the energy with respect to ? and I. The results show that the different terms up to I, but with only 18 characteristic coefficients, are needed to describe reasonably the different ANM saturation properties. Up to four times the saturation density of nuclear matter, some properties such as the energy per nucleon of ANM and pure neutron matter are well expressed by their expansion up to only the quadratic term in I. Based on both Paris and Reid effective interactions and within the symmetric nuclear matter saturation incompressibility range of K=220-250 MeV, the different coefficients of the ANM incompressibility are obtained with the values of K=-348±57 MeV, K=35±31 MeV and K=4±13 MeV.

Seif, W. M.

2012-03-01

18

Standard and quasideuteron pairing in asymmetric nuclear matter

International Nuclear Information System (INIS)

We study the standard 1 S 0 and the quasideuteron 3 S 1-3 D 1 pairing fields in asymmetric nuclear matter, using a Bonn meson-exchange interaction in a Dirac-Hartree-Fock-Bogoliubov approximation. As in earlier calculations, the standard pairing fields fall to zero at densities below saturation, due to relativistic effects. We obtain a quasideuteron field very similar to those found in nonrelativistic calculations at densities below saturation, both in symmetric and asymmetric nuclear matter. This field has the properties of a Bose-Einstein condensate at low densities and those of a BCS condensate at high densities. The quasideuteron pairing field in asymmetric nuclear matter is stable only when accompanied by standard 1 S 0 neutron-neutron and proton-proton pairing fields that are different from the fields obtained when the quasideuteron field is zero. The coupled pairing field configuration is the nuclear matter ground state

19

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.

20

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

21

Asymmetric Nuclear Matter in the Relativistic Brueckner Hartree Fock approach

We present a calculation of asymmetric nuclear matter properties in a relativistic Brueckner Hartree Fock framework. Following other calculations the components of the self-energies are extracted by projecting on Lorentz invariant amplitudes. It is shown that for asymmetric nuclear matter one needs a sixth invariant. We present a set of invariants which in the limit of symmetric nuclear matter reduces to the conventional set. We argue that the existence of such a properly behaving set is also crucial for the application of the projection method in symmetric nuclear matter. Results for the equation of state and other observables are presented. Special attention is payed to an analysis in terms of mean-field effective coupling constants. Apart from the usual ones we also find significant strength in the isovector scalar channel, which can be interpreted as an effective $\\delta$-meson.

De Jong, F

1998-01-01

22

Short-range correlations in asymmetric nuclear matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Study of the asymmetric nuclear matter with pion dressing

International Nuclear Information System (INIS)

We discuss here a self-consistent method to calculate the properties of the cold asymmetric nuclear matter. The nuclear matter is dressed with s-wave pion pairs. The nucleon-nucleon (N-N) interaction is mediated by these pion pairs, ? and ? mesons. The parameters of these interactions are calculated selfconsistently to obtain the saturation properties like equilibrium binding energy, pressure compressibility and symmetry energy. The computed equation of state is then used in the Tolman-Oppenheimer-Volkoff (TOV) equation to study the mass and radius of a neutron star containing neutron matter. (author)

24

Spin polarized states in strongly asymmetric nuclear matter

International Nuclear Information System (INIS)

The possibility of appearance of spin polarized states in strongly asymmetric nuclear matter is analyzed within the framework of a Fermi liquid theory with the Skyrme effective interaction. The zero temperature dependence of the neutron and proton spin polarization parameters as functions of density is found for SLy4 and SLy5 effective forces. It is shown that at some critical density strongly asymmetric nuclear matter undergoes a phase transition to the state with the oppositely directed spins of neutrons and protons while the state with the same direction of spins does not appear. In comparison with neutron matter, even small admixture of protons strongly decreases the threshold density of spin instability. It is clarified that protons become totally polarized within a very narrow density domain while the density profile of the neutron spin polarization parameter is characterized by the appearance of long tails near the transition density

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

Strange particles in asymmetric nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The overbinding problem in {sub {lambda}}{sup 5}He is solved by a coherent {lambda}-{sigma} coupling which is equivalent to the {lambda}NN three-body force. This three-body force has a significant effect in the ground states of {sub {lambda}}{sup 4}H and {sub {lambda}}{sup 4}He. In {sub {lambda}}{sup 6}H a particle-stable bound state appears with a large {lambda}-{sigma} coupling enhanced by excess neutrons. The coherent {lambda}-{sigma} coupling becomes much more important in neutron matter at high densities: It causes large {sigma}{sup 0} mixing of 5 - 25% at {rho}={rho}{sub 0} - 3{rho}{sub 0}. The coherent mixing drastically affects the hyperon composition of neutron-star matter. (author)

Akaishi, Yoshinori [High Energy Accelerator Research Organization, Institute of Particle and Nuclear Studies, Tsukuba, Ibaraki (Japan)

2002-09-01

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 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

28

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

29

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.)

30

The relativistic treatment of symmetric and asymmetric nuclear matter

Energy Technology Data Exchange (ETDEWEB)

In the framework of relativistic nuclear field theory the authors discuss and compare the different approaches in the treatment of nuclear-many-problem with inclusion of two-body correlations. The equations are solved self-consistently in the full Dirac space, so avoiding the ambiguities in the choice of the effective scattering amplitude. The results are compared with the standard method, where one only determines the scattering amplitude for positive energy spinors. Furthermore they tested the assumption of momentum independent self-energy. The results for asymmetric matter are in the structure similar to the outcome of the relativistic Hartree-Fock approximation, but differ from the nonrelativistic treatment. The agreement with the empirical values is quite satisfactory.

Huber, H.; Weigel, M.K. [Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany). Sektion Physik; Weber, F. [Lawrence Berkeley Lab., CA (United States)

1993-11-04

31

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

32

A new decomposition approach of Dirac Brueckner Hartree-Fock G matrix for asymmetric nuclear matter

International Nuclear Information System (INIS)

Asymmetric nuclear matter is investigated by the Dirac Brueckner Hartree-Fock (DBHF) approach with a new decomposition of the Dirac structure of nucleon self-energy from the G matrix. It is found that the isospin dependence of the scalar and vector potentials is relatively weak, although both potentials for neutron (proton) become deep (shallow) in the neutron-rich nuclear matter. The results in asymmetric nuclear matter are rather different from those obtained by a simple method, where the nucleon self-energy is deduced from the single-particle energy. The nuclear binding energy as a function of the asymmetry parameter fulfils the empirical parabolic law up to very extreme isospin asymmetric nuclear matter in the DBHF approach. The behaviour of the density dependence of the asymmetry energy is different from that obtained by non-relativistic approaches, although both give similar asymmetry energy at the nuclear saturation density

33

A new decomposition approach of Dirac Brueckner Hartree-Fock G matrix for asymmetric nuclear matter

Asymmetric nuclear matter is investigated by the Dirac Brueckner Hartree-Fock (DBHF) approach with a new decomposition of the Dirac structure of nucleon self-energy from the G matrix. It is found that the isospin dependence of the scalar and vector potentials is relatively weak, although both potentials for neutron (proton) become deep (shallow) in the neutron-rich nuclear matter. The results in asymmetric nuclear matter are rather different from those obtained by a simple method, where the nucleon self-energy is deduced from the single-particle energy. The nuclear binding energy as a function of the asymmetry parameter fulfils the empirical parabolic law up to very extreme isospin asymmetric nuclear matter in the DBHF approach. The behaviour of the density dependence of the asymmetry energy is different from that obtained by non-relativistic approaches, although both give similar asymmetry energy at the nuclear saturation density

LiuLing

2002-01-01

34

NUCLEAR AND HEAVY ION PHYSICS: Study of various charged ?-meson masses in asymmetric nuclear matter

We study the effective masses of ?-mesons for different charged states in asymmetric nuclear matter (ANM) using the Quantum Hadrodynamics II model. The closed form analytical results are presented for the effective masses of ?-mesons. We have shown that the different charged ?-mesons have mass splitting similar to various charged pions. The effect of the Dirac sea is also examined, and it is found that this effect is very important and leads to a reduction of the different charged ?-meson masses in ANM.

Yao, Hai-Bo; Wu, Shi-Shu

2009-10-01

35

Second-Order Contribution of the Incompressibility in Asymmetric Nuclear Matter

International Nuclear Information System (INIS)

With the complementarity of the nucleonic three-body force, we present the saturation points of symmetric nuclear matter with different interactions adopted within the Brueckner—Hartree—Fock scheme, and a more accurate empirical parameterization function for the equation of state of symmetric nuclear matter and pure neutron matter. On the basis of this fit formula, the symmetry energy and its derivatives are investigated, and ultimately the higher-order coefficient of the isobaric incompressibility for isospin asymmetric nuclear matter is predicted. (nuclear physics)

36

International Nuclear Information System (INIS)

Using the Hugenholtz-Van Hove theorem, we derive general expressions for the quadratic and quartic symmetry energies in terms of the isoscalar and isovector parts of single-nucleon potentials in isospin asymmetric nuclear matter. These expressions are useful for gaining deeper insights into the microscopic origins of the uncertainties in our knowledge on nuclear symmetry energies especially at supra-saturation densities. As examples, the formalism is applied to two model single-nucleon potentials that are widely used in transport model simulations of heavy-ion reactions.

37

Performance test of detectors for probing asymmetric nuclear matter

International Nuclear Information System (INIS)

We have performed incident energy dependence measurements of 115In (28Si, ?) reactions for probing a symmetry energy of nuclear matter. We have used a charged particle multiplicity array and a 14-element pion range-counter, which we have developed last year, together with 28Si beams of 400 A, 600 A, and 800 A MeV accelerated by Heavy Ion Medical Accelerator in Chiba (HIMAC). (author)

38

Equation of State for Isospin Asymmetric Nuclear Matter Using Lane Potential

International Nuclear Information System (INIS)

A mean field calculation for obtaining the equation of state (EOS) for symmetric nuclear matter from a density dependent M3Y interaction supplemented by a zero-range potential is described. The energy per nucleon is minimized to obtain the ground state of symmetric nuclear matter. The saturation energy per nucleon used for nuclear matter calculations is determined from the co-efficient of the volume term of Bethe-Weizsaecker mass formula which is evaluated by fitting the recent experimental and estimated atomic mass excesses from Audi-Wapstra-Thibault atomic mass table by minimizing the mean square deviation. The constants of density dependence of the effective interaction are obtained by reproducing the saturation energy per nucleon and the saturation density of spin and isospin symmetric cold infinite nuclear matter. The EOS of symmetric nuclear matter, thus obtained, provide reasonably good estimate of nuclear incompressibility. Once the constants of density dependence are determined, EOS for asymmetric nuclear matter is calculated by adding to the isoscalar part, the isovector component of the M3Y interaction that do not contribute to the EOS of symmetric nuclear matter. These EOS are then used to calculate the pressure, the energy density and the velocity of sound in symmetric as well as isospin asymmetric nuclear matter. (author)

39

Nucleon mean free path in asymmetric nuclear matter at finite temperature

The nucleon mean free path in symmetric and asymmetric nuclear matter is investigated in the framework of the finite temperature Brueckner theory. The realistic Bonn B two-body nucleon-nucleon interaction in combination with a consistent microscopic three-body force is adopted in the calculations. The results of the nucleon mean free path at zero temperature are in good agreement with the experimental data. The temperature and density and isospin dependence of the mean free path are studied systematically in asymmetric nuclear matter.

Bao, X. J.; Zhang, H. F.; Lombardo, U.; Dong, J. M.; Zuo, W.

2014-10-01

40

Isospin asymmetric nuclear matter and properties of axisymmetric neutron stars

Pure hadronic compact stars, above a limiting value ($\\approx$1.6 M$_\\odot$) of their gravitational masses, to which predictions of most of other EoSs are restricted, can be reached from the EoS obtained using DDM3Y effective interaction. This effective interaction is found to be quite successful in providing unified description of elastic and inelastic scattering, various radioactivities and nuclear matter properties. We present a systematic study of the properties of pure hadronic compact stars. The $\\beta$-equilibrated neutron star matter using this EoS with a thin crust is able to describe highly-massive compact stars, such as PSR B1516+02B with a mass M=1.94$^{+0.17}_{-0.19}$ M$_\\odot$ and PSR J0751+1807 with a mass M=2.1$\\pm$0.2 M$_\\odot$ to a 1$\\sigma$ confidence level.

Chowdhury, Partha Roy; Basu, D N

2010-01-01

41

Boiling Patterns of Iso-asymmetric Nuclear Matter

International Nuclear Information System (INIS)

Limits of thermodynamic metastability of self-bound neutron-rich nuclear matter are explored within the framework of microcanonical thermodynamics of interacting Fermi Gas model in Thomas-Fermi approximation. It is found that as the excitation energy per nucleon of the system is increased beyond a certain limiting value, the system loses metastability and becomes unstable with respect to joint fluctuations in excitation energy per nucleon and in isospin per nucleon. As a result, part of the system is forced to boil off in a form of iso-rich non-equilibrated vapors. Left behind in such a process, identifiable with distillation, is a more iso-symmetric metastable residue at a temperature characteristic of its residual isospin content. With a progressing increase in the initial excitation energy per nucleon, more neutron-rich matter is boiled off and a more iso-symmetric residue is left behind with progressively increasing characteristic temperature. Eventually, when all excess neutrons are shed, the system boils uniformly with a further supply of excitation energy, leaving behind a smaller and smaller residue at a characteristic boiling-point temperature of iso-symmetric matter.

42

International Nuclear Information System (INIS)

In this paper we study the possibility of spontaneous ferromagnetic and antiferromagnetic phase transitions of asymmetrical nuclear matter using the lowest-order constrained variational technique with AV18 potential and employing a microscopic point of view. Our results show that the spontaneous transition to ferromagnetic and antiferromagnetic phases cannot occur for asymmetric nuclear matter.

43

International Nuclear Information System (INIS)

A relativistic HF approximation is developed for a globally chiral invariant model including ?, ?, ?, ? mesons and the axial meson a. Some bulk properties of asymmetric nuclear matter are investigated in this framework and compared with the approximate version of the model where the axial meson is omitted and the ? meson is taken into account in a conventional way. (author)

44

International Nuclear Information System (INIS)

The lowest order constrained variational technique has been used to investigate some of the thermodynamic properties of spin-polarized hot asymmetric nuclear matter, such as the free energy, symmetry energy, susceptibility, and equation of state. We have shown that the symmetry energy of the nuclear matter is substantially sensitive to the value of spin polarization. Our calculations show that the equation of state of the polarized hot asymmetric nuclear matter is stiffer for higher values of the polarization as well as the isospin asymmetry parameter. Our results for the free energy and susceptibility show that spontaneous ferromagnetic phase transition cannot occur for hot asymmetric matter.

45

Symmetric and asymmetric nuclear matter in the Thomas-Fermi model at finite temperatures

Digital Repository Infrastructure Vision for European Research (DRIVER)

The properties of warm symmetric and asymmetric nuclear matter are investigated in the frame of the Thomas-Fermi approximation using a recent modern parametrization of the effective nucleon-nucleon interaction of Myers and Swiatecki. Special attention is paid to the liquid-gas phase transition, which is of special interest in modern nuclear physics. We have determined the critical temperature, critical density and the so-called flash temperature. Furthermore the equation of ...

Strobel, Klaus; Weber, Fridolin; Weigel, Manfred K.

1998-01-01

46

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

47

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)

48

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

49

Considerations on the Dirac-Hartree-Fock-Bogoliubov applied to asymmetric nuclear matter

International Nuclear Information System (INIS)

The Dirac-Hartree-Fock-Bogoliubov (DHFB) approximation has been used successfully to describe $S=0, T=1$ pairing (proton-proton and neutron-neutron pairing) in both symmetric nuclear matter and in finite nuclei . As proton-neutron pairing of both the $S=0, T=1$ and $S=1, T=0$ types also seems to be important in light nuclei, where protons and neutrons occupy the same shell, we are extending the model to include these. Using the DHFB approximation, we obtain the long-range interaction field, the HF field ?, as well as the short-range interaction one, the pairing field ?, as a function of the baryon momenta and of the density. We are including the pn pairing in the model of asymmetric nuclear matter in order to study the relative importance of the two basic types of pairing and to study effects of the asymmetry on the pairing. In this work, we discuss the effect on the states of the system of the broken spatial, spin and isospin symmetries that result when $S=1, T=0 $ pairing is taken into account in asymmetric nuclear matter. (author)

50

Droplet formation in cold asymmetric nuclear matter in the quark-meson-coupling model

International Nuclear Information System (INIS)

The quark-meson-coupling model is used to study droplet formation from the liquid-gas phase transition in cold asymmetric nuclear matter. The critical density and proton fraction for the phase transition are determined in the mean field approximation. Droplet properties are calculated in the Thomas-Fermi approximation. The electromagnetic field is explicitly included and its effects on droplet properties are studied. The results are compared with the ones obtained with the NL1 parametrization of the non-linear Walecka model

51

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Gandolfi, S.; Lovato, A.; Carlson, J.; Schmidt, Kevin E.

2014-01-01

52

Finite size effects in liquid-gas phase transition of asymmetric nuclear matter

International Nuclear Information System (INIS)

Full text: Since the nuclear equation of state has been studied in astrophysical context as an element of neutron star or super-nova theories - a call for an evidence was produced in experimental nuclear physics. Heavy-ion collisions became a tool of study on thermodynamic properties of nuclear matter. A particular interest has been inspired here by critical behavior of nuclear systems, as a phase transition of liquid-gas type. A lot of efforts was put to obtain an experimental evidence of such a phenomenon in heavy-ion collisions. With the use of radioactive beams and high performance identification systems in a near future it will be possible to extend experimental investigation to asymmetric nuclear systems, where neutron-to-proton ratio is far from the stability line. This experimental development needs a corresponding extension of theoretical studies. To obtain a complete theory of the liquid-gas phase transition in small nuclear systems, produced in violent heavy-ion collisions, one should take into account two facts. First, that the nuclear matter forming nuclei is composed of protons and neutrons; this complicates the formalism of phase transitions because one has to deal with two separate, proton and neutron, densities and chemical potentials. The second and more important is that the surface effects are very strong in a system composed of a few hundreds of nucleons. This point is especially difficult to hold, because surface becomes an additional, independent state parameter, depending strongly on the geometrical configuration of the system, and introducing a non-local term in the equation of state. In this presentation we follow the recent calculation by Lee and Mekjian on the finite-size effects in small (A = 102 -103) asymmetric nuclear systems. A zero-range isospin-dependent Skyrme force is used to obtain a density and isospin dependent potential. The potential is then completed by additional terms giving contributions from surface and Coulomb energies. Taking into account the particle number conservation and assuming a specific geometrical configuration we introduce different and more precise formulae for these terms, keeping the main idea presented in unchanged. Applying a mean-field theory of nuclear matter, pressure and chemical potentials are obtained and used to resolve Gibbs conditions, giving properties of gas and liquid phases. (Author)

53

BCS-BEC crossover of neutron pairs in symmetric and asymmetric nuclear matter

International Nuclear Information System (INIS)

We propose new types of density-dependent contact pairing interactions which reproduce the pairing gaps in symmetric and neutron matters obtained by a microscopic treatment based on realistic nucleon nucleon interaction. These interactions are able to simulate the pairing gaps of either the bare interaction or the interaction screened by the medium polarization effects. It is shown that the medium polarization effects cannot be cast into the usual density power law function of the contact interaction and require the introduction of another isoscalar term. The BCS-BEC crossover of neutron pairs in symmetric and asymmetric nuclear matters is studied by using these contact interactions. This work shows that the bare and screened pairing interactions lead to different features of the BCS-BEC crossover in symmetric nuclear matter. For the screened pairing interaction, a two-neutron BEC state is formed in symmetric matter at kFn?0.2 fm-1 (neutron density ?n/?0?10-3). In contrast, the bare interaction does not form the BEC state at any neutron density

54

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

55

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

2013-01-01

56

International Nuclear Information System (INIS)

We investigate the equation of state of asymmetric nuclear matter and its isospin dependence in various spin-isospin ST channels within the framework of the Brueckner-Hartree-Fock approach extended to include a microscopic three-body force (TBF). It is shown that the potential energy per nucleon in the isospin-singlet T=0 channel is mainly determined by the contribution from the tensor SD coupled channel. At high densities, the TBF effect on the isospin-triplet T=1 channel contribution turns out to be much larger than that on the T=0 channel contribution. At low densities around and below the normal nuclear matter density, the isospin dependence is found to come essentially from the isospin-singlet SD channel and the isospin-triplet T=1 component is almost independent of isospin asymmetry. As the density increases, the T=1 channel contribution becomes sensitive to the isospin asymmetry and at high enough densities its isospin dependence may even become more pronounced than that of the T=0 contribution. The present results may provide some microscopic constraints for improving effective nucleon-nucleon interactions in a nuclear medium and for constructing new functionals of effective nucleon-nucleon interaction based on microscopic many-body theories. (authors)

57

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; Providęncia, C; Vidańa, I

2014-01-01

58

Momentum, Density, and Isospin dependence of the Symmetric and Asymmetric Nuclear Matter Properties

Properties of symmetric and asymmetric nuclear matter have been investigated in the relativistic Dirac-Brueckner-Hartree-Fock approach based on projection techniques using the Bonn A potential. The momentum, density, and isospin dependence of the optical potentials and nucleon effective masses are studied. It turns out that the isovector optical potential depends sensitively on density and momentum, but is almost insensitive to the isospin asymmetry. Furthermore, the Dirac mass $m^*_D$ and the nonrelativistic mass $m^*_{NR}$ which parametrizes the energy dependence of the single particle spectrum, are both determined from relativistic Dirac-Brueckner-Hartree-Fock calculations. The nonrelativistic mass shows a characteristic peak structure at momenta slightly above the Fermi momentum $\\kf$. The relativistic Dirac mass shows a proton-neutron mass splitting of $m^*_{D,n} m^*_{NR,p}$ which is in agreement with the results from nonrelativistic calculations.

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

2005-01-01

59

Decomposition of EOS of Asymmetric Nuclear Matter into Different Spin-isospin Channels

We investigate the equation of state of asymmetric nuclear matter and its isospin dependence in various spin-isospin $ST$ channels within the framework of the Brueckner-Hartree-Fock approach extended to include a microscopic three-body force (TBF). It is shown that the potential energy per nucleon in the isospin-singlet T=0 channel is mainly determined by the contribution from the tensor SD coupled channel. At high densities, the TBF effect on the isospin-triplet T=1 channel contribution turns out to be much larger than that on the T=0 channel contribution. At low densities around and below the normal nuclear matter density, the isospin dependence is found to come essentially from the isospin-singlet SD channel and the isospin-triplet T=1 component is almost independent of isospin-asymmetry. As the density increases, the T=1 channel contribution becomes sensitive to the isospin-asymmetry and at high enough densities its isospin-dependence may even become more pronounced than that of the T=0 contribution. The ...

Zuo, Wei; Li, Jun-Qing; Zhao, En-Guang; Scheid, Werner

2013-01-01

60

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

61

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

62

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

63

Critical temperature for $\\alpha$-particle condensation in asymmetric nuclear matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

The critical temperature for $\\alpha$-particle condensation in nuclear matter with Fermi surface imbalance between protons and neutrons is determined. The in-medium four-body Schr\\"odinger 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.

Sogo, Takaaki; Ro?pke, Gerd; Schuck, Peter

2010-01-01

64

Finite temperature collective modes in a two phase coexistence region of asymmetric nuclear matter

The relation between collective modes and the phase transition in low density nuclear matter is examined. The dispersion relations for collective modes in a linear approach are evaluated within a Landau-Fermi liquid scheme by assuming coexisting phases in thermodynamical equilibrium. Temperature and isospin composition are taken as relevant parameters. The in-medium nuclear interaction is taken from a recently proposed density functional model. We found significative modifications in the energy spectrum, within certain range of temperatures and isospin asymmetry, due to the separation of matter into independent phases. We conclude that detailed calculations should not neglect this effect.

Aguirre, R M

2010-01-01

65

We study the properties of cold asymmetric nuclear matter at high density, applying the quark meson coupling model with excluded volume corrections in the framework of the Landau theory of relativistic Fermi liquids. We discuss the role of the finite spatial extension of composite baryons on dynamical and statistical properties such as the Landau parameters, the compressibility, and the symmetry energy. We have also calculated the low lying collective eigenfrequencies arising from the collisionless quasiparticle transport equation, considering both unstable and stable modes. An overall analysis of the excluded volume correlations on the collective properties is performed.

Aguirre, R M

2006-01-01

66

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

67

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

68

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Sammarruca, Francesca

2014-01-01

69

International Nuclear Information System (INIS)

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 transferred 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 the 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 h0?aa decays, while the second predicts a light charged Higgs-like scalar decaying to ??. Direct detection can arise from Higgs exchange in the first model or a nonzero magnetic moment in the second. In supersymmetric models, the would-be lightest supersymmetric partner can decay into pairs of dark matter particles plus standard model particles, possibly with displaced vertices.

70

A general theory for the condensation of strongly bound quartets in infinite nuclear matter is presented. Critical temperatures for symmetric and asymmetric nuclear matter are evaluated. A fully nonlinear theory for the quartet order parameter, based on an analogy of the Gorkov approach to pairing, is presented and solved. The strong qualitative difference with pairing is pointed out.

Schuck, Peter; Röpke, Gerd

2012-01-01

71

Active matter on asymmetric substrates

For collections of particles in a thermal bath interacting with an asymmetric substrate, it is possible for a ratchet effect to occur where the particles undergo a net dc motion in response to an ac forcing. Ratchet effects have been demonstrated in a variety of systems including colloids as well as magnetic vortices in type-II superconductors. Here we examine the case of active matter or self-driven particles interacting with asymmetric substrates. Active matter systems include self-motile colloidal particles undergoing catalysis, swimming bacteria, artificial swimmers, crawling cells, and motor proteins. We show that a ratchet effect can arise in this type of system even in the absence of ac forcing. The directed motion occurs for certain particle-substrate interaction rules and its magnitude depends on the amount of time the particles spend swimming in one direction before turning and swimming in a new direction. For strictly Brownian particles there is no ratchet effect. If the particles reflect off the barriers or scatter from the barriers according to Snell's law there is no ratchet effect; however, if the particles can align with the barriers or move along the barriers, directed motion arises. We also find that under certain motion rules, particles accumulate along the walls of the container in agreement with experiment. We also examine pattern formation for synchronized particle motion. We discuss possible applications of this system for self-assembly, extracting work, and sorting as well as future directions such as considering collective interactions and flocking models.

Olson Reichhardt, C. J.; Drocco, J.; Mai, T.; Wan, M. B.; Reichhardt, C.

2011-10-01

72

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

Using the isospin-dependent quantum molecular dynamics model, we study the N/Z dependence of participant-spectator matter, anisotropic ratio and relative momentum , at different incident energies (E = 100, 200 and 300 MeV per nucleon) and at scaled impact parameters (\\hat {b} = b/b_{\\max } = 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.

Jain, Anupriya; Kumar, Suneel

2012-06-01

73

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)

74

The Deconfinement Phase Transition in Asymmetric Matter

We study the phase transition of asymmetric hadronic matter to a quark-gluon plasma within the framework of a simple two-phase model. The analysis is performed 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. The EOS is obtained in a separate description for the hadronic phase and for the quark-gluon plasma. For the hadrons, a relativistic mean-field model calibrated to the properties of nuclear matter is used, and a bag-model type EOS is used for the quarks and gluons. The model is applied to the deconfinement phase transition that may occur in matter created in ultra-relativistic collisions of heavy ions. Based on the two-dimensional coexistence surface (binodal), various phase separation scenarios and the Maxwell construction through the mixed phase are discussed. In the framework of the two-phase model the phase transition in asymmetric matter is continuous (second-order by...

Müller, H

1997-01-01

75

We investigate the equation of state of asymmetric nuclear matter and its isospin dependence in various spin-isospin ST channels within the framework of the Brueckner-Hartree-Fock approach extended to include a microscopic three-body force (TBF). It is shown that the potential energy per nucleon in the isospin-singlet T = 0 channel is mainly determined by the contribution from the tensor SD coupled channel. At high densities, the TBF effect on the isospin-triplet T = 1 channel contribution turns out to be much larger than that on the T = 0 channel contribution. At low densities around and below the normal nuclear matter density, the isospin dependence is found to come essentially from the isospin-singlet SD channel and the isospin-triplet T = 1 component is almost independent of isospin asymmetry. As the density increases, the T = 1 channel contribution becomes sensitive to the isospin asymmetry and at high enough densities its isospin dependence may even become more pronounced than that of the T = 0 contribution. The present results may provide some microscopic constraints for improving effective nucleon-nucleon interactions in a nuclear medium and for constructing new functionals of effective nucleon-nucleon interaction based on microscopic many-body theories.

Zuo, Wei; Zhou, Shan-Gui; Li, Jun-Qing; Zhao, En-Guang; Scheid, W.

2009-07-01

76

Asymmetric Dark Matter and Effective Operators

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

77

Relic abundance of asymmetric Dark Matter

International Nuclear Information System (INIS)

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

78

Stable bound states of asymmetric dark matter

The simplest renormalizable effective field theories with asymmetric dark matter bound states contain two additional gauge singlet fields, one being the dark matter and the other a mediator particle that the dark matter annihilates into. We examine the physics of one such model with a Dirac fermion as the dark matter and a real scalar mediator. For a range of parameters the Yukawa coupling of the dark matter to the mediator gives rise to stable asymmetric dark matter bound states. We derive properties of the bound states including nuggets formed from N?1 dark matter particles. We also consider the formation of bound states in the early Universe and direct detection of dark matter bound states. Many of our results also hold for symmetric dark matter.

Wise, Mark B.; Zhang, Yue

2014-09-01

79

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

80

Phenomenology of Fermionic Asymmetric Dark Matter

Asymmetric dark matter (ADM) has been an attractive possibility attempting to explain the observed ratio of baryon to dark matter abundance in the universe. While a bosonic ADM is highly constrained by the limits from existence of old neutron stars, a fermionic ADM requires an additional light particle in order to annihilate its symmetric component in the early universe. We revisit the phenomenology of a minimal fermionic ADM model including a light scalar state. The current constraints on this scenario from cosmology, dark matter direct detection, flavour physics and collider searches are investigated in detail. We estimate the future reach on the model parameter space from next-generation dark matter direct detection experiments, Higgs boson property measurements and search for light scalars at the LHC, as well as the determination of Higgs invisible branching ratio at the proposed ILC.

Bhattacherjee, Biplob; Mukhopadhyay, Satyanarayan; Nojiri, Mihoko M

2013-01-01

81

Asymmetric Dark Matter and Dark Radiation

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, pre...

Blennow, Mattias; Mena, Olga; Redondo, Javier; Serra, Paolo

2012-01-01

82

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

83

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

84

Collective flow measurements in asymmetric nuclear collisions

International Nuclear Information System (INIS)

The collective flow measurements presented in this lecture have been performed with the DIOGENE electronic 4?-detector installed at the Saturne synchrotron in Saclay, which can deliver beams up to mass 40. In order to study the properties of dense (and hot) nuclear matter, it is required to measure nucleus-nucleus collisions involving a large number of nucleons. That is the reason why we focused our experiment on asymmetric collisions, with target nuclei heavier than the beam. We measured triple differential cross sections of pseudoprotons (free protons as well as protons bound in light nuclei), inside the acceptance of the DIOGENE pictorial drift chamber (PDC), restricted to 200 0 in polar angle and to kinetic energy larger than ? 40 MeV. We analysed these cross sections in three different ways, which lead to various features of the collective flow: the usual flow parameter F, azimuthal angular distributions dN/d? showing possible evidence for preferential emission transversely to the reaction plane, and finally two-dimensional Gaussian fits giving a more complete characterization of the participants collective flow, with the flow angle and two aspect ratios

85

Isospin violating dark matter being asymmetric

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

86

International Nuclear Information System (INIS)

It is stated that at the Workshop on Nuclear and Dense Matter held at the University of Illinois in May 1977 significant progress was reported that largely resolves many of the questions raised in this journal Vol. 6, p.149, 1976. These include perturbative versus variational methods as applied to nuclear matter, exact solutions for bosons, what is known as the fermion 'homework problem', and various other considerations regarding nuclear matter, including the use of variational methods as opposed to perturbation theory. (15 references) (U.K.)

87

Fixed-velocity chiral sum rules for nuclear matter

International Nuclear Information System (INIS)

Infinite sets of sum rules involving the excitations of infinite nuclear matter are derived using only completeness, the current algebra implicit in QCD, and relativistic covariance. The sum rules can be used for isospin-asymmetric nuclear matter, including neutron matter. They relate the chiral condensate and the isospin density to weighted sums over states with fixed velocity relative to the nuclear matter ground state. (author)

88

Fixed-velocity chiral sum rules for nuclear matter

Energy Technology Data Exchange (ETDEWEB)

Infinite sets of sum rules involving the excitations of infinite nuclear matter are derived using only completeness, the current algebra implicit in QCD, and relativistic covariance. The sum rules can be used for isospin-asymmetric nuclear matter, including neutron matter. They relate the chiral condensate and the isospin density to weighted sums over states with fixed velocity relative to the nuclear matter ground state. (author) 16 refs, 2 figs

Cohen, T.D. [Dept. of Physics, Univ. of Maryland, College Park, MD (United States); Broniowski, W. [The H. Niewodniczanski Inst. of Nuclear Physics, Cracow (Poland)

1997-02-01

89

Upper Bounds on Asymmetric Dark Matter Self Annihilation Cross Sections

Most models for asymmetric dark matter allow for dark matter self annihilation processes, which can wash out the asymmetry at temperatures near and below the dark matter mass. We study the coupled set of Boltzmann equations for the symmetric and antisymmetric dark matter number densities, and derive conditions applicable to a large class of models for the absence of a significant wash-out of an asymmetry. These constraints are applied to various existing scenarios. In the case of left- or right-handed sneutrinos, very large electroweak gaugino masses, or very small mixing angles are required.

Ellwanger, Ulrich

2012-01-01

90

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

91

Asymmetric dark matter and the sun.

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. PMID:20867433

Frandsen, Mads T; Sarkar, Subir

2010-07-01

92

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

93

Hot Nuclear Matter in Asymmetry Chiral Sigma Model

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the frame work of SU(2) chiral sigma model, the nuclear matter properties at zero and finite temperature have been investigated. We have analyzed the nuclear matter equation of state by varying different parameters, which agrees well with the one derived from the heavy-ion collision experiment at extreme densities and reliable realistic(DBHF) model at low density region. We have then calculated the temperature dependent asymmetric nuclear matter, also investigated the cri...

Sahu, P. K.; Jha, T. K.; Panda, K. C.; Patra, S. K.

2003-01-01

94

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

95

Decaying Asymmetric Dark Matter Relaxes the AMS-Fermi Tension

The first result of AMS-02 confirms the positron fraction excess observed by PAMELA, but in the dark matter (DM) interpretation, its softer spectrum brings a tension between AMS-02 and Fermi-LAT, which reported an excess of the electron plus positron flux. In this work we point out that the asymmetric cosmic ray from asymmetric dark matter (ADM) decay relaxes the tension, and find that at the two-body decay level a bosonic ADM around 2.4 TeV and decaying to\\mu^-\\tau^+ can significantly improve the fits. Based on the R-parity-violating supersymmetry with operators LLE^c, we propose a minimal model to realize that ADM scenario: Introducing a pair of singlets (X,\\bar X) and coupling them to the visible sector via LH_uX, we then obtain a leptonic decaying ADM with TeV-scale mass.

Feng, Lei

2013-01-01

96

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

97

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

98

Possible implications of asymmetric fermionic dark matter for neutron stars

Energy Technology Data Exchange (ETDEWEB)

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.

Goldman, I. [Department of Exact Sciences, Afeka Tel Aviv Academic Engineering College, Tel Aviv (Israel); Mohapatra, R.N., E-mail: rmohapat@umd.edu [Maryland Center for Fundamental Physics and Department of Physics, University of Maryland, College Park (United States); Nussinov, S. [School of Physics and Astronomy, Tel Aviv University, Tel Aviv (Israel); Schmid College of Science, Chapman University, Orange, CA 92866 (United States); Rosenbaum, D. [Physics Department, Southern Methodist University, Dallas (United States); Teplitz, V. [Physics Department, Southern Methodist University, Dallas (United States); NASA Goddard Space Flight Center, Greenbelt, MD (United States)

2013-10-01

99

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

100

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 poi...

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

2014-01-01

101

Nucleon properties in nuclear matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

102

International Nuclear Information System (INIS)

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)

103

Asymmetric dark matter from a GeV hidden sector

International Nuclear Information System (INIS)

Asymmetric dark matter (ADM) models relate the dark matter (DM) density to the baryon asymmetry, so that a natural mass scale for ADM is around a few GeV. In existing models of ADM, this mass scale is unexplained; here we generate this GeV scale for DM) from the weak scale via gauge kinetic mixing with a new Abelian dark force. In addition, this dark sector provides an efficient mechanism for suppressing the symmetric abundance of DM through annihilations to the dark photon. We augment this sector with a higher dimensional operator responsible for communicating the baryon asymmetry to the dark sector. Our framework also provides a DM candidate for gauge mediation models. It results in a direct detection cross section of interest for current experiments: ?p -41 cm2 for DM masses in the range 1-15 GeV.

104

Spectral properties of nuclear matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

105

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

106

Nuclear matter under extreme conditions

International Nuclear Information System (INIS)

The microscopic investigations of the equation of state for nuclear matter at high densities are reviewed. The paper was presented to the conference on ''The early universe and its evolution'', Erice, Italy, 1986. Meson-exchange models for nucleon-nucleon interactions, conventional many-body theory of nuclear matter, and subnucleonic degrees of freedom, are all discussed. (U.K.)

107

Nuclear matter and electron scattering

Energy Technology Data Exchange (ETDEWEB)

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.)

Sick, I. [Dept. fuer Physik und Astronomie, Univ. Basel (Switzerland)

1998-06-01

108

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)

109

Hot nuclear matter in asymmetry chiral sigma model

International Nuclear Information System (INIS)

In the frame work of SU(2) chiral sigma model, the nuclear matter properties at zero and finite temperature have been investigated. We have analyzed the nuclear matter equation of state by varying different parameters, which agrees well with the one derived from the heavy-ion collision experiment at extreme densities and reliable realistic (DBHF) model at low density region. We have then calculated the temperature dependent asymmetric nuclear matter, also investigated the critical temperature of liquid gas phase transition and compared with the experimental data. We found that the critical temperature in our model is in the range of 14-20 MeV

110

Hot Nuclear Matter in Asymmetry Chiral Sigma Model

In the frame work of SU(2) chiral sigma model, the nuclear matter properties at zero and finite temperature have been investigated. We have analyzed the nuclear matter equation of state by varying different parameters, which agrees well with the one derived from the heavy-ion collision experiment at extreme densities and reliable realistic(DBHF) model at low density region. We have then calculated the temperature dependent asymmetric nuclear matter, also investigated the critical temperature of liquid gas phase transition and compared with the experimental data. We found that the critical temperature in our model is in the range of 14-20 MeV.

Sahu, P K; Panda, K C; Patra, S K

2004-01-01

111

Hot nuclear matter in asymmetry chiral sigma model

Energy Technology Data Exchange (ETDEWEB)

In the frame work of SU(2) chiral sigma model, the nuclear matter properties at zero and finite temperature have been investigated. We have analyzed the nuclear matter equation of state by varying different parameters, which agrees well with the one derived from the heavy-ion collision experiment at extreme densities and reliable realistic (DBHF) model at low density region. We have then calculated the temperature dependent asymmetric nuclear matter, also investigated the critical temperature of liquid gas phase transition and compared with the experimental data. We found that the critical temperature in our model is in the range of 14-20 MeV.

Sahu, P.K. E-mail: pradip@iopb.res.in; Jha, T.K. E-mail: tarunjha@iopb.res.in; Panda, K.C.; Patra, S.K. E-mail: patra@iopb.res.in

2004-03-08

112

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

113

Magnetic catalysis in nuclear matter

Due to magnetic catalysis, a strong magnetic field enhances the chiral condensate at low temperatures and thus can also be expected to increase the vacuum mass of nucleons. We employ two relativistic field-theoretical models for nuclear matter, the Walecka model and an extended linear sigma model, to discuss the resulting effect on the transition between vacuum and nuclear matter at zero temperature. In both models we find that the creation of nuclear matter in a sufficiently strong magnetic field becomes energetically more costly due to the heaviness of magnetized nucleons, even though it is also found that nuclear matter is more strongly bound in a magnetic field. Our results are potentially important for dense nuclear matter in compact stars, especially since previous studies in the astrophysical context have always ignored the contribution of the magnetized Dirac sea and thus the effect of magnetic catalysis.

Haber, Alexander; Schmitt, Andreas

2014-01-01

114

Condensed Matter Nuclear Science

Preface -- 1. General. Progress in condensed matter nuclear science / A. Takahashi. Summary of ICCF-12 / X. Z. Li. Overview of light water/hydrogen-based low-energy nuclear reactions / G. H. Miley and P. J. Shrestha -- 2. Excess heat and He detection. Development of "DS-reactor" as the practical reactor of "cold fusion" based on the "DS-cell" with "DS-cathode" / Y. Arata and Y.-C. Zhang. Progress in excess of power experiments with electrochemical loading of deuterium in palladium / V. Violante ... [et al.]. Anomalous energy generation during conventional electrolysis / T. Mizuno and Y. Toriyabe. "Excess heat" induced by deuterium flux in palladium film / B. Liu ... [et al.]. Abnormal excess heat observed during Mizuno-type experiments / J.-F. Fauvarque, P. P. Clauzon and G. J.-M. Lallevé. Seebeck envelope calorimetry with a Pd|D[symbol]O + H[symbol]SO[symbol] electrolytic cell / W.-S. Zhang, J. Dash and Q. Wang. Observation and investigation of nuclear fusion and self-induced electric discharges in liquids / A. I. Koldamasov ... [et al.]. Description of a sensitive seebeck calorimeter used for cold fusion studies / E. Storms. Some recent results at ENEA / M. Apicella ... [et al.]. Heat measurement during plasma electrolysis / K. Iizumi ... [et al.]. Effect of an additive on thermal output during electrolysis of heavy water with a palladium cathode / Q. Wang and J. Dash. Thermal analysis of calorimetric systems / L. D'Aulerio ... [et al.]. Surface plasmons and low-energy nuclear reactions triggering / E. Castagna ... [et al.]. Production method for violent TCB jet plasma from cavity / F. Amini. New results and an ongoing excess heat controversy / L. Kowalski ... [et al.] -- 3. Transmutation. Observation of surface distribution of products by X-ray fluorescence spectrometry during D[symbol] gas permeation through Pd Complexes / Y. Iwamura ... [et al.]. Discharge experiment using Pd/CaO/Pd multi-layered cathode / S. Narita ... [et al.]. Producing transmutation element on multi-layered Pd sample by deuterium permeation / H. Yamada ... [et al.]. Experimental observation and combined investigation of high-performance fusion of iron-region isotopes in optimal growing microbiological associations / V. I. Vysotskii ... [et al.]. Research into low-energy nuclear reactions in cathode sample solid with production of excess heat, stable and radioactive impurity nuclides / A. B. Karabut. Influence of parameters of the glow discharge on change of structure and the isotope composition of the cathode materials / I. B. Savvatimova and D. V. Gavritenkov. Elemental analysis of palladium electrodes after Pd/Pd light water critical electrolysis / Y. Toriyabe ... [et al.]. Progress on the study of isotopic composition in metallic thin films undergone to electrochemical loading of hydrogen / M. Apicella ... [et al.]. In situ accelerator analyses of palladium complex under deuterium permeation / A. Kitamura ... [et al.]. High-resolution mass spectrum for deuterium (hydrogen) gas permeating palladium film / Q. M. Wei ... [et al.]. ICP-MS analysis of electrodes and electrolytes after HNO[symbol]/H[symbol]O electrolysis / S. Taniguchi ... [et al.]. The Italy-Japan project - fundamental research on cold transmutation process for treatment of nuclear wastes / A. Takahashi, F. Celani and Y. Iwamura -- 4. Nuclear physics approach. Reproducible nuclear emissions from Pd/PdO:Dx heterostructure during controlled exothermic deuterium desorption / A. G. Lipson ... [et al.]. Correct identification of energetic alpha and proton tracks in experiments on CR-39 charged particle detection during hydrogen desorption from Pd/PdO:H[symbol] heterostructure / A. S. Roussetski ... [et al.]. Intense non-linear soft X-ray emission from a hydride target during pulsed D bombardment / G. H. Miley ... [et al.]. Enhancement of first wall damage in ITER type TOKAMAK due to LENR effects / A. G. Lipson, G. H. Miley and H. Momota. Generation of DD-reactions in a ferroelectric KD[symbol]PO[symbol] single crystal during transition

Takahashi, Akito; Ota, Ken-Ichiro; Iwamura, Yashuhiro

115

Asymmetric inelastic inert doublet dark matter from triplet scalar leptogenesis

Energy Technology Data Exchange (ETDEWEB)

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.

Arina, Chiara, E-mail: chiara.arina@physik.rwth-aachen.de [Institut fuer Theoretische Teilchenphysik und Kosmologie, RWTH Aachen, 52056 Aachen (Germany); Sahu, Narendra, E-mail: Narendra.Sahu@ulb.ac.be [Service de Physique Theorique, Universite Libre de Bruxelles, CP225, Bld du Triomphe, 1050 Brussels (Belgium)

2012-01-21

116

Chiral thermodynamics of nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The equation of state of nuclear matter is calculated at finite temperature in the framework of in-medium chiral perturbation theory up to three-loop order. The dependence of its thermodynamic properties on the isospin-asymmetry is investigated. The chiral quark condensate is evaluated for symmetric nuclear matter. Its behaviour as a function of density and temperature sets important nuclear physics constraints for the QCD phase diagram.

Fiorilla, Salvatore

2012-10-23

117

Chiral thermodynamics of nuclear matter

International Nuclear Information System (INIS)

The equation of state of nuclear matter is calculated at finite temperature in the framework of in-medium chiral perturbation theory up to three-loop order. The dependence of its thermodynamic properties on the isospin-asymmetry is investigated. The chiral quark condensate is evaluated for symmetric nuclear matter. Its behaviour as a function of density and temperature sets important nuclear physics constraints for the QCD phase diagram.

118

Indirect Detection Signatures for the Origin of Asymmetric Dark Matter

We study the decay signatures of Asymmetric Dark Matter (ADM) via higher dimension operators which are responsible for generating the primordial dark matter (DM) asymmetry. Since the signatures are sensitive both to the nature of the higher dimension operator generating the DM asymmetry and to the sign of the baryon or lepton number that the DM carries, indirect detection may provide a window into the nature of the mechanism which generates the DM asymmetry. We consider in particular dimension-6 fermionic operators of the form ${\\cal O}_{ADM} = X {\\cal O}_{B-L}/M^2$, where ${\\cal O}_{B-L} = u^c d^c d^c,~\\ell \\ell e^c,~q \\ell d^c$ (or operators related through a Hermitian conjugate) with the scale $M$ around or just below the GUT scale. We derive constraints on ADM particles both in the natural mass range (around a few GeV), as well as in the range between 100 GeV to 10 TeV. For light ADM, we focus on constraints from the low energy gamma ray data from Fermi. For heavy ADM, we consider $\\gamma$-rays and proton...

Zhao, Yue

2014-01-01

119

Covariant density functional theory for nuclear matter

International Nuclear Information System (INIS)

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 pur

120

Nuclear matter with realistic hamiltonians

International Nuclear Information System (INIS)

In this thesis we first review some of the theoretical methods designed to handle the nuclear matter many-body problem. The emphasis is put on the variational theory developed by Pandharipande and Wiringa. This method treats the so called v6 model, in which the two-nucleon interaction is assumed to have only central, spin, isospin and tensor components, and there are no many nucleon interactions. A realistic v14 model of the two-nucleon interaction is obtained by fitting the available two-body data in S, P, D and F waves. This interaction has terms that are linear and quadratic in spin orbit and quadratic in the relative orbital angular momentum. The variational theory is extended to treat this realistic interaction model and nuclear matter properties are calculated with it neglecting many-nucleon interactions. The results of these calculations show that the empirically known properties of nucelar matter, such as its ground state energy, equilibrium density and compressibility, cannot be explained by this nuclear hamiltonian that incorporates only two-body interactions. Results obtained with other realistic two-nucleon interactions also fail to reproduce the empirical nuclear matter properties. Hence we postulate a form for a three-nucleon interaction (TNI), inspired from the meson theory of nuclear interactions. Instead of attempting to develop a variational theory to treat TNI microscopically in nuclear matter, we parametrize the effect of TNI matter, we parametrize the effect of TNI on the energy of nuclear matter with three parameters. These are varied to obtain the empirical energy, density and compressibility of nuclear matter. The results of our calculations show that the TNI contribution on the energy is much smaller than that of the two-body v14 interaction, as expected, and thus it may be reasonable to neglect four and more nucleon interactions in the nuclear hamiltonian

121

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.

122

Quantum condensates in nuclear matter

Nonrelativistic nuclear matter is considered as a special example of a many-particle system. Quantum statistical methods are applied to treat the formation and dissolution of bound states in dense matter. The formation of quantum condensates is investigated. Special aspects are the transition from Bose-Einstein condensation (BEC) to Bardeen-Cooper-Schrieffer (BCS) pairing as well as the occurrence of quartetting. Consequences for the structure of nuclei are compared with experimental data. Exercises to illustrate the main features of in-medium effects in nuclear matter are given.

Röpke, G.

2008-12-01

123

Bosonic variables in nuclear matters

International Nuclear Information System (INIS)

It is shown that the boson theoretical interpretation of nuclear forces nessecitates the introduction of bosonic variables within the state function of nuclear matter. In this framework the 2-boson exchange plays a decisive role and calls for the introduction of special selfenergy diagrams. This generalized scheme is discussed with the help of a solvable field theoretical model. (orig.)

124

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

125

Spectral properties of nuclear matter

International Nuclear Information System (INIS)

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 super.uid phase is discussed and numerical results are presented for this case. The linear response of a correlated system going beyond the Hartree-Fock+ Random-Phase-Approximation (RPA) scheme is studied. The polarization is obtained by solving a consistent Bethe-Salpeter (BS) equation for the coupling of dressed nucleons to an external field. We find that multipair contributions are important for the spin(isospin) response when the interaction is spin(isospin) dependent

126

Induced interaction stabilizing nuclear matter

International Nuclear Information System (INIS)

Excitation modes of nuclear matter at various densities are investigated including the effects of ? excitations. Collective features are observed at small densities in the scalar-isoscalar channel and at large densities for the longitudinal isovector mode. Using the Brueckner G-matrix for the residual interaction, the RPA approximation predicts an instability of nuclear matter against these modes. The renormalization of the residual interaction by the so called induced interaction yields a stabilization of the collective modes. The effects of the corresponding phonon exchange terms on the particle-hole interaction and on the effective mass are discussed. 8 refs.; 4 figs

127

Energy Technology Data Exchange (ETDEWEB)

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 previously estimated. (orig.)

Heiselberg, H. [NORDITA, Copenhagen (Denmark)

1998-06-01

128

International Nuclear Information System (INIS)

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 previously estimated. (orig.)

129

Nuclear matter: new states of dense matter

International Nuclear Information System (INIS)

Heavy ion collisions when involving incident ion velocity of about a quarter of light speed are powerful tools for understanding the behaviour of nuclear matter. Hot nuclei produced in such collisions decay either by evaporation (emission of particles) or by multifragmentation (production of smaller nuclei) or by vaporization (production of particles and light nuclei). These decay processes show strong analogies with liquid-gas transition. 2 new experimental facts support this interpretation: energy fluctuations and abnormal correlations. In the first case fluctuations show the existence of negative heat capacity and in the second case correlations show the possibility of a spinodal decomposition that was, till now only speculated for liquid-gas transitions. (A.C.)

130

Nuclear matter properties and equation of state of neutron matter

Energy Technology Data Exchange (ETDEWEB)

Correlations among symmetric nuclear matter properties, the neutron matter EOS and the pressure of neutron matter are studied in the Skyrme Hartree-Fock (SHF) and the relativistic mean field (RMF) models. At present, many different parameter sets for the Skyrme interaction and RMF model have been proposed. As a result, the property of neutron matter which is one of extreme conditions depends on the parameter set. We found clear linear correlations between the energy per neutron of neutron matter and the symmetry energy and between the pressure of neutron matter and L which is one of isovector nuclear matter properties at the saturation density of symmetric nuclear matter. We show that values of the energy per neutron and the pressure of neutron matter at the saturation density of symmetric nuclear matter can be obtained by accurate experimental data of the symmetry energy and L.

Yoshida, Satoshi [Science Research Center, Hosei University, 2-17-1 Fujimi, Chiyoda, Tokyo 102-8160 (Japan); Sagawa, Hiroyuki, E-mail: s_yoshi@hosei.ac.jp [Center for Mathematical Sciences, the University of Aizu, Aizu-Wakamatsu, Fukushima 965-8580 (Japan)

2011-09-16

131

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.)

132

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

133

Reflection-asymmetric nuclear deformations within the Density Functional Theory

Within the nuclear density functional theory (DFT) we study the effect of reflection-asymmetric shapes on ground-state binding energies and binding energy differences. To this end, we developed the new DFT solver AXIALHFB that uses an approximate second-order gradient to solve the Hartree-Fock-Bogoliubov equations of superconducting DFT with the quasi-local Skyrme energy density functionals. Illustrative calculations are carried out for even-even isotopes of radium and thorium.

Olsen, E.; Erler, J.; Nazarewicz, W.; Stoitsov, M.

2012-12-01

134

Reflection-asymmetric nuclear deformations within the Density Functional Theory

Within the nuclear density functional theory (DFT) we study the effect of reflection-asymmetric shapes on ground-state binding energies and binding energy differences. To this end, we developed the new DFT solver AxialHFB that uses an approximate second-order gradient to solve the Hartree-Fock-Bogoliubov equations of superconducting DFT with the quasi-local Skyrme energy density functionals. Illustrative calculations are carried out for even-even isotopes of radium and thorium.

Olsen, E; Nazarewicz, W; Stoitsov, M; 10.1088/1742-6596/402/1/012034

2013-01-01

135

Nuclear matter at finite temperature

International Nuclear Information System (INIS)

A method for deriving the equation of state of nuclear matter from realistic nucleon-nucleon potentials is studied. The author starts from a linked diagram expansion of the thermodynamic potential ?, and calculates ? by summing up its particle-particle and particle-hole ring diagrams each to all orders. A model-space finite temperature reaction matrix is introduced. As an intermediate step of his calculation, RPA-type secular equations need to be solved. These equations may have complex solutions, and the possibility that their occurrence may serve as a signal for phase transition is suggested. Results of a recent ring diagram calculation of nuclear matter at zero temperature using Paris and Reid potentials are discussed. 19 refs.; 11 figs

136

Temperature Dependent Nuclear Matter Approach

International Nuclear Information System (INIS)

Full text: The nuclear matter approach provides an effective interaction in the presence of a sea of nucleons. Especially it accounts for the Pauli principle which forbids scattering processes into the occupied states of the nucleonic see. It is well suited to describe the bulk properties of nuclei as well as optical potentials beyond 40 MeV incident energy. Difficulties in the description of nucleon-nucleus reactions beyond 70 MeV may indicate the importance of excited doorway states for reaction processes and therefore the optical potentials. In this contribution we consider the g-matrix approach for excited nuclear matter. The g-matrix is evaluated via the Bethe-Goldstone equation with an exact Pauli operator accounting for excitations with arbitrary occupation distributions. The features of the g-matrix with regard to changes in excitation are discussed. (author)

137

Variational theory of nuclear matter

International Nuclear Information System (INIS)

The variational theory of nuclear matter is reviewed with especial reference to the powerful diagrammatic techniques invented in recent years. The subject is considered under the headings; general cluster expansion theory, the Jastrow energy expectation value, comparison of Jastrow and Brueckner=Bethe theories in low orders, diagrammatic cluster expansions, Fermi hypernetted-chain (FHNC) methods, FHNC calculations for central potentials, state-dependent correlations. 202 references. (UK)

138

Quark matter and nuclear collisions

International Nuclear Information System (INIS)

I summarize briefly and qualitatively the content of my lectures. They treated on one hand quark deconfinement and its theoretical basis in finite temperature QCD, on the other hand high energy nuclear collisions as a way to produce a deconfined state of matter in the laboratory. The material presented will shortly appear in greater detail as a book under the same title as these lectures. (author)

139

Baryogenesis and Asymmetric Dark Matter from The Left-Right Mirror Symmetric Model

The paper suggests a left-right mirror symmetric model to account for the baryogenesis and asymmetric dark matter. The model can simultaneously accommodate the standard model, neutrino physics, matter-antimatter asymmetry and dark matter. In particular, it naturally and elegantly explains the origin of the baryon and dark matter asymmetries, and clearly gives the close interrelations of them. In addition, the model predicts a number of interesting results, e.g. the cold dark matter neutrino mass is $3.1$ times the proton mass. It is also feasible and promising to test the model in future experiments.

Yang, Wei-Min

2014-01-01

140

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

141

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

142

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

143

Three-body Force Effects on the Properties of Neutron-rich Nuclear Matter

We review our research work on the single-particle properties and the equation of state (EOS) of isospin asymmetric nuclear matter within the framework of the Brueckner-Hartree-Fock (BHF) approach extended by including a microscopic three-body force (TBF). The TBF is shown to affect significantly the nuclear matter EOS and the density dependence of nuclear symmetry energy at high densities above the normal nuclear matter density, and it is necessary for reproducing the empirical saturation property of symmetric nuclear matter in a nonrelativistic microscopic framework. The TBF-induced rearrangement effect and the ground state (g.s.) correlation effect on the s.p. properties in neutron-rich nuclear matter are investigated. Both effects turn out to be crucial for predicting reliably the s.p. properties within the Brueckner framework. The TBF effect on nucleon superfluidity in neutron star matter and neutron stars has also been discussed.

Zuo, Wei

2013-01-01

144

Asymmetric dark matter from spontaneous cogenesis in the supersymmetric standard model

International Nuclear Information System (INIS)

The observational relation between the density of baryon and dark matter in the Universe, ?DM/?B?5, is one of the most difficult problems to solve in modern cosmology. We discuss a scenario that explains this relation by combining the asymmetric dark matter scenario and the spontaneous baryogenesis associated with the flat direction in the supersymmetric standard model. A part of baryon asymmetry is transferred to charge asymmetry D that dark matter carries, if a symmetry violating interaction that works at high temperature breaks not only B-L but also D symmetries simultaneously. In this case, the present number density of baryon and dark matter can be same order if the symmetric part of dark matter annihilates sufficiently. Moreover, the baryon number density can be enhanced as compared to that of dark matter if another B-L violating interaction is still in thermal equilibrium after the spontaneous genesis of dark matter, which accommodates a TeV scale asymmetric dark matter model. (orig.)

145

Asymmetric dark matter from spontaneous cogenesis in the supersymmetric standard model

Energy Technology Data Exchange (ETDEWEB)

The observational relation between the density of baryon and dark matter in the Universe, {omega}{sub DM}/{omega}{sub B}{approx_equal}5, is one of the most difficult problems to solve in modern cosmology. We discuss a scenario that explains this relation by combining the asymmetric dark matter scenario and the spontaneous baryogenesis associated with the flat direction in the supersymmetric standard model. A part of baryon asymmetry is transferred to charge asymmetry D that dark matter carries, if a symmetry violating interaction that works at high temperature breaks not only B-L but also D symmetries simultaneously. In this case, the present number density of baryon and dark matter can be same order if the symmetric part of dark matter annihilates sufficiently. Moreover, the baryon number density can be enhanced as compared to that of dark matter if another B-L violating interaction is still in thermal equilibrium after the spontaneous genesis of dark matter, which accommodates a TeV scale asymmetric dark matter model. (orig.)

Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Yamaguchi, Masahide [Tokyo Institute of Technology (Japan). Dept. of Physics

2012-01-15

146

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

147

Does asymmetric dark matter always lead to an anti-neutrino signal?

Under rather generic assumptions, we show that in the asymmetric dark matter (ADM) scenario, the sign of the B-L asymmetry stored in the dark matter sector and the standard model sector are always the same. One particularly striking consequence of this result is that, when the dark matter decays or annihilates in the present universe, the resulting final state always involves an anti-neutrino. As a concrete example of this, we construct a composite ADM model and explore the feasibility of detecting such an anti-neutrino signal in atmospheric neutrino detectors.

Fukuda, Hajime; Mukhopadhyay, Satyanarayan

2014-01-01

148

Light Front Theory Of Nuclear Matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

149

Collective modes in strange and isospin asymmetric hadronic matter

We study the propagation of non-strange and strange meson modes in hadronic matter considering isospin and/or strangeness mixing induced by quantum fluctuations in the medium. Baryons are described using the Quark Meson Coupling model extended to include couplings with strange quarks. In particular we evaluate the dependence of the meson masses on the baryonic density, the strangeness fraction and the isospin asymmetry of the medium. We have found a considerable admixture of strangeness and isospin in the sigma mode at the high density regime.

Aguirre, R M

2004-01-01

150

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 is ruled out for symmetric dark matter, while large portions of para...

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

2014-01-01

151

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

152

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)

153

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 transition and show that at the given quark density, the Hawking-Page transition temperature decreases due to the symmetry energy.

Park, Chanyong

2011-01-01

154

Nuclear Pasta Matter for Different Proton Fractions

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Schuetrumpf, B.; Iida, K.; Maruhn, J. A.; Reinhard, P. -g

2014-01-01

155

Asymmetrical sabotage tactics, nuclear facilities/materials, and vulnerability analysis

International Nuclear Information System (INIS)

Full text: The emerging paradigm of a global community wherein post-modern political violence is a fact of life that must be dealt with by safety and security planners is discussed. This paradigm shift in the philosophy of terrorism is documented by analysis of the emerging pattern of asymmetrical tactics being employed by terrorists. Such philosophical developments in violent political movements suggest a shift in the risks that security and safety personnel must account for in their planning for physical protection of fixed site nuclear source facilities like power generation stations and the eventual storage and transportation of the by-products of these facilities like spent nuclear fuel and other high level wastes. This paper presents a framework for identifying these new political realities and related threat profiles, suggests ways in which security planners and administrators can design physical protection practices to meet these emerging threats, and argues for global adoption of standards for the protection of nuclear facilities that could be used as a source site from which terrorists could inflict a mass contamination event and for standards related to the protection of the waste materials that can be used in the production of radiological weapons of mass victimization. (author)

156

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

157

Asymmetric Inelastic Inert Doublet Dark Matter from Triplet Scalar Leptogenesis

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 ...

Arina, Chiara

2011-01-01

158

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

159

Interaction of nuclear radiation with matter

International Nuclear Information System (INIS)

This chapter of a textbook presents an overview of an important aspect of nuclear physics and nuclear chemistry. The effects of the interaction of nuclear radiation with substances are classified according to the acting particle, and the reacting constituents of the substance. The interactions of alpha radiation with matter (slowing down, scattering), of electron radiation with matter (slowing down, Cherenkov radiation, backscattering, absorption, annihilation), and of gamma radiation with matter (Compton effect, photoelectric effect, pair formation, absorption) are discussed. The reacting constituents are categorized as shell electrons, atomic nuclei, the Coulomb field of nuclei. In the complex interactions, the Auger effect and the photoelectron-induced bremsstrahlung is discussed. (R.P.)

160

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.)

161

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

162

Nuclear matter at a HIRFL-CSR energy regime

We report some recent progress in constraining the symmetry energy Esym(?) at high densities using high-energy heavy-ion collisions. Circumstantial evidence of a soft Esym(?) at supra-saturation density is obtained by comparing the pion ratio ?-/?+ measured recently with FOPI at GSI and the IBUU04 model calculations. Detailed studies indicate that the power of determining the Esym(?) from ?-/?+ is enhanced with decreasing the beam energy to near the pion production threshold, showing a correlation to the increasing nuclear stopping. Among several heavy-ion reaction facilities in the world, the cooling storage ring (HIRFL-CSR), newly commissioned at Lanzhou, delivering heavy-ion beams up to 1 A GeV, to be coupled with advanced detectors will contribute significantly to further studies of the equation of state of asymmetric nuclear matter.

Xiao, Zhigang; Chen, Lie-Wen; Fu, Fen; Li, Bao-An; Jin, Genming; Xu, Hushan; Yong, Gaochan; Zhang, Ming

2009-06-01

163

Asymmetric horseshoe kidney in the infant: value of renal nuclear scanning

International Nuclear Information System (INIS)

Five infants with an abdominal mass were found to have asymmetric horseshoe kidney. In all five, ultrasound and excretory urography were inconclusive; only after renal nuclear imaging was the diagnosis confirmed and planned surgery cancelled

164

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

165

Coupled Cluster studies of infinite nuclear matter

The aim of this work is to develop the relevant formalism for performing Coupled Cluster calculations in nuclear matter and neutron star matter, including thereby important correlations to infinite order in the interaction and testing modern nuclear forces based on chiral effective field theory. Our formalism includes the exact treatment of the so-called Pauli operator in a partial wave expansion of the equation of state. Nuclear and neutron matter calculations are done using a coupled particle-particle and hole-hole ladder approximation. The coupled ladder equations are derived as an approximation of CC theory, leaving out particle-hole and non-linear diagrams from the CC doubles amplitude equation. This study is a first step toward CC calculations for nuclear and neutron matter. We present results for both symmetric nuclear matter and pure neutron matter employing state-of-the-art nucleon-nucleon interactions based on chiral effective field theory. We employ also the newly optimized chiral interaction [A. E...

Baardsen, G; Hagen, G; Hjorth-Jensen, M

2013-01-01

166

Nuclear matter in neutron star crust

Energy Technology Data Exchange (ETDEWEB)

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 a{sub sym}({rho}) is not a linear function of density at low density region. (author)

Kido, Toshihiko; Maruyama, Toshiki; Chiba, Satoshi [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan); Niita, Koji [Research Organization for Information Science and Technology, Tokai, Ibaraki (Japan)

2000-01-01

167

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

168

Relativity damps OPEP in nuclear matter

International Nuclear Information System (INIS)

Using a relativistic Dirac-Brueckner analysis the OPEP contribution to the ground state energy of nuclear matter is studied. In the study the pion is derivative-coupled. The author finds that the role of the tensor force in the saturation mechanism is substantially reduced compared to its dominant role in a usual nonrelativistic treatment. He shows that the damping of derivative-coupled OPEP is actually due to the decrease of M*/M with increasing density. He points out that if derivative-coupled OPEP is the preferred form of nuclear effective lagrangian nonrelativistic treatment of nuclear matter is in trouble. Lacking the notion of M* it cannot replicate the damping. He suggests an examination of the feasibility of using pseudoscalar coupled ?N interaction before reaching a final conclusion about nonrelativistic treatment of nuclear matter

169

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

170

A 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 $6\\sigma$ 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.

Vincent, Aaron C; Serenelli, Aldo

2014-01-01

171

Spin- and isospin-polarized states of nuclear matter in the Dirac-Brueckner-Hartree-Fock model

Spin-polarized isospin asymmetric nuclear matter is studied within the Dirac-Brueckner-Hartree-Fock approach. After a brief review of the formalism, we present and discuss the self-consistent single-particle potentials at various levels of spin and isospin asymmetry. We then move to predictions of the energy per particle, also under different conditions of isospin and spin polarization. Comparison with the energy per particle in isospin symmetric or asymmetric unpolarized nuclear matter shows no evidence for a phase transition to a spin ordered state, neither ferromagnetic nor antiferromagnetic.

Sammarruca, Francesca

2011-01-01

172

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 in the type of pasta shape that is built. The study is performed in two dynamical ranges, once for hot matter and once at temperature zero, to investigate the effect of cooling.

Schuetrumpf, B.; Iida, K.; Maruhn, J. A.; Reinhard, P.-G.

2014-11-01

173

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

174

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

International Nuclear Information System (INIS)

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 of 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. (author)

175

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

176

Phase transitions in high density nuclear matter

International Nuclear Information System (INIS)

A method for the description of spin-isospin phase transitions in nuclear matter is developed. It allows a complete description of the pion condensation phase transition in the framework of the Landau-Migdal Fermi liquid theory. The equation of the order parameters is derived and the condensation energy is calculated. We study the influence of pion condensation on the nuclear equation of state and the temperature dependence of pion condensation. Finally the phase transition from nucleon to quark matter is investigated. The relevance of the color degree of freedom is discussed. (orig.)

177

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

178

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.

179

Femtotechnology: Nuclear Matter with Fantastic Properties

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: At present the term 'nanotechnology' is well known-in its' ideal form, the flawless and completely controlled design of conventional molecular matter from molecules or atoms. Such a power over nature would offer routine achievement of remarkable properties in conventional matter and creation of metamaterials where the structure not the composition brings forth new powers of matter. But even this yet unachieved goal is not the end of material science possibilities. The author herein offers the idea of design of new forms of nuclear matter from nucleons (neutrons, protons, electrons and other nuclear particles. Approach: The researcher researches the nuclear forces. He shows these force may be used for design the new nuclear matter from protons, neutrons, electrons and other nuclear particles. Results: Author shows this new 'AB-Matter' has extraordinary properties (for example, tensile strength, stiffness, hardness, critical temperature, superconductivity, supertransparency and zero friction., which are up to millions of times better than corresponding properties of conventional molecular matter. He shows concepts of design for aircraft, ships, transportation, thermonuclear reactors, constructions and so on from nuclear matter. These vehicles will have unbelievable possibilities (e.g., invisibility, ghost-like penetration through any walls and armor, protection from nuclear bomb explosions and any radiation flux. Conclusion: People may think this fantasy. But fifteen years ago most people and many scientists thought-nanotechnology is fantasy. Now many groups and industrial labs, even startups, spend hundreds of millions of dollars for development of nanotechnological-range products (precise chemistry, patterned atoms, catalysts and meta-materials and we have nanotubes (a new material which does not exist in Nature! and other achievements beginning to come out of the pipeline in prospect. Nanotubes are stronger than steel by a hundred times-surely an amazement to a 19th Century observer if he could behold them. Nanotechnology, in near term prospect, operates with objects (molecules and atoms having the size in nanometer (10-9 m. The researcher here outlines perhaps more distant operations with objects (nuclei having size in the femtometer range, (10-15m, millions of times less smaller than the nanometer scale. The name of this new technology is femtotechnology.

A. A. Bolonkin

2009-01-01

180

We calculate asymmetric neutrino absorption and scattering cross sections on hot and dense magnetized neutron-star matter including hyperons in fully relativistic mean field theory. The absorption/scattering cross sections are suppressed/enhanced incoherently in the direction of the magnetic fielld, B. The asymmetry is 2-4% at the matter density \\rho_0 < \\rho_B < 3\\rho_0 and temperature T < 40 MeV for B=2 X 10^{17} G. This asymmetry is comparable to the effects owing to parity violation or asymmetric magnetic field topology proposed for the origin of pulsar kicks.

Maruyama, Tomoyuki; Yasutake, Nobutoshi; Cheoun, Myung-Ki; Ryu, Chung-Yeol

2010-01-01

181

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

182

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

183

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

184

Anharmonicity of the nuclear matter ground state

International Nuclear Information System (INIS)

The correlation between the compression modulus and the skewness coefficient of the nuclear matter ground state implied by the breathing mode data is compared with predictions of the relativistic Hartree approximation (RHA). Retaining explicit dependence on the renormalization scale, ?, employed in the RHA, this correlation, together with other considerations, suggests a value for ?/M?1.2. (orig.)

185

New type of Pairing interactions in nuclear matter and finite nuclei

Energy Technology Data Exchange (ETDEWEB)

We propose new types of density dependent contact pairing interaction which reproduce pairing gaps in a wide range of nuclear mass table. We discuss also the relation between the proposed paring interactions and the pairing gaps in symmetric and neutron matters obtained by a microscopic treatment based on a bare nucleon-nucleon interaction. It is shown that the isovector type pairing interaction is necessary on top of the isoscalar term to reproduce systematically nuclear empirical pairing gaps. The BCS-BEC crossover of neutrons pairs in symmetric and asymmetric nuclear matters is studied by using these contact interactions. It is shown that the bare and screened pairing interactions lead to different features of the BCS-BEC crossover in symmetric nuclear matter.

Sagawa, H [Center for Mathematics and Physics, University of Aizu, Aizu-Wakamatsu, 965-8580 Fukushima (Japan); Margueron, J [Institut de Physique Nucleaire, Universite Paris-Sud, IN2P3-CNRS, F-91406 Orsay Cedex (France); Hagino, K, E-mail: sagawa@u-aizu.ac.jp [Department of Physics, Tohoku University, Sendai, 980-8578 (Japan)

2011-09-16

186

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

187

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.

188

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

189

NUCLEAR PHYSICS: Nucleon 3PF2 Superfluid Pairing Gap in Asymmetry Nuclear Matter

The 3PF2 superfluidity of neutron and proton is investigated in isospin-asymmetric nuclear matter within the Brueckner-Hartree-Fock approach and the BCS theory by adopting the Argonne V14 and the Argonne V18 nucleon-nucleon interactions. We find that pairing gaps in the 3PF2 channel predicted by adopting the AV14 interaction are much larger than those by the AV18 interaction. As the isospin-asymmetry increases, the neutron 3PF2 superfluidity is found to increase rapidly, whereas the proton one turns out to decrease and may even vanish at high enough asymmetries. As a consequence, the neutron 3PF2 superfluidity is much stronger than the proton one at high asymmetries and it predominates over the proton one in dense neutron-rich matter.

Mi, Ai-Jun; Zuo, Wei; Li, Zeng-Hua; Lombardo, Umberto

2009-06-01

190

Hadronic matter exploration with nuclear reactions

International Nuclear Information System (INIS)

Properties of hadronic matter produced in the region far away from the standard nuclear matter density by the high energy nuclear reactions are reviewed. At first an overview of the phase diagram of the hadronic matter is introduced. In the low temperature and low density nuclear matter, the first order gas-liquid phase transition is observed in the calorimetric curve of heavy ion collisions. When the baryon density is increased keeping the temperature low, as in the neutron stars, the Fermi energy and nucleon interaction increase to result in creation of various hadrons. Among them, particles containing strangeness quark play important roles. The equation of state greatly depends on the hyperon potential at various densities. Lagrangean is formulated based on the relativistic mean field theory considering the flavor SU(3) symmetry. Recent experimental studies to measure hyperon potential in nuclear matter and hypernuclear physics are described taking the KEK experiment of (?-, K+) reaction as an example. In high temperature and/or high density matter, the greatest objective at present is to observe the quark gluon plasma (QGP) in which state quarks and gluons are released from confinement. Recent progress of theoretical predictions of the QGP phase is described. Two QGP signals observed at RHIC experiments are taken up. The first one is the jet quenching in the high momentum region which is the disappearance of the parton jet because of the parance of the parton jet because of the parton energy loss in QGP that could be observed otherwise. The second one is the collective flow in the low momentum region. The large collective flow estimated from the experiment cannot be reproduced by the hadron model without secondary scattering by QGP. Finally the intermediate momentum region is discussed and 'recombination and fragmentation' model is presented. (S. Funahashi)

191

Digging deeper in nuclear matter

International Nuclear Information System (INIS)

This trend article presents a survey of the nuclear research programs of the secton NIKHEF-K with the 500 MeV electron-accelerator MEA in Amsterdam. After an introductory review of the principles of studying nuclei with electron-scattering experiments, some characteristic examples are discussed of inclusive (e,e')-experiments, in which only the scattered electron is detected, and exclusive (e,e'X)-experiments, in which the electron as well as the reaction product X are measured in coincidence. Finally an experiment with the 13C(?,?-minus)13N is discussed which includes the study of pion-degrees of freedom in the nucleus. (H.W.). 7 figs

192

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

193

Hot nuclear matter in asymmetry chiral sigma model

International Nuclear Information System (INIS)

In the frame work SU(2) chiral sigma (CS) model, the nuclear matter properties at zero and finite temperature has been investigated, in the mean field approach, up to three times normal nuclear matter density

194

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

195

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

196

Consequences of DM/antiDM oscillations for asymmetric WIMP dark matter

International Nuclear Information System (INIS)

Assuming the existence of a primordial asymmetry in the dark sector, a scenario usually dubbed Asymmetric Dark Matter (aDM), we study the effect of oscillations between dark matter and its antiparticle on the re-equilibration of the initial asymmetry before freeze-out, which enable efficient annihilations to recouple. We calculate the evolution of the DM relic abundance and show how oscillations re-open the parameter space of aDM models, in particular in the direction of allowing large (WIMP-scale) DM masses. A typical WIMP with a mass at the EW scale ( ? 100 GeV – 1 TeV) presenting a primordial asymmetry of the same order as the baryon asymmetry naturally gets the correct relic abundance if the DM-number-violating ?(DM) = 2 mass term is in the ? meV range. The re-establishment of annihilations implies that constraints from the accumulation of aDM in astrophysical bodies are evaded. On the other hand, the ordinary bounds from BBN, CMB and indirect detection signals on annihilating DM have to be considered

197

The alpha-particle in nuclear matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

Among the light nuclear clusters the alpha-particle is by far the strongest bound system and therefore expected to play a significant role in the dynamics of nuclei and the phases of nuclear matter. To systematically study the properties of the alpha-particle we have derived an effective four-body equation of the Alt-Grassberger-Sandhas (AGS) type that includes the dominant medium effects, i.e. self energy corrections and Pauli-blocking in a consistent way. The equation is s...

Beyer, M.; Sofianos, S. A.; Kuhrts, C.; Roepke, G.; Schuck, P.

2000-01-01

198

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.)

199

Chiral effective field theory for nuclear matter

International Nuclear Information System (INIS)

Recently a novel chiral power counting for nuclear matter with nucleons and pions as degrees of freedom has been developed. It allows for a systematic expansion taking into account both local and pion-mediated inter-nucleon interactions. It also identifies some non-perturbative strings of diagrams, related to iterated nucleon-nucleon interactions, which have to be re-summed. Unitary chiral perturbation theory has been proven to be a useful tool for taking into account the non-perturbative nature of the nucleon-nucleon interaction. In my talk I review the most recent progress employing both techniques and present results of the calculations for the ground state energy density of nuclear matter and the in-medium chiral quark condensate.

200

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)

201

Nuclear matter with off-shell propagation

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

202

Nuclear law: nuclear matter and ionizing radiation sources. Wastes

International Nuclear Information System (INIS)

The object of this work is since its first edition in 1983 under the title 'Collection of nuclear activities legislation and regulation ' to realize an ordered collection of texts constituting the juridical and institutional frame of nuclear activities, gathering the legislative, regulatory and technical texts; the international, European and national texts. Aiming to include the whole of the atom applications, this collection tackles various themes, in ten chapters.The volume number two includes the following chapters: nuclear matters and ionizing radiations sources; wastes. Previously edited by the Cea, that realizes it it is now published in the collection 'Legislation and regulation' of officials journals editions. (N.C.)

203

Anatomy of symmetry energy of dilute nuclear matter

The symmetry energy coefficients of dilute clusterized nuclear matter are evaluated in the $S$-matrix framework. Employing a few different definitions commonly used in the literature for uniform nuclear matter, it is seen that the different definitions lead to perceptibly different results for the symmetry coefficients for dilute nuclear matter. They are found to be higher compared to those obtained for uniform matter in the low density domain. The calculated results are in reasonable consonance with those extracted recently from experimental data.

De, J N; Agrawal, B K

2010-01-01

204

Nuclear dynamics of mass asymmetric systems at balance energy

International Nuclear Information System (INIS)

In the search of nuclear equation of state as well as of nuclear interactions and forces, collective transverse flow has been found to be of immense importance. At low incident energies, the collective transverse flow is dominated by attractive interactions and the flow is expected to be negative, while at high incident energies, the flow is dominated by nucleon-nucleon repulsive interactions and is expected to be positive. While going from low to high incident energies, collective transverse flow vanishes at a particular value of energy, which is termed as Balance Energy (Ebal). The Ebal has been reported to be of significance toward the understanding of nuclear interactions and related dynamics

205

Nuclear dynamics of mass asymmetric systems at balance energy

International Nuclear Information System (INIS)

In search of nuclear equation of state as well as of nuclear interactions and forces, collective transverse flow has been found to be of immense importance. At low incident energies, the collective transverse flow is dominated by attractive interactions and the flow is expected to be negative, while at high incident energies, the flow is dominated by nucleon-nucleon repulsive interactions and is expected to be positive. A complete systematic analysis of the nuclear dynamics at the Ebal for nearly symmetric reactions is reported in the literature, but no attempt has been made to see the effect of mass asymmetry on the nuclear dynamics at balance energy. The aim is to address this question in the present study using Quantum Molecular Dynamics (QMD) model

206

Dark Matter Particle Spectroscopy at the LHC: Generalizing MT2 to Asymmetric Event Topologies

International Nuclear Information System (INIS)

We consider SUSY-like missing energy events at hadron colliders and critically examine the common assumption that the missing energy is the result of two identical missing particles. In order to experimentally test this hypothesis, we generalize the subsystem MT2 variable to the case of asymmetric event topologies, where the two SUSY decay chains terminate in different 'children' particles. In this more general approach, the endpoint MT2(max) of the MT2 distribution now gives the mass (tilde M)p((tilde M)c(a), (tilde M)c(b)) of the parent particles as a function of two input children masses (tilde M)c(a) and (tilde M)c(b). We propose two methods for an independent determination of the individual children masses Mc(a) and Mc(b). First, in the presence of upstream transverse momentum PUTM the corresponding function (tilde M)p((tilde M)c(a), (tilde M)c(b), PUTM) is independent of PUTM at precisely the right values of the children masses. Second, the previously discussed MT2 'kink' is now generalized to a 'ridge' on the 2-dimensional surface (tilde M)p((tilde M)c(a), (tilde M)c(b)). As we show in several examples, quite often there is a special point along that ridge which marks the true values of the children masses. Our results allow collider experiments to probe a multi-component dark matter sector directly and without any theoretical prejudice.

207

International Nuclear Information System (INIS)

A full (3+1)-dimensional calculation using Lagrangian hydrodynamics is proposed for relativistic nuclear collisions. This calculation enables us to evaluate the anisotropic flow of the hadronic matter which appears in non-central and/or asymmetrical relativistic nuclear collisions. Applying hydrodynamical calculations to the deformed uranium collisions in the AGS energy region, we discuss the nature of the space-time structure and particle distributions in detail. (orig.)

208

Neutrino neutral current interactions in nuclear matter

International Nuclear Information System (INIS)

Detailed knowledge of neutrino transport properties in matter is crucial for an understanding of the evolution of supernovae and of neutron star cooling. We investigate screening of neutrino scattering from a dense degenerate gas of electrons, protons and neutrons. We take into account correlations induced by the Coulomb interactions of the electrons and protons, and the strong interactions of the protons and neutrons. Nuclear matter is described by the ?? model of quantum hadrodynamics. Results are presented for typical astrophysical scenarios. The differential cross section is strongly reduced at large energy transfer, where electrons dominate, and slightly reduced for small energy transfer, where nucleons dominate. At large densities, the nucleon effective mass is considerably lower than the free mass, and the region dominated by nucleons extends to larger energy transfer than for free nucleons. (orig.)

209

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

210

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

211

Is nuclear matter a quantum crystal?

A possible alternative to the ordinary gas-like computation for nuclear matter is investigated under the assumption that the nucleons are arranged in a lattice. BCC, FCC and HCP structures are investigated. Only HCP shows a minimum in the energy vs. density curve with a modest binding energy of -1.5 MeV. The very low density limit is investigated and sensible results are obtained only if the tensor force decreases with the density. A study of the elastic properties indicates that the previous structures are mechanically unstable against shearing stresses.

Canuto, V.; Chitre, S. M.

1973-01-01

212

Chiral symmetry, strangeness and nuclear matter

International Nuclear Information System (INIS)

In this talk we review the important role played by chiral SU(3) symmetry in hadron physics. Exciting new results on the formation of baryon resonances as implied by chiral coupled-channel dynamics are presented and discussed. The results are the consequence of progress made in formulating a consistent effective field theory for the meson-baryon scattering processes in the resonance region. Strangeness channels are found to play a decisive role in the formation of resonances. As a further application of chiral coupled-channel dynamics the properties of antikaons and hyperon resonances in cold nuclear matter are reviewed. (orig.)

213

Nuclear interaction rates for dark matter detectors

International Nuclear Information System (INIS)

I describe nuclear shell model calculations of the spin-dependent elastic cross sections of supersymmetric particles on the nuclei 73Ge and 29Si, which are being used in the construction of dark matter detectors. To check the accuracy of the wave functions I have calculated excited state energy spectra, magnetic moments, and spectroscopic factors for each of the nuclei. Our results differ significantly from previous estimates based upon the independent single particle shell model and the odd group model. I at% discuss the modifications that occur when finite momentum transfer between the neutralino and nucleus is included

214

History of the nuclear matter safety and control law

International Nuclear Information System (INIS)

In this text we give the history of the law creation on the control and safety of nuclear matter. Initially based on the CEA regulation single owner of nuclear matter, the development of nuclear energy has conducted the French government to edict law in relation with IAEA and Euratom recommendations

215

Variations on a theme of nuclear matter

International Nuclear Information System (INIS)

The authors review new techniques developed to apply the variational method to the nuclear matter problem. The variational wave function is taken to be (SPi/sub i/< jF/sub i/j) Phi; the correlation operators F/sub i/j can in principle induce central, backflow, spin isospin, tensor, etc. correlations, and Phi is the ideal Fermi gas wave function. The application of diagrammatic cluster expansion and chain summation techniques to calculate expectation values with such wave functions is discussed in detail. The authors also give a brief overview of various other approaches to the calculation of the binding energies of quantum fluids, and a comparison of results for simple systems such ad helium liquids. Results obtained by various methods for simplified models of nuclear matter, which include central, spin, isospin, and tensor forces, have converged significantly in recent months. Results obtained with more realistic models which include the spin--orbit potentials are also discussed. The potential models considered so far either give too little binding or too high equilibrium density

216

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

217

The $\\eta$ decay into 3$\\pi$ in asymmetric nuclear medium

We explore how the $\\eta$-$\\pi^0$ mixing angle and the $\\eta$ meson decay into $\\pi^{+}\\pi^{-}\\pi^0$ and 3$\\pi^{0}$ are modified in the nuclear medium on the basis of the in-medium chiral effective theory with the isospin asymmetry $\\alpha$ varied, where $\\alpha\\equiv \\delta\\rho/\\rho$ with $\\delta \\rho=\\rho_n-\\rho_p$ and $\\rho=\\rho_n+\\rho_p$. We find that the larger the isospin asymmetry $\\delta \\rho$ and smaller the total density $\\rho$, the more enhanced the mixing angle. We show that the decay width in the nuclear medium has an additional density dependence which cannot be renormalized into that of the mixing angle: The additional term originates from the vertex proportional to a low energy constant $c_1$, which only comes into play in the nuclear medium but not in the free space. It turns out that the resultant density effect on the decay widths overwhelms that coming from the isospin asymmetry, and the higher the $\\rho$, the more enhanced the decay widths; the width for the $\\pi^{+}\\pi^{-}\\pi^0$ decay is...

Sakai, Shuntaro

2014-01-01

218

Constraints on the skewness coefficient of symmetric nuclear matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

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, ...

Cai, Bao-jun; Chen, Lie-wen

2014-01-01

219

Dark Matter Particle Spectroscopy at the LHC: Generalizing M(T2) to Asymmetric Event Topologies

Energy Technology Data Exchange (ETDEWEB)

We consider SUSY-like missing energy events at hadron colliders and critically examine the common assumption that the missing energy is the result of two identical missing particles. In order to experimentally test this hypothesis, we generalize the subsystem M{sub T2} variable to the case of asymmetric event topologies, where the two SUSY decay chains terminate in different 'children' particles. In this more general approach, the endpoint M{sub T2(max)} of the M{sub T2} distribution now gives the mass {tilde M}p({tilde M}{sub c}{sup (a)}, {tilde M}{sub c}{sup (b)}) of the parent particles as a function of two input children masses {tilde M}{sub c}{sup (a)} and {tilde M}{sub c}{sup (b)}. We propose two methods for an independent determination of the individual children masses M{sub c}{sup (a)} and M{sub c}{sup (b)}. First, in the presence of upstream transverse momentum PUTM the corresponding function {tilde M}p({tilde M}{sub c}{sup (a)}, {tilde M}{sub c}{sup (b)}, P{sub UTM}) is independent of P{sub UTM} at precisely the right values of the children masses. Second, the previously discussed MT2 'kink' is now generalized to a 'ridge' on the 2-dimensional surface {tilde M}p({tilde M}{sub c}{sup (a)}, {tilde M}{sub c}{sup (b)}). As we show in several examples, quite often there is a special point along that ridge which marks the true values of the children masses. Our results allow collider experiments to probe a multi-component dark matter sector directly and without any theoretical prejudice.

Konar, Partha; /Florida U.; Kong, Kyoungchul; /SLAC; Matchev, Konstantin T.; Park, Myeonghun; /Florida U.

2012-04-03

220

Chiral Fermi liquid description of nuclear matter

Energy Technology Data Exchange (ETDEWEB)

We employ Landau's theory of normal Fermi liquids to study the bulk properties of nuclear matter with high-precision two- and three-nucleon interactions derived within the framework of chiral effective field theory. The L=0,1 Landau parameters, characterizing the isotropic and p-wave interaction between two quasiparticles on the Fermi surface, are computed to second order in many-body perturbation theory (MBPT) with chiral and low-momentum two-nucleon forces. Already at this order a number of observables are well described in the theory, including the nuclear isospin asymmetry energy, the quasiparticle effective mass and the spin-isospin response. An adequate description of the nuclear compression modulus (encoded in the Landau parameter F{sub 0}) requires the inclusion of the leading-order (N{sup 2}LO) chiral three-nucleon force, which we include to first order in MBPT. The remaining L=0 Landau parameters receive only small corrections from the chiral three-nucleon force, and the L=1 parameters are all reduced, resulting in an effective interaction of apparent short range. We then employ renormalization group techniques to study the scale dependence of the quasiparticle interaction, which allows for an estimation of theoretical uncertainties.

Holt, Jeremy; Kaiser, Norbert; Weise, Wolfram [Technische Universitaet Muenchen (Germany)

2012-07-01

221

Chiral Fermi liquid description of nuclear matter

International Nuclear Information System (INIS)

We employ Landau's theory of normal Fermi liquids to study the bulk properties of nuclear matter with high-precision two- and three-nucleon interactions derived within the framework of chiral effective field theory. The L=0,1 Landau parameters, characterizing the isotropic and p-wave interaction between two quasiparticles on the Fermi surface, are computed to second order in many-body perturbation theory (MBPT) with chiral and low-momentum two-nucleon forces. Already at this order a number of observables are well described in the theory, including the nuclear isospin asymmetry energy, the quasiparticle effective mass and the spin-isospin response. An adequate description of the nuclear compression modulus (encoded in the Landau parameter F0) requires the inclusion of the leading-order (N2LO) chiral three-nucleon force, which we include to first order in MBPT. The remaining L=0 Landau parameters receive only small corrections from the chiral three-nucleon force, and the L=1 parameters are all reduced, resulting in an effective interaction of apparent short range. We then employ renormalization group techniques to study the scale dependence of the quasiparticle interaction, which allows for an estimation of theoretical uncertainties.

222

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

223

Hirschegg '95: Dynamical properties of hadrons in nuclear matter. Proceedings

International Nuclear Information System (INIS)

The following topics were dealt with: Chiral symmetry, chiral condensates, in-medium effective chiral Lagrangians, ?'s in nuclei, nonperturbative QCD, electron scattering from nuclear matter, nuclear shadowing, QCD sum rules, deconfinement, ultrarelativistic heavy ion collisions, nuclear dimuon and electron pair production, photoproduction from nuclei, subthreshold K+ production, kaon polarization in nuclear matter, charged pion production in relativistic heavy ion collisions, the Nambu-Jona-Lasinio model, the SU(3)LxSU(3)R sigma model, nonequilibrium dense nuclear matter, pion pair production at finite temperature. (HSI)

224

Relativistic calculation of polarized nuclear matter

International Nuclear Information System (INIS)

The binding energy of nuclear matter with excess of neutrons, of spin-up neutrons, and spin-up protons (characterized by the corresponding parameters, ?sub(tau) = (N - Z)/A, ?sub(N) = (N - N )/A, and ?sub(p) = (Z - Z)/A)), contains three symmetry energies: the isospin symmetry energy epsilon sub(?), the spin symmetry energy epsilon sub(?), and the spin-isospin symmetry energy epsilon sub(?tau). The relativistic corrections to epsilon sub(tau), epsilon sub(?) and epsilon sub(?tau) are found to be -2.06, -2.6 and -0.89 MeV respectively. The relativistic correction to the compression modulus is -10.8 MeV. (author)

225

Attenuation of ? mesons in cold nuclear matter

International Nuclear Information System (INIS)

The attenuation of ? mesons in cold nuclear matter has been investigated via the time-dependent multiple-scattering Monte Carlo multicollisional (MCMC) intranuclear cascade model. The inelastic ? width deduced from CBELSA/TAPS Collaboration data of meson transparency in complex nuclei (?*?30 MeV/c2) is approximately 5 times lower than the value obtained with recent theoretical models and consistent with an in-medium total ?N cross section within 25-30 mb for an average meson momentum of 1.1 GeV/c . The momentum-dependent transparency ratios suggest an elastic/total cross-section ratio around 40%. For the case of CLAS Collaboration data a much higher width is deduced (?* > or approx. 120 MeV/c2), with the MCMC model providing a consistent interpretation of the data, assuming a much higher meson absorption (??N* > or approx. 100 mb) for p??1.7 GeV/c.

226

Bulk Properties of Symmetric Nuclear and Pure Neutron Matter

Directory of Open Access Journals (Sweden)

Full Text Available We study the equation of state (EOS of symmetric nuclear and neutron matter within the framework of the Brueckner-Hartree-Fock (BHF approach which is extended by including a density-dependent contact interaction to achieve the empirical saturation property of symmetric nuclear matter. This method is shown to affect significantly the nuclear matter EOS and the density dependence of nuclear symmetry energy at high densities above the normal nuclear matter density, and it is necessary for reproducing the empirical saturation property of symmetric nuclear matter in a nonrelativistic microscopic framework. Realistic nucleon-nucleon interactions which reproduce the nucleon-nucleon phase shifts are used in the present calculations.

Khaled Hassaneen

2013-05-01

227

International Nuclear Information System (INIS)

Properties of nuclear matter and neutron stars and their density-dependent correlations are discussed in a nonlinear ?-?-? mean-field approximation with self-interactions and mixed-interactions of mesons. The nonlinear interactions are renormalized as effective masses (MN*, m?*, m?*, m?*) and effective coupling constants (g?*, g?*, g?*) required by the theory of conserving approximations, which generates a thermodynamically consistent approximation essential to examine density-dependent correlations. The nonlinear ?-?-? mean-field approximation becomes equivalent to Hartree approximation with effective masses and effective coupling constants, and self-consistent structure is clarified. The current nonlinear mean-field approximation is applied to neutron-rich nuclear matter which is defined as isospin asymmetric and beta-equilibrium nuclear matter. The density-dependent correlations between properties of isospin symmetric and asymmetric nuclear matter, the saturation of symmetry energy in high densities are discussed in terms of density-dependent, effective masses and effective coupling constants induced by nonlinear interactions. The accumulating data and accurate measurements of effective masses and effective coupling constants, observables in high energy density will supply significant information in order to understand and testify theoretical consistency of nuclear modelsstency of nuclear models

228

Strangeness and charm in nuclear matter

International Nuclear Information System (INIS)

The properties of strange (K, KŻ and KŻ?) and open-charm (D, DŻ 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, KŻ and KŻ? 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+K??A? reaction, which we propose as a tool to detect in-medium modifications of the KŻ? 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+ and 3/2+ 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

229

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

230

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

231

Probing isospin- and momentum-dependent nuclear effective interactions in neutron-rich matter

International Nuclear Information System (INIS)

The single-particle potential for nucleons and hyperons in neutron-rich matter generally depends on the density and isospin asymmetry of the medium as well as the momentum and isospin of the particle. It further depends on the temperature of the matter if the latter is in thermal equilibrium. We review here the extension of a Gogny-type isospin- and momentum-dependent interactions in several aspects made in recent years and their applications in studying intermediate-energy heavy-ion collisions, thermal properties of asymmetric nuclear matter and properties of neutron stars. The importance of the isospin and momentum dependence of the single-particle potential, especially the momentum dependence of the isovector potential, is clearly revealed throughout these studies. (orig.)

232

Probing isospin- and momentum-dependent nuclear effective interactions in neutron-rich matter

The single-particle potentials for nucleons and hyperons in neutron-rich matter generally depends on the density and isospin asymmetry of the medium as well as the momentum and isospin of the particle. It further depends on the temperature of the matter if the latter is in thermal equilibrium. We review here the extension of a Gogny-type isospin- and momentum-dependent interaction in several aspects made in recent years and their applications in studying intermediate-energy heavy ion collisions, thermal properties of asymmetric nuclear matter and properties of neutron stars. The importance of the isospin- and momentum-dependence of the single-particle potential, especially the momentum dependence of the isovector potential, is clearly revealed throughout these studies.

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

2013-01-01

233

On the thermal properties of polarized nuclear matter

International Nuclear Information System (INIS)

The thermal properties of polarized nuclear matter are calculated using Skyrme III interaction modified by Dabrowski for polarized nuclear matter. The temperature dependence of the volume, isospin, spin and spin isospin pressure and energies are determined. The temperature, isospin, spin and spin isospin dependence of the equilibrium Fermi momentum is also discussed. (author)

234

On the thermal properties of polarised nuclear matter

International Nuclear Information System (INIS)

The thermal properties of polarised nuclear matter are calculated using the Skyrme-III interaction as modified by Dabrowski (Nukleonika;21:143 (1977)) for polarised nuclear matter. The temperature dependences of the volume, isospin, spin and spin-isospin pressure and energies are determined. The temperature, isospin, spin and spin-isospin dependences of the equilibrium Fermi momentum are also discussed. (author)

235

Symmetry energy: from nuclear matter to finite nuclei

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 charac...

Kolomietz, V. M.; Sanzhur, A. I.

2014-01-01

236

Nucleons, Nuclear Matter and Quark Matter: A unified NJL approach

Energy Technology Data Exchange (ETDEWEB)

We use an effective quark model to describe both hadronic matter and deconfined quark matter. By calculating the equations of state and the corresponding neutron star properties, we show that the internal properties of the nucleon have important implications for the properties of these systems.

S. Lawley; W. Bentz; A.W. Thomas

2006-02-10

237

Properties of stellar matter in supernova explosions and nuclear multifragmentation

During the collapse of massive stars, and the supernova type-II explosions, stellar matter reaches densities and temperatures which are similar to the ones obtained in intermediate-energy nucleus-nucleus collisions. The nuclear multifragmentation reactions can be used for determination of properties of nuclear matter at subnuclear densities, in the region of the nuclear liquid-gas phase transition. It is demonstrated that the modified properties of hot nuclei (in particular, their symmetry energy) extracted from the multifragmentation data can essentially influence nuclear composition of stellar matter. The effects on weak processes, and on the nucleosynthesis are also discussed.

Botvina, A S; Trautmann, W

2006-01-01

238

K-meson condensation and phase transition from nuclear matter to color-flavor-locked matter

International Nuclear Information System (INIS)

We investigate effects of discontinuous K-meson condensation on the phase transition from nuclear matter to color-flavor-locked quark matter. Two specific scenarios (one is a first-order transition via mixing of opposite-charged phases, whereas the other is a coexisting phase of the nuclear matter with K-meson condensation and the color-flavor-locked matter) are examined. It is found that the presence of electrically neutral color-flavor-locked matter is preceded by the coexisting phase in the sense of the hadron-quark continuity, once K-meson condensation occurs in a neutron star environment

239

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)

240

Strangeness and charm in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The properties of strange (K, K{sup Ż} and K{sup Ż?}) and open-charm (D, D{sup Ż} 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 Ż} and K{sup Ż?} 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 Ż?} 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 Autňnoma de Barcelona, Facultat de Cičncies, 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 Matčria, 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

241

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

242

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.)

243

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

244

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

245

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.)

246

Energy Technology Data Exchange (ETDEWEB)

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 {sigma}-, {omega}- and {rho}-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.)

Typel, S.; Wolter, H.H. [Sektion Physik, Univ. Muenchen, Garching (Germany)

1998-06-01

247

Pion effect of nuclear matter in a chiral sigma model

International Nuclear Information System (INIS)

We develop a new framework for the study of the nuclear matter based on the linear sigma model. We introduce a completely new viewpoint on the treatment of the nuclear matter with the inclusion of the pion. We extend the relativistic chiral mean field model by using the similar method in the tensor optimized shell model. We also regulate the pion-nucleon interaction by considering the form-factor and short range repulsion effects. We obtain the equation of state of nuclear matter and study the importance of the pion effect. (authors)

248

Transverse charge densities in the nucleon in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

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, E-mail: yakhshiev@inha.ac.kr; Kim, Hyun-Chul, E-mail: hchkim@inha.ac.kr

2013-10-07

249

Deuteron-, triton - and alpha - clusters in nuclear matter

International Nuclear Information System (INIS)

It is studied with a simple model how deuteron-, triton- and ?-clusters behave concerning their cluster structure identities during the scatterring process and just after reaching nuclear matter of finite size. (Author)

250

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

251

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)

252

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

253

Many-body theory of nuclear and neutron star matter

Energy Technology Data Exchange (ETDEWEB)

We present results obtained for nuclei, nuclear and neutron star matter, and neutron star structure obtained with the recent Argonne v{sub 18} 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.)

Pandharipande, V.R.; Akmal, A.; Ravenhall, D.G. [Dept. of Physics, Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)

1998-06-01

254

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.)

255

Asymmetric Sneutrino Dark Matter and the $\\Omega_{\\rm{b}}/\\Omega_{\\rm{DM}}$ Puzzle

The inferred values of the cosmological baryon and dark matter densities are strikingly similar, but in most theories of the early universe there is no true explanation of this fact; in particular, the baryon asymmetry and thus density depends upon unknown, and {\\it a priori} small, CP-violating phases which are independent of all parameters determining the dark matter density. We consider models of dark matter possessing a particle-antiparticle asymmetry where this asymmetry determines both the baryon asymmetry and strongly effects the dark matter density, thus naturally linking $\\Omega_{\\rm{b}}$ and $\\Omega_{\\rm{dm}}$. We show that sneutrinos can play the role of such dark matter in a previously studied variant of the MSSM in which the light neutrino masses result from higher-dimensional supersymmetry-breaking terms.

Hooper, D; West, S M; Hooper, Dan; March-Russell, John; West, Stephen M.

2004-01-01

256

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

257

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)=[h2/m KA/2>]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 Ksub(A)sup(S), whereas this is not the case with the constrained model. Some semi-empirical relations between the coefficients of the expansion of Ksub(A)sup(S) 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(nm)=220+-20 MeV, in good agreement with more microscopic analysis

258

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)

259

National control of nuclear matters. Protection against malicious intent

International Nuclear Information System (INIS)

This talk deals with, at first, the regulatory dispositions taken to guarantee the protection and the control of nuclear matters in installations and during transportation, and then with the general principles kept to evaluate the nuclear installations protection against malicious intent. (TEC)

260

Energy Dependence of Direct Detection Cross Section for Asymmetric Mirror Dark Matter

In a recent paper, four of the present authors proposed a class of dark matter models where generalized parity symmetry leads to equality of dark matter abundance with baryon asymmetry of the Universe and predicts dark matter mass to be around 5 GeV. In this note we explore how this model can be tested in direct search experiments. In particular, we point out that if the dark matter happens to be the mirror neutron, the direct detection cross section has the unique feature that it increases at low recoil energy unlike the case of conventional WIMPs. It is also interesting to note that the predicted spin-dependent scattering could make significant contribution to the total direct detection rate, especially for light nucleus. With this scenario, one could explain recent DAMA and CoGeNT results.

An, Haipeng; Mohapatra, Rabindra N; Nussinov, Shmuel; Zhang, Yue

2010-01-01

261

Appearance of the Gyroid Network Phase in Nuclear Pasta Matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. As the most prominent result, we identify for the first time the single gyroid network structure of cubic chiral symmetry, a well known configura...

Schuetrumpf, B.; Klatt, M. A.; Iida, K.; Schroeder-turk, G. E.; Maruhn, J. A.; Mecke, K.; Reinhard, P. -g

2014-01-01

262

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.)

263

The Dirac structure of the interaction in nuclear matter

International Nuclear Information System (INIS)

The G matrix derived from a modern, realistic one-boson-exchange potential is parametrized in the framework of a relativistic meson-exchange model, which also accounts for the degrees of freedom contained in the Dirac-Brueckner-Hartree-Fock approach for nuclear matter. The effects of two-particle correlations on the relativistic potential are shown. Because of its simple form the resulting effective interaction, which reproduces the saturation properties of nuclear matter in the Hartree-Fock approximation, can be easily applied in further studies of the nuclear structure. As first application the momentum-depenence of the relativistic self-energy and the effective mass of the nucleons is studied. This momentum-dependence is proved to be weak. In the framework of quantum hadrodynamics for this the single components of the nucleon self-energy are also for tensor- and pseudovector coupling consistently derived in the Dirac-Hartree-Fock approximation. Relativistic effects however play also a role, if the properties of a resulting nuclear matter is compared with those of two penetrating systems of nuclear matter. The effective interaction of two nucleons in a system of two colliding heavy ions is determined by calculation of the Brueckner G matrix for a realistic nucleon-nucleon interaction under assumption of two mutually penetrating nuclear-matter systems. The analysis of the resulting interaction pursues in the framework of a relativistic mean-field-theory model. The eflativistic mean-field-theory model. The effective coupling constants obtained in this analysis regard both the Fock exchange term and the two-particle correlations. The dependence of this effective coupling constant on the density of the nuclear matter and the relative momentum of the two heavy ions respectively the energy of the heavy ion collision is extensively discussed. (orig.)

264

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.)

265

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

266

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

267

Holographic cold nuclear matter as dilute instanton gas

We study cold nuclear matter based on the holographic gauge theory, where baryons are introduced as the instantons in the probe D8/$\\bar{\\rm D8}$ branes according to the Sakai-Sugimoto model. Within a dilute gas approximation of instantons, we seek for the stable states via the variational method and fix the instanton size. We find the first order phase transition from the vacuum to the nuclear matter phase as we increase the chemical potential. At the critical chemical potential, we could see a jump of the baryon density from zero to a finite definite value. While the size of the baryon in the nuclear matter is rather small compared to the nucleus near the transition point, where the charge density is also small, it increases with the baryon density. Those behaviors obtained here are discussed by relating to the force between baryons.

Ghoroku, Kazuo; Tachibana, Motoi; Taminato, Tomoki; Toyoda, Fumihiko

2012-01-01

268

Dark Matter Particle Spectroscopy at the LHC: Generalizing MT2 to Asymmetric Event Topologies

We consider SUSY-like missing energy events at hadron colliders and critically examine the common assumption that the missing energy is the result of two identical missing particles. In order to experimentally test this hypothesis, we generalize the subsystem MT2 variable to the case of asymmetric event topologies, where the two SUSY decay chains terminate in different "children" particles. In this more general approach, the endpoint MT2max of the MT2 distribution now gives the mass Mp(Mc(a),Mc(b)) of the parent particle as a function of two input children masses Mc(a) and Mc(b). We propose two methods for an independent determination of the individual children masses Mc(a) and Mc(b). First, in the presence of upstream transverse momentum P(UTM) the corresponding function Mp(Mc(a),Mc(b),P(UTM)) is independent of P(UTM) at precisely the right values of the children masses. Second, the previously discussed MT2 "kink" is now generalized to a "ridge" on the 2-dimensional surface Mp(Mc(a),Mc(b)). As we show in sev...

Konar, Partha; Matchev, Konstantin T; Park, Myeonghun

2009-01-01

269

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

270

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

271

Thermal properties of nuclear matter under the periodic boundary condition

Energy Technology Data Exchange (ETDEWEB)

We present the thermal properties of nuclear matter under the periodic boundary condition by the use of our hadronic nucleus-nucleus cascade model (HANDEL) which is developed to treat relativistic heavy-ion collisions from BNL-AGS to CERN-SPS. We first show some results of p-p scattering calculation in our new version which is improved in order to treat isospin ratio and multiplicity more accurately. We then display the results of calculation of nuclear matter with baryon density {rho}{sub b} = 0.77 fm{sup 3} at some energy densities. Time evolution of particle abundance and temperature are shown. (author)

Otuka, Naohiko; Ohnishi, Akira [Division of Physics, Graduate School of Science, Hokkaido Univ., Sapporo, Hokkaido (Japan)

1999-08-01

272

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)

273

Nuclear matter phase diagram from compound nucleus decay

Directory of Open Access Journals (Sweden)

Full Text Available The finite size of nuclei and the Coulomb interaction make it difficult to describe systems interacting through the strong force into thermodynamic terms. Our task is to extract the phase diagram of the theoretical infinite symmetrical uncharged nuclear matter from experiments of nuclear collisions where the systems are neither infinite, symmetrical, nor uncharged. Decay yields from such experiments are translated into coexistence densities and pressures by use of Fisher's droplet model. This method is tested on model systems such as the Ising model and a system of particles interacting via the Lennard-Jones potential. The specific problems inherent to nuclear reactions are considered. These include finite size effects, Coulomb repulsion, and the lack of a physical vapor in contact with a decaying system. Experimental data of compound nucleus experiments are studied within this framework, which is also shown to extend to higher energy reactions. Finally, the phase diagram of nuclear matter is extracted.

Lake P.T.

2012-02-01

274

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

275

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

276

Magnetic structure of isospin-asymmetric QCD matter in neutron stars

We study QCD under the influence of background magnetic fields and isospin chemical potentials using lattice simulations. This setup exhibits a sign problem which is circumvented using a Taylor expansion in the magnetic field. The ground state of the system in the pion condensation phase is found to exhibit a pronounced diamagnetic response. We elaborate on how this diamagnetism may contribute to the pressure balance in the inner core of strongly magnetized neutron stars. In addition we show that the onset of pion condensation shifts to larger chemical potentials due to the enhancement of the charged pion mass for growing magnetic fields. Finally, we summarize the magnetic nature of QCD matter on the temperature-isospin chemical potential phase diagram.

Endr?di, G.

2014-11-01

277

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

278

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

279

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

280

Microscopic calculations in few-body systems and nuclear matter

International Nuclear Information System (INIS)

Recent results obtained for s-shell nuclei are discussed in connection with plausible models of three-nucleon interaction. Recent progress on the applications of correlated basis function theory in nuclear matter calculations are surveyed. The effects of correlations on momentum distribution and enhancement factor of the dipole sum rule are discussed

281

Anharmonicity of the nuclear matter ground state and the RHA

The correlation between the compression modulus and the skewness coefficient of the nuclear matter ground state implied by the breathing mode data is compared with predictions of the relativistic Hartree approximation (RHA). Retaining explicit dependence on the renormalization scale ?, employed in the RHA, this correlation, together with other considerations, suggests a value for ?/M ? 1.2.

Ellis, Paul J.; Heide, Erik K.; Rudaz, Serge; Prakash, M.

1994-07-01

282

Anharmonicity of the nuclear matter ground state and the RHA

International Nuclear Information System (INIS)

The correlation between the compression modulus and the skewness coefficient of the nuclear matter ground state implied by the breathing mode data is compared with predictions of the relativistic Hartree approximation (RHA). Retaining explicit dependence on the renormalization scale ?, employed in the RHA, this correlation, together with other considerations, suggests a value for ?/M similar eq1.2. ((orig.))

283

Nuclear Matter Approach to the Interaction Potential Between Heavy Ions

A simple theory of the interaction potential between heavy ions V, based on the local density approach and the frozen density model, is presented for nuclei with neutron excess. The energy density needed for calculating V is expressed in a simple way through the known properties of nuclear matter.

Dabrowski, J

2003-01-01

284

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

285

Matter in extremis: Ultrarelativistic nuclear collisions at RHIC

International Nuclear Information System (INIS)

We review the physics of nuclear matter at high energy density and the experimental search for the Quark-Gluon Plasma at the Relativistic Heavy Ion Collider (RHIC). The data obtained in the first three years of the RHIC physics program provide several lines of evidence that a novel state of matter has been created in the most violent, head-on collisions of Au nuclei at ?s = 200 GeV. Jet quenching and global measurements show that the initial energy density of the strongly interacting medium generated in the collision is about two orders of magnitude larger than that of cold nuclear matter, well above the critical density for the deconfinement phase transition predicted by lattice QCD. The observed collective flow patterns imply that the system thermalizes early in its evolution, with the dynamics of its expansion consistent with ideal hydrodynamic flow based on a Quark-Gluon Plasma equation of state

286

Sigma condensed nuclear matter in the extended linear sigma model

International Nuclear Information System (INIS)

We apply the linear sigma model to nuclear matter with finite nuclear density. Although the linear sigma model has no repulsive interaction, we introduce vector meson contributions to satisfy the saturation property of the nuclear matter. We also consider a nucleon mass term, scalar meson mass terms, and a sigma meson-chiral loop interaction, which are not chiral invariant, in addition to chiral-invariant higher-power chiral loop terms. The bulk properties of the nuclear matter are estimated on the assumption of sigma meson condensation. The parameters introduced in this model are determined such that the energy per nucleon of the system realizes its minimum at the normal nuclear density, ?B=0.19/fm3 (the Fermi momentum pF=278.5 MeV/c), with the value -15.75 MeV, and the incompressibility is given by K ? 200 MeV. With these parameter values, the effective pion mass squared is often negative at low densities. A negative pion mass squared implies the existence of a pion classical field. Here, we do not consider the pion condensed state, and therefore we seek parameter values that result in a positive pion mass squared at normal density. (author)

287

Spin-isospin excitations in finite nuclei and nuclear matter

International Nuclear Information System (INIS)

The residual interaction for spin-isospin excitations in 16O and nuclear matter is investigated considering the Brueckner G-matrix derived from a realistic meson-exchange potential. An attempt is made to approximate the G-matrix by an interaction containing ? plus rho exchange plus a repulsive constant g'. This approximation, which is commonly being used in the literature, turns out to be insufficient to represent the complete G-matrix. The constant g' which is adjusted to obtain roughly the same isovector states of unnatural parity in 16O as the G-matrix is weaker than the constant g'obtained from an analysis of nuclear matter excitations. This difference can be traced back to the more complicated momentum-dependence of the G-matrix. It is shown, that an improved parametrisation can account for this dependence. Possible differences in the collective excitations of finite and infinite nuclear systems are discussed. (orig.)

288

International Nuclear Information System (INIS)

The properties of nuclear matter and nuclear scattering reactions were studied from the same effective nucleon-nucleon interactions. In this project, we used CDM3Y and M3Y-Pn interaction version as the input to build the nuclear interaction potential (nuclear optical potential). After that, nuclear scattering reactions were studied by coupled channel formalism and folding model for scattering potential. The theoretical calculated cross sections of (alpha, nucleus) and (nucleon, nucleus) scattering system have been compared with the experimental values. Using the above interactions, the properties of nuclear matter: (i) biding energy, (ii) pressure and (iii) Compressibility were deduced in the Hartree-Fock calculation frame work. From the consistence between theory and experiment, the information of nuclear structure has been extracted. (author)

289

Phase transitions in high excited nuclear matter

International Nuclear Information System (INIS)

This work is a study of the mechanism of thermal multifragmentation, which takes place in collisions of light relativistic projectiles with heavy targets. This is a new multibody decay process of very hot nuclei (target spectator) with emission of a number of intermediate mass fragments (IMF, 2 4He and 12C with Au. The main results are the following: - The mean IMF multiplicity () saturates at 2.2 ± 0.2.This fact cannot be rendered by the traditional approach with the intranuclear cascade (INC) followed by Statistical Multifragmentation Models (SMM). Considering the expansion phase between two parts of the calculations, the excitation energies and the residual masses are empirically modified to obtain agreement with the measured IMF- multiplicities. The mean excitation energy is found to be around 500 MeV for the beam energies above 5 GeV. This modified model is denoted as INC + ? + SMM where ? indicates the preequilibrium processes. - The expansion is driven by the thermal pressure. It is larger for 4He and 12C induced collisions because of higher initial temperature. The kinetic energy spectra of IMF become harder and the expansion flow is visible. The total flow energy of the system is estimated to be around 115 MeV both for the He and the carbon beams. - The analysis of the data reveals very interesting information on the fragment space distribution inside the break-up volume. Heavier IMF are formed predominately in the interior of the fragmenting nucleus possibly due to a density gradient. This conclusion is in contrast to the predictions of the Statistical Multifragmentation Model (SMM). - This study of the multifragmentation using a range of projectiles demonstrates a transition from pure '' thermal decay '' (for p + Au collisions) to disintegration '' completed by '' the onset of a collective flow for the heavier projectiles. Nevertheless, in case of reaction caused by fast protons the decay mechanism should be considered as a thermal multifragmentation. - The time scale of the thermal multifragmentation in p + Au collision at 8.1 GeV has been measured for the first time (by the analysis of IMF-IMF angular correlations). The mean decay time of the fragmenting system was found to be ? = (50 ± 18) fm/c in accordance with the scenario of a '' simultaneous '' multibody decay of a hot and expanded nuclear system. The measured time-scale is close to that for the density fluctuation in the diluted nuclear system. Hence, the thermal multifragmentation can be interpreted as the first order nuclear liquid-fog phase transition in the spinodal region. - Characteristic temperature Tf is less than Tc - critical temperature for the liquid-gas phase transition. Tc -critical temperature for the liquid-gas phase transition is found to be (17 ± 2) MeV, which is significantly larger than the temperature of fragmenting system (5 - 6 MeV). This is a very important observation in favour of the mechanism of spinodal disintegration. - It is concluded that the decay process of hot nuclei is characterized by two size parameters: transition state and freeze-out volumes. The IMF emission time is related to the mean rupture time at the multi-scission point, which corresponds to the kinetic freeze-out configuration. (author)

290

Temporally asymmetric gradient profiles in nuclear magnetic resonance diffusion experiments are investigated using modified Stejskal-Tanner gradients. Three novel findings are presented. 1. The phase of the diffusion-weighted signal contains information about the confining geometry. This information can be extracted from the 'diffusion-weighted phase'. 2. In the motional narrowing regime, it is possible to exactly determine the confining boundary in closed domains. 3. Diffusion-weighting gradients can act like imaging gradients.

Stieltjes, Frederik Bernd Laun Wolfhard Semmler Bram

2010-01-01

291

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

292

Climate Change, Nuclear Power and Nuclear Proliferation: Magnitude Matters

Energy Technology Data Exchange (ETDEWEB)

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 0.64oC 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.

Robert J. Goldston

2010-03-03

293

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.

294

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)

295

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

296

Strange nuclear matter within Brueckner-Hartree-Fock Theory

We have developed a formalism for microscopic Brueckner-type calculations of dense nuclear matter that includes all types of baryon-baryon interactions and allows to treat any asymmetry on the fractions of the different species (n, p, results for the different single-particle potentials focussing on situations that can be relevant in future microscopic studies of beta-stable neutron star matter with strangeness. We find the both the hyperon-nucleon and hyperon-hyperon interactions play a non-negligible role in determining the chemical potentials of the different species.

Vidańa, I; Ramos, A; Hjorth-Jensen, M; Stoks, V G J

2000-01-01

297

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

298

Relativistic mean-field hadronic models under nuclear matter constraints

Background: The microscopic composition and properties of infinite hadronic matter at a wide range of densities and temperatures have been subjects of intense investigation for decades. The equation of state (EoS) relating pressure, energy density, and temperature at a given particle number density is essential for modeling compact astrophysical objects such as neutron stars, core-collapse supernovae, and related phenomena, including the creation of chemical elements in the universe. The EoS depends not only on the particles present in the matter, but, more importantly, also on the forces acting among them. Because a realistic and quantitative description of infinite hadronic matter and nuclei from first principles in not available at present, a large variety of phenomenological models has been developed in the past several decades, but the scarcity of experimental and observational data does not allow a unique determination of the adjustable parameters. Purpose: It is essential for further development of the field to determine the most realistic parameter sets and to use them consistently. Recently, a set of constraints on properties of nuclear matter was formed and the performance of 240 nonrelativistic Skyrme parametrizations was assessed [M. Dutra et al., Phys. Rev. C 85, 035201 (2012), 10.1103/PhysRevC.85.035201] in describing nuclear matter up to about three times nuclear saturation density. In the present work we examine 263 relativistic-mean-field (RMF) models in a comparable approach. These models have been widely used 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 in medium. Method: Three different sets of constraints related to symmetric nuclear matter, pure neutron matter, symmetry energy, and its derivatives were used. The first set (SET1) was the same as used in assessing the Skyrme parametrizations. The second and third sets (SET2a and SET2b) were more suitable for analysis of RMF and included, up-to-date theoretical, experimental and empirical information. Results: The sets of updated constraints (SET2a and SET2b) differed somewhat in the level of restriction but still yielded only 4 and 3 approved RMF models, respectively. A similarly small number of approved Skyrme parametrizations were found in the previous study with Skyrme models. An interesting feature of our analysis has been that the results change dramatically if the constraint on the volume part of the isospin incompressibility (K? ,v) is eliminated. In this case, we have 35 approved models in SET2a and 30 in SET2b. Conclusions: Our work provides a new insight into application of RMF models to properties of nuclear matter and brings into focus their problematic proliferation. The assessment performed in this work should be used in future applications of RMF models. Moreover, the most extensive set of refined constraints (including nuclear matter and finite-nuclei-related properties) should be used in future determinations of new parameter sets to provide models that can be used with more confidence in a wide range of applications. Pointing to reasons for the many failures, even of the frequently used models, should lead to their improvement and to the identification of possible missing physics not included in present energy density functionals.

Dutra, M.; Lourenço, O.; Avancini, S. S.; Carlson, B. V.; Delfino, A.; Menezes, D. P.; Providęncia, C.; Typel, S.; Stone, J. R.

2014-11-01

299

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

300

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

301

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.

302

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

303

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

304

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.

305

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.)

306

Relativistic nuclear matter with alternative derivative coupling models

International Nuclear Information System (INIS)

Effective Lagrangians involving nucleons coupled to scalar and vector fields are investigated within the framework of relativistic mean-field theory. The study presents the traditional Walecka model and different kinds of scalar derivative coupling suggested by Zimanyi and Moszkowski. The incompressibility (presented in an analytical form), scalar potential, and vector potential at the saturation point of nuclear matter are compared for these models. The real optical potential for the models are calculated and one of the models fits well the experimental curve from-50 to 400 MeV while also gives a soft equation of state. By varying the coupling constants and keeping the saturation point of nuclear matter approximately fixed, only the Walecka model presents a first order phase transition of finite temperature at zero density. (author)

307

Equation of state of nuclear matter from empirical constraints

From empirically determined values of some of the characteristic constants associated with homogeneous nuclear matter at saturation and sub-saturation densities, within the framework of a Skyrme-inspired energy density functional, we construct an equation of state (EoS) of nuclear matter.This EoS is then used to predict values of density slope parameters of symmetry energy $L(\\rho)$, isoscalar incompressibility $K(\\rho)$ and a few related quantities. The close consonance of our predicted values with the currently available ones for the density dependence of symmetry energy and incompressibility gleaned from diverse approaches offers the possibility that our method may help in settling their values in tighter bounds. Extrapolation of our EoS at supranormal densities shows that it is in good harmony with the one extracted from experimental data.

Alam, N; De, J N; Samaddar, S K; Colň, G

2014-01-01

308

Strangeness in nuclear matter at DA{Phi}NE

Energy Technology Data Exchange (ETDEWEB)

The low energy kaons from the {phi} meson produced at DA{Phi}NE offer a unique opportunity to study strangeness in nuclear matter. The interaction of kaons with hadronic matter can be investigated at DA{Phi}NE using three main approaches: study of hypernuclei production and decay, kaons scattering on nucleons, kaonic atoms formation. These studies explore kaon-nucleon and hyperon-nucleon forces at very low energy, the nuclear shell model in presence of strangeness quantum number and eventual quarks deconfinement phenomena. The experiments devoted to study this physical program at DA{Phi}NE are FINUDA and DEAR. The physics topics of both experiments are illustrated together with a detailed descriptions of the two detectors.

Gianotti, P. [INFN, Laboratori Nazionali di Frascati, Rome (Italy)

1998-01-01

309

Strangeness in nuclear matter at DA?NE

International Nuclear Information System (INIS)

The low energy kaons from the ? meson produced at DA?NE offer a unique opportunity to study strangeness in nuclear matter. The interaction of kaons with hadronic matter can be investigated at DA?NE using three main approaches: study of hypernuclei production and decay, kaons scattering on nucleons, kaonic atoms formation. These studies explore kaon-nucleon and hyperon-nucleon forces at very low energy, the nuclear shell model in presence of strangeness quantum number and eventual quarks deconfinement phenomena. The experiments devoted to study this physical program at DA?NE are FINUDA and DEAR. The physics topics of both experiments are illustrated together with a detailed descriptions of the two detectors

310

Pure Neutron Matter Constraints and Nuclear Symmetry Energy

International Nuclear Information System (INIS)

In this review, we will discuss the results of our recent work [1] 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 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 ?(J) sym, (b) the symmetry energy at supra-saturation densities, and (c) the radius of neutron stars.

311

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

312

Four-particle correlations and quantum condensates in nuclear matter

International Nuclear Information System (INIS)

Starting from a Green function approach to nuclear matter, the formation of bound states and quantum condensates is treated within the cluster-mean field approach. In particular, quartetting in symmetric matter is considered. Nucleonic correlations are of importance in low-density matter, e.g. near the surface of nuclei. Self-conjugate 4n nuclei exhibit an ?-like cluster structure. A new ?-cluster wave function is proposed which is of the ?-particle condensate type. Applications to 12C and 16O show that states of low density close to the three- resp. four-?-particle threshold in both nuclei are possibly of this kind. Furthermore, the occurrence of deformed condensates is discussed. In particular, excited 8Be is described as deformed gas-like two-?-particle states. (author)

313

Properties of the ? meson in dense nuclear matter

International Nuclear Information System (INIS)

In order to reach a description of the ? meson, which is in accordance with the principles of the gauge invariance of the electromagnetic interaction, the vector-dominance hypothesis, and the unitarity a model for the ? meson in the vacuum is developed. Thereafter follows the calculation of the properties of the ? meson in nuclear matter. First the connection between the spectral function of the ? meson and the dilepton production rate for an equilibrium state is derived. Then the model for the pion in nuclear matter is described. Following approximations are applied: The description of the pion-baryon interaction pursues non-relativistically and both the width of the delta resonance and the short-range repulsive delta-nucleon interaction is neglected. The self-energy of the ? meson in nuclear matter following from this description is formally derived from the requirement to couple the ? meson to a conserved current. The corrections for the 3-point and 4-point vertex resulting from this are calculated and discussed. Thereafter the physical consequences of the changed self-energy of the ? meson in nuclear matter are considered. By means of the spectral function it is shown that up to the two-fold of the ground-state density the position of the resonance is nearly not changed. At still higher densities the resonances is a little shifted to higher energies. In the range of an invariant mass of about 400 meV a strong increasement concentrated on a small range results. This is caused by coupling to a naked delta-hole state and a pion. Finally the possibilities are discussed to apply the results of this thesis to the prediction of experimental data. Thereby it is proved to be necessary to base on a simulation of the heavy ion reaction. (orig./HSI)

314

The Landau parameters of nuclear matter in relativistic Hartree approximation

International Nuclear Information System (INIS)

The Landau parameters of nuclear matter have been calculated in relativistic Hartree approximation as a function of a renormalization scale. The results have then been compared to the empirical values deduced from constraints on isoscalar compression modes, spin-orbit splitting in nuclei and energy dependence of the nucleon-nucleus optical potential. For comparison, the results obtained for relativistic non-linear models and Dirac-Brueckner-Hartree-Fock calculations are also shown. (author)

315

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

316

High-density nuclear matter with nonlocal confining solitons

An infinite system of nonlocal, individually confining solitons is considered as a model of high-density nuclear matter. The soliton-lattice problem is discussed in the Wigner-Seitz approximation. The cell size is varied to study the density dependence of physical quantities of interest. A transition to a system where quarks can migrate between solitons is found. We argue that this signals quark deconfinement. The model is applied to the calculation of selected in-medium properties.

Johnson, C W; Johnson, Charles W.; Fai, George

1997-01-01

317

In medium T-matrix for superfluid nuclear matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study a generalized ladder resummation in the superfluid phase of the nuclear matter. The approach is based on a conserving generalization of the usual T-matrix approximation including also anomalous self-energies and propagators. The approximation here discussed is a generalization of the usual mean-field BCS approach and of the in medium T-matrix approximation in the normal phase. The numerical results in this work are obtained in the quasi-particle approximation. Prope...

Bozek, P.

2001-01-01

318

The symmetry energy in nuclei and in nuclear matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

We discuss to what extent information on ground-state properties of finite nuclei (energies and radii) can be used to obtain constraints on the symmetry energy in nuclear matter and its dependence on the density. The starting point is a generalized Weizsäcker formula for ground-state energies. In particular effects from the Wigner energy and shell structure on the symmetry energy are investigated. Strong correlations in the parameter space prevent a clear isolation of the surface contributio...

Isacker, P.; Dieperink, A. E. L.

2006-01-01

319

Two-particle properties in nuclear matter at finite temperatures

Digital Repository Infrastructure Vision for European Research (DRIVER)

Correlation effects in nuclear matter at finite temperatures are studied for subnuclear densities ($\\rho<\\rho_0$) and medium excitation energy, where a nonrelativistic potential approach is possible. A quantum statistical approach is given, where clusters are treated under the influence of a clustered medium treated within a mean field approximation. Spectral functions, in-medium cross sections, and reaction rates are considered as well as the formation of a quantum condensa...

Roepke, G.; Schnell, A.

1998-01-01

320

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

321

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.)

322

Neutron and nuclear matter in Jastrow variational approach

International Nuclear Information System (INIS)

The 'factor cluster' expansion method (FIY) developed by Clark and Ristig, which furnishes a powerful device for the calculations of the expectation values of the observables of a many-fermion system with respect to dynamically correlated state vectors, is briefly discussed. Attempts to calculate the equation of state of a uniform extended system of neutrons interacting by the Reid potential within the Jastrow variational framework due to Clark and his associates and other groups, met with limited success. All results however clearly reveal that, truncations at low cluster order even with 'suitable' constraints are only of limited value and break down at high densities. Extended system of neutrons should be studied now a days by employing hypernetted-chain procedures or more highly summed expansions. The problem of lowest order cluster calculations in nuclear matter is however different. Here one wishes to develop simple but efficient cluster approximations in low order with suitable constraints for nuclear matter at reliable density aiming to develop practical methods for dealing with finite nuclei (where fancy HNC methods cannot be used). The problem of inclusion of tensor force in nuclear matter calculations within the Jastrow variational approach is also discussed. (auth.)

323

Separable NN potentials from inverse scattering for nuclear matter studies

International Nuclear Information System (INIS)

Low-rank separable potentials greatly simplify perturbation-theory based many-body computations and are especially useful in finite temperature and nonequilibrium nuclear matter studies. With local potentials such calculations become very lengthy. In this paper, we present a first version of a separable potential constructed directly from available empirical nucleon-nucleon phase shifts (Elab3S1-3D1 channel, where the deuteron wave function serves as off-shell input at the binding energy. The simplest potential thus constructed in this channel has rank 4. The deuteron wave function is nevertheless empirically undetermined at high momenta, prompting us to adopt as well as construct several model wave functions that all fit the low momentum deuteron data while allowing variations at high momenta. The effects of these off-shell variations on predicted nuclear matter properties are discussed. No off-shell information is included in the other channels, leading to potentials of rank either 1 or 2. With this simple model potential we perform standard Brueckner nuclear matter ground state calculations and compare the results with Machleidt's using Bonn OBEP. The agreement is good in the S channels and in the singlet D2 channel. Other channels show larger discrepancies, the most significant of which coming from the 3P1 and 3D1 channels. These results are explained by the off-shell behavior of our model potential as compared to the Bonn OBEP. (Abstract Truncated)

324

Justifying Condensed Matter Nuclear Phenomena Using Hot Fusion Data

The selective resonant tunneling model [1] has been successful in describing 6 major fusion cross-section data (d+T, d+D, d+He3, t+T, t+He3, p+D). The new formula needs only 3 parameters; however, it gives much better results than what were given by the 5-parameter formula in NRL Plasma Formulary. It provides an opportunity to find the resonance energy level which is necessary to explain the Condensed Matter Nuclear Phenomena in metal-hydrides. The proton-lithium fusion data, the astrophysical S-factor data, the K-electron capture data of beryllium, and the anomalous ratio of the isotope abundance of lithium in palladium-hydride (7Li/6Li) will be presented as an example for this justification. Thus, selective resonant tunneling model explains not only the 3 puzzles in Condensed Matter Nuclear Science (i.e. tunneling the Coulomb barrier, excess heat without commensurate neutron radiation, and the missing gamma radiation), but also 7 sets of hot fusion data. It predicts that there must be neutrino radiation accompanied with Condensed Matter Nuclear Phenomena in metal-hydrides. [4pt] [1] Xing Z. Li, et al., Nucl. Fusion 48 125003 (2008).

Li, Xing Zhong

2011-03-01

325

Open-charm systems in cold nuclear matter

International Nuclear Information System (INIS)

We study the spectral distributions of charmed meson with JP=0- quantum numbers in cold nuclear matter applying a self-consistent and covariant many-body approach established previously for the nuclear dynamics of kaons. At leading orders the computation requires as input the free-space two-body scattering amplitudes only. Our results are based on the s-wave meson-nucleon amplitudes obtained recently in terms of a coupled-channel approach. The amplitudes are characterized by the presence of many resonances in part so far not observed. This gives rise to an intriguing dynamics of charmed mesons in nuclear matter. At nuclear saturation density we predict a pronounced two-mode structure of the D+ mesons with a main branch pushed up by about 32 MeV. The lower branch reflects the coupling to two resonance-hole states that are almost degenerate. For the D- we obtain a single mode pushed up by about 18 MeV relative to the vacuum mode. Most spectacular are the results for the Ds+ meson. The presence of an exotic resonance-hole state gives rise to a rather broad and strongly momentum dependent spectral distribution

326

Modification of the ?-Meson Lifetime in Nuclear Matter

Information on hadron properties in the nuclear medium has been derived from the photoproduction of ? 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 ?-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 ? width is found to be 130 150MeV/c2 at normal nuclear matter density for an average 3-momentum of 1.1GeV/c. In the rest frame of the ? meson, this inelastic ? width corresponds to a reduction of the ? lifetime by a factor ?30. For the first time, the momentum dependent ?N cross section has been extracted from the experiment and is in the range of 70 mb.

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.

2008-05-01

327

Neutron skin and nuclear matter equation of state

International Nuclear Information System (INIS)

The equation of state of nuclear matter, which consists of neutrons and protons, has the term that depends on the difference between the neutron and proton densities. Determination of the term, the symmetry energy term, is quite important for nuclear physics as well as nuclear astrophysics. The symmetry energy is one of key ingredients to determine e.g. the radius and internal structure of a neutron star as well as supernoval explosion dynamics. The first order density dependence, slop parameter, of the symmetry energy has a close correlation with the thickness of the neutron skin, which is a neutron rich layer than appears on the surface of heavy nuclei. We pick up three recent measurements on the neutron skin thickness of the 208Pb nucleus by using each of weak, electromagnetic, and strong interactions, and report the present situation on the determination of the slope parameter. (author)

328

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

329

Chiral four-body interactions in nuclear matter

International Nuclear Information System (INIS)

An exploratory study of chiral four-nucleon interactions in nuclear and neutron matter is performed. The leading-order terms arising from pion-exchange in combination with the chiral 4?-vertex and the chiral NN3?-vertex are found to be very small. Their attractive contribution to the energy per particle stays below 0.6 MeV in magnitude for densities up to ? = 0.4 fm-3. We consider also the four-nucleon interaction induced by pion-exchange and twofold ?-isobar excitation of nucleons. For most of the closed four-loop diagrams the occurring integrals over four Fermi spheres can either be solved analytically or reduced to easily manageable one- or two-parameter integrals. After summing the individually large contributions from 3-ring, 2-ring and 1-ring diagrams of alternating signs, one obtains at nuclear matter saturation density ? 0 = 0.16 fm-3 a moderate contribution of 2.35 MeV to the energy per particle. The curve anti E(?) rises rapidly with density, approximately with the third power of ?. In pure neutron matter the analogous chiral four-body interactions lead, at the same density ? n, to a repulsive contribution that is about half as strong. The present calculation indicates that long-range multi-nucleon forces, in particular those provided by the strongly coupled ?N ?-system with its small mass-gap of 293 MeV, can still play an appreciable role for the equation of state of nuclear and neutron matter. (orig.)

330

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 relativistic nuclear fragmentation is introduced. A phenomenological analysis of recent FNAL data involving proton-nucleus collisions (E591) is carried out

331

Relativistic mean-field models and nuclear matter constraints

Energy Technology Data Exchange (ETDEWEB)

This work presents a preliminary study of 147 relativistic mean-field (RMF) hadronic models used in the literature, regarding their behavior in the nuclear matter regime. We analyze here different kinds of such models, namely: (i) linear models, (ii) nonlinear {sigma}{sup 3}+{sigma}{sup 4} models, (iii) {sigma}{sup 3}+{sigma}{sup 4}+{omega}{sup 4} models, (iv) models containing mixing terms in the fields {sigma} and {omega}, (v) density dependent models, and (vi) point-coupling ones. In the finite range models, the attractive (repulsive) interaction is described in the Lagrangian density by the {sigma} ({omega}) field. The isospin dependence of the interaction is modeled by the {rho} meson field. We submit these sets of RMF models to eleven macroscopic (experimental and empirical) constraints, used in a recent study in which 240 Skyrme parametrizations were analyzed. Such constraints cover a wide range of properties related to symmetric nuclear matter (SNM), pure neutron matter (PNM), and both SNM and PNM.

Dutra, M.; Lourenco, O.; Carlson, B. V. [Departamento de Fisica, Instituto Tecnologico de Aeronautica-CTA, 12228-900, Sao Jose dos Campos, SP (Brazil); Delfino, A. [Instituto de Fisica, Universidade Federal Fluminense, 24210-150, Boa Viagem, Niteroi, RJ (Brazil); Menezes, D. P.; Avancini, S. S. [Departamento de Fisica, CFM, Universidade Federal de Santa Catarina, CP. 476, CEP 88.040-900, Florianopolis, SC (Brazil); Stone, J. R. [Oxford Physics, University of Oxford, OX1 3PU Oxford (United Kingdom) and Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States); Providencia, C. [Centro de Fisica Computacional, Department of Physics, University of Coimbra, P-3004-516 Coimbra (Portugal); Typel, S. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Theorie, Planckstrasse 1,D-64291 Darmstadt (Germany)

2013-05-06

332

Phase transitions in a saturating chiral theory of nuclear matter

International Nuclear Information System (INIS)

The formalism of a relatively covariant saturating chiral field theory of nuclear matter is developed in the mean field approximation, and some of the properties are studied. The theory possesses the normal saturated state of nuclear matter and is compatible with the data on neutron star masses. The finite temperature properties are examined. A normal gas-liquid phase equilibrium region exists below T approx. = 23 MeV. At all temperatures but low densities an abnormal phase exists which at zero temperature is an isolated point at zero baryon density. At finite temperature the abnormal phase, for which the baryon effective mass is vanishingly small, and in which there is an abundance of pairs, extends to finite density. The normal and abnormal phases are disconnected except at a single point where phase equilibrium occurs. Above a critical temperature the normal branch at low density disappears and the abnormal one is the only existing branch. The abnormal characteristic of small effective mass however is confined to low density. Chiral symmetry is restored in this sense as the temperature is increased, but only in matter of low baryon density

333

Composition and thermodynamics of nuclear matter with light clusters

We investigate nuclear matter at finite temperature and density, including the formation of light clusters up to the alpha particle. The novel feature of this work is to include the formation of clusters as well as their dissolution due to medium effects in a systematic way using two many-body theories: a microscopic quantum statistical (QS) approach and a generalized relativistic mean field (RMF) model. Nucleons and clusters are modified by medium effects. Both approaches reproduce the limiting cases of nuclear statistical equilibrium (NSE) at low densities and cluster-free nuclear matter at high densities. The treatment of the cluster dissociation is based on the Mott effect due to Pauli blocking, implemented in slightly different ways in the QS and the generalized RMF approaches. We compare the numerical results of these models for cluster abundances and thermodynamics in the region of medium excitation energies with temperatures T <= 20 MeV and baryon number densities from zero to a few times saturatio...

Typel, S; Klähn, T; Blaschke, D; Wolter, H H

2009-01-01

334

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.)

335

Electric-dipole sum rule in correlated nuclear matter

International Nuclear Information System (INIS)

The enhancement of the photonuclear Thomas-Reiche-Kuhn E1 sum rule due to exchange forces is studied in the large-A (nuclear matter) limit, neglecting retardation effects. Semi-realistic non-central models of the nucleon-nucleon interaction (Gammel-Christian-Tahler, Hamada-Johnston ?6 and Reid ?6) are employed, together with variational ground-state wave functions incorporating state-dependent correlations. The resulting theoretical estimates of the enhancement factor K are in generally good agreement with the value K = 0.75 +- 0.15 (essentially independent of A) implied by the recent Saclay measurements of photoneutron yields in heavy nuclei. (orig.)

336

Thermostatic properties of semi-infinite polarized nuclear matter

International Nuclear Information System (INIS)

The surface and curvature properties of semi-infinite polarized nuclear matter (SPNM) are calculated using an expansion for the Fermi integrals up to T2. A density matrix expansion is obtained for a modified form of Seyler-Blanchard interaction. New parameters that characterize the surface and curvature properties of SPNM are introduced. The level density parameter is extracted from the low temperature expansion of the free energy and compared with previous calculations. A reasonable agreement is obtained for the parameters calculated before. (author). 78 refs, 1 fig., 5 tabs

337

Spin Instability in Nuclear Matter and the Skyrme Interaction

In the present work the problem of spin instability of nuclear matter with the Skyrme interaction is analyzed. The three-body part of the interaction is replaced by using a density dependent potential which is a modification to that given previously by Dabrowski. The symmetry energies are calculated and their rearrangement corrections. Good agreement is obtained with previous calculations.Translated AbstractSpininstabilität in Kernmaterie und Skyrme-WechselwirkungDie vorliegende Arbeit analysiert die Spininstabilität von Kernmaterie mit Skyrme-Wechselwirkung. Der Dreikörperanteil der Wechselwirkung ist durch ein dichteabhängiges Potential ersetzt. Die Symmetrieenergien und ihre Umordnungskorrekturen werden berechnet. Sie stimmen gut mit vorhergehenden Rechnungen überein.

Mansour, H. M. M.

338

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

339

Energy weighted sum rules for spectral functions in nuclear matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

The energy weighted sum rule of single-particle spectral functions in nuclear matter is studied. The spectral functions include the influence of short-range correlations as generated by the Reid potential in the framework of the self-consistent Greens function method. For the range of momenta studied, the sum rule is rather accurately fulfilled numerically (within 5%). It is observed that the high-energy tail of the particle part of the spectral function exhausts most of the sum rule, which c...

Polls Marti?, Artur; Ramos Go?mez, A?ngels; Ventura, J.; Amari, S.; Dickhoff, Willem H.

1994-01-01

340

Chiral relativistic model of nuclear matter including effects of confinement mechanism

International Nuclear Information System (INIS)

This work aims at constructing a model for symmetric and asymmetric nuclear matter in a relativistic approach including effects from quantum chromodynamics, in particular chiral symmetry and confinement. We consider an assembly of nucleons interacting via meson exchange. The attraction is due to a chiral invariant scalar field associated with the fluctuations of the chiral condensate. The inclusion of scalar nucleonic effects due to the quark substructure of the nucleon ensures the saturation to occur. The parameters corresponding to the scalar sector of the interaction and to the quarks confinement in the nucleon are obtained from lattice calculations. The rest of the parameters are obtained as much as possible by hadron phenomenology. With such constrained inputs, the results are nevertheless very good: this constitutes the originality of this work. In one part, we chose to work at the mean-field level in the Hartree-Fock scheme. The propagation of the scalar field in the Hartree-Fock terms induce some rearrangement effects which play an essential role in the Hugenholtz-Van Hove theorem. We discuss also the role of the tensor part of the ? interaction in the symmetry energy and the isospin dependence of the Landau effective mass. Then, in the idea to enlarge this work to neutron stars, we give the equation of state predicted by our model. The last step corresponds to the introduction of effects after the mean-field including the correlation energy due to pion loops. An important ingredient is the Landau-Migdal parameter controlling short range interactions. The correlation energy enhances the description of the saturation point of nuclear matter. (author)

341

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

342

Antikaons and hyperons in nuclear matter with saturation

We evaluate the antikaon and hyperon spectral functions in a self-consistent and covariant many-body approach. The computation is based on coupled-channel dynamics derived from the chiral SU(3) Lagrangian. A novel subtraction scheme is developed that avoids kinematical singularities and medium-induced power divergencies all together. Scalar and vector mean fields are used to model nuclear binding and saturation. The effect of the latter is striking for the antikaon spectral function that becomes significantly more narrow at small momenta. Attractive mass shifts of about 30 and 40 MeV are predicted for the Lambda(1405) and Sigma(1385) resonances. Once scalar and vector mean fields for the nucleon are switched on the Lambda(1520) resonances dissolves almost completely in nuclear matter.

Lutz, M F M; Möller, M

2007-01-01

343

Modern Energy Density Functional for Nuclei and Nuclear Matter

We search for a modern energy density functional for nuclei and nuclear matter, based on the Skyrme type effective interaction. This interaction has been widely used for decades and many parameterizations have been realized to best reproduce binding energies, charge root mean square radii, and other properties of nuclei. Now that more experimental data is available, we are able to fit our results to a broader collection of nuclei at and far from the stability line. We implement the Simulated Annealing Method to search for the particular set of Skyrme parameters that best reproduces a collection of nuclear data. The data consist of binding energies, charge root mean square (rms) radii, rms radii for valence neutrons, spin-orbit splittings and breathing mode energies. The results we obtain using this new parameterization are in good agreement with a wide range of experimental measurements.

Hinojosa, Alberto

2008-10-01

344

International Nuclear Information System (INIS)

Thermodynamically self-consistent class of nuclear matter equations of state are considered. For two different equations of state with deconfinement phase transition the compression shock adiabats are calculated. The shock stability for mixed phase formation is studied. 17 refs.; 4 figs

345

International Nuclear Information System (INIS)

We explore the abundance of light clusters in asymmetric nuclear matter at subsaturation density. With increasing density, binding energies and wave functions are modified due to medium effects. The method of Albergo, Costa, Costanzo, and Rubbino (ACCR) for determining the temperature and free nucleon density of a disassembling hot nuclear source from fragment yields is modified to include, in addition to Coulomb effects and flow, also effects of medium modifications of cluster properties, which become of importance when the nuclear matter density is above 10-3 fm-3. We show how the analysis of cluster yields, to infer temperature and nucleon densities, is modified if the shifts in binding energies of in medium clusters are included. Although, at low densities, the temperature calculated from given yields changes only modestly if medium effects are taken into account, larger discrepancies are observed when the nucleon densities are determined from measured yields

346

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

347

Holographic meson mass splitting in the Nuclear Matter

We study the holographic light meson spectra and their mass splitting in the nuclear medium. In order to describe the nuclear matter, we take into account the thermal charged AdS geometry with two flavor charges, which can be reinterpreted as the number densities of proton and neutron after some field redefinitions. We show that the meson mass splitting occurs when there exists the density difference between proton and neutron. Depending on the flavor charge, the mass of the positively (negatively) charged meson increases (decreases) as the density difference increases, whereas the neutral meson mass is independent of the density difference. In the regime of the large nucleon density with a relatively large number difference between proton and neutron, we find that negatively charged pion becomes massless in the nuclear medium, so the pion condensate can occur. We also investigate the binding energy of a heavy quarkonium in the nuclear medium, in which the binding energy of a heavy quarkonium becomes weaker a...

Lee, Bum-Hoon; Park, Chanyong; Mamedov, Shahin

2013-01-01

348

Chiral four-body interactions in nuclear matter

An exploratory study of chiral four-nucleon interactions in nuclear and neutron matter is performed. The leading-order terms arising from pion-exchange in combination with the chiral $4\\pi$-vertex and the chiral NN$3\\pi$-vertex are found to be very small. Their attractive contribution to the energy per particle stays below $0.6\\,$MeV in magnitude for densities up to $\\rho =0.4\\,$fm$^{-3}$. We consider also the four-nucleon interaction induced by pion-exchange and twofold $\\Delta$-isobar excitation of nucleons. For most of the closed four-loop diagrams the occurring integrals over four Fermi spheres can either be solved analytically or reduced to easily manageable one- or two-parameter integrals. After summing the individually large contributions from 3-ring, 2-ring and 1-ring diagrams of alternating signs, one obtains at nuclear matter saturation density $\\rho_0=0.16\\,$fm$^{-3}$ a moderate contribution of $2.35\\,$MeV to the energy per particle. The curve $\\bar E(\\rho)$ rises rapidly with density, approximatel...

Kaiser, N

2012-01-01

349

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

350

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

351

Hot nuclear matter in an extended Brueckner approach

International Nuclear Information System (INIS)

The properties of cold and hot nuclear matter are studied in the frame of the Brueckner theory, extended to finite temperature. The basic task is the evaluation of the two-hole line diagram using the Paris potential supplemented by the introduction of three-body forces, coming from the exchange of ? and rho mesons. The latter have an important saturating effect, but not sufficient to reach correct saturation. The latter is achieved by a phenomenological treatment. The properties of hot nuclear matter, for temperatures around 10 MeV, are investigated. Particular attention is paid to one-body properties. The density and temperature dependence of many quantities, like the single-particle energy spectrum, the optical potential, the effective mass, the non-locality of the single-particle field, the mean free path, is displayed and analyzed. The relative importance of the temperature dependence of the g-matrix and of phase space is investigated, especially in relation with the imaginary part of the optical potential and the mean free path. The temperature dependence of the effective mass is particularly studied. It is shown that the peak due to the so-called core polarization effect disappears rapidly as the matter is heated. The evaluation of the entropy and of the level density parameter a, which are closely related, is discussed, and the failure of the Hartree-Fock approach to reproduce the value of a correctly is explained. The two-body properties are also investigated. The temperature and density dependence of the two-body correlations are displayed. Particular attention is paid to the temperature dependence of the effective interaction. The latter is exhibited in a simple manner. It is shown that the effective force felt by low-energy nucleons does not change by more than a few percent when the temperature goes from 0 to 10 MeV. For high-energy nucleons, the change may be as large as 10%. (orig.)

352

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

353

Study of superfluidity in nuclear matter with quantum hadrodynamics

International Nuclear Information System (INIS)

We have closely investigated the superfluidity in nuclear matter with quantum hadrodynamics (QHD) paying attention particularly to the high-momentum behavior of the NN interaction adapted to the gap equation. We examined the effects of hadron mass decrease on superfluidity in symmetric nuclear matter. Such decrease of hadron masses, particularly of vector meson mass, is one of the hot issues with reference to partial restoration of chiral symmetry in hadronic physics. The Brown-Rho(BR) scaling is the outcome of studies by means of effective hadronic theories. For the sake of creditability and tractability, we have employed in medium Bonn potential proposed by Rapp et al., which was constructed in combination with the BR-scaling. Significant reduction of the paring gap is found with this potential in comparison with the case of the original Bonn-B potential. The resulting maximal gap is about 2.0 MeV. Using the meson theoretic potential reveals that the decrease of vector meson masses accounts for this significant reduction. Next, we have constructed phenomenologically the relativistic particle-particle channel interaction for the gap equation by introducing a momentum-cutoff in the form of simple sudden cutoff at the upper bound of the momentum-space integrals, and of the familiar form factors inserted at the vertices. One additional parameter, cutoff ?, is determined so as to minimize the difference of the paring properties between the RMF interaction and the Bonn-Between the RMF interaction and the Bonn-B potential. The latter is treated as a pseudo-experimental input for the fit. In relativistic Hartree-Bogoliubov (RHB) calculation, it is shown that the paring properties obtained from Bonn-B potential are reproduced each by sudden cutoff, monopole, and dipole form factor in a wide and physically relevant density range. Furthermore the resulting cutoff ? has a qualitatively physical value in spite of simplicity of the method. Our results stated above strongly support the past observation that the high-momentum components of the original RMF interaction should be refined to obtain accurate properties of superfluidity in nuclear matter. (S.Y.)

354

...EA-09-147, NRC-2010- 0028] In the Matter of Beta Gamma Nuclear Radiology; Confirmatory Order Modifying License (Effective Immediately) I Beta Gamma Nuclear Radiology (BGNR) (Licensee) is the holder of medical License No....

2010-01-29

355

Constraints on the equation of state of cold dense matter from nuclear physics and astrophysics

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Brussels-Montreal equations of state of cold dense nuclear matter that have been recently developed are tested against various constraints coming from both nuclear physics and astrophysics. The nuclear physics constraints include the analysis of nuclear flow and kaon production in heavy-ion collision experiments, as well as recent microscopic many-body calculations of infinite homogeneous neutron matter. Astrophysical observations, especially recent neutron-star mass measurements, provide...

2014-01-01

356

Liquid-gas instability and superfluidity in nuclear matter

We study effects of the medium polarization on superfluidity in symmetric nuclear matter in a relativistic formalism. An effect of the liquid-gas instability is emphasized. We examine two types of decomposition of the nucleon propagator; the standard Feynman-density and the particle-hole-antiparticle ones. In both cases, the medium polarization effect is determined by a characteristic cancellation among the \\sigma, the longitudinal \\omega, and the \\sigma-\\omega mixed polarizations. The instability leads to increase of pairing gap. Around the saturation density that is free from the instability the medium polarization enhances pairing gap in the former case whereas reduces in the latter. At the lowest density that is also free from the instability the gap increases in both cases.

Matsuzaki, M

2006-01-01

357

Covariant Feynman rules at finite temperature: Application to nuclear matter

International Nuclear Information System (INIS)

A unified treatment of relativistic many-body systems at finite temperature and density, incorporating both real- and imaginary-time formalisms, is applied to hadronic field theories of nuclear matter (quantum hadrodynamics). Covariant Feynman rules are given, which permit direct calculations in any convenient reference frame or in manifestly covariant form. The real-time rules are illustrated by the derivation of covariant expressions for the one-loop energy-momentum tensor. Next, the partition function is evaluated at one-loop order, which yields the thermodynamic potential and pressure in covariant form and verifies the virial theorem. Finally, covariant imaginary-time rules are shown to reproduce the real-time one-loop calculations

358

Unstable three dimensional nuclear matter in stochastic mean field approach

International Nuclear Information System (INIS)

A semi-classical stochastic mean-field approach is discussed. In the case of unstable infinite nuclear matter, the characteristic time of the exponential growing of fluctuations and the diffusion coefficients associated to the unstable modes are calculated in the framework of the Boltzmann-Langevin theory. In order to make realistic 3D calculations feasible, the complicated Boltzmann-Langevin theory is suggested to be replaced by a simpler stochastic meanfield approach corresponding to a standard Boltzmann evolution, complemented by a simple noise chosen to reproduce the dynamics of the most unstable modes. Finally, it is explained how to approximately implement this method by simply tuning the noise associated to the use of a finite number of test particles in Boltzmann-like calculations. (authors) 17 refs., 5 figs

359

Unstable infinite nuclear matter in stochastic mean field approach

International Nuclear Information System (INIS)

In this article, we consider a semiclassical stochastic mean-field approach. In the case of unstable infinite nuclear matter, we calculate the characteristic time of the exponential growing of fluctuations and the diffusion coefficients associated to the unstable modes, in the framework of the Boltzmann-Langevin theory. These two quantities are essential to describe the dynamics of fluctuations and instabilities since, in the unstable regions, the evolution of the system will be dominated by the amplification of fluctuations. In order to make realistic 3D calculations feasible, we suggest to replace the complicated Boltzmann-Langevin theory by a simpler stochastic mean-field approach corresponding to a standard Boltzmann evolution, complemented by a simple noise chosen to reproduce the dynamics of the most unstable modes. Finally we explain how to approximately implement this method by simply tuning the noise associated to the use of a finite number of test particles in Boltzman-like calculations

360

Resilience of nuclear matter in light ion induced reactions

International Nuclear Information System (INIS)

Cavitation and heating of the target nucleus in the first instances of 3He-induced collisions in the GeV/u range are investigated in an intranuclear cascade model for the formation of this structure and a stochastic one-body dynamics calculation to study its evolution. The hard collisions having essentially ceased when the structure is fully developed, the latter model is particularly suited to study the possible break-up of the system. It is shown, however, that the target recovers a spherical shape rather rapidly, and has thus a good chance to decay by standard evaporation, justifying the use of a cascade + evaporation model to analyze the data. It is also shown that the system should be modified to break up into pieces instead of recovering a compact shape: in these reactions, it is thus expected that nuclear matter is resilient to shape deformation and thermal excitation. (author)

361

$\\rho$ - meson spectral function in hot nuclear matter

We study the $\\rho$-meson spectral function in hot nuclear matter by taking into account the isospin-symmetric pion and the nucleon loops within the quantum hadrodynamics (QHD) model as well as using an effective chiral SU(3) model. The spectral function of the $\\rho$ meson is studied in the mean field approximation (MFA) as well as in the relativistic Hartree (RHA) approximation. The inclusion of the nucleon loop considerably changes the $\\rho$-meson spectral function. Due to a larger mass drop of $ \\rho $ meson in the RHA, it is seen that the spectral function shifts towards the low invariant mass region, whereas in the MFA the spectral function is seen to be slightly shifted towards the high mass region. Moreover, while the spectral function is observed to be sharper with the nucleon-antinucleon polarization in RHA, the spectral function is seen to be broader in the MFA.

Bhageerathi, P C Raje

2010-01-01

362

Quark-based description of nuclear matter with simulated annealing

We calculate ground-state properties of a many-quark system in the string-flip model using variational Monte Carlo methods. The many-body potential energy of the system is determined by finding the optimal grouping of quarks into hadrons. This (optimal) assignment problem is solved by using the stochastic optimization technique of simulated annealing. Results are presented for the energy and length-scale for confinement as a function of density. These results show how quarks clustering decreases with density and characterize the nuclear- to quark-matter transition. We compare our results to a previously published work with a similar model which uses, instead, a pairing approach to the optimization problem.

Frichter, G M; Frichter, George M.

1993-01-01

363

A constraint for saturation binding energy in nuclear matter

International Nuclear Information System (INIS)

In Dirac-Brueckner-Hartree-Fock calculations for nuclear matter, the average binding energy per nucleon versus density curve is not uniquely defined if coupling to anti-particles is neglected. The requirement that the nucleon separation energy equal the Fermi energy at saturation density, i.e. Hugenholtz-Van Hove (HV) theorem, places a constraint on the possible curves obtainable. We have developed a new self-consistency scheme for the RBBG theory by applying the HV theorem which guarantees the first law of thermodynamics at the saturation point. Using the Bonn interaction, we show that making the phenomenological choice that the binding energy per nucleon is -15.8 MeV leads to momentum-independent self-energies and effective mass, at a density of 1.41 fm-1, consistent with previous calculations. (orig.)

364

A constraint for saturation binding energy in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

In Dirac-Brueckner-Hartree-Fock calculations for nuclear matter, the average binding energy per nucleon versus density curve is not uniquely defined if coupling to anti-particles is neglected. The requirement that the nucleon separation energy equal the Fermi energy at saturation density, i.e. Hugenholtz-Van Hove (HV) theorem, places a constraint on the possible curves obtainable. We have developed a new self-consistency scheme for the RBBG theory by applying the HV theorem which guarantees the first law of thermodynamics at the saturation point. Using the Bonn interaction, we show that making the phenomenological choice that the binding energy per nucleon is -15.8 MeV leads to momentum-independent self-energies and effective mass, at a density of 1.41 fm{sup -1}, consistent with previous calculations. (orig.).

Lee, Y.J.; Nuppenau, C.; MacKellar, A.D. (Kentucky Univ., Lexington (USA). Dept. of Physics and Astronomy)

1989-11-20

365

Quantum Vacuum in Hot Nuclear Matter A Nonperturbative Treatment

We derive the equation of state for hot nuclear matter using Walecka model in a nonperturbative formalism. We include here the vacuum polarisation effects arising from the nucleon and scalar mesons through a realignment of the vacuum. A ground state structure with baryon-antibaryon condensates yields the results obtained through the relativistic Hartree approximation (RHA) of summing baryonic tadpole diagrams. Generalization of such a state to include the quantum effects for the scalar meson fields through the $\\sigma$-meson condensates amounts to summing over a class of multiloop diagrams. The techniques of thermofield dynamics (TFD) method are used for the finite temperature and finite density calculations. The in-medium nucleon and sigma meson masses are also calculated in a self consistent manner. We examine the liquid-gas phase transition at low temperatures ($\\approx$ 20 MeV), as well as apply the formalism to high temperatures to examine for a possible chiral symmetry restoration phase transition.

Mishra, A K; Greiner, W; Mishra, Amruta

2001-01-01

366

A new state of nuclear matter observed in transfer reactions

International Nuclear Information System (INIS)

The cross section curves for the formation, at the barrier, of trans-target isotopes of a heavy element by bombardment of a heavy target with various heavy ions, and those for the formation of isotopes of a superheavy element by complete fusion projectile and target, both are similar to the distribution of the neutron number N of a fission fragment around its most probable value. This situation suggests that nucleons are transferred according to one and the same law in the fission reaction and in the transfer reactions: This law results from the creation of a new state of nuclear matter, having a lifetime of only 0.17 yoctosecond, and causing uncertainties in the neutron number N of the product amounting to 2.54 atomic mass unit, as measured by J. Terrell in his study of the prompt neutron emission.

367

Collective expansion of hot and compressed nuclear matter

International Nuclear Information System (INIS)

Central collisions of Au + Au at incident energies of 90, 150, 250 and 400 A· MeV were studied with the complete FOPI - facility at GSI Darmstadt. The complete phase space distributions at 250 A· MeV confirms the spherical symmetry. The energies corresponding to the onset of collective expansion and side-flow are obtained and compared with the transition energies at which the azimuthal distributions show a change from in-plane to out-of-plane enhancement. A semianalytical model for the expansion and clusterization of hot and compressed nuclear matter is used to explain some of the experimental trends. Modulation of the mean value and the slope of the energy spectra for different fragments as a function of azimuth is evidenced for mid-central collisions. (authors)

368

Temperature dependence of the response function of hot nuclear matter

International Nuclear Information System (INIS)

The description of collective motion in nuclei at finite temperature using the framework of the random phase approximation is discussed. We focus on the special case of the isovector response function of hot nuclear matter using various effective Skyrme interactions. For such interactions analytic expressions for the response function were derived. From these analytic formulae we shown that one can gain an understanding of the temperature dependence of the giant dipole resonance in finite nuclei. We showed that zero sound type modes become less collective as temperature rises and sometimes disappear at temperatures of a few MeV. We also shown that for effective interactions with an effective mass close to unite, collective effects are small already at zero temperature and depend weakly on temperature. We will thus argue that the temperature dependence of the giant dipole resonance provides valuable information on the effective interactions. (authors)

369

Directory of Open Access Journals (Sweden)

Full Text Available One of the most interesting application of the many-body methods to the nuclear physics is the calculation of the properties of the nuclear matter, especially its binding energy. In this paper, we have studied the influence of ? -isobar on the properties of the symmetrical nuclear matter using the lowest order constrained variational (LOCV method with the V28 potential. It is shown that the inclusion of ?- isobar substantially affect the saturation properties of the symmetrical nuclear matter. We have shown that, at low (high densities, the saturation curve of nuclear matter is shifted downward (upward. This is due to the fact that the repulsive effect of the V28 potential increases by increasing density. It is seen that the equation of state of nuclear matter with the V28 potential is much harder than those with the A V14 potential.

G. H. Bordbar

2001-12-01

370

Test of the nuclear matter G-matrix interaction in nuclear structure calculations

International Nuclear Information System (INIS)

A nuclear matter G-matrix interaction, based on the one-boson exchange model for the nuclear force, has been tested in the description of collective excited states of nuclei. It is explicitly demonstrated that this interaction leads to an instability in heavier nuclei such as 208Pb when used as effective particle-hole interaction within the framework of the random-phase approximation. The necessity to include two-particle-two-hole processes in a consistent way is discussed in a schematic model. (orig.)

371

Symmetry Energy of Nuclear Matter at Low Densities and Clustering at the Nuclear Surface

International Nuclear Information System (INIS)

We present a density functional theory which connects nuclear matter equation of state, which incorporates clustering at low densities, with clustering in medium and heavy nuclei at the nuclear surface. This explains the large values of symmetry energy reported by Natowitz et al for densities ?3 in addition to the binding energies and charge rms radii of 367 spherical nuclei. The present theory which is partly macroscopic competes with other high quality microscopic-macroscopic approaches. Merits of the results with clustering and no-clustering are discussed. We also make connection with realistic interactions (AV18+UIX/IL2) which have been used in ab initio calculations in s- and p-shell nuclei and neutron matter. Theory predicts new situations and regimes to be explored both theoretically and experimentally. It is demonstrated that, due to clustering, the neutron skin thickness reduces significantly.

372

Directory of Open Access Journals (Sweden)

Full Text Available We review on a novel chiral power counting scheme for in-medium chiral perturbation theory with nucleons and pions as degrees of freedom. It allows for a systematic expansion taking into account local as well as pion-mediated inter-nucleon interactions. Based on this power counting, one can identify classes of nonperturbative diagrams that require a resummation. As a method for performing those resummations we review on the techniques of Unitary Chiral Pertubation Theory for nucleon-nucleon interactions. We then apply both power counting and non-perturbative methods to the example of calculating the pion self-energy in asymmetric nuclear matter up-to-and-including next-to-leading order. It is shown that the leading corrections involving in-medium nucleon-nucleon interactions cancel between each other at given chiral orders.

Oller J.A.

2010-04-01

373

Short-range correlations in quark and nuclear matter

Energy Technology Data Exchange (ETDEWEB)

In the first part of this thesis, the role of short-range correlations in quark matter is explored within the framework of the Nambu-Jona-Lasinio model. Starting from a next-to-leading order expansion in the inverse number of the quark colors, a fully self-consistent model constructed that employs the close relations between spectral functions and self-energies. In contrast to the usual quasiparticle approximations, this approach allows the investigation of the collisional broadening of the quark spectral function. Numerical calculations at various chemical potentials and zero temperature show that the short-range correlations do not only induce a finite width of the spectral function but also have some influence on the structure of the chiral phase transition. In the second part of this thesis, the temperature and density dependence of the nucleon spectral function in symmetric nuclear matter is investigated. The short-range correlations can be well described by a simple, self-consistent model on the one-particle-two-hole and two-particle-one-hole level (1p2h, 2p1h). The thermodynamically consistent description of the mean-field properties of the nucleons is ensured by incorporating a Skyrme-type potential. Calculations at temperatures and densities that can also be found in heavy-ion collisions or supernova explosions and the formation of neutron stars show that the correlations saturate at high temperatures and densities. (orig.)

Froemel, Frank

2007-06-15

374

Short-range correlations in quark and nuclear matter

International Nuclear Information System (INIS)

In the first part of this thesis, the role of short-range correlations in quark matter is explored within the framework of the Nambu-Jona-Lasinio model. Starting from a next-to-leading order expansion in the inverse number of the quark colors, a fully self-consistent model constructed that employs the close relations between spectral functions and self-energies. In contrast to the usual quasiparticle approximations, this approach allows the investigation of the collisional broadening of the quark spectral function. Numerical calculations at various chemical potentials and zero temperature show that the short-range correlations do not only induce a finite width of the spectral function but also have some influence on the structure of the chiral phase transition. In the second part of this thesis, the temperature and density dependence of the nucleon spectral function in symmetric nuclear matter is investigated. The short-range correlations can be well described by a simple, self-consistent model on the one-particle-two-hole and two-particle-one-hole level (1p2h, 2p1h). The thermodynamically consistent description of the mean-field properties of the nucleons is ensured by incorporating a Skyrme-type potential. Calculations at temperatures and densities that can also be found in heavy-ion collisions or supernova explosions and the formation of neutron stars show that the correlations saturate at high temperatures and densities. (

375

Nuclear binding energy and symmetry energy of nuclear matter with modern nucleon-nucleon potentials

The binding energy of nuclear matter at zero temperature in the Brueckner-Hartree-Fock approximation with modern nucleon-nucleon potentials is studied. Both the standard and continuous choices of single particle energies are used. These modern nucleon-nucleon potentials fit the deuteron properties and are phase shifts equivalent. Comparison with other calculations is made. In addition we present results for the symmetry energy obtained with different potentials, which is of great importance in astrophysical calculation.

Hassaneen, Kh. S. A.; Abo-Elsebaa, H. M.; Sultan, E. A.; Mansour, H. M. M.

2011-03-01

376

For transport model simulations of collisions between two nuclei which have $N/Z$ significantly different from unity one needs a one-body potential which is both isospin and momentum dependent. This work provides sets of such potentials.

Das, C B; Gale, C; Li, B A; Li, Bao-An

2003-01-01

377

Quantum Corrections on Relativistic Mean Field Theory for Nuclear Matter

International Nuclear Information System (INIS)

We propose a quantization procedure for the nucleon-scalar meson system, in which an arbitrary mean scalar meson field ? is introduced. The equivalence of this procedure with the usual one is proven for any given value of ?. By use of this procedure, the scalar meson field in the Walecka's MFA and in Chin's RHA are quantized around the mean held. Its corrections on these theories are considered by perturbation up to the second order. The arbitrariness of ? makes us free to fix it at any stage in the calculation. When we fix it in the way of Walecka's MFA, the quantum corrections are big, and the result does not converge. When we fix it in the way of Chin's RHA, the quantum correction is negligibly small, and the convergence is excellent. It shows that RHA covers the leading part of quantum field theory for nuclear systems and is an excellent zeroth order approximation for further quantum corrections, while the Walecka's MFA does not. We suggest to fix the parameter ? at the end of the whole calculation by minimizing the total energy per-nucleon for the nuclear matter or the total energy for the finite nucleus, to make the quantized relativistic mean field theory (QRMFT) a variational method. (general)

378

Quantum Corrections on Relativistic Mean Field Theory for Nuclear Matter

We propose a quantization procedure for the nucleon-scalar meson system, in which an arbitrary mean scalar meson field varphi is introduced. The equivalence of this procedure with the usual one is proven for any given value of varphi. By use of this procedure, the scalar meson field in the Walecka's MFA and in Chin's RHA are quantized around the mean held. Its corrections on these theories are considered by perturbation up to the second order. The arbitrariness of varphi makes us free to fix it at any stage in the calculation. When we fix it in the way of Walecka's MFA, the quantum corrections are big, and the result does not converge. When we fix it in the way of Chin's RHA, the quantum correction is negligibly small, and the convergence is excellent. It shows that RHA covers the leading part of quantum field theory for nuclear systems and is an excellent zeroth order approximation for further quantum corrections, while the Walecka's MFA does not. We suggest to fix the parameter varphi at the end of the whole calculation by minimizing the total energy per-nucleon for the nuclear matter or the total energy for the finite nucleus, to make the quantized relativistic mean field theory (QRMFT) a variational method.

Zhang, Qi-Ren; Gao, Chun-Yuan

2011-05-01

379

Quantum Molecular Dynamics Approach to the Nuclear Matter Below the Saturation Density

Digital Repository Infrastructure Vision for European Research (DRIVER)

Quantum molecular dynamics is applied to study the ground state properties of nuclear matter at subsaturation densities. Clustering effects are observed as to soften the equation of state at these densities. The structure of nuclear matter at subsaturation density shows some exotic shapes with variation of the density.

Maruyama, Toshiki; Niita, Koji; Oyamatsu, Kazuhiro; Maruyama, Tomoyuki; Chiba, Satoshi; Iwamoto, Akira

1997-01-01

380

The effect of an incipient pion condensate on the effective mass in nuclear matter

International Nuclear Information System (INIS)

The effect of soft spin-isospin density excitations of short wavelength (incipient pion condensate) on the effective mass in nuclear matter is investigated. The effective mass is found to decrease rapidly with density. This raises the threshold for pion condensation in symmetric nuclear matter considerably. (Auth.)

381

Directional Search for Isospin-Violating Dark Matter with Nuclear Emulsion

Some of direct dark matter searches reported not only positive signals but also annual modulation of the signal event. However, the parameter spaces have been excluded by other experiments. Isospin violating dark matter solves the contradiction by supposing different coupling to proton and neutron. We study the possibility to test the favored parameter region by isospin violating dark matter model with the future detector of dark matter using the nuclear emulsion. Since the nuclear emulsion detector has directional sensitivity, the detector is expected to examine whether the annual modulations observed other experiments is caused by dark matter or background signals.

Nagao, Keiko I

2012-01-01

382

International Nuclear Information System (INIS)

Non-destructive analytical methods based on interactions of nuclear radiation with matter are overviewed in this chapter of the textbook. The three major categories discussed are Moessbauer spectroscopy based on the nuclear resonance absorption of gamma radiation, positronium chemistry developed from the study of the interaction of positive beta radiation with matter, and the chemistry of muonium and muonic atoms connected with the interaction of mesons with matter. (R.P.)

383

Self-consistent tensor effects on nuclear matter system under relativistic Hartree-Fock approach

With the relativistic representation of the nuclear tensor force that is included automatically by the Fock diagrams, we explored the self-consistent tensor effects on the properties of nuclear matter system. The analysis were performed within the density-dependent relativistic Hartree-Fock (DDRHF) theory. The tensor force is found to notably influence the saturation mechanism, the equation of state and the symmetry energy of nuclear matter, as well as the neutron star properties. Without introducing any additional free parameters, the DDRHF approach paves a natural way to reveal the tensor effects on the nuclear matter system.

Jiang, Li Juan; Dong, Jian Min; Long, Wen Hui

2014-01-01

384

Functional renormalization group approach to neutron matter

The chiral nucleon-meson model, previously applied to systems with equal number of neutrons and protons, is extended to asymmetric nuclear matter. Fluctuations are included in the framework of the functional renormalization group. The equation of state for pure neutron matter is studied and compared to recent advanced many-body calculations. The chiral condensate in neutron matter is computed as a function of baryon density. It is found that, once fluctuations are incorporated, the chiral restoration transition for pure neutron matter is shifted to high densities, much beyond three times the density of normal nuclear matter.

Drews, Matthias; Weise, Wolfram

2014-11-01

385

Shear viscosity of hot nuclear matter by the mean free path method

Digital Repository Infrastructure Vision for European Research (DRIVER)

The shear viscosity of hot nuclear matter is investigated by using the mean free path method within the framework of IQMD model. Finite size nuclear sources at different density and temperature are initialized based on the Fermi-Dirac distribution. The results show that shear viscosity to entropy density ratio decreases with the increase of temperature and tends toward a constant value for $\\rho\\sim\\rho_0$, which is consistent with the previous studies on nuclear matter form...

Fang, D. Q.; Ma, Y. G.; Zhou, C. L.

2014-01-01

386

General properties of the pion production reaction in nuclear matter

Energy Technology Data Exchange (ETDEWEB)

The pion production reaction {pi}{sup +}{yields}{pi}{sup +}{pi}{sup {+-}} on {sup 45}Sc was studied at incident pion energies of T{sub {pi}{sup +}}=240, 260, 280, 300, and 320 MeV. The experiment was performed using the M11 pion-channel at TRIUMF, and multiparticle events, ({pi}{sup +},{pi}{sup +}{pi}{sup {+-}}) and ({pi}{sup +},{pi}{sup +}{pi}{sup {+-}}p), were detected with the CHAOS spectrometer. Results are reported in the form of both differential and total cross sections, and are compared to theoretical predictions and the reaction phase space. The present investigation of the T-dependence of the {pi}{sup +}A{yields}{pi}{sup +}{pi}{sup {+-}}A' reaction complements earlier examinations of the A-dependence of the reaction, which was measured using {sup 2}H, {sup 4}He, {sup 12}C, {sup 16}O, {sup 40}Ca, and {sup 208}Pb targets at {approx}280 MeV. Some general properties of the pion-induced pion production reaction in nuclear matter will be presented, based on the combined results of the two studies.

Camerini, P.; Fragiacomo, E.; Grion, N. E-mail: nevio.grion@ts.infn.it; Piano, S.; Rui, R.; Clark, J.; Felawka, L.; Gibson, E.F.; Hofman, G.; Mathie, E.L.; Meier, R.; Moloney, G.; Ottewell, D.; Raywood, K.; Sevior, M.E.; Smith, G.R.; Tacik, R

2004-04-19

387

Nuclear techniques and the particulate matter pollution in big harbours

International Nuclear Information System (INIS)

The impact of big harbours on the air quality is in important issue both from the environmental and the economical point of view. The harbour of Genoa is the largest in Italy and one of the major ports of the Mediterranean. We have determined the fraction of Particulate Matter (P M) concentration in town due to the heavy oil combustion of the diesel engines of the vessels in the harbour. This turned out to be 12% in P M10 and 25% in P M2.5 and P M1, with about 85% of the P M from this source concentrated in particles with aerodynamic diameter, D-ac < 1 ?m. We could also point out a link between concentration peaks of the tracers of heavy oil combustion (V and Ni) and the ferryboats traffic. The key toot in this work was the coupling between particular sampling devices and some Ion Beam Analysis (IBA) techniques, in particular Particle Induced X-ray Emission (PIXE), which belong to the broader category of nuclear techniques in applied physics.

388

Resilience of nuclear matter in light ion induced reactions

International Nuclear Information System (INIS)

Cavitation and heating of the target nucleus in the first instances of 3He-induced collisions in the GeV/nucleon range are investigated in an intranuclear cascade model for the formation of this structure and a stochastic one-body dynamics calculation to study its evolution. The hard collisions having essentially ceased when the structure is fully developed, the latter model is particularly suited to study the possible breakup of the system. It is shown, however, that the target recovers a spherical shape rather rapidly, and has thus a good chance to decay by standard evaporation, justifying the use of a cascade + evaporation model to analyze the data. It is also shown that the system has to be much more modified to break up into pieces instead of recovering a compact shape: in these reactions, it is thus expected that nuclear matter is resilient to shape deformation and thermal excitation. Arguments are given to explain that expansion of the system, not important in these reactions, is required to overcome this resilience. copyright 1997 The American Physical Society

389

Spin instabilities of infinite nuclear matter and effective tensor interactions

We study the effects of the tensor force, present in modern effective nucleon-nucleon interactions, in the spin instability of nuclear and neutron matter. Stability conditions of the system against certain very low energy excitation modes are expressed in terms of Landau parameters. It is shown that in the spin case, the stability conditions are equivalent to the condition derived from the spin susceptibility, which is obtained as the zero-frequency and long-wavelength limit of the spin response function calculated in the Random Phase Approximation. Zero-range forces of the Skyrme type and finite-range forces of M3Y and Gogny type are analyzed. It is shown that for the Skyrme forces considered, the tensor effects are sizeable, and tend to increase the spin instability which appears at smaller densities than in the case that the tensor is not taken into account. On the contrary, the tensor contribution of finite range forces to the spin susceptibility is small or negligible for both isospin channels of symmetr...

Navarro, J

2013-01-01

390

The Brueckner G matrix for a slab of nuclear matter

International Nuclear Information System (INIS)

The Brueckner theory G matrix is investigated for the slab geometry. A method of calculating the G matrix in a slab of nuclear matter is developed for the case of a separate form of the NN-interaction potential. In particular, the separable representation of the Paris potential is used. The singlet 1S0 and triplet 3S1-3D1 channels are examined. The mixed coordinate-momentum representation is used, the momentum one in the slab plane and the coordinate one, in the perpendicular direction. The complete Hilbert space is split onto a rather small model subspace and the complementary one. The 2-particle propagators are considered explicitly in the model space, whereas the local-potential approximation is used in the complementary one. This approximation was suggested previously for treating the effective pairing interaction. Numerical calculations are carried out for the case of the model space constructed from the negative energy single-particle states. The G matrix contains a parametric dependence on the two-particle energy E and the total perpendicular momentum Pperpendicular. Keeping in mind the subsequent use of the G matrix for evaluating the Landau-Migdal interaction amplitude, we fix the value of E =- 2?, where ? is the chemical potential of the system under consideration. The detailed calculations were made for the value of Pperpendicular = 0. The contribution of nonzero values of Pperpendicular is evaluated. A pronounced ? dependence of the G matrix in the surface region is demonstrated

391

A new explanation to the cold nuclear matter effects in heavy ion collisions

The J/Psi cross section ratios of p-A/p-p under different collision energy is calculated with cold nuclear matter effects redefined in this paper. The advantage of these new definitions is that all cold nuclear matter effects have clear physical origins.The radios are compared with the corresponding experiment data and that calculated with classic nuclear effects. The ratios calculated with new definitions can reproduce almost all existing J/Psi measurements in p-A collisions more accuratly than that calculated with classic nuclear effects. Hence, this paper presents a new approach to explain cold nuclear effects in the hardproduction of quarkonium.

Liu, Zhi-Feng

2014-01-01

392

Formation of hot, dense matter in fast nuclear collisions

International Nuclear Information System (INIS)

scillations of the expanding dense quark matter may lead to pulsed emission of matter. These oscillating quark blobs may explain the abnormally enhanced geometrical cross sections observed recently in secondary collisions of projectile fragments with target nuclei. (author)

393

We report on microscopic calculations of the nuclear and neutron matter equations of state at zero temperature obtained from NLO, N$^2$LO, and N$^3$LO (next-to-next-to-next-to-leading order) nucleon-nucleon forces derived within the framework of chiral effective field theory. The leading N$^2$LO chiral three-nucleon force, with low-energy constants $c_D$ and $c_E$ fitted in the present work to reproduce the binding energies of $^3$H and $^3$He as well as the beta-decay lifetime of $^3$H, is also taken into account. The energy per particle of nuclear and neutron matter is then computed in the particle-particle ladder approximation up to densities several times that of saturated nuclear matter. We focus attention on the order-by-order convergence of the predicted nuclear and neutron matter equations of state, as well as the symmetry energy. Our study assesses the relevance of missing higher-order contributions in the chiral expansion that provide an important source of uncertainty not normally considered in nuc...

Sammarruca, F; Holt, J W; Itaco, N; Machleidt, R; Marcucci, L E

2014-01-01

394

Pressure ensemble and dense nuclear matter with finite size nucleons at zero temperature

International Nuclear Information System (INIS)

The aim of this study is to find the equations of state of dense nuclear matter near the phase transition to quark-gluon-plasma. The effect of finite particle volume on the equation of state is calculated for both a hard sphere and a variable size particle Fermi gas using the pressure ensemble formalism in statistical physics and the MIT bag model. It is found that for high baryon densities only the variable volume description of the nuclear gas yields physically sensible results in that P/? < 1/3. The equations of state of nuclear matter at several times normal nuclear density show properties similar to those found by other methods

395

Constraints on the equation of state of cold dense matter from nuclear physics and astrophysics

Directory of Open Access Journals (Sweden)

Full Text Available The Brussels-Montreal equations of state of cold dense nuclear matter that have been recently developed are tested against various constraints coming from both nuclear physics and astrophysics. The nuclear physics constraints include the analysis of nuclear flow and kaon production in heavy-ion collision experiments, as well as recent microscopic many-body calculations of infinite homogeneous neutron matter. Astrophysical observations, especially recent neutron-star mass measurements, provide valuable constraints on the high-density part of the equation of state that is not accessible in laboratory experiments.

Fantina A. F.

2014-03-01

396

Energy Technology Data Exchange (ETDEWEB)

This book contains 102 scientific contributions in the areas of nuclear and condensed matter physics. The conference was attended by 144 physicists, most of them belonging to the Sicilian Universities of Palermo, Catania and Messina.

Messina, A. [ed.

2000-12-31

397

Nuclear matter equation of state including few-nucleon correlations $(A\\leq 4)$

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. Moreover, the contribution of continuum states to the equation of state is considered. The effect of correlations within the nuclear medium on the quasiparticle energies is estimated. The properties of light clusters and continuum correlations in dense matter are of interest for nuclear structure calculations, heavy ion collisions, and for astrophysical applications such as the formation of neutron stars in core-collapse supernovae.

Röpke, G

2014-01-01

398

Nuclear receptors (NRs) regulate gene expression through DNA- and ligand-binding and thus represent crucial therapeutic targets. The ultraspiracle protein/ecdysone receptor (USP/EcR) complex binds to half-sites with a one base pair spaced inverted repeat (IR1), a palindromic DNA response element (RE) reminiscent of IRs observed for vertebrate steroid hormone receptors. Here we present the cryo electron microscopy structure of the USP/EcR complex bound to an IR1 RE which provides the first description of a full IR-bound NR complex. The structure reveals that even though the DNA is almost symmetric, the complex adopts a highly asymmetric architecture in which the ligand-binding domains (LBDs) are positioned 5' off-centred. Additional interactions of the USP LBD with the 5'-flanking sequence trigger transcription activity as monitored by transfection assays. The comparison with DR-bound NR complexes suggests that DNA is the major allosteric driver in inversely positioning the LBDs, which serve as the main binding-site for transcriptional regulators. PMID:24942373

Maletta, Massimiliano; Orlov, Igor; Roblin, Pierre; Beck, Yannick; Moras, Dino; Billas, Isabelle M L; Klaholz, Bruno P

2014-01-01

399

Fractal structure of near-threshold quarkonium production off cold nuclear matter

We investigate near-threshold production of quarkonium resonances in cold nuclear matter through a scaling theory with two exponents which are fixed by existing data on near-threshold J/psi production in proton-nucleus collisions. Interestingly, it seems possible to extend one of the multifractal dimensions to the production of other mesons in cold nuclear matter. The scaling theory can be tested and refined in experiments at the upcoming high-intensity FAIR accelerator complex in GSI.

Bhaduri, Partha Pratim

2013-01-01

400

The Collective Excitation Spectra of $\\sigma, \\omega$ and $\\pi$ Mesons in Nuclear Matter

The recent progress on the study of the collective excitation in relativistic nuclear matter is reviewed. The collective excitation modes are derived by meson propagators in nuclear matter. The mesons we study are $\\sigma, řmega, particle - hole, delta - hole excitations but also antiparticle excitations, such as particle - antiparticle, antidelta - particle, delta - antiparticle excitations. By calculating the dispersion relation and the spin - isospin dependent response function, the effects of all these excitation are studied.

Liu, L

1999-01-01

401

The phase diagram of nuclear and quark matter at high baryon density

We review theoretical approaches to explore the phase diagram of nuclear and quark matter at high baryon density. We first look over the basic properties of quantum chromodynamics (QCD) and address how to describe various states of QCD matter. In our discussions on nuclear matter we cover the relativistic mean-field model, the chiral perturbation theory, and the approximation based on the large-Nc limit where Nc is the number of colors. We then explain the liquid-gas phase transition and the inhomogeneous meson condensation in nuclear matter with emphasis put on the relevance to quark matter. We commence the next part focused on quark matter with the bootstrap model and the Hagedorn temperature. Then we turn to properties associated with chiral symmetry and exposit theoretical descriptions of the chiral phase transition. There emerge some quark-matter counterparts of phenomena seen in nuclear matter such as the liquid-gas phase transition and the inhomogeneous structure of the chiral condensate. The third reg...

Fukushima, Kenji

2013-01-01

402

Does nuclear fragmentation explore the gas-liquid phase transition of nuclear matter

International Nuclear Information System (INIS)

The phase space of channels is calculated into which a nucleus may decay after being hit by a proton with Esub(p) > 10 GeV. Special care is given to the finite size of the system and to the Coulomb interaction between the fragments. Both effects are shown to be of crucial and dominant importance. At a temperature of 4-5 MeV the target decays into many fragments simultaneously. The mass yields is reproduced by the model over the entire mass range. Monte Carlo simulations show that also the energy spectra may realistically be reproduced and the slope parameter (the apparent temperature) Tsub(app) is --2 times larger than the true temperature. This is due to considerable fluctuations in the number of fragments and in their mutual Coulomb-interaction. The gasliquid phase transition in nuclear matter is dramatically modified by these finite size and strong Coulomb effects. Some general features of this transition are discussed. (author)

403

Energy Technology Data Exchange (ETDEWEB)

Various {sup 2}H and {sup 31}P nuclear magnetic resonance (NMR) spectroscopy techniques are applied to probe the component dynamics of the binary glass former tripropyl phosphate (TPP)/polystyrene-d{sub 3} (PS) over the full concentration range. The results are quantitatively compared to those of a dielectric spectroscopy (DS) study on the same system previously published [R. Kahlau, D. Bock, B. Schmidtke, and E. A. Rössler, J. Chem. Phys. 140, 044509 (2014)]. While the PS dynamics does not significantly change in the mixtures compared to that of neat PS, two fractions of TPP molecules are identified, one joining the glass transition of PS in the mixture (?{sub 1}-process), the second reorienting isotropically (?{sub 2}-process) even in the rigid matrix of PS, although at low concentration resembling a secondary process regarding its manifestation in the DS spectra. Pronounced dynamical heterogeneities are found for the TPP ?{sub 2}-process, showing up in extremely stretched, quasi-logarithmic stimulated echo decays. While the time window of NMR is insufficient for recording the full correlation functions, DS results, covering a larger dynamical range, provide a satisfactory interpolation of the NMR data. Two-dimensional {sup 31}P NMR spectra prove exchange within the broadly distributed ?{sub 2}-process. As demonstrated by {sup 2}H NMR, the PS matrix reflects the faster ?{sub 2}-process of TPP by performing a spatially highly hindered motion on the same timescale.

Bock, D.; Kahlau, R.; Pötzschner, B.; Körber, T.; Wagner, E.; Rössler, E. A., E-mail: ernst.roessler@uni-bayreuth.de [Experimentalphysik II, Universität Bayreuth, 95440 Bayreuth (Germany)

2014-03-07

404

International Nuclear Information System (INIS)

Various 2H and 31P nuclear magnetic resonance (NMR) spectroscopy techniques are applied to probe the component dynamics of the binary glass former tripropyl phosphate (TPP)/polystyrene-d3 (PS) over the full concentration range. The results are quantitatively compared to those of a dielectric spectroscopy (DS) study on the same system previously published [R. Kahlau, D. Bock, B. Schmidtke, and E. A. Rössler, J. Chem. Phys. 140, 044509 (2014)]. While the PS dynamics does not significantly change in the mixtures compared to that of neat PS, two fractions of TPP molecules are identified, one joining the glass transition of PS in the mixture (?1-process), the second reorienting isotropically (?2-process) even in the rigid matrix of PS, although at low concentration resembling a secondary process regarding its manifestation in the DS spectra. Pronounced dynamical heterogeneities are found for the TPP ?2-process, showing up in extremely stretched, quasi-logarithmic stimulated echo decays. While the time window of NMR is insufficient for recording the full correlation functions, DS results, covering a larger dynamical range, provide a satisfactory interpolation of the NMR data. Two-dimensional 31P NMR spectra prove exchange within the broadly distributed ?2-process. As demonstrated by 2H NMR, the PS matrix reflects the faster ?2-process of TPP by performing a spatially highly hindered motion on the same timescale

405

Asymmetric radiation of seismic waves from an atoll: nuclear tests in French Polynesia

Seismic records of nuclear tests detonated in the Mururoa Atoll in French Polynesia show large unpredicted arrivals 2.2 and 4.5 seconds (X1 and X2) after the P-wave at the Australian Warramunga Array. These arrivals are not observed at the Canadian Yellowknife Array. X1 and X2 are also absent on Warramunga Array recordings of tests carried out at the Fangataufa Atoll situated 40 km SSE of Mururoa. Array analysis shows that X1 and X2 are produced within the source area. The layered crustal structure of the atoll, significant local inhomogeneities, and focusing effects due to the elongated shape and the steep flanks of the Mururoa Atoll are most likely responsible for X1 and X2. The form of Mururoa (28 × 10 km) and its East-West orientation is due to its location on the Austral Fracture Zone (AFZ). The Fangataufa Atoll on the other hand is almost circular (10 km diameter) and is unaffected by the dynamics along the AFZ. Our observations demonstrate that complicated structures in the source area can significantly alter the wave field at teleseismic distances and produce a large magnitude (mb) bias. A better understanding of the exact cause of these unusual seismic observations will only become possible, if the coordinates of the tests and information on the detailed 3-D structure of the atolls are released.

Weber, Michael; Wicks, Charles W., Jr.; Krüger, Frank; Jahnke, Gunnar; Schlittenhardt, Jörg

1998-01-01

406

Computational methods for the nuclear and neutron-matter problems. Progress report

International Nuclear Information System (INIS)

A new proposal for a nuclear matter/nucleus wavefunction to allow the application of Monte Carlo methods to nuclear structure problems is described. Work on calculating the binding energy of a droplet of a few 3He or 4He atoms is discussed. Also, research on choosing optimal nodal surfaces is discussed

407

Nuclear matter saturation point and symmetry energy with modern nucleon-nucleon potentials

We determine the saturation properties of nuclear matter within the Brueckner-Hartree-Fock approach based on a large set of modern nucleon-nucleon potentials and confirm the validity of the Coester band. The improvement of the saturation point when including nuclear three-body forces is pointed out and comparison with the Dirac-Brueckner-Hartree-Fock results is made.

Li, Z. H.; Lombardo, U.; Schulze, H.-J.; Zuo, W.; Chen, L. W.; Ma, H. R.

2006-10-01

408

Fraunhofer diffraction of coherent and incoherent nuclear matter waves by complementary screens

The analogy between Fraunhofer diffraction effects observed in nuclear and subnuclear collisions and those observed with light diffracted by complementary screens is revisited. Emphasis will be put on the collision mechanisms playing a role analogous to that of an aperture in light diffraction. These analogies are illustrated with examples involving coherent and incoherent nuclear matter waves.

da Silveira, R.; Leclercq-Willain, Ch.

2013-06-01

409

Dynamical self-consistent description of exotic structures in nuclear matter at subnuclear densities

We investigate the occurrence of exotic structures in nuclear matter at subnuclear densities within the framework of the dywan model. This approach, developed ab initio for the description of nuclear collisions, is a microscopic dynamical approach in which the numerical treatment makes use of wavelet representation techniques. Before tackling the effects of multi-particle correlations on the overall dynamics, we focused the present work on the study of cold matter within a pure mean field description. Starting from inhomogeneous initial conditions provided by an arrangement of nuclei located on an initial crystalline lattice, the exotic structures result from the dynamical self-consistent evolution. The nuclear system can freely self-organize, it can modify or even break the lattice structure and the initial symmetries of matter distribution. This approach goes beyond the Wigner-Seitz approximation and no assumption of final shapes of matter is made. In this framework, different effects, as the sensitivity of...

de la Mota, Virginia; Figerou, Sébastien

2010-01-01

410

Clusterized nuclear matter in the (proto-)neutron star crust and the symmetry energy

Though generally agreed that the symmetry energy plays a dramatic role in determining the structure of neutron stars and the evolution of core-collapsing supernovae, little is known in what concerns its value away from normal nuclear matter density and, even more important, the correct definition of this quantity in the case of unhomogeneous matter. Indeed, nuclear matter traditionally addressed by mean-field models is uniform while clusters are known to exist in the dilute baryonic matter which constitutes the main component of compact objects outer shells. In the present work we investigate the meaning of symmetry energy in the case of clusterized systems and the sensitivity of the proto-neutron star composition and equation of state to the effective interaction. To this aim an improved Nuclear Statistical Equilibrium (NSE) model is developed, where the same effective interaction is consistently used to determine the clusters and unbound particles energy functionals in the self-consistent mean-field approxi...

Raduta, Ad R; Gulminelli, F

2013-01-01

411

International Nuclear Information System (INIS)

Production and discharge rates of radioactive matter from nuclear power plants are described. Off-air, vent and filtersystems are discussed. Based on the amounts of radiactive matter released to the atmosphere it was concluded that the technological facilities for the retention of such matter within nuclear power plants are sufficient.

412

Equation of state for superdense nuclear matter is considered in the framework of relativistic mean-field theory, when the scalar-isovector -meson effective field is taken into account, as well. Assuming that the transition to the strange quark matter is a usual first-order phase transition described by Maxwells construction, the changes of the parameters of phase transition caused by the presence of -meson field are investigated. To describe a quark phase the advanced version of the MIT bag model is used, in which the interactions between quarks are taken into account in the one-gluon exchange approximation. For different values of the bag constant B, some series of the equations of the state of matter with deconfinement phase transition are constructed. Also the upper bound, Bcr, corresponding to the unstable state of the infinitizimal quark core in a neutron star is found.

Alaverdyan, G

2008-01-01

413

Energy Technology Data Exchange (ETDEWEB)

Dielectric spectroscopy as well as {sup 2}H and {sup 31}P nuclear magnetic resonance spectroscopy (NMR) are applied to probe the component dynamics of the binary glass former tripropyl phosphate (TPP)/polystyrene (PS/PS-d{sub 3}) in the full concentration (c{sub TPP}) range. In addition, depolarized light scattering and differential scanning calorimetry experiments are performed. Two glass transition temperatures are found: T{sub g1}(c{sub TPP}) reflects PS dynamics and shows a monotonic plasticizer effect, while the lower T{sub g2}(c{sub TPP}) exhibits a maximum and is attributed to (faster) TPP dynamics, occurring in a slowly moving or immobilized PS matrix. Dielectric spectroscopy probing solely TPP identifies two different time scales, which are attributed to two sub-ensembles. One of them, again, shows fast TPP dynamics (?{sub 2}-process), the other (?{sub 1}-process) displays time constants identical with those of the slow PS matrix. Upon heating the ?{sub 1}-fraction of TPP decreases until above some temperature T{sub c} only a single ?{sub 2}-population exists. Inversely, below T{sub c} a fraction of the TPP molecules is trapped by the PS matrix. At low c{sub TPP} the ?{sub 2}-relaxation does not follow frequency-temperature superposition (FTS), instead it is governed by a temperature independent distribution of activation energies leading to correlation times which follow Arrhenius laws, i.e., the ?{sub 2}-relaxation resembles a secondary process. Yet, {sup 31}P NMR demonstrates that it involves isotropic reorientations of TPP molecules within a slowly moving or rigid matrix of PS. At high c{sub TPP} the super-Arrhenius temperature dependence of ?{sub 2}(T), as well as FTS are recovered, known as typical of the glass transition in neat systems.

Kahlau, R.; Bock, D.; Schmidtke, B.; Rössler, E. A., E-mail: ernst.roessler@uni-bayreuth.de [Experimentalphysik II, Universität Bayreuth, 95440 Bayreuth (Germany)

2014-01-28

414

International Nuclear Information System (INIS)

Dielectric spectroscopy as well as 2H and 31P nuclear magnetic resonance spectroscopy (NMR) are applied to probe the component dynamics of the binary glass former tripropyl phosphate (TPP)/polystyrene (PS/PS-d3) in the full concentration (cTPP) range. In addition, depolarized light scattering and differential scanning calorimetry experiments are performed. Two glass transition temperatures are found: Tg1(cTPP) reflects PS dynamics and shows a monotonic plasticizer effect, while the lower Tg2(cTPP) exhibits a maximum and is attributed to (faster) TPP dynamics, occurring in a slowly moving or immobilized PS matrix. Dielectric spectroscopy probing solely TPP identifies two different time scales, which are attributed to two sub-ensembles. One of them, again, shows fast TPP dynamics (?2-process), the other (?1-process) displays time constants identical with those of the slow PS matrix. Upon heating the ?1-fraction of TPP decreases until above some temperature Tc only a single ?2-population exists. Inversely, below Tc a fraction of the TPP molecules is trapped by the PS matrix. At low cTPP the ?2-relaxation does not follow frequency-temperature superposition (FTS), instead it is governed by a temperature independent distribution of activation energies leading to correlation times which follow Arrhenius laws, i.e., the ?2-relaxation resembles a secondary process. Yet, 31P NMR demonstrates that it involves isotropic reorientations of TPP molecules within a slowly moving or rigid matrix of PS. At high cTPP the super-Arrhenius temperature dependence of ?2(T), as well as FTS are recovered, known as typical of the glass transition in neat systems

415

The matter of probability controlling melting of nuclear ship reactor

International Nuclear Information System (INIS)

In the first part of this work beside description of split power, power of radioactivity disintegration and afterpower and its ability to extinguish, the genera condition of melting nuclear reactor core and its detailed versions were described. This paper also include the description of consequences melting nuclear reactor core both in case of stationary and mobile (ship) reactor and underline substantial differences. Next, fulfilled with succeed, control under melting of stationary nuclear reactor core was characterized.The middle part describe author's idea of controlling melting of nuclear ship reactor core. It is based on: - the suggestion of prevention pressure's untightness in safety tank of nuclear ship reactor by '' corium '' - and the suggestion of preventing walls of this tank from melting by '' corium ''. In the end the technological and construction barriers of the prevention from melting nuclear ship reactor and draw conclusions was presented. (author)

416

The PHENIX experiment has measured open heavy-flavor production via semileptonic decay over the transverse momentum range 1 < p(T) < 6??GeV/c at forward and backward rapidity (1.4 < |y| < 2.0) in d+Au and p + p collisions at ?sNN = 200??GeV. In central d+Au collisions, relative to the yield in p + p collisions scaled by the number of binary nucleon-nucleon collisions, a suppression is observed at forward rapidity (in the d-going direction) and an enhancement at backward rapidity (in the Au-going direction). Predictions using nuclear-modified-parton-distribution functions, even with additional nuclear-p(T) broadening, cannot simultaneously reproduce the data at both rapidity ranges, which implies that these models are incomplete and suggests the possible importance of final-state interactions in the asymmetric d + Au collision system. These results can be used to probe cold-nuclear-matter effects, which may significantly affect heavy-quark production, in addition to helping constrain the magnitude of charmonia-breakup effects in nuclear matter. PMID:25014805

Adare, A; Aidala, C; Ajitanand, N N; Akiba, Y; Akimoto, R; Al-Bataineh, H; Al-Ta'ani, H; Alexander, J; Andrews, K R; Angerami, A; Aoki, K; Apadula, N; Appelt, E; Aramaki, Y; Armendariz, R; Aschenauer, E C; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Bannier, B; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Ben-Benjamin, J; Bennett, R; Bhom, J H; Blau, D S; Bok, J S; Boyle, K; Brooks, M L; Broxmeyer, D; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Campbell, S; Caringi, A; Castera, P; Chen, C-H; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Conesa Del Valle, Z; Connors, M; Csanád, M; Csörg?, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Dayananda, M K; Denisov, A; Deshpande, A; Desmond, E J; Dharmawardane, K V; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; D'Orazio, L; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Gal, C; Garishvili, I; Glenn, A; Gong, H; Gong, X; Gonin, M; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grim, G; Grosse Perdekamp, M; Gunji, T; Guo, L; Gustafsson, H-Ĺ; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Harper, C; Hashimoto, K; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Hollis, R S; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hori, Y; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Iinuma, H; Ikeda, Y; Imai, K; Inaba, M; Iordanova, A; Isenhower, D; Ishihara, M; Issah, M; Ivanischev, D; Iwanaga, Y; Jacak, B V; Jia, J; Jiang, X; Jin, J; John, D; Johnson, B M; Jones, T; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kamin, J; Kaneti, S; Kang, B H; Kang, J H; Kang, J S; Kapustinsky, J; Karatsu, K; Kasai, M; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kikuchi, J; Kim, A; Kim, B I; Kim, D J; Kim, E-J; Kim, Y-J; Kim, Y K; Kinney, E; Kiss, A; Kistenev, E; Kleinjan, D; Kline, P; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kotov, D; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K B; Lee, K S; Lee, S H; Lee, S R; Leitch, M J; Leite, M A L; Li, X; Lichtenwalner, P; Liebing, P; Lim, S H; Linden Levy, L A; Liška, T; Liu, H; Liu, M X; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Malik, M D; Manion, A; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; McGlinchey, D; McKinney, C; Means, N; Mendoza, M; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Miki, K; Milov, A; Mitchell, J T; Miyachi, Y; Mohanty, A K; Moon, H J; Morino, Y; Morreale, A; Morrison, D P; Motschwiller, S; Moukhanova, T V; Murakami, T; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nam, S; Newby, J; Nguyen, M; Nihashi, M; Nouicer, R; Nyanin, A S; Oakley, C; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, B H; Park, I H; Park, S K; Park, W J; Pate, S F; Patel, L; Pei, H; Peng, J-C; Pereira, H; Peressounko, D Yu; Petti, R; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Qu, H; Rak, J; Ravinovich, I; Read, K F; Rembeczki, S; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Ruži?ka, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sarsour, M; Sato, T; Savastio, M; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shim, H H; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slune?ka, M; Sodre, T; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sun, J; Sziklai, J; Takagui, E M; Takahara, A; Taketani, A; Tanabe, R; Tanaka, Y; Taneja, S; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tennant, E; Themann, H; Thomas, D; Thomas, T L; Togawa, M; Toia, A; Tomášek, L; Tomášek, M; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Utsunomiya, K; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Virius, M; Vossen, A; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Watanabe, Y S; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Woody, C L; Wright, R M; Wysocki, M

2014-06-27

417

The link between non-linear chiral effective Lagrangians and the Walecka model description of bulk nuclear matter [1] is questioned. This fact is by itself due to the Mean Field Approximation (MFA) which in nuclear mater makes the picture of a nucleon-nucleon interaction based on scalar(vector) meson exchange, equivalent to the description of a nuclear matter based on attractive and repulsive contact interactions. We present a linear chiral model where this link between the Walecka model and an underlying to chiral symmetry realization still holds, due to MFA.

Delfino, A; Frederico, T

1996-01-01

418

International Nuclear Information System (INIS)

The link between non-linear chiral effective Lagrangians and the Walecka model description of bulk nuclear matter is questioned. This fact is by itself due to the Mean Field Approximation (MFA) which in nuclear mater makes the picture of a nucleon-interaction based on scalar (vector) meson exchange equivalent to the description of a nuclear matter based on attractive and repulsive contact interactions. We present a linear chiral model where this link between the Walecka model and an underlying to chiral symmetry realization still holds, due to MFA. (author)

419

Unified description of equation of state and transport properties of nuclear matter

Digital Repository Infrastructure Vision for European Research (DRIVER)

Correlated basis function perturbation theory and the formalism of cluster expansions have been recently employed to obtain an effective interaction from a state-of-the-art nucleon nucleon potential model. The approach based on the effective interaction allows for a consistent description of the nuclear matter ground state and nucleon-nucleon scattering in the nuclear medium. This paper reports the the results of numerical calculations of different properties of nuclear and ...

Benhar, Omar; Farina, Nicola; Fiorilla, Salvatore; Valli, Marco

2008-01-01

420

A beyond-mean-field example with zero-range effective interactions in infinite nuclear matter

Zero-range effective interactions are commonly used in nuclear physics to describe a many-body system in the mean-field framework. If they are employed in beyond- mean-field models, an artificial ultraviolet divergence is generated by the zero-range of the interaction. We analyze this problem in symmetric nuclear matter with the t0-t3 Skyrme model. In this case, the second-order energy correction diverges linearly with the momentum cutoff. After that, we extend the work to the case of nuclear matter with the full Skyrme interaction. A strong divergence related to the velocity-dependent terms of the interaction is obtained. Moreover, a global fit can be simultaneously performed for both symmetric and nuclear matter with different neutron-to-proton ratios. These results pave the way for applications to finite nuclei in the framework of beyond mean-field theories.

Moghrabi, K; Roca-Maza, X; Coló, G; Van Giai, N; 10.1051/epjconf/20123806002

2013-01-01

421

Brueckner Theory of Nuclear Matter with Nonnucleonic Degrees of Freedom and Relativity

For the past 40 years, Brueckner theory has proven to be a most powerful tool to investigate systematically models for nuclear matter. I will give an overview of the work done on nuclear matter theory, starting with the simplest model and proceeding step by step to more sophisticated models by extending the degrees of freedom and including relativity. The final results of a comprehensive hadronic theory of nuclear matter are compared to the predictions by currently fashionable two-nucleon force models. It turns out that a two-nucleon force can, indeed, reproduce those results if the potential is nonlocal, since nonlocality is an inherent quality of the more fundamental fieldtheoretic approach. This nonlocality is crucial for creating sufficient nuclear binding.

Machleidt, R

1999-01-01

422

The particle-hole interaction and pion condensation in nuclear matter

International Nuclear Information System (INIS)

Following a general introduction in chapter one, the second chapter describes the calculation of the pion p-wave self-energy in nuclear matter. This quantity represents the amount of binding a pion gains by interacting with the medium. The third chapter exploits the formalism developed to work out a simple conclusion which can be drawn from the general notion of the divergence of a series of diagrams. Clearly, if the pion propagator in the medium develops a pole at some density, this implies that the one-pion-exchange NN interaction in the medium will be drastically modified. In Chapter four, the contribution to the binding energy of nuclear matter is calculated for a special set of diagrams - ring diagrams. Finally, in chapter five the low and intermediate momentum components of the nuclear matter G matrix which are relevant for nuclear structure, are studied. (Auth.)

423

From nuclear matter to finite nuclei. I. Parametrization of the Dirac-Brueckner G matrix

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

424

In this contribution, we review the most important physics presented originally in our recent publications. Some new analyses, insights and perspectives are also provided. We showed recently that the symmetry energy $E_{sym}(\\rho)$ and its density slope $L(\\rho)$ at an arbitrary density $\\rho$ can be expressed analytically in terms of the magnitude and momentum dependence of the single-nucleon potentials using the Hugenholtz-Van Hove (HVH) theorem. These relationships provide new insights about the fundamental physics governing the density dependence of nuclear symmetry energy. Using the isospin and momentum (k) dependent MDI interaction as an example, the contribution of different terms in the single-nucleon potential to the $E_{sym}(\\rho)$ and $L(\\rho)$ are analyzed in detail at different densities. It is shown that the behavior of $E_{sym}(\\rho)$ is mainly determined by the first-order symmetry potential $U_{sym,1}(\\rho,k)$ of the single-nucleon potential. The density slope $L(\\rho)$ depends not only on th...

Xu, Chang; Chen, Lie-Wen

2013-01-01

425

International Nuclear Information System (INIS)

In this contribution, we review the most important physics presented originally in our recent publications. Some new analyses, insights and perspectives are also provided. We showed recently that the symmetry energy Esym (?) and its density slope L(?) at an arbitrary density ? can be expressed analytically in terms of the magnitude and momentum dependence of the single-nucleon potentials using the Hugenholtz-Van Hove (HVH) theorem. These relationships provide new insights about the fundamental physics governing the density dependence of nuclear symmetry energy. Using the isospin and momentum (k) dependent MDI interaction as an example, the contribution of different terms in the single-nucleon potential to the Esym (?) and L(?) are analyzed in detail at different densities. It is shown that the behavior of Esym is mainly determined by the first-order symmetry potential Usym,1(?, k) of the single-nucleon potential. The density slope L(?) depends not only on the first-order symmetry potential Usym,1(?, k) but also on the second-order one Usym,2(?, k). Both the Usym,1(?, k) and Usym,2(?, k) at normal density ? 0 are constrained by the isospin- and momentum-dependent nucleon optical potential extracted from the available nucleon-nucleus scattering data. The Usym,2(?, k) especially at high density and momentum affects significantly the L(?), but it is theoretically poorly understood and currently there is almost no experimental constraints known. (orig.)

426

From nuclear reactions to compact stars: a unified approach

An equation of state (EoS) for symmetric nuclear matter is constructed using the density dependent M3Y effective interaction and extended for isospin asymmetric nuclear matter. Theoretically obtained values of symmetric nuclear matter incompressibility, isobaric incompressibility, symmetry energy and its slope agree well with experimentally extracted values. Folded microscopic potentials using this effective interaction, whose density dependence is determined from nuclear matter calculations, provide excellent descriptions for proton, alpha and cluster radioactivities, elastic and inelastic scattering. The nuclear deformation parameters extracted from inelastic scattering of protons agree well with other available results. The high density behavior of symmetric and asymmetric nuclear matter satisfies the constraints from the observed flow data of heavy-ion collisions. The neutron star properties studied using $\\beta$-equilibrated neutron star matter obtained from this effective interaction for pure hadronic m...

Basu, D N; Mishra, Abhishek

2014-01-01

427

Effective interaction: From nuclear reactions to neutron stars

An equation of state (EoS) for symmetric nuclear matter is constructed using the density dependent M3Y effective interaction and extended for isospin asymmetric nuclear matter. Theoretically obtained values of symmetric nuclear matter incompressibility, isobaric incompressibility, symmetry energy and its slope agree well with experimentally extracted values. Folded microscopic potentials using this effective interaction, whose density dependence is determined from nuclear matter calculations, provide excellent descriptions for proton, alpha and cluster radioactivities, elastic and inelastic scattering. The nuclear deformation parameters extracted from inelastic scattering of protons agree well with other available results. The high density behavior of symmetric and asymmetric nuclear matter satisfies the constraints from the observed flow data of heavy-ion collisions. The neutron star properties studied using $\\beta$-equilibrated neutron star matter obtained from this effective interaction reconcile with the ...

Basu, D N

2013-01-01

428

Energy Technology Data Exchange (ETDEWEB)

In this contribution, we review the most important physics presented originally in our recent publications. Some new analyses, insights and perspectives are also provided. We showed recently that the symmetry energy E{sub sym} (?) and its density slope L(?) at an arbitrary density ? can be expressed analytically in terms of the magnitude and momentum dependence of the single-nucleon potentials using the Hugenholtz-Van Hove (HVH) theorem. These relationships provide new insights about the fundamental physics governing the density dependence of nuclear symmetry energy. Using the isospin and momentum (k) dependent MDI interaction as an example, the contribution of different terms in the single-nucleon potential to the E{sub sym} (?) and L(?) are analyzed in detail at different densities. It is shown that the behavior of E{sub sym} is mainly determined by the first-order symmetry potential U{sub sym,1}(?, k) of the single-nucleon potential. The density slope L(?) depends not only on the first-order symmetry potential U{sub sym,1}(?, k) but also on the second-order one U{sub sym,2}(?, k). Both the U{sub sym,1}(?, k) and U{sub sym,2}(?, k) at normal density ? {sub 0} are constrained by the isospin- and momentum-dependent nucleon optical potential extracted from the available nucleon-nucleus scattering data. The U{sub sym,2}(?, k) especially at high density and momentum affects significantly the L(?), but it is theoretically poorly understood and currently there is almost no experimental constraints known. (orig.)

Xu, Chang [Nanjing University, Department of Physics