Downloads & Free Reading Options - Results

The motion of massive test particles in dark matter is studied. It is shown that if the energy density of the dark matter making up a galactic halo has a large $r$ behavior of $1/r^2$, then contrary to intuition the motion of these test particles are not govern by Newtonian gravity, but rather by the equations of geodesic motion from Einstein's theory of general relativity. Moreover, the rotational velocity curves of orbiting massive test particles in this energy density do not approach a constant value at large $r$ but will instead always increase with the radius of the orbit $r_c$.

Effects of the inhomogeneous matter density on the three-generation neutrino oscillation probability are analyzed. Realistic profile of the matter density is expanded into a Fourier series. Taking in the Fourier modes one by one, we demonstrate that each mode has its corresponding target energy. The high Fourier mode selectively modifies the oscillation probability of the low-energy region. This rule is well described by the parametric resonance between the neutrino oscillation and the matter effect. The Fourier analysis gives a simple guideline to systematically control the uncertainty of the oscillation probability caused by the uncertain density of matter. Precise analysis of the oscillation probability down to the low-energy region requires accurate evaluation of the Fourier coefficients of the matter density up to the corresponding high modes.

Analytical and geometrical properties of generalized power-law (GPL) density profiles are investigated in detail. In particular, a one-to-one correspondence is found between mathematical parameters and geometrical parameters. Then GPL density profiles are compared with simulated dark haloes (SDH) density profiles, and nonlinear least-absolute values and least-squares fits involving the above mentioned five parameters (RFSM5 method) are prescribed. More specifically, the sum of absolute values or squares of absolute logarithmic residuals is evaluated on a large number of points making a 5-dimension hypergrid, through a few iterations. The size is progressively reduced around a fiducial minimum, and superpositions on nodes of earlier hypergrids are avoided. An application is made to a sample of 17 SDHs on the scale of cluster of galaxies, within a flat $\Lambda$CDM cosmological model (Rasia et al. 2004). In dealing with the mean SDH density profile, a virial radius, averaged over the whole sample, is assigned, which allows the calculation of the remaining parameters. Using a RFSM5 method provides a better fit with respect to other methods. No evident correlation is found between SDH dynamical state (relaxed or merging) and asymptotic inner slope of the logarithmic density profile or (for SDH comparable virial masses) scaled radius. Mean values and standard deviations of some parameters are calculated, and a comparison with previous results is made with regard to the scaled radius. A certain degree of degeneracy is found in fitting GPL to SDH density profiles. If it is intrinsic to the RFSM5 method or it could be reduced by the next generation of high-resolution simulations, still remains an open question.

Recent years have seen extensive applications of the Nambu--Jona-Lasinio (NJL) model in the study of matter at high density. There is a good deal of interest in the predictions of diquark condensation and color superconductivity, with suggested applications to the study the properties of neutron stars. As the researchers in this field note, the NJL model does not describe confinement, so that one is limited to the study of the deconfined phase, which may set in at several times nuclear matter density. Recently, we have extended the NJL model to include a covariant confinement model. In the present work our goal is to include a phenomenological model of deconfinement at finite matter density, using some analogy to what is known concerning "string breaking" and deconfinement at finite temperature. Various models may be used, but for this work we choose a specific model for the density dependence of the parameters of our confining interaction. We perform relativistic random-phase-approximation (RPA) calculations of the properties of the $\pi(138), K(495), f_0(980), a_0(980)$ and $K_0^*(1430)$ mesons and their radial excitations. In the model chosen for this work, there are no mesonic states beyond about $2\rho_{NM}$, where $\rho_{NM}$ is the density of nuclear matter. This inability of the model to support hadronic excitations at large values of the density is taken as a signal of deconfinement. In addition to the density dependence of the confining interaction, we use the density-dependent quark mass values obtained in either the SU(2) or SU(3)-flavor versions of the NJL model.

Recent years have seen extensive applications of the Nambu--Jona-Lasinio (NJL) model in the study of matter at high density. There is a good deal of interest in the predictions of diquark condensation and color superconductivity, with suggested applications to the study the properties of neutron stars. As the researchers in this field note, the NJL model does not describe confinement, so that one is limited to the study of the deconfined phase, which may set in at several times nuclear matter density. Recently, we have extended the NJL model to include a covariant confinement model. In the present work our goal is to include a phenomenological model of deconfinement at finite matter density, using some analogy to what is known concerning "string breaking" and deconfinement at finite temperature. Various models may be used, but for this work we choose a specific model for the density dependence of the parameters of our confining interaction. We perform relativistic random-phase-approximation (RPA) calculations of the properties of the $\pi(138), K(495), f_0(980), a_0(980)$ and $K_0^*(1430)$ mesons and their radial excitations. In the model chosen for this work, there are no mesonic states beyond about $2\rho_{NM}$, where $\rho_{NM}$ is the density of nuclear matter. This inability of the model to support hadronic excitations at large values of the density is taken as a signal of deconfinement. In addition to the density dependence of the confining interaction, we use the density-dependent quark mass values obtained in either the SU(2) or SU(3)-flavor versions of the NJL model.

Rotation curves of galaxies show a wide range of shapes, which can be paramaterized as scatter in Vrot(1kpc)/Vmax i.e.the ratio of the rotation velocity measured at 1kpc and the maximum measured rotation velocity. We examine whether the observed scatter can be accounted for by combining scatters in disc scale-lengths, the concentration-halo mass relation, and the M*-Mhalo relation. We use these scatters to create model galaxy populations; when housed within dark matter halos that have universal, NFW density profiles, the model does not match the lowest observed values of Vrot(1kpc)/Vmax and has too little scatter in Vrot(1kpc)/Vmax compared to observations. By contrast, a model using a mass dependent dark matter profile, where the inner slope is determined by the ratio of M*/Mhalo, produces galaxies with low values of Vrot(1kpc)/Vmax and a much larger scatter, both in agreement with observation. We conclude that the large observed scatter in Vrot(1kpc)/Vmax favours density profiles that are significantly affected by baryonic processes. Alternative dark matter core formation models such as SIDM may also account for the observed variation in rotation curve shapes, but these observations may provide important constraints in terms of core sizes, and whether they vary with halo mass and/or merger history.

We study the propagation of the light mesons sigma, omega, rho, and a0(980) in dense hadronic matter in an extended derivative scalar coupling model. Within the scheme proposed it is possible to unambiguously define effective density-dependent couplings at the Lagrangian level. We first apply the model to study asymmetric nuclear matter with fixed isospin asymmetry, and then we pay particular attention to hypermatter in beta-equilibrium. The equation of state and the potential contribution to the symmetry coefficient arising from the mean field approximation are investigated.

The group theory framework developed by Fukutome for a systematic analysis of the various broken symmetry types of Hartree-Fock solutions exhibiting spin structures is here extended to the general many body context using spinor-Green function formalism for describing magnetic systems. Consequences of this theory are discussed for examining the magnetism of itinerant electrons in nanometric systems of current interest as well as bulk systems where a vector spin-density form is required, by specializing our work to spin-density-functional formalism. We also formulate the linear response theory for such a system and compare and contrast them with the recent results obtained for localized electron systems. The various phenomenological treatments of itinerant magnetic systems are here unified in this group-theoretical description.

For a class of viable cosmological models in $f(R)$ gravity which deviation from the Einstein gravity decreases as a inverse power law of the Ricci scalar $R$ for large $R$, an analytic solution for density perturbations in the matter component during the matter dominated stage is obtained in terms of hypergeometric functions. An analytical expression for the matter transfer function at scales much less than the present Hubble scale is also obtained.

Formalism for a unified description of distinct superfluid phases of a deconfined QCD matter at finite density together with the phase of spontaneously broken chiral symmetry is presented. Dispersion laws of the quasiquark excitations in both diamagnetic and ferromagnetic phases with spontaneously broken chiral symmetry are exhibited explicitly.

We present the solution of the time development of an unstable initial density perturbation in the linearized Vlasov equation, completing the previous analysis in the literature. The additional contributions found are usually damped and can be neglected at large times in the unstable region. The work clarifies also the problem of the normalization of the solution with respect to the initial perturbation of the density.

We propose in this article that if the chemical potential exceeds a critical value in dense hadronic medium, a first-order phase transition to a new state of matter with Lorentz symmetry spontaneously broken (in addition to the explicit breaking) takes place. As a consequence, light vector mesons get excited as ``almost'' Goldstone bosons. Since the light vector mesons dominantly couple to photons, the presence of these new vector mesons could lead to an enhancement in the dilepton production from dense medium at an invariant mass lower than the free-space vector-meson mass. We provide a low-energy quark model which demonstrates that the above scenario is a generic case for quark theories with a strong interaction in the vector channel. We discuss possible relevance of this phase to the phenomenon of the enhanced dilepton production at low invariant masses in relativistic heavy-ion collisions.

A cosmological magnetic field affects the time evolution of the cosmic matter density field. The squared Alfven velocity of the cosmic fluid is proportional to an ensemble average energy density of a primordial magnetic field (PMF), and it prevents the matter density field from collapsing in the horizon scale. The matter-radiation equality time also is delayed by the presence of an ensemble average energy density of a PMF. The ensemble average energy density of the PMF also affects the matter power spectrum (MPS) through the Meszaros effect and the potential decay. Since the ensemble average energy density of the PMF is not a first order perturbation but a zero order source in the linear perturbation equations for the cosmology, to correctly understand the overall effects of the PMF on the MPS, we should significantly revise previous approaches to research for the MPS with the PMF by considering both the effects of the zero and first order sources from the PMF in the linear perturbation theory. We apply the effects of the zero order sources from the PMF to theoretical computations of the MPS for the first time. We also analyze the overall PMF effects on the MPS. The CMB polarizations are affected the weak lensing. The weak lensing is determined by the MPS. Therefore, we have to consider the zero order sources of the PMF to gain a correct understanding not only of the MPS but also the CMB polarization.

In this paper, we analyze the enthalpy, enthalpy energy density, thermodynamic volume, and the equation of state of a modified white hole. We obtain new possible mathematical connections with some sectors of Number Theory, Ramanujan Recurring Numbers, DN Constant and String Theory, that enable us to extract the quantum geometrical properties of these thermodynamic equations and the implication to the quantum vacuum spacetime geometry of our early universe as they act as the constraints to the nature of quantum gravity of the universe.

Here we examine the detectability of collisionless dark matter candidates that may constitute not all but only a subdominant component of galactic cold dark matter. We show that current axion searches are not suited for a subdominant component, while direct WIMP searches would not be severely affected by the reduced density. In fact, the direct detection rates of neutralinos stay almost constant even if neutralinos constitute 1% of the halo dark matter. Only for lower densities do the rates decrease with density. Even neutralinos accounting for only $10^{-4}$ of the local dark halo density are within proposed future discovery limits. We comment also on indirect WIMP searches.

It is shown that in the presence of a background magnetic field within solar interior a cavity for low frequency MHD eigen modes (with periods 1-10 days) near equatorial plane can arise. The lower boundary of the cavity coincides with the centre of the Sun while the upper one corresponds to the Alfven resonant layer where high accumulation of wave energy takes place. The localization and the width of the Alfven resonance layer are determined by: (i) the node number of eigen modes n = 1, 2,..., (ii) by the angle of oblique propagation of waves with respect to the magnetic field, and (iii) by a low magnitude of the background magnetic field itself, B=1-100 G. The amplitude of eigen oscillations in a resonant layer determines the density fluctuation value that is restricted through the imaginary part of eigen frequences. For large node numbers n>>1 there appear many narrow resonant layers where a neutrino propagates through a large density fluctuation \delta\rho/\rho with the oscillation length that is much bigger than the width of a resonant layer. It is shown that neutrino crosses many such bumps on the exponential background profile that motivates to consider these MHD waves as a plausible matter noise for the MSW solution to the Solar Neutrino Problem (SNP).

The pattern of acoustic peaks in the sub-horizon power spectrum of primordial density anisotropies at recombination can be naturally understood in the framework of standard Friedmann-Robertson-Walker cosmology (without inflation) as a consequence of the boundary conditions imposed by the causal horizon on the statistical two-points correlation functions: the sub-horizon spectrum is discrete (harmonic), with comoving modes located at $k_n = n \frac{\pi}{H^{-1}_{eq}}$, $n = 1,2,...$, because the causally connected patch of the universe at recombination is compact, with comoving radius $H^{-1}_{eq}$. The results presented in this paper complement those presented in [1], where it was shown that the scale invariance of the primordial density anisotropies over comoving scales of cosmological size is also a consequence of the boundary conditions imposed by causality. Together these results lay an appealing theoretical alternative to the inflationary paradigm as the ultimate answer for the origin of cosmological structures in standard cosmology.

Spatial correlation characteristics of the anomalous density matrix $\kappa$ in a slab of nuclear matter with the Paris and Argonne v18 forces are calculated. A detailed comparison with predictions of the effective Gogny force is made. It is found that the two realistic forces lead to very close results which are qualitatively similar to those for the Gogny force. At the same time, the magnitude of $\kappa$ for realistic forces is essentially smaller than the one for the Gogny force. The correlation characteristics are practically independent of the magnitude of $\kappa$ and turn out to be quite close for the three kinds of the force. In particular, all of them predict a small value of the local correlation length at the surface of the slab and a big one, inside. These results are in agreement with those obtained recently by Pillet at al. for finite nuclei with the Gogny force.

The dynamic response of asymmetric nuclear matter is studied by using a Time-Dependent Local Isospin Density (TDLIDA) approximation approach. Calculations are based on a local density energy functional derived by an Auxiliary Field Diffusion Monte Carlo (AFDMC) calculation of bulk nuclear matter. Three types of excited states emerge: collective states, a continuum of quasi-particle-quasi-hole excitations and unstable solutions. These states are analyzed and discussed for different values of the nuclear density $\rho$ and isospin asymmetry $\xi=(N-Z)/A$. An analytical expression of the compressibility as a function of $\rho$ and $\xi$ is derived which show explicitly an instability of the neutron matter around $\rho\simeq 0.09 fm^{-3}$ when a small fraction of protons is added to the system.

We have obtained two-dimensional velocity fields of the dwarf spiral galaxy NGC 2976 in Halpha and CO. The high spatial (~75 pc) and spectral (13 km/s and 2 km/s, respectively) resolution of these observations, along with our multicolor optical and near-infrared imaging, allow us to measure the shape of the density profile of the dark matter halo with good precision. We find that the total (baryonic plus dark matter) mass distribution of NGC 2976 follows a rho_tot ~ r^(-0.27 +/- 0.09) power law out to a radius of 1.8 kpc, assuming that the observed radial motions provide no support. The density profile attributed to the dark halo is even shallower, consistent with a nearly constant density of dark matter over the entire observed region. A maximal disk fit yields an upper limit to the K-band stellar mass-to-light ratio (M*/L_K) of 0.09^{+0.15}_{-0.08} M_sun/L_sun,K (including systematic uncertainties), with the caveat that for M*/L_K > 0.19 M_sun/L_sun,K the dark matter density increases with radius, which is unphysical. Assuming 0.10 M_sun/L_sun,K < M*/L_K < 0.19 M_sun/L_sun,K, the dark matter density profile lies between rho_dm ~ r^-0.17 and rho_dm ~ r^-0.01. Therefore, independent of any assumptions about the stellar disk or the functional form of the density profile, NGC 2976 does not contain a cuspy dark matter halo. We also investigate some of the systematic effects that can hamper rotation curve studies, and show that 1) longslit rotation curves are far more vulnerable to systematic errors than two-dimensional velocity fields, 2) NGC 2976 contains large radial motions at small radii, and 3) the Halpha and CO velocity fields of NGC 2976 agree within their uncertainties. [slightly abridged]

We compare the central mass concentration of Cold Dark Matter halos found in cosmological N-body simulations with constraints derived from the Milky Way disk dynamics and from the Tully-Fisher relation. For currently favored values of the cosmological parameters ($\Omega_0 \sim 0.3$; $\Lambda_0=1-\Omega_0 \sim 0.7$; $h \sim 0.7$; COBE- and cluster abundance-normalized $\sigma_8$; Big-Bang nucleosynthesis $\Omega_b$), we find that halos with circular velocities comparable to the rotation speed of the Galaxy have typically {\it three times} more dark matter inside the solar circle than inferred from observations of Galactic dynamics. Such high central concentrations of dark matter on the scale of galaxy disks also imply that stellar mass-to-light ratios much lower than expected from population synthesis models must be assumed in order to reproduce the zero-point of the Tully-Fisher relation. Indeed, even under the extreme assumption that {\it all} baryons in a dark halo are turned into stars, disks with conventional $I$-band stellar mass-to-light ratios ($M/L_I \sim 2 \pm 1 (M/L_I)_{\odot}$) are about two magnitudes fainter than observed at a given rotation speed. We examine several modifications to the $\Lambda$CDM model that may account for these discrepancies and conclude that agreement can only be accomplished at the expense of renouncing other major successes of the model. Reproducing the observed properties of disk galaxies thus appears to demand substantial revision to the currently most successful model of structure formation.

Flat density cores have been obtained for a limited number of clusters of galaxies by strong gravitational lensing. This paper explores the possibility that the degeneracy pressure of fermionic dark matter accounts for the flat top density profiles. This is a case study of A1689 for which the density profile has been obtained from the inner region out to 1Mpc by the combination of strong and weak lensing. In the case that the dark matter consists of the mixture of degenerate relic neutrinos and collisionless cold dark matter particles, the acceptable mass range for relic neutrinos is between 1 and 2 eV, if the ratio of the two kinds of dark matter particles is fixed to its cosmic value.

It is shown that the quark spin polarization may occur for each quark flavor by the use of the Nambu-Jona-Lasinio model with a tensor-type four-point interaction between quarks, while the two-flavor color superconducting phase in two-flavor case may be realized at high density quark matter.

We study how properties of discrete dark matter halos depend on halo environment, characterized by the mass density around the halos on scales from 0.5 to 16 $h^{-1}{\rm Mpc}$. We find that low mass halos (those less massive than the characteristic mass $M_{\rm C}$ of halos collapsing at a given epoch) in high-density environments have lower accretion rates, lower spins, higher concentrations, and rounder shapes than halos in median density environments. Halos in median and low-density environments have similar accretion rates and concentrations, but halos in low density environments have lower spins and are more elongated. Halos of a given mass in high-density regions accrete material earlier than halos of the same mass in lower-density regions. All but the most massive halos in high-density regions are losing mass (i.e., being stripped) at low redshifts, which causes artificially lowered NFW scale radii and increased concentrations. Tidal effects are also responsible for the decreasing spins of low mass halos in high density regions at low redshifts $z < 1$, by preferentially removing higher angular momentum material from halos. Halos in low-density regions have lower than average spins because they lack nearby halos whose tidal fields can spin them up. We also show that the simulation density distribution is well fit by an Extreme Value Distribution, and that the density distribution becomes broader with cosmic time.

We study how properties of discrete dark matter halos depend on halo environment, characterized by the mass density around the halos on scales from 0.5 to 16 $h^{-1}{\rm Mpc}$. We find that low mass halos (those less massive than the characteristic mass $M_{\rm C}$ of halos collapsing at a given epoch) in high-density environments have lower accretion rates, lower spins, higher concentrations, and rounder shapes than halos in median density environments. Halos in median and low-density environments have similar accretion rates and concentrations, but halos in low density environments have lower spins and are more elongated. Halos of a given mass in high-density regions accrete material earlier than halos of the same mass in lower-density regions. All but the most massive halos in high-density regions are losing mass (i.e., being stripped) at low redshifts, which causes artificially lowered NFW scale radii and increased concentrations. Tidal effects are also responsible for the decreasing spins of low mass halos in high density regions at low redshifts $z < 1$, by preferentially removing higher angular momentum material from halos. Halos in low-density regions have lower than average spins because they lack nearby halos whose tidal fields can spin them up. We also show that the simulation density distribution is well fit by an Extreme Value Distribution, and that the density distribution becomes broader with cosmic time.

We introduce a mass dependent density profile to describe the distribution of dark matter within galaxies, which takes into account the stellar-to-halo mass dependence of the response of dark matter to baryonic processes. The study is based on the analysis of hydrodynamically simulated galaxies from dwarf to Milky Way mass, drawn from the MaGICC project, which have been shown to match a wide range of disk scaling relationships. We find that the best fit parameters of a generic double power-law density profile vary in a systematic manner that depends on the stellar-to-halo mass ratio of each galaxy. Thus, the quantity Mstar/Mhalo constrains the inner ($\gamma$) and outer ($\beta$) slopes of dark matter density, and the sharpness of transition between the slopes($\alpha$), reducing the number of free parameters of the model to two. Due to the tight relation between stellar mass and halo mass, either of these quantities is sufficient to describe the dark matter halo profile including the effects of baryons. The concentration of the haloes in the hydrodynamical simulations is consistent with N-body expectations up to Milky Way mass galaxies, at which mass the haloes become twice as concentrated as compared with pure dark matter runs. This mass dependent density profile can be directly applied to rotation curve data of observed galaxies and to semi analytic galaxy formation models as a significant improvement over the commonly used NFW profile.

We introduce a mass dependent density profile to describe the distribution of dark matter within galaxies, which takes into account the stellar-to-halo mass dependence of the response of dark matter to baryonic processes. The study is based on the analysis of hydrodynamically simulated galaxies from dwarf to Milky Way mass, drawn from the MaGICC project, which have been shown to match a wide range of disk scaling relationships. We find that the best fit parameters of a generic double power-law density profile vary in a systematic manner that depends on the stellar-to-halo mass ratio of each galaxy. Thus, the quantity Mstar/Mhalo constrains the inner ($\gamma$) and outer ($\beta$) slopes of dark matter density, and the sharpness of transition between the slopes($\alpha$), reducing the number of free parameters of the model to two. Due to the tight relation between stellar mass and halo mass, either of these quantities is sufficient to describe the dark matter halo profile including the effects of baryons. The concentration of the haloes in the hydrodynamical simulations is consistent with N-body expectations up to Milky Way mass galaxies, at which mass the haloes become twice as concentrated as compared with pure dark matter runs. This mass dependent density profile can be directly applied to rotation curve data of observed galaxies and to semi analytic galaxy formation models as a significant improvement over the commonly used NFW profile.

We introduce a mass dependent density profile to describe the distribution of dark matter within galaxies, which takes into account the stellar-to-halo mass dependence of the response of dark matter to baryonic processes. The study is based on the analysis of hydrodynamically simulated galaxies from dwarf to Milky Way mass, drawn from the MaGICC project, which have been shown to match a wide range of disk scaling relationships. We find that the best fit parameters of a generic double power-law density profile vary in a systematic manner that depends on the stellar-to-halo mass ratio of each galaxy. Thus, the quantity Mstar/Mhalo constrains the inner ($\gamma$) and outer ($\beta$) slopes of dark matter density, and the sharpness of transition between the slopes($\alpha$), reducing the number of free parameters of the model to two. Due to the tight relation between stellar mass and halo mass, either of these quantities is sufficient to describe the dark matter halo profile including the effects of baryons. The concentration of the haloes in the hydrodynamical simulations is consistent with N-body expectations up to Milky Way mass galaxies, at which mass the haloes become twice as concentrated as compared with pure dark matter runs. This mass dependent density profile can be directly applied to rotation curve data of observed galaxies and to semi analytic galaxy formation models as a significant improvement over the commonly used NFW profile.

This talk summarizes some results of our recent work focusing on the possibility to test solar matter density fluctuations by the future Borexino experiment.

We perform a joint likelihood analysis of the power spectra of the 2dF Galaxy Redshift Survey (2dFGRS) and the cosmic microwave background (CMB) anisotropies under the assumptions that the initial fluctuations were adiabatic, Gaussian and well described by power laws with scalar and tensor indices of n_s and n_t. On its own, the 2dFGRS sets tight limits on the parameter combination Omega_m h, but relatively weak limits on the fraction of the cosmic matter density in baryons Omega_b/Omega_m. The CMB anisotropy data alone set poor constraints on the cosmological constant and Hubble constant because of a `geometrical degeneracy' among parameters. Furthermore, if tensor modes are allowed, the CMB data allow a wide range of values for the physical densities in baryons and cold dark matter. Combining the CMB and 2dFGRS data sets helps to break both the geometrical and tensor mode degeneracies. The values of the parameters derived here are consistent with the predictions of the simplest models of inflation, with the baryon density derived from primordial nucleosynthesis and with direct measurements of the Hubble parameter. In particular, we find strong evidence for a positive cosmological constant with a pm 2sigma range of 0.65 < Omega_Lambda < 0.85, completely independently of constraints on Omega_\Lambda derived from Type Ia supernovae.

We derive rotation curves for four nearby, low-mass spiral galaxies and use them to constrain the shapes of their dark matter density profiles. This analysis is based on high-resolution two-dimensional Halpha velocity fields of NGC 4605, NGC 5949, NGC 5963, and NGC 6689 and CO velocity fields of NGC 4605 and NGC 5963. In combination with our previous study of NGC 2976, the full sample of five galaxies contains density profiles that span the range from alpha_dm = 0 to alpha_dm = 1.20, where alpha_dm is the power law index describing the central density profile. The scatter in alpha_dm from galaxy to galaxy is 0.44, three times as large as in Cold Dark Matter (CDM) simulations, and the mean density profile slope is alpha_dm = 0.73, shallower than that predicted by the simulations. These results call into question the hypothesis that all galaxies share a universal dark matter density profile. We show that one of the galaxies in our sample, NGC 5963, has a cuspy density profile that closely resembles those seen in CDM simulations, demonstrating that while galaxies with the steep central density cusps predicted by CDM do exist, they are in the minority. In spite of these differences between observations and simulations, the relatively cuspy density profiles we find do not suggest that this problem represents a crisis for CDM. Improving the resolution of the simulations and incorporating additional physics may resolve the remaining discrepancies. We also find that four of the galaxies contain detectable radial motions in the plane of the galaxy. We investigate the hypothesis that these motions are caused by a triaxial dark matter halo, and place lower limits on the ellipticity of the orbits in the plane of the disk of 0.043 - 0.175.

We calculate the equation of state (EoS) of dense matter, using a relativistic mean field (RMF) model with a density dependent coupling that is a slightly modified form of the original NL3 interaction. For nonuniform nuclear matter we approximate the unit lattice as a spherical Wigner-Seitz cell, wherein the meson mean fields and nucleon Dirac wave functions are solved fully self-consistently. We also calculate uniform nuclear matter for a wide range of temperatures, densities, and proton fractions, and match them to non-uniform matter as the density decreases. The calculations took over 6,000 CPU days in Indiana University's supercomputer clusters. We tabulate the resulting EoS at over 107,000 grid points in the proton fraction range $Y_P$ = 0 to 0.56. For the temperature range $T$ = 0.16 to 15.8 MeV we cover the density range $n_B$ = 10$^{-4}$ to 1.6 fm$^{-3}$; and for the higher temperature range $T$ = 15.8 to 80 MeV we cover the larger density range $n_B$ = 10$^{-8}$ to 1.6 fm$^{-3}$. In the future we plan to study low density, low temperature (T$

We present new spectroscopic observations of the gravitational arcs and the brightest cluster galaxy (BCG) in the cluster MS2137-23 (z=0.313) obtained with the Echelle Spectrograph and Imager on the Keck II telescope. We find that the tangential and radial arcs arise from sources at almost identical redshifts (z=1.501,1.502). We combine the measured stellar velocity dispersion profile of the BCG with a lensing analysis to constrain the distribution of dark and stellar matter in the central 100 kpc of the cluster. Our data indicate a remarkably flat inner slope for the dark matter profile, rho_d propto r^-beta, with beta

The quantum-mechanical consideration of a passage of fast dimesoatoms through matter is given. A set of quantum-kinetic equations for the density matrix elements describing their internal state evolution is derived. It is shown that probabilistic description of internal dynamics of hydrogen-like atoms is impossible even at sufficiently low energies because of the ``accidental'' degeneracy of their energy levels.

In this paper we propose a new method for reconstructing the surface density of matter in flat disks of spiral galaxies. The surface density is expressed through observational rotation velocity curves of visible matter in the disks of spiral galaxies. The new method is not based on quadrature of special functions. The found solution is used for processing and analysis of observational data from several spiral galaxies. The new method can be used to more accurately estimate the amount of dark matter in spiral galaxies.

This paper reports preliminary results of a study of the HA production process in e+e- collisions at a 1 TeV linear collider and their implication in the study of dark matter at particle colliders. The analysis is carried out using full Geant-4 simulation and reconstruction for the LDC detector model.

In this article we study spontaneous chiral symmetry breaking for quark matter in the background of static and homogeneous parallel electric field $\bm E$ and magnetic field $\bm B$. We use a Nambu-Jona-Lasinio model with a local kernel interaction to compute the relevant quantities to describe chiral symmetry breaking at finite temperature for a wide range of $E$ and $B$. We study the effect of this background on inverse catalysis of chiral symmetry breaking for $E$ and $B$ of the same order of magnitude. We then focus on the effect of equilibration of chiral density, $n_5$, produced dynamically by axial anomaly on the critical temperature. The equilibration of $n_5$, a consequence of chirality flipping processes in the thermal bath, allows for the introduction of the chiral chemical potential, $\mu_5$, which is computed self-consistently as a function of temperature and field strength by coupling the number equation to the gap equation, and solving the two within an expansion in $E/T^2$, $B/T^2$ and $\mu_5^2/T^2$. We find that even if chirality is produced and equilibrates within a relaxation time $\tau_M$, it does not change drastically the thermodynamics, with particular reference to the inverse catalysis induced by the external fields, as long as the average $\mu_5$ at equilibrium is not too large.

micrOMEGAs2.0 is a code which calculates the relic density of a stable massive particle in an arbitrary model. The underlying assumption is that there is a conservation law like R-parity in supersymmetry which guarantees the stability of the lightest odd particle. The new physics model must be incorporated in the notation of CalcHEP, a package for the automatic generation of squared matrix elements. Once this is done, all annihilation and coannihilation channels are included automatically in any model. Cross-sections at $v=0$, relevant for indirect detection of dark matter, are also computed automatically. The package includes three sample models: the minimal supersymmetric standard model (MSSM), the MSSM with complex phases and the NMSSM. Extension to other models, including non supersymmetric models, is described.

Low-density nuclear matter at finite temperature is considered representing the strong coupling situation of a highly correlated fermion system. One-particle se lf-energies and the density of states in the vicinity of the pairing transition point are presented. Within the Green function approach model calculations are p erformed using the thermodynamic $T$ matrix in ladder approximation. As a main r esult the formation of a pseudogap in the level density near the critical temper ature of the pairing phase transition has been found. It is shown that compared to mean field, the picture of the onset of the pairing transition is essentially changed if correlations are taken into account.

In this paper, we show numerically that a symmetric Earth matter density profile can, in principle, be reconstructed from a single baseline energy spectrum up to a certain precision. For the numerical evaluations in the high dimensional parameter space we use a genetic algorithm.

No Abstract Available

Some observations of galaxies, and in particular dwarf galaxies, indicate a presence of cored density profiles in apparent contradiction with cusp profiles predicted by dark matter N-body simulations. We constructed an analytical model, using particle distribution functions (DFs), to show how a supernova (SN) explosion can transform a cusp density profile in a small-mass dark matter halo into a cored one. Considering the fact that a SN efficiently removes matter from the centre of the first haloes, we study the effect of mass removal through a SN perturbation in the DFs. We found that the transformation from a cusp into a cored profile is present even for changes as small as 0.5% of the total energy of the halo, that can be produced by the expulsion of matter caused by a single SN explosion.

We provide a brief review and detailed analysis of the spin-orbit density wave (SODW), proposed as a possible explanation to the `hidden order' phase of URu2Si2. Due to the interplay between inter-orbital Coulomb interaction and spin-orbit coupling (SOC) in this compound, the SODW is shown to arise from Fermi surface nesting instability between two spin-orbit split bands. An effective low-energy Hamiltonian including single-particle SOC and two-particle SODW is derived, while numerical results are calculated by using density-functional theory (DFT) based band structure input. Computed gapped quasiparticle spectrum, entropy loss and spin-excitation spectrum are in detailed agreement with experiments. Interestingly, despite the fact that SODW governs dynamical spin-excitations, the static magnetic moment is calculated to be zero, owing to the time-reversal invariance imposed by SOC. As a consequence, SODW can be destroyed by finite magnetic field even at zero temperature. Our estimation of the location of the quantum critical point is close to the experimental value of Bc ~ 35 T. Finally, we extend the idea of SODW to other SOC systems including iridium oxides (iridates) and two-dimensional electronic systems such as BiAg2 surface and LaAlO3/SrTiO3 interface. We show hints of quasiparticle gapping, reduction of preexisting magnetic moment, large magneto-resistance etc. in these systems which can be explained consistently within the SODW theory.

The notion induced symmetry breaking (ISB) is introduced as a generalization of the spontaneous symmetry breaking mechanism and is illustrated in a simple two flavor spin model. In the case of QCD at finite baryon density, I argue that the quark interaction induced by zero sound satisfies the prerequisites which are necessary for a ISB scenario. In this scenario, the quark condensate sharply drops at the critical value of the chemical potential in coincidence with a rapid increase of the baryon density. The spectrum of the light particles is discussed below and above this phase transition. The consequences of the ISB mechanism for heavy ion collisions are briefly addressed.

The main goal of this paper is deriving Density of states $g(\epsilon)$ (degeneracy function) per volume for an equation of state (EOS) $p=-\rho$ (we called it dark energy(DE)).We have concluded that thermodynamic quantities such as pressure and energy density are simple functions of temperature, fugacity, curvature and mass of Bosons. Our work has been expressed the origin of some claims about the negativity of the entropy for the scalar fields models of DE.

The back-reaction of baryons on the dark matter halo density profile is of great interest, not least because it is an important systematic uncertainty when attempting to detect the dark matter. Here, we draw on a large suite of high resolution cosmological hydrodynamical simulations, to systematically investigate this process and its dependence on the baryonic physics associated with galaxy formation. The inclusion of baryons results in significantly more concentrated density profiles if radiative cooling is efficient and feedback is weak. The dark matter halo concentration can in that case increase by as much as 30 (10) per cent on galaxy (cluster) scales. The most significant effects occur in galaxies at high redshift, where there is a strong anti-correlation between the baryon fraction in the halo centre and the inner slope of both the total and the dark matter density profiles. If feedback is weak, isothermal inner profiles form, in agreement with observations of massive, early-type galaxies. However, we find that AGN feedback, or extremely efficient feedback from massive stars, is necessary to match observed stellar fractions in groups and clusters, as well as to keep the maximum circular velocity similar to the virial velocity as observed for disk galaxies. These strong feedback models reduce the baryon fraction in galaxies by a factor of 3 relative to the case with no feedback. The AGN is even capable of reducing the baryon fraction by a factor of 2 in the inner region of group and cluster haloes. This in turn results in inner density profiles which are typically shallower than isothermal and the halo concentrations tend to be lower than in the absence of baryons.

Title: Virtual Graviton Density and the Dark Matter Phenomenon: A Predictive Framework from the Grand Unified Field Theory of Asymmetry Description: This paper presents a bold and predictive alternative to the dark matter hypothesis by proposing that the anomalous gravitational effects attributed to dark matter—such as flat galactic rotation curves, excess gravitational lensing, and the large-scale structure of the universe—can be fully explained as emergent effects of virtual graviton density. Rooted in the Grand Unified Field Theory of Asymmetry (GUFT), the theory treats spacetime as a coherent phase of a Dark Energy Quantum Field (DEQF), with gravity emerging from quantized excitations in the graviton quantum field (GQF). Unlike other gauge bosons, virtual gravitons accumulate unipolarly and contribute a net attractive effect that modifies gravitational dynamics on large scales. These effects manifest through an effective stress-energy tensor, altering Einstein's field equations without invoking exotic matter. Key predictions include: A natural explanation for flat galactic rotation curves. Enhanced gravitational lensing due to virtual graviton curvature. A mechanism for cosmic structure formation without cold dark matter (CDM). The framework is falsifiable, mathematically grounded, and fully predictive. It eliminates the need for hypothetical dark matter particles, offering a unified, field-centric cosmological model. This paper builds on prior work in GUFT and provides a compelling new paradigm for interpreting gravitational anomalies. Author: James Scott Trimm, Independent Researcher Contact: [email protected] Date: July 6, 2025

We investigate cosmological constraints on an energy density contribution of elastic dark matter self-interactions characterized by the mass of the exchange particle and coupling constant. Because of the expansion behaviour in a Robertson-Walker metric we investigate self-interacting dark matter that is warm in the case of thermal relics. The scaling behaviour of dark matter self-interaction energy density shows that it can be the dominant contribution (only) in the very early universe. Thus its impact on primordial nucleosynthesis is used to restrict the interaction strength, which we find to be at least as strong as the strong interaction. Furthermore we explore dark matter decoupling in a self-interaction dominated universe, which is done for the self-interacting warm dark matter as well as for collisionless cold dark matter in a two component scenario. We find that strong dark matter self-interactions do not contradict super-weak inelastic interactions between self-interacting dark matter and baryonic matter and that the natural scale of collisionless cold dark matter decoupling exceeds the weak scale and depends linearly on the particle mass. Finally structure formation analysis reveals a linear growing solution during self-interaction domination; however, only non-cosmological scales are enhanced.

An annihilation signal of dark matter is searched for from the central region of the Milky Way. Data acquired in dedicated ON/OFF observations of the Galactic center region with H.E.S.S. are analyzed for this purpose. No significant signal is found in a total of $\sim 9$ h of ON/OFF observations. Upper limits on the velocity averaged cross section, $ $, for the annihilation of dark matter particles with masses in the range of $\sim 300$ GeV to $\sim 10$ TeV are derived. In contrast to previous constraints derived from observations of the Galactic center region, the constraints that are derived here apply also under the assumption of a central core of constant dark matter density around the center of the Galaxy. Values of $ $ that are larger than $3\cdot 10^{-24}\:\mathrm{cm^3/s}$ are excluded for dark matter particles with masses between $\sim 1$ and $\sim 4$ TeV at 95% CL if the radius of the central dark matter density core does not exceed $500$ pc. This is the strongest constraint that is derived on $ $ for annihilating TeV mass dark matter without the assumption of a centrally cusped dark matter density distribution in the search region.

We investigate the role of a scalar tetraquark state for the description of nuclear matter within the parity doublet model in the mirror assignment. In the dilatation-invariant version of the model a nucleon-nucleon interaction term mediated by the lightest scalar tetraquark field naturally emerges. At nonzero density one has, beyond the usual chiral condensate, also a tetraquark condensate. The behavior of both condensates and the restoration of chiral symmetry at high density are studied. It is shown that this additional scalar degree of freedom affects non negligibly the properties of the medium.