We demonstrate that the high-quality cooling data observed for the young neutron star in the supernova remnant Cassiopeia A over the past 10 years--as well as all other reliably known temperature data of neutron stars--can be comfortably explained wi
thin the nuclear medium cooling scenario. The cooling rates of this scenario account for medium-modified one-pion exchange in dense matter and polarization effects in the pair-breaking formations of superfluid neutrons and protons. Crucial for the successful description of the observed data is a substantial reduction of the thermal conductivity, resulting from a suppression of both the electron and nucleon contributions to it by medium effects. We also find that possibly in as little as about ten years of continued observation, the data may tell whether or not fast cooling processes are active in this neutron star.
We introduce the free quantum noncommutative fields as described by braided tensor products. The multiplication of such fields is decomposed into three operations, describing the multiplication in the algebra M of functions on noncommutative space-ti
me, the product in the algebra H of deformed field oscillators, and the braiding by factor Psi_{M,H} between algebras M and H. For noncommutativity generated by the twist factor we shall employ the star-product realizations of the algebra M in terms of functions on standard Minkowski space. The covariance of single noncommutative quantum fields under deformed Poincare symmetries is described by the algebraic covariance conditions which are equivalent to the deformation of generalized Heisenberg equations on Poincare group manifold. We shall calculate the covariant braided field commutator, which for free quantum noncommutative fields provides the field quantization condition and is given by standard Pauli-Jordan function. For ilustration of our new scheme we present explicit calculations for the well-known case in the literature of canonically deformed free quantum fields.
In the present work a closed system of kinetic equations is obtained for the description of the vacuum creation of an electron - positron plasma and secondary photons due to a strong laser field. An estimate for the photon energy distribution is obta
ined. In the Markovian approximation the photon distribution has a 1/k spectrum (flicker noise).
Elastic scattering of transversely polarized electron antineutrino beam off unpolarized electrons can be used to detect the CP-violating effects by measuring the azimuthal asymmetry of recoil electrons caused by the interference terms between the sta
ndard vector $c_{V}^{L}$, axial $c_{A}^{L}$ couplings of left-chirality antineutrinos and exotic scalar $c_{S}^{R}$ coupling of right-chirality ones in the differential cross section. It would be a positive evidence for the existence of the exotic antineutrino states. Moreover, we also show that the differential cross section for the $overline{ u} e^- $ scattering can be obtained from the one for the $ u e$ scattering, if one makes the substitution $c_{T}^{R} to -c_{T}^{R}$, $c_{A}^{L} to -c_{A}^{L}$, ${bf q}to -{bf q}$, ${boldmath $hat{eta}_{ u}$}to -{boldmath $hat{eta}_{ u}$}$.
Two one-parameter families of twists providing kappa-Minkowski * -product deformed spacetime are considered: Abelian and Jordanian. We compare the derivation of quantum Minkowski space from two perspectives. The first one is the Hopf module algebra p
oint of view, which is strictly related with Drinfelds twisting tensor technique. The other one relies on an appropriate extension of deformed realizations of nondeformed Lorentz algebra by the quantum Minkowski algebra. This extension turns out to be de Sitter Lie algebra. We show the way both approaches are related. The second path allows us to calculate deformed dispersion relations for toy models ensuing from different twist parameters. In the Abelian case one recovers kappa-Poincare dispersion relations having numerous applications in doubly special relativity. Jordanian twists provide a new type of dispersion relations which in the minimal case (related to Weyl-Poincare algebra) takes an energy-dependent linear mass deformation form.
We investigate the effects of Pauli blocking on the properties of hydrogen at high pressures, where recent experiments have shown a transition from insulating behavior to metal-like conductivity. Since the Pauli principle prevents multiple occupation
of electron states (Pauli blocking), atomic states disintegrate subsequently at high densities (Mott effect). We calculate the energy shifts due to Pauli blocking and discuss the Mott effect solving an effective Schroedinger equation for strongly correlated systems. The ionization equilibrium is treated on the basis of a chemical approach. Results for the ionization equilibrium and the pressure in the region 4.000 K < T < 20.000 K are presented. We show that the transition to a highly conducting state is softer than found in earlier work. A first order phase transition is observed at T < 6.450 K, but a diffuse transition appears still up to 20.000 K.
We discuss an idea for how accreting millisecond pulsars could contribute to the understanding of the QCD phase transition in the high-density nuclear matter equation of state (EoS). It is based on two ingredients, the first one being a ``phase diagr
am of rapidly rotating compact star configurations in the plane of spin frequency and mass, determined with state-of-the-art hybrid equations of state, allowing for a transition to color superconducting quark matter. The second is the study of spin-up and accretion evolution in this phase diagram. We show that the quark matter phase transition leads to a characteristic line in the Omega-M plane, the phase border between neutron stars and hybrid stars with a quark matter core. Along this line a change in the pulsars moment of inertia entails a waiting point phenomenon in the accreting millisecond X-ray pulsar (AMXP) evolution: most of these objects should therefore be found along the phase border in the Omega-M plane, which may be viewed as the AMXP analog of the main sequence in the Hertzsprung-Russell diagram for normal stars. In order to prove the existence of a high-density phase transition in the cores of compact stars we need population statistics for AMXPs with sufficiently accurate determination of their masses and spin frequencies.
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David Blaschke (Uniwersytet Wroclawski
, Wroclaw
, Poland & Bogoliubovn Laboratory for Theoretical Physics
2008
Depending on the density reached in the cores of neutron stars, such objects may contain stable phases of novel matter found nowhere else in the Universe. This article gives a brief overview of these phases of matter and discusses astrophysical const
raints on the high-density equation of state associated with ultra-dense nuclear matter.
This paper together with the previous one (arXiv:hep-th/0604146) presents the detailed description of all quantum deformations of D=4 Lorentz algebra as Hopf algebra in terms of complex and real generators. We describe here in detail two quantum defo
rmations of the D=4 Lorentz algebra o(3,1) obtained by twisting of the standard q-deformation U_{q}(o(3,1)). For the first twisted q-deformation an Abelian twist depending on Cartan generators of o(3,1) is used. The second example of twisting provides a quantum deformation of Cremmer-Gervais type for the Lorentz algebra. For completeness we describe also twisting of the Lorentz algebra by standard Jordanian twist. By twist quantization techniques we obtain for these deformations new explicit formulae for the deformed coproducts and antipodes of the o(3,1)-generators.
We show how some classical r-matrices for the D=4 Poincare algebra can be supersymmetrized by an addition of part depending on odd supercharges. These r-matrices for D=4 super-Poincare algebra can be presented as a sum of the so-called subordinated r
-matrices of super-Abelian and super-Jordanian type. Corresponding twists describing quantum deformations are obtained in an explicit form. These twists are the super-extensions of twists obtained in the paper arXiv:0712.3962.
