Collective modes of the order parameter in a triplet superfluid neutron liquid

Leinson, L. B.

doi:10.1103/physrevc.85.065502

Cited by 31 publications

(36 citation statements)

References 35 publications

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“…Nematic phases preserve the time reversal symmetry (TRS), while the cyclic and ferromagnetic phases are non-unitary states with spontaneously broken TRS. The richness of 3 P 2 order parameters brings about various types of massive/massless bosonic modes [40][41][42][43][44][45][46][47][48] and exotic topological defects, including spontaneously magnetized vortices, fractional, and non-abelian vortices [36,[49][50][51][52]. In contrast to "bosonic" excitations, there have been no studies on the topology of "fermions" in 3 P 2 superfluids.…”

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confidence: 99%

P23superfluids are topological

2017

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We clarify topology of 3 P2 superfluids which are expected to be realized in the inner cores of neutron stars and cubic odd-parity superconductors.3 P2 phases include uniaxial/biaxial nematic phases and nonunitary ferromagnetic and cyclic phases. We here show that all the phases are accompanied by different types of topologically protected gapless fermions: Surface Majorana fermions in nematic phases and a quartet of (single) itinerant Majorana fermions in the cyclic (ferromagnetic) phase. Using the superfluid Fermi liquid theory, we also demonstrate that dihedral-two and -four biaxial nematic phases are thermodynamically favored in the weak coupling limit under a magnetic field. It is shown that the tricritical point exists on the phase boundary between these two phases and may be realized in the core of realistic magnetars. We unveil the intertwining of symmetry and topology behind mass acquisition of surface Majorana fermions in nematic phases.

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confidence: 99%

P23superfluids are topological

2017

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“…[10][11][12], where the anomalous effective vertices are found as the solution of the Dyson's equations in the ladder approximation. Poles of the found analytical solutions [13,14] indicate the existence of the undamped collective oscillations of the order parameter in the superfluid 3 P 2 condensate of neutrons with m j = 0. Some of the collective excitations with the excitation energy smaller than the superfluid energy gap are able to decay into neutrino pairs.…”

Section: Introductionmentioning

confidence: 91%

“…[14], the corresponding nonunitary oscillations look like the "normal-flapping" mode in 3 He-A [30]. A solution to Eq.…”

Section: B Swd Channelmentioning

confidence: 97%

“…Such approach results in 2 s → 1/20 or, equivalently, ω av s (T )/ √ 5 with a simple temperature dependence of the excitation energy only through the gap amplitude. However, the more accurate calculation [14] has shown that, for the eigenmodes, the average-angle approximation is valid only in the limit T → T c . The gap anisotropy leads to a strong decreasing of the energy of the flapping mode at lowering of the temperature, and ω s tends to zero when T → 0, as shown in Fig.…”

Section: B Swd Channelmentioning

confidence: 99%

“…It was found [14] that the gap anisotropy leads to a strong decreasing of the level energy along with a lowering of the temperature. One can expect that this is to suppress substantially the neutrino energy losses caused by the spin wave decays because the rate of neutrino losses is strongly dependent on the wave energy.…”

Section: Introductionmentioning

confidence: 99%

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Neutrino emissivity of anisotropic neutron superfluids

Leinson

2013

Phys. Rev. C

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We examine the influence of the anisotropy of the superfluid energy gap and residual Fermi-liquid interactions in the triplet-correlated neutron liquid onto neutrino energy losses through neutral weak currents. The neutrino-pair emission caused by the pair breaking and formation processes and by the spin-wave decays is considered for the case of the $^{3}P_{2}$ pairing in the state with $m_{j}=0$. The simple analytical formulae are obtained. A comparison with the previous results of the average-angle approach shows that the gap anisotropy leads to quenching of the neutrino emissivity caused by the pair recombination processes on about 15% and to substantial suppression of the spin-wave decays. Residual particle-hole interactions increase the energy losses in both the channels on about 5%.Comment: 22 pages, 6 figure

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Reaction Rates and Transport in Neutron Stars

Schmitt

Shternin

2018

Astrophysics and Space Science Library

122

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Understanding signals from neutron stars requires knowledge about the transport inside the star. We review the transport properties and the underlying reaction rates of dense hadronic and quark matter in the crust and the core of neutron stars and point out open problems and future directions. arXiv:1711.06520v3 [astro-ph.HE] 29 Oct 2018 65 References 66 I. INTRODUCTION A. ContextTransport describes how conserved quantities such as energy, momentum, particle number, or electric charge are transferred from one region to another. Such a transfer occurs if the system is out of equilibrium, for instance through a temperature gradient or a non-uniform chemical composition. Different theoretical methods are used to understand transport, depending on how far the system is away from its equilibrium state. If the system is close to equilibrium locally and perturbations are on large scales in space and time, hydrodynamics is a powerful technique. Further away from equilibrium other techniques are required, for example kinetic theory, which can also be used to provide the transport coefficients needed in the hydrodynamic equations. In any case, transport is determined by interactions on a microscopic level, and it is the resulting transport properties that we are concerned with in this review.Signals from neutron stars are sensitive to equilibrium properties such as the equation of state but also, to a large extent, to transport properties -here, by neutron stars we mean all objects with a radius of about 10 km and a mass of about 1-2 solar masses, including the possibilities of hybrid stars, which have a quark matter core, and pure quark stars. Therefore, understanding transport is crucial to interpret astrophysical observations, and, turning the argument around, we can use astrophysical observations to improve our understanding of transport in dense matter and thus ultimately our understanding of the microscopic interactions.Transport properties are most commonly computed from particle collisions. (Although, in strongly coupled systems, the picture of well-defined particles scattering off each other has to be taken with care.) These can be scattering processes in which energy and momentum is exchanged without changing the chemical composition of the system, or these can be flavor-changing processes from the electroweak interaction. Understanding transport thus amounts to understanding the rates of these processes, as a function of temperature and density. Electroweak processes are well understood, but large uncertainties arise if the strong interaction is involved in a reaction that contributes to transport. Therefore, approximations such as weak-coupling techniques or one-pion exchange for nucleon-nucleon collisions are being used, and efforts in current research aim at improving these approximations.In a neutron star, most of the particles involved in these processes are fermions: electrons, muons, neutrinos, neutrons, protons, hyperons, and quarks. Since the Fermi momenta of these fermions are typically much larger tha...

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Collective modes of the order parameter in a triplet superfluid neutron liquid

Cited by 31 publications

References 35 publications

P23superfluids are topological

P23superfluids are topological

Neutrino emissivity of anisotropic neutron superfluids

Reaction Rates and Transport in Neutron Stars

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