Rapid cooling of the compact star in Cassiopea A as a phase transition in dense QCD

We present a model of the compact star in Cassiopea A that accounts for its unusually fast cooling behavior. This feature is interpreted as an enhancement in the neutrino emission triggered by a transition from a fully gapped, two-flavor, color-superconducting phase to a crystalline phase or an alternative gapless, color-superconducting phase. By fine-tuning a single parameter -- the temperature of this transition -- a specific cooling scenario can be selected that fits the Cas A data. Such a scenario requires a massive $M\sim 2M_{\odot}$ star and is, therefore, distinctive from models invoking canonical 1.4 $M_{\odot}$ mass star with nucleonic pairing alone.Comment: 5 pages, 3 figures, v2 and v3: minor changes, matches the version publised in A & A Letter

Determination of bound state energies for a one-dimensional potential field

A method for determination of bound state energies for an asymmetric quantum well with an arbitrary shape of the bottom is suggested. It is shown that how the equation determining the energy levels can be easily derived if one knows the electron transmission and reflection amplitudes corresponding to the part of potential inside the well. The results are applied to three difference test problems.Comment: a file with three figure

Exploring phases of dense QCD with compact stars

I review a number of recent developments in the physics of compact stars containing deconfined quark matter, including (a)~their cooling with possible phase transition from a fully gapped to a gapless phase of QCD at low temperatures and large isospin, (b)~the transport coefficients of the 2SC phase and the role played by the Aharonov-Bohm interactions between flux-tubes and unpaired fermions; (c)~rapidly rotating compact stars and spin-down and spin-up induced phase transition between hadronic and QCD matter as well as between different phases of QCD.Comment: 11 pages, 6 figures, Proceedings of the 5th International Conference on New Frontiers in Physics (ICNFP2016), 6-14 July 2016, Kolymbari, Crete, Greec

Dense QCD and phenomenology of compact stars

I discuss three topics in physics of massive (two solar-mass and larger) neutron stars containing deconfined quark matter: (i) the equation of state of deconfined dense quark matter and its color superconducting phases, (ii) the thermal evolution of stars with quark cores, (iii) color-magnetic flux tubes in type-II superconducting quark matter and their dynamics driven by Aharonov-Bohm interactions with unpaired fermions.Comment: 8 pages, 3 figures. Contribution to the proceedings of "Xth Quark Confinement and the Hadron Spectrum", October 8-12, 2012, Munich, German

On the problem of an electron scattering in an arbitrary one-dimensional potential field

Recurrent representations for an electron transmission and reflection amplitudes for a one-dimensional chain are obtained. The linear differential equations for scattering amplitudes of an arbitrary potential are found.Comment: 6 pages, no figs. To be submitted to Phys. Lett.