Jos Van Doorsselaere

Galileons from Lovelock actions

We demonstrate how, for an arbitrary number of dimensions, the Galileon actions and their covariant generalizations can be obtained through a standard Kaluza-Klein compactification of higher-dimensional Lovelock gravity. In this setup, the dilaton takes on the role of the Galileon. In addition, such compactifications uncover other more general Galilean actions, producing purely second-order equations in the weak-field limit, now both for the Galileon and the metric perturbations.

Electromagnetically superconducting phase of the vacuum in a strong magnetic field: Structure of superconductor and superfluid vortex lattices in the ground state

Recently it was shown that vacuum in a background of a strong enough magnetic field becomes an electromagnetic superconductor due to interplay between strong and electromagnetic forces. The superconducting ground state of the vacuum is associated with a spontaneous emergence of quark-antiquark condensates which carry quantum numbers of charged rho mesons. The rho-meson condensate is an inhomogeneous structure made of the so-called rho vortices, which are parallel to the magnetic field axis. The condensation of the charged rho mesons induces a (much weaker) superfluid-like condensate with quantum numbers of the neutral rho((0)) mesons. In this paper we show that the vortices in the superconducting condensate organize themselves in an equilateral triangular lattice similarly to an ordinary type-II superconductor. We show that each of these superconductor vortices is accompanied by three superfluid vortices and three superfluid antivortices made of the neutral rho meson condensate. The superconductor vortex overlaps with one of the superfluid vortices. The superposition of the superconductor and superfluid vortex lattices has a honeycomb pattern.

On chromoelectric (super)conductivity of the Yang-Mills vacuum

Abstract We argue that in the Copenhagen (“spaghetti”) picture of the QCD vacuum the chromomagnetic flux tubes exhibit chromoelectric superconductivity. We show that the superconducting chromoelectric currents in the tubes may be induced by the topological charge density.

Spontaneous electromagnetic superconductivity and superfluidity of QCD QED vacuum in strong magnetic field

It was recently shown that the vacuum in the background of a strong enough magnetic field may become an electromagnetic superconductor due to interplay between strong and electromagnetic forces. The superconducting ground state of the QCD QED sector of the vacuum is associated with magnetic‐field‐assisted emergence of quark‐antiquark condensates which carry quantum numbers of charged r mesons (i.e., of electrically charged vector particles made of lightest, u and d, quarks and antiquarks). Here we demonstrate that this exotic electromagnetic superconductivity of vacuum is also accompanied by even more exotic superfluidity of the neutral r mesons. The superfluid component ‐ despite being electrically neutral ‐ turns out to be sensitive to an external electric field as the superfluid may ballistically be accelerated by a test background electric field along the magnetic‐field axis. In the ground state both superconducting and superfluid components are inhomogeneous periodic functions of the transversal (with respect to the axis of the magnetic field) spatial coordinates. The superconducting part of the ground state resembles an Abrikosov ground state in a type‐II superconductor: the superconducting condensate organizes itself in periodic structure which possesses the symmetry of an equilateral triangular lattice. Each elementary lattice cell contains a stringlike topological defect (superconductor vortex) in the charged r condensates as well as three superfluid vortices and three superfluid antivortices made of the neutral r condensate. The superposition of the superconductor and superfluid vortex lattices has a complicated “kaleidoscopic” pattern. Sixth International Conference on Quarks and Nuclear Physics

Properties of symmetry restoration in the electroweak vacuum in very high magnetic fields

We discuss properties of the electroweak vacuum as a function of an external magnetic field. The interest in these properties arises due to possible existence of the electromagnetically superconducting phase of QCD in the background of a sufficiently strong magnetic field. In the electroweak theory, a superconducting vacuum exists for a well defined range of magnetic background fields, and the interest of the current paper is the behaviour near the upper critical magnetic field. We determine this critical field and calculate the vacuum condensates to leading order.

Fermion zero modes in a chromomagnetic vortex lattice

We prove the existence of zero modes of massless quarks in a background of spaghetti vacuum of chromomagnetic vortices in QCD. We find a general solution for the zero modes and show that the modes can be localized at pairs of vortices.

Phonon spectrum of the QCD vacuum in a magnetic-field-induced superconducting phase

In the background of a sufficiently strong magnetic field the vacuum was suggested to become an ideal electric conductor (highly anisotropic superconductor) due to an interplay between the strong and electromagnetic forces. The superconducting ground state resembles an Abrikosov lattice state in an ordinary type-II superconductor: it is an inhomogeneous structure made of a (charged vector) quark-antiquark condensate pierced by vortices. In this paper the acoustic (phonon) vibrational modes of the vortex lattice are studied at zero temperature. Using an effective model based on a vector meson dominance, we show that in the infrared limit the longitudinal (transverse) acoustic vibrations of the vortex lattice possess a linear (quadratic) dispersion relation corresponding to type-I (type-II) Nambu-Goldstone modes.