Related papers: Quasi-Nambu-Goldstone Modes in Bose-Einstein Conde…
We analyze the group-theoretical ramifications of the Nambu-Goldstone [NG] theorem in the self-consistent relativistic variational Gaussian wave functional approximation to spinless field theories. In an illustrative example we show how the…
Explaining cosmic inflation by the effective dynamics of an $SU(N_C)$ pure gauge theory of scale $\La\sim 10^{-6} M_p$ is lacking an explanation of the (Gaussian) spatial curvature perturbations needed to seed the formation of large-scale…
We propose a bosonic quantum breakdown Hubbard model, which generalizes the Bose-Hubbard model by adding an asymmetric breakdown interaction turning one boson into two between adjacent sites. When the normal hopping is zero, this model has…
We propose a grand unified theory (GUT) pseudo-Nambu-Goldstone boson (pNGB) dark matter (DM) model based on $SU(7)$ gauge symmetry. In the GUT model, the Standard Model (SM) gauge symmetry $G_{\rm SM} := SU(3)_C\times SU(2)_L\times U(1)_Y$…
Like classical fluids, quantum gases may suffer from hydrodynamic instabilities. Our paper develops a quantum version of the classical stability analysis in fluids, the Bogoliubov theory of elementary excitations in unstable Bose-Einstein…
The realisation of Bose-Einstein condensation under grand-canonical conditions has provided the experimental evidence for the simultaneous occurrence of macroscopic fluctuations and phase coherence of the condensate. The observation of…
The nuclear breathing-mode giant monopole resonance is studied within an improved relativistic Boltzmann-Uehling-Uhlenbeck (BUU) transport approach. As a new feature, the numerical treatment of ground state nuclei and their phase-space…
We present an analogue spacetime model that reproduces the salient features of the most common ansatz for quantum gravity phenomenology. We do this by investigating a system of two coupled Bose-Einstein condensates. This system can be tuned…
In spacetime dimensions larger than 2, whenever a global symmetry G is spontaneously broken to a subgroup H, and G and H are Lie groups, there are Nambu-Goldstone modes described by fields with values in G/H. In two-dimensional spacetimes…
We introduce a system of phenomenological equations for Bose-Einstein condensates of magnons in the one-dimensional setting. The nonlinearly coupled equations, written for amplitudes of the right-and left-traveling waves, combine basic…
We study the equilibrium dynamics of a weakly interacting Bose-Einstein condensate trapped in a box. In our approach we use a semiclassical approximation similar to the description of a multi-mode laser. In dynamical equations derived from…
The one-dimensional flat-band ferromagnetic Tasaki model exhibits spontaneous symmetry breaking from ${\rm SU}(2)$ to ${\rm U}(1)$ with one type-B Goldstone mode, featuring that the highest weight state is entangled at quarter filling, but…
We present an exact quantum mechanical analysis of collinear four-wave mixing in a multicomponent Bose-Einstein condensate consisting of sodium atoms in the F=1 ground state. Technically, this is achieved by taking advantage of the…
It is commonly known that two-dimensional mean-field models of optical and matter waves with the cubic self-attraction cannot produce stable solitons in free space because of the occurrence of the collapse in the same setting. By means of…
The report reviews the problem of topological coherent modes, which are nonlinear collective states of Bose-condensed atoms. Such modes can be generated by means of alternating external fields, whose frequencies are in resonance with the…
The Bogoliubov theory is extended to a Bose-Einstein condensation with internal degrees of freedom, realized recently in $^{23}$Na gases where several hyperfine states are simultaneously cooled optically. Starting with a Hamiltonian…
The Goldstone theorem states that there should be a massless mode for each spontaneously broken symmetry generator. There is no such rotational mode in crystals, however superconducting quantum nematics should carry rotational Goldstone…
The discovery of quasicrystals with crystallographically forbidden rotational symmetries has changed the notion of the ordering in materials, yet little is known about the dynamical emergence of such exotic forms of order. Here we…
In this work, we study a pseudo-Nambu-Goldstone boson (pNGB) dark matter model extended with a real scalar. The dark sector is assumed to be feebly coupled with the standard model (SM) via a Higgs portal, so that the pNGB dark matter is…
We study the energy-momentum relations of the Nambu-Goldstone modes in quantum antiferromagnetic Heisenberg models on a hypercubic lattice. This work is a sequel to the previous series about the models. We prove that the Nambu-Goldstone…