Domain Walls Seeding the Electroweak Phase Transition.

Topological defects can act as local impurities that seed cosmological phase transitions. In this Letter, we study the case of domain walls and how they can affect the electroweak phase transition in the singlet-extended standard model with a Z_{2}-symmetric potential. When the transition occurs in two steps, the early breaking of the Z_{2} symmetry implies the formation of domain walls which then act as nucleation sites for the second step.

Dynamical Phase Transition from Nonequilibrium Dynamics of Dark Solitons.

By holographic duality, we identify a novel dynamical phase transition which results from the temperature dependence of nonequilibrium dynamics of dark solitons in a superfluid. For a nonequilibrium superfluid system with an initial density of dark solitons, there exists a critical temperature T_{d}, above which the system relaxes to equilibrium by producing sound waves, while below which it goes through an intermediate phase with a finite density of vortex-antivortex pairs. In particular, as T_{d} is approached from below, the density of vortex pairs scales as (T_{d}-T)^{γ} with the critical exponent γ=1/2.

Unifying Type-II Strings by Exceptional Groups.

We construct the exceptional sigma model: a two-dimensional sigma model coupled to a supergravity background in a manifestly (formally) E_{D(D)}-covariant manner. This formulation of the background is provided by exceptional field theory (EFT), which unites the metric and form fields of supergravity in E_{D(D)} multiplets before compactification. The realization of the symmetries of EFT on the world sheet uniquely fixes the Weyl-invariant Lagrangian and allows us to relate our action to the usual type-IIA fundamental string action and a form of the type-IIB (m, n) action.

Yang-Mills as massive Chern-Simons theory: a third way to three-dimensional gauge theories.

The Yang-Mills (YM) equation in three spacetime dimensions (3D) can be modified to include a novel parity-preserving interaction term, with an inverse mass parameter, in addition to a possible topological mass term. The novelty is that the modified YM equation is not the Euler-Lagrange equation of any gauge-invariant local action for the YM gauge potential alone. Instead, consistency is achieved in the "third way" exploited by 3D minimal massive gravity.

Metal-insulator transition by holographic charge density waves.

We construct a gravity dual for charge density waves (CDWs) in which the translational symmetry along one spatial direction is spontaneously broken. Our linear perturbation calculation on the gravity side produces the frequency dependence of the optical conductivity, which exhibits the two familiar features of CDWs, namely, the pinned collective mode and gapped single-particle excitation. These two features indicate that our gravity dual also provides a new mechanism to implement the metal to insulator phase transition by CDWs, which is further confirmed by the fact that dc conductivity decreases with the decreased temperature below the critical temperature.

Twenty-four near-instabilities of Caspar-Klug viruses.

Group theoretical arguments combined with normal mode analysis techniques are applied to a coarse-grained approximation of icosahedral viral capsids which incorporates areas of variable flexibility. This highlights a remarkable structure of the low-frequency spectrum in this approximation, namely, the existence of a plateau of 24 near zero modes with universal group theory content.