We use the framework of generalised global symmetries to study various hydrodynamic regimes of hot electromagnetism. We formulate the hydrodynamic theories with an unbroken or a spontaneously broken U(1) one-form symmetry. The latter of these describes a one-form superfluid, which is characterised by a vector Goldstone mode and a two-form superfluid velocity. Two special limits of this theory have been studied in detail: the string fluid limit where the U(1) one-form symmetry is partly restored, and the electric limit in which the symmetry is completely broken. The transport properties of these theories are investigated in depth by studying the constraints arising from the second law of thermodynamics and Onsager's relations at first order in derivatives. We also construct a hydrostatic effective action for the Goldstone modes in these theories and use it to characterise the space of all equilibrium configurations. To make explicit contact with hot electromagnetism, the traditional treatment of magnetohydrodynamics, where the electromagnetic photon is incorporated as dynamical degrees of freedom, is extended to include parity-violating contributions. We argue that the chemical potential and electric fields are not independently dynamical in magnetohydrodynamics, and illustrate how to eliminate these within the hydrodynamic derivative expansion using Maxwell's equations. Additionally, a new hydrodynamic theory of non-conducting, but polarised, plasmas is formulated, focusing primarily on the magnetically dominated sector. Finally, it is shown that the different limits of one-form superfluids formulated in terms of generalised global symmetries are exactly equivalent to magnetohydrodynamics and the hydrodynamics of non-conducting plasmas at the non-linear level.1 Throughout this work, we often refer to to this formulation as the string fluid formulation of MHD. 2 This process of dualisation is commonly applied in the context of numerical studies of MHD [27]. The conservation of the two-form current splits into what is usually denoted as the induction equation and the no-monopole constraint. However, no formal study of the hydrodynamic properties and expansion in this context had been performed. This is one of the goals of this paper.3 It may be possible to relax the assumptions of the string fluid formulation in order to be able to describe plasmas that are not electrically neutral. Further comments on this point are left to a more speculative discussion in sec. 8. 1. Introduction | 6 2. The setup of one-form hydrodynamics | 7 Comments on related workDuring the completion of this work, we became aware of an upcoming related work that investigates different aspects of magnetohydrodynamics [30], and which has considerable overlap with [24]. We have provided a comparison between our work and that of [30] in app. B. We also generalised parts of [30] as to construct an ideal order effective Lagrangian for the hydrodynamic theories of sec. 3 and 4. Additionally, we have also formulated an order parameter that describes t...

We formulate the theory of nonlinear viscoelastic hydrodynamics of anisotropic crystals in terms of dynamical Goldstone scalars of spontaneously broken translational symmetries, under the assumption of homogeneous lattices and absence of plastic deformations. We reformulate classical elasticity effective field theory using surface calculus in which the Goldstone scalars naturally define the position of higher-dimensional crystal cores, covering both elastic and smectic crystal phases. We systematically incorporate all dissipative effects in viscoelastic hydrodynamics at first order in a long-wavelength expansion and study the resulting rheology equations. In the process, we find the necessary conditions for equilibrium states of viscoelastic materials. In the linear regime and for isotropic crystals, the theory includes the description of Kelvin-Voigt materials. Furthermore, we provide an entirely equivalent description of viscoelastic hydrodynamics as a novel theory of higher-form superfluids in arbitrary dimensions where the Goldstone scalars of partially broken generalised global symmetries play an essential role. An exact map between the two formulations of viscoelastic hydrodynamics is given. Finally, we study holographic models dual to both these formulations and map them one-to-one via a careful analysis of boundary conditions. We propose a new simple holographic model of viscoelastic hydrodynamics by adopting an alternative quantisation for the scalar fields.

A combination of additive group contributions and nonadditive molecular parameters is employed to estimate the normal melting points of 1215 organic compounds. The melting points are calculated from the ratio of the total phase change enthalpy and entropy of melting. The total phase change enthalpy of melting is calculated from the enthalpic group contributions, whereas the total phase change entropy of melting is estimated using a semiempirical equation based on only two nonadditive molecular parameters. The average absolute error in estimating the melting points of these organic compounds is 33.2 K. This is a relatively low value considering the wide range of pharmaceutically and environmentally relevant organic compounds included in this data set.

We show that relativistic magnetohydrodynamics (MHD) can be recast as a novel theory of superfluidity. This new theory formulates MHD just in terms of conservation equations, including dissipative effects, by introducing appropriate variables such as a magnetic scalar potential, and providing necessary and sufficient conditions to obtain equilibrium configurations. We show that this scalar potential can be interpreted as a Goldstone mode originating from the spontaneous breaking of a one-form symmetry, and present the most generic constitutive relations at one derivative order for a parity-preserving plasma in this new superfluid formulation.

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We formulate a theory of dissipative hydrodynamics with spontaneously broken translations, describing charge density waves in a clean isotropic electronic crystal. We identify a novel linear transport coefficient, lattice pressure, capturing the effects of background strain and thermal expansion in a crystal. We argue that lattice pressure is a generic feature of systems with spontaneously broken translations and must be accounted for while building and interpreting holographic models. We also provide the first calculation of the coefficients of thermal and chemical expansion in a holographic electronic crystal.