Interacting SUSY-singlet matter in non-relativistic Chern-Simons theory

We construct an example of supersymmetric Chern-Simons-matter theory with a matter field transforming as a singlet representation of the supersymmetry algebra, where the bosonic and fermionic degrees of freedom do not match. This is obtained as a non-relativistic limit of the N=2 Chern-Simons-matter theory in 1+2 dimensions, where the particle and anti-particle coexist. We also study the index to investigate the mimatch of bosonic and fermionic degrees of freedom.Comment: 11page

Quantum criticality and black holes

Many condensed matter experiments explore the finite temperature dynamics of systems near quantum critical points. Often, there are no well-defined quasiparticle excitations, and so quantum kinetic equations do not describe the transport properties completely. The theory shows that the transport co-efficients are not proportional to a mean free scattering time (as is the case in the Boltzmann theory of quasiparticles), but are completely determined by the absolute temperature and by equilibrium thermodynamic observables. Recently, explicit solutions of this quantum critical dynamics have become possible via the AdS/CFT duality discovered in string theory. This shows that the quantum critical theory provides a holographic description of the quantum theory of black holes in a negatively curved anti-de Sitter space, and relates its transport co-efficients to properties of the Hawking radiation from the black hole. We review how insights from this connection have led to new results for experimental systems: (i) the vicinity of the superfluid-insulator transition in the presence of an applied magnetic field, and its possible application to measurements of the Nernst effect in the cuprates, (ii) the magnetohydrodynamics of the plasma of Dirac electrons in graphene and the prediction of a hydrodynamic cyclotron resonance.Comment: 12 pages, 2 figures; Talk at LT25, Amsterda

A tunneling picture of dual giant Wilson loop

We further discuss a rotating dual giant Wilson loop (D3-brane) solution constructed in Lorentzian AdS by Drukker et al. The solution is shown to be composed of a dual giant Wilson loop and a dual giant graviton by minutely examining its shape. This observation suggests that the corresponding gauge-theory operator should be a k-th symmetric Wilson loop with the insertions of dual giant graviton operators. To support the correspondence, the classical action of the solution should be computed and compared with the gauge-theory result. For this purpose we first perform a Wick rotation to the Lorentzian solution by following the tunneling prescription and obtain Euclidean solutions corresponding to a circular or a straight-line Wilson loop. In Euclidean signature boundary terms can be properly considered in the standard manner and the classical action for the Euclidean solutions can be evaluated. The result indeed reproduces the expectation value of the k-th symmetric Wilson loop as well as the power-law behavior of the correlation function of dual giant graviton operators.Comment: 34 pages, 19 figures, v2: references adde

A family of super Schrodinger invariant Chern-Simons matter systems

We investigate non-relativistic limits of the N=3 Chern-Simons matter system in 1+2 dimensions. The relativistic theory can generate several inequivalent super Schodinger invariant theories, depending on the degrees of freedom we choose to retain in the non-relativistic limit. The maximally supersymmetric Schrodinger invariant theory is obtained by keeping all particle degrees of freedom. The other descendants, where particles and anti-particles coexist, are also Schrodinger invariant but preserve less supersymmetries. Thus, we have a family of super Schrodinger invariant field theories produced from the parent relativistic theory.Comment: 1+35 pages, references added and typos fixe

Instabilities of Black Strings and Branes

We review recent progress on the instabilities of black strings and branes both for pure Einstein gravity as well as supergravity theories which are relevant for string theory. We focus mainly on Gregory-Laflamme instabilities. In the first part of the review we provide a detailed discussion of the classical gravitational instability of the neutral uniform black string in higher dimensional gravity. The uniform black string is part of a larger phase diagram of Kaluza-Klein black holes which will be discussed thoroughly. This phase diagram exhibits many interesting features including new phases, non-uniqueness and horizon-topology changing transitions. In the second part, we turn to charged black branes in supergravity and show how the Gregory-Laflamme instability of the neutral black string implies via a boost/U-duality map similar instabilities for non- and near-extremal smeared branes in string theory. We also comment on instabilities of D-brane bound states. The connection between classical and thermodynamic stability, known as the correlated stability conjecture, is also reviewed and illustrated with examples. Finally, we examine the holographic implications of the Gregory-Laflamme instability for a number of non-gravitational theories including Yang-Mills theories and Little String Theory.Comment: 119 pages, 16 figures. Invited review for Classical and Quantum Gravit

Universal TT-linear resistivity and Planckian dissipation in overdoped cuprates

International audienceThe perfectly linear temperature dependence of the electrical resistivity observed as T$\rightarrow$ 0 in a variety of metals close to a quantum critical point is a major puzzle of condensed-matter physics . Here we show that T-linear resistivity as T$\rightarrow$0 is a generic property of cuprates, associated with a universal scattering rate. We measured the low-temperature resistivity of the bilayer cuprate Bi$_2$Sr$_2$CaCu$_2$O$_{8+\lambda}$ and found that it exhibits a T-linear dependence with the same slope as in the single-layer cuprates Bi$_2$Sr$_2$CuO$_{6+\delta}$ , La$_{1.6−x}$Nd$_{0.4}$Sr$_x$CuO$_4$ and La$_{2−x}$Sr$_x$CuO$_4$ , despite their very different Fermi surfaces and structural, superconducting and magnetic properties. We then show that the T-linear coefficient (per CuO$_2$ plane), A1$^□$, is given by the universal relation A1$^□$T$_F$=$h/2e^2$ , where $e$ is the electron charge, $h$ is the Planck constant and $T_F$ is the Fermi temperature. This relation, obtained by assuming that the scattering rate 1/$\tau$ of charge carriers reaches the Planckian limit, whereby $\hbar$/$\tau$=$k_BT$, works not only for holedoped cuprates but also for electron-doped cuprates, despite the different nature of their quantum critical point and strength of their electron correlations