Wiedemann-Franz law in a non-Fermi liquid and Majorana central charge: Thermoelectric transport in a two-channel Kondo system

Abstract We study the torus partition functions of free bosonic CFTs in two dimensions. Integrating over Narain moduli defines an ensemble-averaged free CFT. We calculate the averaged partition function and show that it can be reinterpreted as a sum over topologies in three dimensions. This result leads us to conjecture that an averaged free CFT in two dimensions is holographically dual to an exotic theory of three-dimensional gravity with U(1)c×U(1)c symmetry and a composite boundary graviton. Additionally, for small central charge c, we obtain general constraints on the spectral gap of free CFTs using the spinning modular bootstrap, construct examples of Narain compactifications with a large gap, and find an analytic bootstrap functional corresponding to a single self-dual boson.

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Propagation of shear stress in strongly interacting metallic Fermi liquids enhances transmission of terahertz radiation

Scientific Reports ◽

10.1038/s41598-021-86356-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

D. Valentinis ◽

J. Zaanen ◽

D. van der Marel

Keyword(s):

Shear Stress ◽

Terahertz Radiation ◽

Fermi Liquid ◽

Zero Sound ◽

Strongly Correlated Electron ◽

Correlated Electron Systems ◽

Correlated Electron ◽

Collisionless Regime ◽

Propagating Shear ◽

Mass Enhancement

AbstractA highlight of Fermi-liquid phenomenology, as explored in neutral $$^3$$ 3 He, is the observation that in the collisionless regime shear stress propagates as if one is dealing with the transverse phonon of a solid. The existence of this “transverse zero sound” requires that the quasiparticle mass enhancement exceeds a critical value. Could such a propagating shear stress also exist in strongly correlated electron systems? Despite some noticeable differences with the neutral case in the Galilean continuum, we arrive at the verdict that transverse zero sound should be generic for mass enhancement higher than 3. We present an experimental setup that should be exquisitely sensitive in this regard: the transmission of terahertz radiation through a thin slab of heavy-fermion material will be strongly enhanced at low temperature and accompanied by giant oscillations, which reflect the interference between light itself and the “material photon” being the actual manifestation of transverse zero sound in the charged Fermi liquid.

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Towards the classification of rank-r $$ \mathcal{N} $$ = 2 SCFTs. Part I. Twisted partition function and central charge formulae

Journal of High Energy Physics ◽

10.1007/jhep12(2020)021 ◽

2020 ◽

Vol 2020 (12) ◽

Author(s):

Mario Martone

Keyword(s):

Partition Function ◽

Central Charge ◽

Singular Locus ◽

Companion Paper ◽

Coulomb Branch ◽

Energy Limit ◽

Superconformal Field Theories ◽

Rank 2 ◽

Explicit Formulae

Abstract We derive explicit formulae to compute the a and c central charges of four dimensional $$ \mathcal{N} $$ N = 2 superconformal field theories (SCFTs) directly from Coulomb branch related quantities. The formulae apply at arbitrary rank. We also discover general properties of the low-energy limit behavior of the flavor symmetry of $$ \mathcal{N} $$ N = 2 SCFTs which culminate with our $$ \mathcal{N} $$ N = 2 UV-IR simple flavor condition. This is done by determining precisely the relation between the integrand of the partition function of the topologically twisted version of the 4d $$ \mathcal{N} $$ N = 2 SCFTs and the singular locus of their Coulomb branches. The techniques developed here are extensively applied to many rank-2 SCFTs, including new ones, in a companion paper.This manuscript is dedicated to the memory of Rayshard Brooks, George Floyd, Breonna Taylor and the countless black lives taken by US police forces and still awaiting justice. Our hearts are with our colleagues of color who suffer daily the consequences of this racist world.

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