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1. Large logarithms from quantum gravitational corrections to a massless, minimally coupled scalar on de Sitter

   https://doi.org/10.1007/JHEP03(2022)088  

   Glavan, D.; Miao, S. P.; Prokopec, T.; Woodard, R. P. (March 2022, Journal of High Energy Physics)

   A bstract We consider single graviton loop corrections to the effective field equation of a massless, minimally coupled scalar on de Sitter background in the simplest gauge. We find a large temporal logarithm in the approach to freeze-in at late times, but no correction to the feeze-in amplitude. We also find a large spatial logarithm (at large distances) in the scalar potential generated by a point source, which can be explained using the renormalization group with one of the higher derivative counterterms regarded as a curvature-dependent field strength renormalization. We discuss how these results set the stage for a project to purge gauge dependence by including quantum gravitational corrections to the source which disturbs the effective field and to the observer who measures it. 

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2. A heterotic Kodaira-Spencer theory at one-loop

   https://doi.org/10.1007/JHEP10(2023)130  

   Ashmore, Anthony; Murgas_Ibarra, Javier José; McNutt, David Duncan; Strickland-Constable, Charles; Svanes, Eirik Eik; Tennyson, David; Winje, Sander (October 2023, Journal of High Energy Physics)

   A<sc>bstract</sc> We consider a heterotic version of six-dimensional Kodaira-Spencer gravity derived from the heterotic superpotential. We compute the one-loop partition function and find it can be expressed as a product of holomorphic Ray-Singer torsions. We discuss its topological properties and potential gauge and gravitational anomalies. We show these anomalies can be cancelled using Green-Schwarz-like counter-terms. We also discuss the dependence on the background geometry, and in particular the choice of hermitian metric needed for quantisation. Given suitable topological constraints, this dependence may again be cancelled by the addition of purely background-dependent counter-terms. We also explain how our methods provide the one-loop partition functions of a large class of more general holomorphic field theories in terms of holomorphic Ray-Singer torsions. 

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3. Goldstone bosons and fluctuating hydrodynamics with dipole and momentum conservation

   https://doi.org/10.1007/JHEP05(2023)022  

   Glorioso, Paolo; Huang, Xiaoyang; Guo, Jinkang; Rodriguez-Nieva, Joaquin F.; Lucas, Andrew (May 2023, Journal of High Energy Physics)

   A<sc>bstract</sc> We develop a Schwinger-Keldysh effective field theory describing the hydrodynamics of a fluid with conserved charge and dipole moments, together with conserved momentum. The resulting hydrodynamic modes are highly unusual, including sound waves with quadratic (magnon-like) dispersion relation and subdiffusive decay rate. Hydrodynamics itself is unstable below four spatial dimensions. We show that the momentum density is, at leading order, the Goldstone boson for a dipole symmetry which appears spontaneously broken at finite charge density. Unlike an ordinary fluid, the presence or absence of energy conservation qualitatively changes the decay rates of the hydrodynamic modes. This effective field theory naturally couples to curved spacetime and background gauge fields; in the flat spacetime limit, we reproduce the “mixed rank tensor fields” previously coupled to fracton matter. 

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4. Deforming soft algebras for gauge theory

   https://doi.org/10.1007/JHEP03(2023)233  

   Melton, Walker; Narayanan, Sruthi A; Strominger, Andrew (March 2023, Journal of High Energy Physics)

   A<sc>bstract</sc> Symmetry algebras deriving from towers of soft theorems can be deformed by a short list of higher-dimension Wilsonian corrections to the effective action. We study the simplest of these deformations in gauge theory arising from a massless complex scalar coupled toF². The soft gauge symmetry ‘s-algebra’, compactly realized as a higher-spin current algebra acting on the celestial sphere, is deformed and enlarged to an associative algebra containing soft scalar generators. This deformed soft algebra is found to be non-abelian even in abelian gauge theory. A two-parameter family of central extensions of thes-subalgebra are generated by shifting and decoupling the scalar generators. It is shown that these central extensions can also be generated by expanding around a certain non-trivial but Lorentz invariant shockwave type background for the scalar field. 

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5. Gauge independent quantum gravitational corrections to Maxwell’s equation

   https://doi.org/10.1007/JHEP10(2021)029  

   Katuwal, S.; Woodard, R. P. (October 2021, Journal of High Energy Physics)

   A bstract We consider quantum gravitational corrections to Maxwell’s equations on flat space background. Although the vacuum polarization is highly gauge dependent, we explicitly show that this gauge dependence is canceled by contributions from the source which disturbs the effective field and the observer who measures it. Our final result is a gauge independent, real and causal effective field equation that can be used in the same way as the classical Maxwell equation. 

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