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A<sc>bstract</sc> The Gepner model (2)⁴describes the sigma model of the Fermat quartic K3 surface. Moving through the nearby moduli space using conformal perturbation theory, we investigate how the conformal weights of its fields change at first and second order and find approximate minima. This serves as a toy model for a mechanism that could produce new chiral fields and possibly new nearby rational CFTs. 

A bstract We analyze how deforming symmetric product orbifolds of two-dimensional $$ \mathcal{N} $$ N = 2 conformal field theories by an exactly marginal operator lifts higher spin currents present at the orbifold point. We find on the one hand that these currents are universally lifted regardless of the underlying CFT. On the other hand the details of the lifting are surprisingly non-universal, with dependence on the central charge of the underlying CFT and the specific marginal operator in use. In the context of the AdS/CFT correspondence, our results illustrate the mechanism by which the stringy spectrum turns into a supergravity spectrum when moving through the moduli space. They also provide further evidence that symmetric product orbifolds of $$ \mathcal{N} $$ N = 2 minimal models are holographic. 

Abstract. Emissions are a central component of atmosphericchemistry models. The Harmonized Emissions Component (HEMCO) is a softwarecomponent for computing emissions from a user-selected ensemble of emissioninventories and algorithms. It allows users to re-grid, combine, overwrite,subset, and scale emissions from different inventories through aconfiguration file and with no change to the model source code. Theconfiguration file also maps emissions to model species with appropriateunits. HEMCO can operate in offline stand-alone mode, but more importantlyit provides an online facility for models to compute emissions at runtime.HEMCO complies with the Earth System Modeling Framework (ESMF) forportability across models. We present a new version here, HEMCO 3.0, thatfeatures an improved three-layer architecture to facilitate implementationinto any atmospheric model and improved capability for calculatingemissions at any model resolution including multiscale and unstructuredgrids. The three-layer architecture of HEMCO 3.0 includes (1) the Data InputLayer that reads the configuration file and accesses the HEMCO library ofemission inventories and other environmental data, (2) the HEMCO Core thatcomputes emissions on the user-selected HEMCO grid, and (3) the ModelInterface Layer that re-grids (if needed) and serves the data to theatmospheric model and also serves model data to the HEMCO Core forcomputing emissions dependent on model state (such as from dust or vegetation). The HEMCO Core is common to the implementation in all models, whilethe Data Input Layer and the Model Interface Layer are adaptable to themodel environment. Default versions of the Data Input Layer and ModelInterface Layer enable straightforward implementation of HEMCO in any simplemodel architecture, and options are available to disable features such asre-gridding that may be done by independent couplers in more complexarchitectures. The HEMCO library of emission inventories and algorithms iscontinuously enriched through user contributions so that new inventoriescan be immediately shared across models. HEMCO can also serve as a generaldata broker for models to process input data not only for emissions but forany gridded environmental datasets. We describe existing implementations ofHEMCO 3.0 in (1) the GEOS-Chem “Classic” chemical transport model withshared-memory infrastructure, (2) the high-performance GEOS-Chem (GCHP)model with distributed-memory architecture, (3) the NASA GEOS Earth SystemModel (GEOS ESM), (4) the Weather Research and Forecasting model withGEOS-Chem (WRF-GC), (5) the Community Earth System Model Version 2 (CESM2),and (6) the NOAA Global Ensemble Forecast System – Aerosols(GEFS-Aerosols), as well as the planned implementation in the NOAA Unified ForecastSystem (UFS). Implementation of HEMCO in CESM2 contributes to theMulti-Scale Infrastructure for Chemistry and Aerosols (MUSICA) by providinga common emissions infrastructure to support different simulations ofatmospheric chemistry across scales.