88 research outputs found
6d, N=(1,0) Coulomb Branch Anomaly Matching
6d QFTs are constrained by the analog of 't Hooft anomaly matching: all
anomalies for global symmetries and metric backgrounds are constants of RG
flows, and for all vacua in moduli spaces. We discuss an anomaly matching
mechanism for 6d N=(1,0) theories on their Coulomb branch. It is a global
symmetry analog of Green-Schwarz-West-Sagnotti anomaly cancellation, and
requires the apparent anomaly mismatch to be a perfect square, . Then is cancelled by making an
electric / magnetic source for the tensor multiplet, so background gauge field
instantons yield charged strings. This requires the coefficients in to be
integrally quantized. We illustrate this for N=(2,0) theories. We also consider
the N=(1,0) SCFTs from N small instantons, verifying that the recent
result for its anomaly polynomial fits with the anomaly matching mechanism.Comment: 12 pages, no figure
Fusion Residues
We discuss when and how the Verlinde dimensions of a rational conformal field
theory can be expressed as correlation functions in a topological LG theory. It
is seen that a necessary condition is that the RCFT fusion rules must exhibit
an extra symmetry. We consider two particular perturbations of the Grassmannian
superpotentials. The topological LG residues in one perturbation, introduced by
Gepner, are shown to be a twisted version of the Verlinde dimensions.
The residues in the other perturbation are the twisted Verlinde dimensions of
another RCFT; these topological LG correlation functions are conjectured to be
the correlation functions of the corresponding Grassmannian topological sigma
model with a coupling in the action to instanton number.Comment: 16 page
Supersymmetric asymptotic safety is not guaranteed
It was recently shown that certain perturbatively accessible,
non-supersymmetric gauge-Yukawa theories have UV asymptotic safety, without
asymptotic freedom: the UV theory is an interacting RG fixed point, and the IR
theory is free. We here investigate the possibility of asymptotic safety in
supersymmetric theories, and use unitarity bounds, and the a-theorem, to rule
it out in broad classes of theories. The arguments apply without assuming
perturbation theory. Therefore, the UV completion of a non-asymptotically free
susy theory must have additional, non-obvious degrees of freedom, such as those
of an asymptotically free (perhaps magnetic dual) extension.Comment: 12 pages, ReVTeX. Version to match the published version. Note adde
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