274 research outputs found
Weyl Invariance and Spurious Black Hole in Two-Dimensional Dilaton Gravity
In two-dimensional dilaton gravity theories, there may exist a global Weyl
invariance which makes black hole spurious. If the global invariance and the
local Weyl invariance of the matter coupling are intact at the quantum level,
there is no Hawking radiation. We explicitly verify the absence of anomalies in
these symmetries for the model proposed by Callan, Giddings, Harvey and
Strominger. The crucial observation is that the conformal anomaly can be
cohomologically trivial and so not truly anomalous in such dilaton gravity
models.Comment: 28 pages, KANAZAWA-93-0
Super-Virasoro Anomaly, Super-Weyl Anomaly and the Super-Liouville Action for 2D Supergravity
The relation between super-Virasoro anomaly and super-Weyl anomaly in
NSR superstring coupled with 2D supergravity is investigated from canonical
theoretical view point. The WZW action canceling the super-Virasoro anomaly is
explicitly constructed. It is super-Weyl invariant but nonlocal functional of
2D supergravity. The nonlocality can be remedied by the super-Liouvlle action,
which in turn recovers the super-Weyl anomaly. The final gravitational
effective action turns out to be local but noncovariant super-Liouville action,
describing the dynamical behavior of the super-Liouville fields. The BRST
invariance of this approach is examined in the superconformal gauge and in the
light-cone gauge.Comment: 45 page
Majorana bound state of a Bogoliubov-de Gennes-Dirac Hamiltonian in arbitrary dimensions
We study a Majorana zero-energy state bound to a hedgehog-like point defect
in a topological superconductor described by a Bogoliubov-de Gennes (BdG)-Dirac
type effective Hamiltonian. We first give an explicit wave function of a
Majorana state by solving the BdG equation directly, from which an analytical
index can be obtained. Next, by calculating the corresponding topological
index, we show a precise equivalence between both indices to confirm the index
theorem. Finally, we apply this observation to reexamine the role of another
topological invariant, i.e., the Chern number associated with the Berry
curvature proposed in the study of protected zero modes along the lines of
topological classification of insulators and superconductors. We show that the
Chern number is equivalent to the topological index, implying that it indeed
reflects the number of zero-energy states. Our theoretical model belongs to the
BDI class from the viewpoint of symmetry, whereas the spatial dimension of the
system is left arbitrary throughout the paper.Comment: 12 page
Contrastive Multiple Correspondence Analysis (cMCA): Using Contrastive Learning to Identify Latent Subgroups in Political Parties
Scaling methods have long been utilized to simplify and cluster
high-dimensional data. However, the latent spaces derived from these methods
are sometimes uninformative or unable to identify significant differences in
the data. To tackle this common issue, we adopt an emerging analysis approach
called contrastive learning. We contribute to this emerging field by extending
its ideas to multiple correspondence analysis (MCA) in order to enable an
analysis of data often encountered by social scientists -- namely binary,
ordinal, and nominal variables. We demonstrate the utility of contrastive MCA
(cMCA) by analyzing three different surveys of voters in Europe, Japan, and the
United States. Our results suggest that, first, cMCA can identify substantively
important dimensions and divisions among (sub)groups that are overlooked by
traditional methods; second, for certain cases, cMCA can still derive latent
traits that generalize across and apply to multiple groups in the dataset;
finally, when data is high-dimensional and unstructured, cMCA provides
objective heuristics, above and beyond the standard results, enabling more
complex subgroup analysis.Comment: Both authors contributed equally to the paper and listed
alphabetically. This manuscript is currently under revie
- …