We examine the thermodynamics of Euclidean dyonic Taub-NUT/Bolt-AdS4 black holes for a variety horizon geometries to understand how gauge field regularity conditions influence thermodynamic relations. find several distinct features that distinguish NUT-charged case from its Reissner-Nordstrom counterpart. For NUT solution, vanishes at and so is ensured. Bolt solution we norm required vanish in ...

We investigate the geometry of Hermitian manifolds endowed with a compact Lie group action by holomorphic isometries principal orbits codimension one. In particular, we focus on special class these constructed following B\'erard-Bergery which includes, among others, line bundles $\mathbb C\mathbb P^{m-1}$, linear Hopf and Hirzebruch surfaces. characterize their invariant metrics, such as balanc...

We show that some embedded standard $13$-spheres in Shimada's exotic $15$-spheres have $\mathbb{Z}_2$ quotient spaces, $P^{13}$s, are fake real $13$-dimensional projective i.e., they homotopy equivalent, but not diffeomorphic to the $\mathbb{R}\mathrm{P}^{13}$. As observed by F. Wilhelm and second named author [RW], Davis $\mathsf{SO}(2)\times \mathsf{G}_2$ actions on descend cohomogeneity one ...

At the leading order, the low-energy effective field equations in string theory admit solutions of the form of products of Minkowski spacetime and a Ricci-flat Calabi-Yau space. The equations of motion receive corrections at higher orders in α′, which imply that the Ricci-flat Calabi-Yau space is modified. In an appropriate choice of scheme, the Calabi-Yau space remains Kähler, but is no longer...

in this paper, we give a classification of non simply connected seven dimensional reimannian manifolds of constant positive curvature which admit irreducible cohomogeneity-one actions. we characterize the acting groups and describe the orbits. the first and second homo-topy groups of the orbits have been presented as well.

We classify, up to orbit equivalence, all cohomogeneity one actions on the hyperbolic planes over the complex, quaternionic and Cayley numbers, and on the complex hyperbolic spaces CH, n ≥ 3. For the quaternionic hyperbolic spaces HH, n ≥ 3, we reduce the classification problem to a problem in quaternionic linear algebra and obtain partial results. For real hyperbolic spaces, this classificatio...

We consider hypersurfaces in Einstein-Sasaki 5-manifolds which are tangent to the characteristic vector field. We introduce evolution equations that can be used to reconstruct the 5-dimensional metric from such a hypersurface, analogous to the (nearly) hypo and half-flat evolution equations in higher dimensions. We use these equations to classify Einstein-Sasaki 5-manifolds of cohomogeneity one...