DGT - Artículos
https://hdl.handle.net/10481/29855
2024-11-12T21:54:11Z
2024-11-12T21:54:11Z
Embedding Unimodular Gravity in string theory
Garay Erizondo, Luis Javier
García-Moreno, Gerardo
https://hdl.handle.net/10481/95699
2024-10-09T06:37:22Z
Embedding Unimodular Gravity in string theory
Garay Erizondo, Luis Javier; García-Moreno, Gerardo
Unimodular Gravity is a theory displaying Weyl rescalings of the metric and
transverse (volume-preserving) diffeomorphisms as gauge symmetries, as opposed to the full
set of diffeomorphisms displayed by General Relativity. Recently, we presented a systematic
comparison of both theories, concluding that both of them are equivalent in everything but
the behaviour of the cosmological constant under radiative corrections. A careful study of
how Unimodular Gravity can be embedded in the string theory framework has not been
provided yet and was not analyzed there in detail. In this article, we provide such an
explicit analysis, filling the gap in the literature. We restrict ourselves to the unoriented
bosonic string theory in critical dimension for the sake of simplicity, although we argue that
no differences are expected for other string theories. Our conclusions are that both a Diff
and a WTDiff invariance principle are equally valid for describing the massless excitations
of the string spectrum.
Translators of the Mean Curvature Flow in Hyperbolic Einstein’s Static Universe
Ortega Titos, Miguel
Yalçın, Buse
https://hdl.handle.net/10481/95086
2024-09-25T11:28:26Z
Translators of the Mean Curvature Flow in Hyperbolic Einstein’s Static Universe
Ortega Titos, Miguel; Yalçın, Buse
In this study, we deal with non-degenerate translators of the mean curvature flow in the wellknown
hyperbolic Einstein’s static universe. We classify translators foliated by horospheres and
rotationally invariant ones, both space-like and time-like. For space-like translators, we show a
uniqueness theorem as well as a result to extend an isometry of the boundary of the domain to the
whole translator, under simple conditions. As an application, we obtain a characterization of the
the bowl when the boundary is a ball, and of certain translators foliated by horospheres whose
boundary is a rectangle.
Constant sectional curvature surfaces with a semi-symmetric non-metric connection
Evren Aydin, Muhittin
López Camino, Rafael
Mihai, Adela
https://hdl.handle.net/10481/95056
2024-09-25T09:09:49Z
Constant sectional curvature surfaces with a semi-symmetric non-metric connection
Evren Aydin, Muhittin; López Camino, Rafael; Mihai, Adela
Consider the Euclidean space R3endowed with a canonical semi-symmetric non-metric connection determined by a vector field C ∈X(R3). We study surfaces when the sectional curvature with respect to this connection is constant. In case that the surface is cylindrical, we obtain full classification when the rulings are orthogonal or parallel to C. If the surface is rotational, we prove that the rotation axis is parallel to Cand we classify all conical rotational surfaces with constant sectional curvature. Finally, for the particular case 12of the sectional curvature, the existence of rotational surfaces orthogonally intersecting the rotation axis is also obtained.
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CMC-1 Surfaces in Hyperbolic and de Sitter Spaces with Cantor Ends
Castro Infantes, Ildefonso
Hidalgo, Jorge
https://hdl.handle.net/10481/93920
2024-09-04T10:30:20Z
CMC-1 Surfaces in Hyperbolic and de Sitter Spaces with Cantor Ends
Castro Infantes, Ildefonso; Hidalgo, Jorge
We prove that on every compact Riemann surface M, there is a Cantor set C ⊂ M such that M\C admits a proper conformal constant mean curvature one (CMC-1) immersion into hyperbolic 3-space H3. Moreover, we obtain that every bordered Riemann surface admits an almost proper CMC-1 face into de Sitter 3-space S31, and we show that on every compact Riemann surface M, there is a Cantor set C ⊂ M such that M\C admits an almost proper CMC-1 face into S31. These results follow from different uniform approximation theorems for holomorphic null curves in C2 × C* that we also establish in this paper.
Classical and quantum field theory in a box with moving boundaries: A numerical study of the dynamical Casimir effect
García Martín-Caro, Alberto
García-Moreno, Gerardo
Olmedo, Javier
Sánchez Velázquez, Jose M.
https://hdl.handle.net/10481/93710
2024-07-31T11:04:38Z
Classical and quantum field theory in a box with moving boundaries: A numerical study of the dynamical Casimir effect
García Martín-Caro, Alberto; García-Moreno, Gerardo; Olmedo, Javier; Sánchez Velázquez, Jose M.
We present a detailed description of a quantum scalar field theory within a flat spacetime confined to a
cavity with perfectly reflecting moving boundaries. Moreover, we establish an equivalence between this
time-dependent setting and a field theory on an acoustic metric with static Dirichlet boundary conditions.
We discuss the classical and quantum aspects of the theory from the latter perspective, accompanied by the
introduction of novel numerical techniques designed for the (nonperturbative) computation of particle
production attributed to the dynamical Casimir effect, applicable to arbitrary boundary trajectories. As an
illustrative example of these methodologies, we compute the particle production for a massless field in
1 þ 1 dimensions. Notably, our approaches readily extend to encompass scenarios involving massive fields
and higher dimensions.