اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدCCNV Space-Times as Potential Supergravity Solutions
412
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
It is of interest to study supergravity solutions preserving a non-minimal fraction of supersymmetries. A necessary condition for supersymmetry to be preserved is that the spacetime admits a Killing spinor and hence a null or timelike Killing vector field. Any spacetime admitting a covariantly constant null vector field ($CCNV$) belongs to the Kundt class of metrics, and more importantly admits a null Killing vector field. We investigate the existence of additional non-spacelike isometries in the class of higher-dimensional $CCNV$ Kundt metrics in order to produce potential solutions that preserve some supersymmetries.
قيم البحث
اقرأ أيضاً
The gauged sigma model with target $mathbb{P}^1$, defined on a Riemann surface $Sigma$, supports static solutions in which $k_+$ vortices coexist in stable equilibrium with $k_-$ antivortices. Their moduli space is a noncompact complex manifold $M_{(
k_+,k_-)}(Sigma)$ of dimension $k_++k_-$ which inherits a natural Kahler metric $g_{L^2}$ governing the models low energy dynamics. This paper presents the first detailed study of $g_{L^2}$, focussing on the geometry close to the boundary divisor $D=partial M_{(k_+,k_-)}(Sigma)$. On $Sigma=S^2$, rigorous estimates of $g_{L^2}$ close to $D$ are obtained which imply that $M_{(1,1)}(S^2)$ has finite volume and is geodesically incomplete. On $Sigma=mathbb{R}^2$, careful numerical analysis and a point-vortex formalism are used to conjecture asymptotic formulae for $g_{L^2}$ in the limits of small and large separation. All these results make use of a localization formula, expressing $g_{L^2}$ in terms of data at the (anti)vortex positions, which is established for general $M_{(k_+,k_-)}(Sigma)$. For arbitrary compact $Sigma$, a natural compactification of the space $M_{(k_+,k_-)}(Sigma)$ is proposed in terms of a certain limit of gauged linear sigma models, leading to formulae for its volume and total scalar curvature. The volume formula agrees with the result established for $Vol(M_{(1,1)}(S^2))$, and allows for a detailed study of the thermodynamics of vortex-antivortex gas mixtures. It is found that the equation of state is independent of the genus of $Sigma$, and that the entropy of mixing is always positive.
We define the notion of geodesic completeness for semi-Riemannian metrics of low regularity in the framework of the geometric theory of generalized functions. We then show completeness of a wide class of impulsive gravitational wave space-times.
The aim of this work is to describe the complete family of non-expanding Plebanski-Demianski type D space-times and to present their possible interpretation. We explicitly express the most general form of such (electro)vacuum solutions with any cosmo
logical constant, and we investigate the geometrical and physical meaning of the seven parameters they contain. We present various metric forms, and by analyzing the corresponding coordinates in the weak-field limit we elucidate the global structure of these space-times, such as the character of possible singularities. We also demonstrate that members of this family can be understood as generalizations of classic B-metrics. In particular, the BI-metric represents an external gravitational field of a tachyonic (superluminal) source, complementary to the AI-metric which is the well-known Schwarzschild solution for exact gravitational field of a static (standing) source.
We consider travelling times of billiard trajectories in the exterior of an obstacle K on a two-dimensional Riemannian manifold M. We prove that given two obstacles with almost the same travelling times, the generalised geodesic flows on the non-trap
ping parts of their respective phase-spaces will have a time-preserving conjugacy. Moreover, if M has non-positive sectional curvature we prove that if K and L are two obstacles with strictly convex boundaries and almost the same travelling times then K and L are identical.
We construct new smooth solutions to the Hull-Strominger system, showing that the Fu-Yau solution on torus bundles over K3 surfaces can be generalized to torus bundles over K3 orbifolds. In particular, we prove that, for $13 leq k leq 22$ and $14leq
rleq 22$, the smooth manifolds $S^1times sharp_k(S^2times S^3)$ and $sharp_r (S^2 times S^4) sharp_{r+1} (S^3 times S^3)$, have a complex structure with trivial canonical bundle and admit a solution to the Hull-Strominger system.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
