On the generalized $m$-Kropina metrics
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866912670530142208 |
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| author | Taha, Ebtsam H. |
| author_facet | Taha, Ebtsam H. |
| contents | Generalized $m$-Kropina metrics appear naturally as a spacetime geometry compatible with Lorentz symmetry breaking, leading to useful applications in modified gravity and cosmology. We prove that a generalized $m$-Kropina metric $F$ is an almost rational Finsler metric. Thereby, we study the rationality of its Finslerian geometric objects in the directional variable $y$. For example, its geodesic spray coefficients are rational in $y$. Consequently, we prove that if $F$ is an Einstein metric with $m \notin \mathbb{Z}$, then it is Ricci-flat. Moreover, for $m \in 2 \mathbb{Z}$, if $F$ has isotropic mean Berwald curvature, or has relatively isotropic Landsberg curvature, or has almost vanishing $\mathbf{H}$-curvature, then $F$ is weakly Berwaldian, or $F$ is Landsbergian, or $\mathbf{H}=0$, respectively. We, hence, deduce under what conditions a generalized $m$-Kropina metric $F$ becomes an exact solution to either "Chen and Shen's Finslerian nonvcuum field equations"or "Pfeifer and Wohlfath's vacuum field equation". Finally, some examples of generalized $m$-Kropina metrics in dimension $4$, which has significant applications in modified gravity and cosmology, are provided. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2510_22466 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | On the generalized $m$-Kropina metrics Taha, Ebtsam H. Differential Geometry General Relativity and Quantum Cosmology 53B40, 53C60, 53C30, 58B20, 58J60 Generalized $m$-Kropina metrics appear naturally as a spacetime geometry compatible with Lorentz symmetry breaking, leading to useful applications in modified gravity and cosmology. We prove that a generalized $m$-Kropina metric $F$ is an almost rational Finsler metric. Thereby, we study the rationality of its Finslerian geometric objects in the directional variable $y$. For example, its geodesic spray coefficients are rational in $y$. Consequently, we prove that if $F$ is an Einstein metric with $m \notin \mathbb{Z}$, then it is Ricci-flat. Moreover, for $m \in 2 \mathbb{Z}$, if $F$ has isotropic mean Berwald curvature, or has relatively isotropic Landsberg curvature, or has almost vanishing $\mathbf{H}$-curvature, then $F$ is weakly Berwaldian, or $F$ is Landsbergian, or $\mathbf{H}=0$, respectively. We, hence, deduce under what conditions a generalized $m$-Kropina metric $F$ becomes an exact solution to either "Chen and Shen's Finslerian nonvcuum field equations"or "Pfeifer and Wohlfath's vacuum field equation". Finally, some examples of generalized $m$-Kropina metrics in dimension $4$, which has significant applications in modified gravity and cosmology, are provided. |
| title | On the generalized $m$-Kropina metrics |
| topic | Differential Geometry General Relativity and Quantum Cosmology 53B40, 53C60, 53C30, 58B20, 58J60 |
| url | https://arxiv.org/abs/2510.22466 |