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| Main Authors: | , , |
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| Format: | Preprint |
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2024
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| Online Access: | https://arxiv.org/abs/2409.01819 |
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| _version_ | 1866910606452326400 |
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| author | Bao, Zhigang Lee, Jaehun Xu, Xiaocong |
| author_facet | Bao, Zhigang Lee, Jaehun Xu, Xiaocong |
| contents | In this paper, we consider the rectangular random matrix $X=(x_{ij})\in \mathbb{R}^{N\times n}$ whose entries are iid with tail $\mathbb{P}(|x_{ij}|>t)\sim t^{-α}$ for some $α>0$. We consider the regime $N(n)/n\to \mathsf{a}>1$ as $n$ tends to infinity. Our main interest lies in the right singular vector corresponding to the smallest singular value, which we will refer to as the "bottom singular vector", denoted by $\mathfrak{u}$. In this paper, we prove the following phase transition regarding the localization length of $\mathfrak{u}$: when $α<2$ the localization length is $O(n/\log n)$; when $α>2$ the localization length is of order $n$. Similar results hold for all right singular vectors around the smallest singular value. The variational definition of the bottom singular vector suggests that the mechanism for this localization-delocalization transition when $α$ goes across $2$ is intrinsically different from the one for the top singular vector when $α$ goes across $4$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2409_01819 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Phase transition for the bottom singular vector of rectangular random matrices Bao, Zhigang Lee, Jaehun Xu, Xiaocong Probability Mathematical Physics In this paper, we consider the rectangular random matrix $X=(x_{ij})\in \mathbb{R}^{N\times n}$ whose entries are iid with tail $\mathbb{P}(|x_{ij}|>t)\sim t^{-α}$ for some $α>0$. We consider the regime $N(n)/n\to \mathsf{a}>1$ as $n$ tends to infinity. Our main interest lies in the right singular vector corresponding to the smallest singular value, which we will refer to as the "bottom singular vector", denoted by $\mathfrak{u}$. In this paper, we prove the following phase transition regarding the localization length of $\mathfrak{u}$: when $α<2$ the localization length is $O(n/\log n)$; when $α>2$ the localization length is of order $n$. Similar results hold for all right singular vectors around the smallest singular value. The variational definition of the bottom singular vector suggests that the mechanism for this localization-delocalization transition when $α$ goes across $2$ is intrinsically different from the one for the top singular vector when $α$ goes across $4$. |
| title | Phase transition for the bottom singular vector of rectangular random matrices |
| topic | Probability Mathematical Physics |
| url | https://arxiv.org/abs/2409.01819 |