arXiv subjects

Akihiro Sei

Publications and source records attributed to Akihiro Sei.

4 recordsLinked to original sources

arXiv2026

Line operator indices of S-fold theories

We study superconformal indices in the presence of line operators in S-fold theories. We consider two types of lines, realized by fundamental strings and fivebranes, respectively, in AdS$_5 \times S^5/\mathbb{Z}_k$. For fundamental lines, we analyze the corresponding indices including finite-$N$ corrections arising from giant graviton configurations. For $k=2$, we compare the holographic results with line operator indices in $\mathcal{N}=4$ super Yang-Mills theories with orthogonal gauge groups. For $k=3,4$ and $6$, we focus on the rank $2$ case, in which the supersymmetry is enhanced to ${\cal N}=4$, and compare them with the corresponding Wilson-'t Hooft line operator indices. In both cases, we find improved agreement once giant graviton contributions are included. For line operators realized by fivebranes, after confirming agreement for $k=2$, we construct BPS configurations for $k\geq 3$ explicitly using fivebrane junctions and derive the indices in the large $N$ limit by the mode analysis on the fivebrane junctions.

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arXiv2025

D1-brane correction to a line operator index

Wilson line operators in the rank $k$ totally symmetric tensor representation of ${\cal N}=4$ $U(N)$ sypersymmetric Yang-Mills theories are expected to be realized as D3-branes expanded in $AdS_5$. Although there is a mismatch between the corresponding line operator indices even in the large $N$ and large $k$ limit, it is possible to calculate the finite $k$ correction on the AdS side as the contribution from D1-branes. We analyze D1-brane fluctuation modes and calculate the leading finite $k$ correction to the line operator index on the AdS side.

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arXiv2024

Giant graviton expansion for general Wilson line operator indices

We propose a giant graviton expansion for Wilson line operator indices in general representations. The inserted line operators are specified by power sum symmetric polynomials $p_λ$ labeled by partitions $λ$. We interpret the partitions as the structure of fundamental string worldsheets wrapping around the temporal circle. The strings may or may not end on giant gravitons, and by summing the contributions from all brane configurations consistent with the specified partitions, we obtain the finite $N$ line operator index. The proposed formula is consistent with known results and passes highly non-trivial numerical tests.

hep-th↗

arXiv2023

Character Expansion Methods for $\mathrm{USp}(2N)$, $\mathrm{SO}(n)$, and $\mathrm{O}(n)$ using the Characters of the Symmetric Group

In theories with supersymmetry, we can calculate a special partition function, known as the superconformal index. In particular, for a gauge group of $\mathrm{U}(N)$ and particles belonging to the adjoint representation, there is a fast method known as the character expansion method, which uses the characters of the symmetric group. In this paper, we extend this method to theories of particles belonging to specific representations of the gauge groups: $\mathrm{USp}(2N)$, $\mathrm{SO}(n)$, and $\mathrm{O}(n)$. Furthermore, we propose a formula, which gives the large $N$ limit without using the characters.

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