AHAkikazu Hashimoto
Akikazu Hashimoto
*This is an algorithmically generated author record based on publicly available information.
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Akikazu Hashimoto has a total of 19 co-authors. Here are the top co-authors by number of shared publications:
- Amit Giveon
Racah Institute of Physics The Hebrew University 91904 Jerusalem Israel
7 shared publications - Soumangsu Chakraborty
The Ohio State University
7 shared publications - David Kutasov
University of Chicago
5 shared publications - William Cottrell
Department of Physics, University of Wisconsin, Madison, U.S.A.
5 shared publications - Peter Ouyang
Department of Physics, University of Wisconsin, Madison, U.S.A.
3 shared publications - Masahito Yamazaki
University of Tokyo
2 shared publications
Latest Publications
- Open Access
- 14 May 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (5) , 1-14
CFT correlators from (0, 2) heterotic string
In [1], we argued that the (0, 2) heterotic string gives rise in spacetime to left and right-moving symmetric product CFT’s. In this paper we confirm this claim by showing that it computes correlation functions in these CFT’s.
- 14 May 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (5) , 1-14
Open AccessCFT correlators from (0, 2) heterotic string
In [1], we argued that the (0, 2) heterotic string gives rise in spacetime to left and right-moving symmetric product CFT’s. In this paper we confirm this claim by showing that it computes correlation functions in these CFT’s.
- Open Access
- 1 April 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (4) , 1-38
$ \mathcal{N} $ = 2 heterotic strings revisitedWe show that 1 + 1 dimensional vacua of the (0, 2) heterotic string have many properties in common with more recently studied physical systems. The free theory exhibits a symmetric product CFT structure. The single-string Hilbert space splits into sectors labeled by the string winding, w, that contain purely left-moving (for w > 0) and right-moving (for w < 0) excitations. These sectors exhibit infinite-dimensional left and right-moving symmetry algebras, respectively, with central extensions that depend on w. String interactions between left and right-movers appear to lead to a $$ T\overline{T} $$ deformation of the free theory.- 1 April 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (4) , 1-38
Open Access$ \mathcal{N} $ = 2 heterotic strings revisitedWe show that 1 + 1 dimensional vacua of the (0, 2) heterotic string have many properties in common with more recently studied physical systems. The free theory exhibits a symmetric product CFT structure. The single-string Hilbert space splits into sectors labeled by the string winding, w, that contain purely left-moving (for w > 0) and right-moving (for w < 0) excitations. These sectors exhibit infinite-dimensional left and right-moving symmetry algebras, respectively, with central extensions that depend on w. String interactions between left and right-movers appear to lead to a $$ T\overline{T} $$ deformation of the free theory. - Open Access
- 19 December 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (12) , 1-22
Path integral of free fields and the determinant of Laplacian in warped space-time
A bstract: We revisit the problem of computing the determinant of Klein-Gordon operator ∆ = −∇ 2 + M 2 on Euclideanized AdS 3 with the Euclideanized time coordinate compactified with period β , H 3 / Z , by explicitly computing its eigenvalues and computing their product. Upon assuming that eigenfunctions are normalizable on H 3 / Z , we found that there are no such eigenfunctions. Upon closer examination, we discover that the intuition that H 3 / Z is like a box with normalizable eigenfunctions was false, and that there is, instead, a set of eigenfunctions which forms a continuum. Somewhat to our surprise, we find that there is a different operator $$ \overset{\sim }{\Delta } $$ = r 2 ∆, which has the property that (1) the determinant of ∆ and the determinant of r 2 ∆ have the same dependence on β , and that (2) the Green’s function of ∆ can be spectrally decomposed into eigenfunctions of $$ \overset{\sim }{\Delta } $$ . We identify the $$ \overset{\sim }{\Delta } $$ operator as the “weighted Laplacian” in the context of warped compactifications, and comment on possible applications.- 19 December 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (12) , 1-22
Open AccessPath integral of free fields and the determinant of Laplacian in warped space-time
A bstract: We revisit the problem of computing the determinant of Klein-Gordon operator ∆ = −∇ 2 + M 2 on Euclideanized AdS 3 with the Euclideanized time coordinate compactified with period β , H 3 / Z , by explicitly computing its eigenvalues and computing their product. Upon assuming that eigenfunctions are normalizable on H 3 / Z , we found that there are no such eigenfunctions. Upon closer examination, we discover that the intuition that H 3 / Z is like a box with normalizable eigenfunctions was false, and that there is, instead, a set of eigenfunctions which forms a continuum. Somewhat to our surprise, we find that there is a different operator $$ \overset{\sim }{\Delta } $$ = r 2 ∆, which has the property that (1) the determinant of ∆ and the determinant of r 2 ∆ have the same dependence on β , and that (2) the Green’s function of ∆ can be spectrally decomposed into eigenfunctions of $$ \overset{\sim }{\Delta } $$ . We identify the $$ \overset{\sim }{\Delta } $$ operator as the “weighted Laplacian” in the context of warped compactifications, and comment on possible applications. - Open Access
CFT Correlators from (0,2) Heterotic String
In \cite{Giveon:2024fhz}, we argued that the (0,2) heterotic string gives rise in spacetime to left and right-moving symmetric product CFT's. In this paper we confirm this claim by showing that it computes correlation functions in these CFT's.
Open AccessCFT Correlators from (0,2) Heterotic String
In \cite{Giveon:2024fhz}, we argued that the (0,2) heterotic string gives rise in spacetime to left and right-moving symmetric product CFT's. In this paper we confirm this claim by showing that it computes correlation functions in these CFT's.
- Open Access
N=2 Heterotic Strings Revisited
We show that $1+1$ dimensional vacua of the $(0,2)$ heterotic string have many properties in common with more recently studied physical systems. The free theory exhibits a symmetric product CFT structure. The single-string Hilbert space splits into sectors labeled by the string winding, $w$, that contain purely left-moving (for $w>0$) and right-moving (for $w<0$) excitations. These sectors exhibit infinite-dimensional left and right-moving symmetry algebras, respectively, with central extensions that depend on $w$. String interactions between left and right-movers appear to lead to a $T\bar T$ deformation of the free theory.Open AccessN=2 Heterotic Strings Revisited
We show that $1+1$ dimensional vacua of the $(0,2)$ heterotic string have many properties in common with more recently studied physical systems. The free theory exhibits a symmetric product CFT structure. The single-string Hilbert space splits into sectors labeled by the string winding, $w$, that contain purely left-moving (for $w>0$) and right-moving (for $w<0$) excitations. These sectors exhibit infinite-dimensional left and right-moving symmetry algebras, respectively, with central extensions that depend on $w$. String interactions between left and right-movers appear to lead to a $T\bar T$ deformation of the free theory. - Open Access
- 16 July 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (7) , 1-46
Thermal partition function of $ {J}_3{\overline{J}}_3 $ deformed AdS3We derive a compact formula for the one-loop, bosonic string partition function of Euclideanized $$ {J}_3{\overline{J}}_3 $$ deformed AdS 3 with periodic Euclidean time as an integral transform of the partition function of the undeformed Euclideanized AdS 3. Such a deformation is interpretable as an irrelevant “single-trace $$ T\overline{T} $$ deformation” of the boundary. We will do this by first establishing a formal procedure to compute a worldsheet torus zero point function for an exactly marginal $$ J\overline{J} $$ deformation of a sigma model with U(1) L × U(1) R global symmetry. We then describe how this procedure is implemented on SL(2, R) sigma model and its Euclidean continuation. Finally, we describe the embedding of the deformed SL(2, R) torus amplitude into critical string theory and interpret the result as the leading perturbative contribution to the thermal partition function of the deformed theory.- 16 July 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (7) , 1-46
Open AccessThermal partition function of $ {J}_3{\overline{J}}_3 $ deformed AdS3We derive a compact formula for the one-loop, bosonic string partition function of Euclideanized $$ {J}_3{\overline{J}}_3 $$ deformed AdS 3 with periodic Euclidean time as an integral transform of the partition function of the undeformed Euclideanized AdS 3. Such a deformation is interpretable as an irrelevant “single-trace $$ T\overline{T} $$ deformation” of the boundary. We will do this by first establishing a formal procedure to compute a worldsheet torus zero point function for an exactly marginal $$ J\overline{J} $$ deformation of a sigma model with U(1) L × U(1) R global symmetry. We then describe how this procedure is implemented on SL(2, R) sigma model and its Euclidean continuation. Finally, we describe the embedding of the deformed SL(2, R) torus amplitude into critical string theory and interpret the result as the leading perturbative contribution to the thermal partition function of the deformed theory. - Open Access
- 26 April 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (4) , 1-11
On string theory on deformed BTZ and $ \textrm{T}\overline{\textrm{T}} $Aspects of superstring theory on deformed BTZ black holes, formed near k NS5 branes by p fundamental strings, and single-trace $$ T\overline{T} $$ holography, are presented. The excitation energy of a singly wound long string plus its contribution to the energy of the black hole, 1/p fraction of the black-hole energy, is the same as that in $$ T\overline{T} $$ deformed CFT2 with c = 6k. This supports the claim that the black hole can be thought of as a state in a symmetric product of p CFT2’s of central charge 6k, where the black-hole energy is split equally among all p factors. A comment on superstring theory on deformed global AdS3 is also presented.- 26 April 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (4) , 1-11
Open AccessOn string theory on deformed BTZ and $ \textrm{T}\overline{\textrm{T}} $Aspects of superstring theory on deformed BTZ black holes, formed near k NS5 branes by p fundamental strings, and single-trace $$ T\overline{T} $$ holography, are presented. The excitation energy of a singly wound long string plus its contribution to the energy of the black hole, 1/p fraction of the black-hole energy, is the same as that in $$ T\overline{T} $$ deformed CFT2 with c = 6k. This supports the claim that the black hole can be thought of as a state in a symmetric product of p CFT2’s of central charge 6k, where the black-hole energy is split equally among all p factors. A comment on superstring theory on deformed global AdS3 is also presented. - Open AccessThermal partition function of $J_3 \bar{J}_3$ deformed $AdS_3$We derive a compact formula for the one-loop, bosonic string partition function of Euclideanized $J_3 \bar J_3$ deformed $AdS_3$ with periodic Euclidean time as an integral transform of the partition function of the undeformed Euclideanized $AdS_3$. Such a deformation is interpretable as an irrelevant "single-trace $T \bar T$ deformation" of the boundary. We will do this by first establishing a formal procedure to compute a worldsheet torus zero point function for an exactly marginal $J \bar J$ deformation of a sigma model with $U(1)_L \times U(1)_R$ global symmetry. We then describe how this procedure is implemented on $SL(2,R)$ sigma model and its Euclidean continuation. Finally, we describe the embedding of the deformed $SL(2,R)$ torus amplitude into critical string theory and interpret the result as the leading perturbative contribution to the thermal partition function of the deformed theory.Open AccessThermal partition function of $J_3 \bar{J}_3$ deformed $AdS_3$We derive a compact formula for the one-loop, bosonic string partition function of Euclideanized $J_3 \bar J_3$ deformed $AdS_3$ with periodic Euclidean time as an integral transform of the partition function of the undeformed Euclideanized $AdS_3$. Such a deformation is interpretable as an irrelevant "single-trace $T \bar T$ deformation" of the boundary. We will do this by first establishing a formal procedure to compute a worldsheet torus zero point function for an exactly marginal $J \bar J$ deformation of a sigma model with $U(1)_L \times U(1)_R$ global symmetry. We then describe how this procedure is implemented on $SL(2,R)$ sigma model and its Euclidean continuation. Finally, we describe the embedding of the deformed $SL(2,R)$ torus amplitude into critical string theory and interpret the result as the leading perturbative contribution to the thermal partition function of the deformed theory.
- Open AccessOn string theory on deformed BTZ and $T\bar T$Aspects of superstring theory on deformed BTZ black holes, formed near $k$~NS5 branes by $p$~fundamental strings, and single-trace $T\bar T$ holography, are presented. The excitation energy of a singly wound long string plus its contribution to the energy of the black hole, $1/p$ fraction of the black-hole energy, is the same as that in $T\bar T$ deformed $CFT_2$ with $c=6k$. This supports the claim that the black hole can be thought of as a state in a symmetric product of $p$~$CFT_2$'s of central charge~$6k$, where the black-hole energy is split equally among all $p$ factors. A comment on superstring theory on deformed global $AdS_3$ is also presented.Open AccessOn string theory on deformed BTZ and $T\bar T$Aspects of superstring theory on deformed BTZ black holes, formed near $k$~NS5 branes by $p$~fundamental strings, and single-trace $T\bar T$ holography, are presented. The excitation energy of a singly wound long string plus its contribution to the energy of the black hole, $1/p$ fraction of the black-hole energy, is the same as that in $T\bar T$ deformed $CFT_2$ with $c=6k$. This supports the claim that the black hole can be thought of as a state in a symmetric product of $p$~$CFT_2$'s of central charge~$6k$, where the black-hole energy is split equally among all $p$ factors. A comment on superstring theory on deformed global $AdS_3$ is also presented.
- Open Access
- 8 February 2023
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2023 (2) , 1-27
A worldsheet description of instant folded strings
Time-like linear dilaton backgrounds admit a classical solution that describes a closed folded string that is created at an instant. We refer to such strings as Instant Folded Strings (IFS). We study an exact worldsheet CFT description of an IFS that involves two vertex operators which describe two open string modes that propagate on a time-like FZZT-brane, which plays the role of a regulator to the IFS. We take advantage of this description to calculate the most basic quantity associated with IFSs — their production rate. Some implications of this calculation to stringy cosmology and black hole interior are briefly discussed.
- 8 February 2023
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2023 (2) , 1-27
Open AccessA worldsheet description of instant folded strings
Time-like linear dilaton backgrounds admit a classical solution that describes a closed folded string that is created at an instant. We refer to such strings as Instant Folded Strings (IFS). We study an exact worldsheet CFT description of an IFS that involves two vertex operators which describe two open string modes that propagate on a time-like FZZT-brane, which plays the role of a regulator to the IFS. We take advantage of this description to calculate the most basic quantity associated with IFSs — their production rate. Some implications of this calculation to stringy cosmology and black hole interior are briefly discussed.