arXiv subjects

Arkady A. Tseytlin

Publications and source records attributed to Arkady A. Tseytlin.

At least 37 records · Page 2Linked to original sources

arXiv2024

On AdS/CFT duality in the twisted sector of string theory on $AdS_5 \times S^5/\mathbb{Z}_2$ orbifold background

We consider type IIB string theory on an $AdS_5 \times S^5/\mathbb{Z}_2$ orbifold background, which should be dual to 4d $\mathcal{N}=2$ superconformal $SU(N)\times SU(N)$ gauge theory with two bi-fundamental hypermultiplets. The correlator of two chiral BPS operators from the twisted sector of this quiver CFT exhibits non-trivial dependence on the 't Hooft coupling $λ$ already in the planar limit. This dependence was recently determined using localisation and the expansion at large $λ$ contains a subleading contribution proportional to $ζ(3) λ^{-3/2}$. We address the question of how to reproduce this correction on the string theory side by starting with the $ζ(3) α'^3$ term in the type IIB string effective action. We find a solution of type IIB supergravity which represents a resolution of the $AdS_5 \times S^5/\mathbb{Z}_2$ orbifold singularity and demonstrate that the relevant light twisted sector states may be identified as additional supergravity 2-form modes "wrapping" a finite 2-cycle in the resolution space. Reproducing the structure of the gauge theory result becomes more transparent in the large R-charge or BMN-like limit in which the resolved background takes a pp-wave form with the transverse space being a product of $\mathbb R^4$ and the Eguchi-Hanson space.

hep-th↗

arXiv2024

Large N expansion of superconformal index of k=1 ABJM theory and semiclassical M5 brane partition function

It was shown in arXiv:2309.10786 that the leading non-perturbative contribution to the large $N$ expansion of superconformal index of (2,0) 6d theory (which describes low-energy dynamics of $N$ coincident M5 branes) is reproduced by the semiclassical partition function of quantum M2 brane wrapped on $S^{1}\times S^{2}$ in a twisted version of AdS$_{7}\times S^{4}$ background. Here we demonstrate an analogous relation for the leading non-perturbative contribution to the large $N$ expansion of the superconformal index of the ${n}=8$ supersymmetric level-one $U(N) \times U(N)$ ABJM theory (which describes low-energy dynamics of $N$ coincident M2 branes). The roles of M2 and M5 branes get effectively interchanged. Namely, the large $N$ correction to the ABJM index is found to be given by the semiclassical partition function of quantum M5 brane wrapped on $S^1 \times S^5$ in a twisted version of AdS$_{4}\times S^{7}$ background. This effectively confirms the suggestion for the "M5 brane index" made in arXiv:2007.05213 on the basis of indirect superconformal algebra considerations.

hep-th↗

arXiv2023

(2,0) theory on $S^5 \times S^1$ and quantum M2 branes

The superconformal index $Z$ of the 6d (2,0) theory on $S^5 \times S^1$ (which is related to the localization partition function of 5d SYM on $S^5$) should be captured at large $N$ by the quantum M2 brane theory in the dual M-theory background. Generalizing the type IIA string theory limit of this relation discussed in arXiv:2111.15493 and arXiv:2304.12340, we consider semiclassically quantized M2 branes in a half-supersymmetric 11d background which is a twisted product of thermal AdS$_7$ and $S^4$. We show that the leading non-perturbative term at large $N$ is reproduced precisely by the 1-loop partition function of an "instanton" M2 brane wrapped on $S^1\times S^2$ with $S^2\subset S^4$. Similarly, the (2,0) theory analog of the BPS Wilson loop expectation value is reproduced by the partition function of a "defect" M2 brane wrapped on thermal AdS$_3\subset$ AdS$_7$. We comment on a curious analogy of these results with similar computations in arXiv:2303.15207 and arXiv:2307.14112 of the partition function of quantum M2 branes in AdS$_4 \times S^7/\mathbb Z_k$ which reproduced the corresponding localization expressions in the ABJM 3d gauge theory.

hep-th↗

arXiv2023

Instanton contributions to the ABJM free energy from quantum M2 branes

We present a quantum M2 brane computation of the instanton prefactor in the leading non-perturbative contribution to the ABJM 3-sphere free energy at large $N$ and fixed level $k$. Using supersymmetric localization, such instanton contribution was found earlier to take the form $F^{\rm inst}(N,k) = - ({\sin^{2} \frac{2π}{k}} )^{-1} \, \exp (-2π\sqrt\frac{2N}{k}) + \cdots$ . The exponent comes from the action of an M2 brane instanton wrapped on $S^3/{\mathbb Z}_k$, which represents the M-theory uplift of the $\mathbb{C}P^1$ instanton in type IIA string theory on AdS$_4 \times \mathbb{C}P^3$. The IIA string computation of the leading large $k$ term in the instanton prefactor was recently performed in arXiv:2304.12340. Here we find that the exact value of the prefactor $({\sin^{2} \frac{2π}{k}})^{-1} $ is reproduced by the 1-loop term in the M2 brane partition function expanded near the $S^3/\mathbb{Z}_k$ instanton configuration. As in the Wilson loop example in arXiv:2303.15207, the quantum M2 brane computation is well defined and produces a finite result in exact agreement with localization.

hep-th↗

arXiv2023

Comments on ABJM free energy on $S^{3}$ at large $N$ and perturbative expansions in M-theory and string theory

We compare large $N$ expansion of the localization result for the free energy $F$ in the 3d $\mathcal{N}=6$ superconformal $U(N)_k \times U(N)_{-k}$ Chern-Simons-matter theory to its AdS/CFT counterpart, i.e. to the perturbative expansion of M-theory partition function on AdS$_{4}\times S^{7}/\mathbb{Z}_{k}$ and to the weak string coupling expansion of type IIA effective action on AdS$_{4}\times {\rm CP}^3$. We show that the general form of the perturbative expansions of $F$ on the two sides of the AdS/CFT duality is indeed the same. Moreover, the transcendentality properties of the coefficients in the large $N$, large $k$ expansion of $F$ match those in the corresponding M-theory or string theory expansions. To shed light on the structure of the 1-loop M-theory partition function on AdS$_{4}\times S^{7}/\mathbb{Z}_{k}$ we use the expression for the 1-loop 4-graviton scattering amplitude in the 11d supergravity. We also use the known information about the transcendental coefficients of the leading curvature invariants in the low-energy effective action of type II string theory. Matching of the remaining rational factors in the coefficients requires a precise information about currently unknown RR field strength terms in the corresponding superinvariants.

hep-th↗

arXiv2023

Wilson loops at large $N$ and the quantum M2 brane

The Wilson loop operator in the $U(N)_k \times U(N)_{-k}$ ABJM theory at large $N$ and fixed level $k$ has a dual description in terms of a wrapped M2 brane in the M-theory background AdS$_4 \times S^7/\mathbb Z_k$. We consider the localization result for the $1\over 2$-BPS circular Wilson loop expectation value $W$ in this regime, and compare it to the prediction of the M2 brane theory. The leading large $N$ exponential factor is matched as expected by the classical action of the M2 brane solution with AdS$_2\times S^1$ geometry. We show that the subleading $k$-dependent prefactor in $W$ is also exactly reproduced by the one-loop term in the partition function of the wrapped M2 brane (with all Kaluza-Klein modes included). This appears to be the first case of an exact matching of the overall numerical prefactor in the Wilson loop expectation value against the dual holographic result. It provides an example of a consistent quantum M2 brane computation, suggesting various generalizations.

hep-th↗

arXiv2023

On the structure of non-planar strong coupling corrections to correlators of BPS Wilson loops and chiral primary operators

Starting with some known localization (matrix model) representations for correlators involving 1/2 BPS circular Wilson loop $\cal W$ in ${\cal N}=4$ SYM theory we work out their $1/N$ expansions in the limit of large 't Hooft coupling $λ$. Motivated by a possibility of eventual matching to higher genus corrections in dual string theory we follow arXiv:2007.08512 and express the result in terms of the string coupling $g_{\rm s} \sim g^2_{\rm YM} \sim λ/N$ and string tension $T\sim \sqrt λ$. Keeping only the leading in $1/T$ term at each order in $g_{\rm s} $ we observe that while the expansion of $\langle {\cal W} \rangle$ is a series in $g^2_{\rm s} /T$, the correlator of the Wilson loop with chiral primary operators ${\cal O}_J $ has expansion in powers of $g^2_{\rm s}/T^2$. Like in the case of $\langle {\cal W} \rangle$ where these leading terms are known to resum into an exponential of a "one-handle" contribution $\sim g^2_{\rm s} /T$, the leading strong coupling terms in $\langle {\cal W}\, {\cal O}_J \rangle$ sum up to a simple square root function of $g^2_{\rm s}/T^2$. Analogous expansions in powers of $g^2_{\rm s}/T$ are found for correlators of several coincident Wilson loops and they again have a simple resummed form. We also find similar expansions for correlators of coincident 1/2 BPS Wilson loops in the ABJM theory.

hep-th↗

arXiv2022

Integrability vs. RG flow in $G \times G$ and $G \times G /H$ sigma models

We consider a class of 2d $σ$-models on products of group spaces that provide new examples of a close connection between integrability and stability under the RG flow. We first study the integrable $G \times G$ model derived from the affine Gaudin construction (for which the 1-loop $β$-functions were found in arXiv:2010.07879) and show that its condition of integrability is preserved also by the 2-loop RG flow. We then investigate the RG flow in the gauged $G \times G /H$ model, in particular the integrable $T^{1,1}$ model found in arXiv:2010.05573. We also construct a new class of integrable $G \times G /H$ models in the case when the subgroup $H$ is abelian. In the simplest case of $G=SU_2$, $H=U_1$ this leads to an integrable $σ$-model on the $T^{1,q}$ space (with a particular $B$-field). This model is also shown to be stable under the 2-loop RG flow, and we relate this property to its invariance under T-duality in an isometric $U_1$ direction. This $T^{1,q}$ model may be interpreted as an integrable deformation of the GMM model (of two coupled WZW theories with generic levels) away from the conformal point.

hep-th↗

arXiv2022

Integrable supersymmetric deformations of $\rm AdS_3 \times S^3 \times T^4$

We construct a family of type IIB string backgrounds that are deformations of $\rm AdS_3 \times S^3 \times T^4$ with a "squashed" $\rm AdS_3 \times S^3$ metric supported by a combination of NSNS and RR fluxes. They have global $\rm SU(1,1) \times SU(2)$ symmetry, regular curvature, constant dilaton and preserve 8 supercharges. Upon compactification to 4 dimensions they reduce to $\mathcal N=2$ supersymmetric $\rm AdS_2 \times S^2$ solutions with electric and magnetic Maxwell fluxes. These type IIB supergravity solutions can be found from the undeformed $\rm AdS_3 \times S^3 \times T^4$ background by a combination of T-dualities and S-duality. In contrast to T-duality, S-duality transformations of a type IIB supergravity background do not generally preserve the classical integrability of the corresponding Green-Schwarz superstring sigma model. Nevertheless, we show that integrability is preserved in the present case. Indeed, we find that these backgrounds can be obtained, up to T-dualities, from an integrable inhomogeneous Yang-Baxter deformation (with unimodular Drinfel'd-Jimbo R-matrix) of the original $\rm AdS_3 \times S^3$ supercoset model.

hep-th↗

arXiv2022

BPS Wilson loop in $\mathcal N=2$ superconformal $SU(N)$ "orientifold" gauge theory and weak-strong coupling interpolation

We consider the expectation value $\langle \cal W \rangle$ of the circular BPS Wilson loop in ${\cal N}=2$ superconformal $SU(N)$ gauge theory containing a vector multiplet coupled to two hypermultiplets in rank-2 symmetric and antisymmetric representations. This model admits a regular large $N$ expansion, is planar-equivalent to ${\cal N}=4$ SYM theory and is expected to be dual to a certain orbifold/orientifold projection of AdS$_5\times S^5$ superstring theory. On the string theory side $\langle\cal W \rangle $ is represented by the path integral expanded near the same AdS$_2$ minimal surface as in the maximally supersymmetric case. Following the string theory argument in arXiv:2007.08512, we suggest that as in the ${\cal N}=4$ SYM case and in the ${\cal N}=2$ $SU(N) \times SU(N)$ superconformal quiver theory discussed in arXiv:2102.07696, the coefficient of the leading non-planar $1/N^2$ correction in $\langle\cal W \rangle $ should have the universal $λ^{3/2}$ scaling at large 't Hooft coupling. We confirm this prediction by starting with the localization matrix model representation for $\langle\cal W \rangle $. We complement the analytic derivation of the $λ^{3/2}$ scaling by a numerical high-precision resummation and extrapolation of the weak-coupling expansion using conformal mapping improved Padé analysis.

hep-th↗

arXiv2022

$1/N$ expansion of circular Wilson loop in $\mathcal N=2$ superconformal $SU(N)\times SU(N)$ quiver

Localization approach to $\mathcal N=2$ superconformal $SU(N) \times SU(N)$ quiver theory leads to a non-Gaussian two-matrix model representation for the expectation value of BPS circular $SU(N)$ Wilson loop $\langle\mathcal W\rangle$. We study the subleading $1/N^2$ term in the large $N$ expansion of $\langle\mathcal W\rangle$ at weak and strong coupling. We concentrate on the case of the symmetric quiver with equal gauge couplings which is equivalent to the $\mathbb Z_{2}$ orbifold of the $SU(2N)$ $\mathcal N=4$ SYM theory. This orbifold gauge theory should be dual to type IIB superstring in ${\rm AdS}_5\times (S^{5}/\mathbb Z_{2})$. We present a string theory argument suggesting that the $1/N^2$ term in $\langle\mathcal W\rangle$ in the orbifold theory should have the same strong-coupling asymptotics $ λ^{3/2}$ as in the $\mathcal N=4$ SYM case. We support this prediction by a numerical study of the localization matrix model on the gauge theory side. We also find a relation between the $1/N^2$ term in the Wilson loop expectation value and the derivative of the free energy of the orbifold gauge theory on 4-sphere.

hep-th↗

arXiv2022

On type 0 string theory in solvable RR backgrounds

Motivated by a possibility of solving non-supersymmetric type 0 string theory in $AdS_5 \times S^5$ background using integrability, we revisit the construction of type 0 string spectrum in some solvable examples of backgrounds with RR fluxes that are common to type IIB and type 0B theories. The presence of RR fluxes requires the use of a Green-Schwarz description for type 0 string theory. Like in flat space, the spectrum of type 0 theory can be derived from the type II theory spectrum by a $(-1)^F$ orbifolding, i.e. combining the untwisted sector where GS fermions are periodic with the twisted sector where GS fermions are antiperiodic (and projecting out all spacetime fermionic states). This construction of the type 0 spectrum may also be implemented using a Melvin background that allows to continuously interpolate between the type II and type 0 theories. As an illustration, we discuss the type 0B spectrum in the pp-wave background which is the Penrose limit of $AdS_5 \times S^5$ with RR 5-form flux and also in the pp-wave background which is the Penrose limit of $AdS_3 \times S^3 \times T^4$ supported by mixed RR and NSNS 3-form fluxes. We show that increasing the strength of the RR flux increases the value of the effective normal ordering constant (which determines the mass of the type 0 tachyon) and thus effectively decreases the momentum-space domain of instability of the ground state. We also comment on the semiclassical sector of states of type 0B theory in $AdS_5 \times S^5$.

hep-th↗

arXiv2021

Defect CFT in the 6d (2,0) theory from M2 brane dynamics in AdS$_7 \times$S$^4$

Surface operators in the 6d (2,0) theory at large $N$ have a holographic description in terms of M2 branes probing the AdS$_7 \times S^4$ M-theory background. The most symmetric, 1/2-BPS, operator is defined over a planar or spherical surface, and it preserves a 2d superconformal group. This includes, in particular, an $SO(2,2)$ subgroup of 2d conformal transformations, so that the surface operator may be viewed as a conformal defect in the 6d theory. The dual M2 brane has an AdS$_3$ induced geometry, reflecting the 2d conformal symmetry. Here we use the holographic description to extract the defect CFT data associated to the surface operator. The spectrum of transverse fluctuations of the M2 brane is found to be in one-to-one correspondence with a protected multiplet of operator insertions on the surface, which includes the displacement operator. We compute the one-loop determinants of fluctuations of the M2 brane, and extract the conformal anomaly coefficient of the spherical surface to order $N^0$. We also briefly discuss the RG flow from the non-supersymmetric to the 1/2-BPS defect operator, and its consistency with a "$b$-theorem" for the defect CFT. Starting with the M2 brane action, we then use AdS$_3$ Witten diagrams to compute the 4-point functions of the elementary bosonic insertions on the surface operator, and extract some of the defect CFT data from the OPE. The 4-point function is shown to satisfy superconformal Ward identities, and we discuss a related subsector of "twisted" scalar insertions, whose correlation functions are constrained by the residual superconformal symmetry.

hep-th↗

arXiv2021

Higher order RG flow on the Wilson line in $\mathcal{N}=4$ SYM

Extending earlier work, we find the two-loop term in the beta-function for the scalar coupling $ζ$ in a generalized Wilson loop operator of the $\mathcal{N}=4$ SYM theory, working in the planar weak-coupling expansion. The beta-function for $ζ$ has fixed points at $ζ=\pm 1$ and $ζ=0$, corresponding respectively to the supersymmetric Wilson-Maldacena loop and to the standard Wilson loop without scalar coupling. As a consequence of our result for the beta-function, we obtain a prediction for the two-loop term in the anomalous dimension of the scalar field inserted on the standard Wilson loop. We also find a subset of higher-loop contributions (with highest powers of $ζ$ at each order in `t Hooft coupling) coming from the scalar ladder graphs determining the corresponding terms in the five-loop beta-function. We discuss the related structure of the circular Wilson loop expectation value commenting, in particular, on consistency with a 1d defect version of the F-theorem. We also compute (to two loops in the planar ladder approximation) the two-point correlators of scalars inserted on the Wilson line.

hep-th↗

arXiv2021

On non-supersymmetric generalizations of the Wilson-Maldacena loops in N=4 SYM

Building on our previous work arXiv:1712.06874 we consider one-parameter Polchinski-Sully generalization of the Wilson-Maldacena (WM) loops in planar N=4 SYM theory. This breaks local supersymmetry of WM loop and leads to running of the deformation parameter $ζ$. We compute the three-loop ladder diagram contribution to the expectation value of the circular loop which gives the full answer for large $ζ$. The limit $ζ\gg 1$, $λζ^2=$ fixed in which the expectation value is determined by the Gaussian adjoint scalar path integral might be exactly solvable despite the lack of global supersymmetry. We study similar generalization of the 1/4-BPS "latitude" WM loop which depends on two parameters (in addition to the 't Hooft coupling $λ$). One may also introduce another supersymmetry-breaking parameter -- the winding number of the scalar coupling circle. We find the two-loop expression for the expectation value of the associated loop by combining the ladder diagram contribution with an indirect determination of the non-ladder contribution using 1d defect CFT perturbation theory.

hep-th↗

arXiv2020

Sigma models with local couplings: a new integrability -- RG flow connection

We consider several classes of $σ$-models (on groups and symmetric spaces, $η$-models, $λ$-models) with local couplings that may depend on the 2d coordinates, e.g. on time $τ$. We observe that (i) starting with a classically integrable 2d $σ$-model, (ii) formally promoting its couplings $h_α$ to functions $h_α(τ)$ of 2d time, and (iii) demanding that the resulting time-dependent model also admits a Lax connection implies that $h_α(τ)$ must solve the 1-loop RG equations of the original theory with $τ$ interpreted as RG time. This provides a novel example of an 'integrability - RG flow' connection. The existence of a Lax connection suggests that these time-dependent $σ$-models may themselves be understood as integrable. We investigate this question by studying the possibility of constructing non-local and local conserved charges. Such $σ$-models with $D$-dimensional target space and time-dependent couplings subject to the RG flow naturally appear in string theory upon fixing the light-cone gauge in a $(D+2)$-dimensional conformal $σ$-model with a metric admitting a covariantly constant null Killing vector and a dilaton linear in the null coordinate.

hep-th↗

arXiv2020

Generalised Schwarzschild metric from double copy of point-like charge solution in Born-Infeld theory

We discuss possible application of classical double copy procedure to construction of a generalisation of the Schwarzschild metric starting from an $α'$-corrected open string analogue of Coulomb solution. The latter is approximated by a point-like charge solution of the Born-Infeld action, which represents the open string effective action for an abelian vector field in the limit when derivatives of the field strength are small. The Born-Infeld solution has a regular electric field which is constant near the origin, suggesting that corrections from derivative terms in the open string effective action may be small there. The generalization of the Schwarschild metric obtained by the double copy construction from the Born-Infeld solution looks non-singular but the corresponding curvature invariants still blow up at $r=0$. We discuss the origin of this singularity and comment on possible generalisations.

hep-th↗

arXiv2020

Boundary correlators in WZW model on AdS$_2$

Boundary correlators of elementary fields in some 2d conformal field theories defined on AdS$_2$ have a particularly simple structure. For example, the correlators of the Liouville scalar happen to be the same as the correlators of the chiral component of the stress tensor on a plane restricted to the real line. Here we show that an analogous relation is true also in the WZW model: boundary correlators of the WZW scalars have the same structure as the correlators of chiral Kač-Moody currents. This is checked at the level of the tree and one-loop Witten diagrams in AdS$_2$. We also compute some tree-level correlators in a generic $σ$-model defined on AdS$_2$ and show that they simplify only in the WZW case where an extra Kač-Moody symmetry appears. In particular, the terms in 4-point correlators having logarithmic dependence on 1d cross-ratio cancel only at the WZW point. One motivation behind this work is to learn how to compute AdS$_2$ loop corrections in 2d models with derivative interactions related to the study of correlators of operators on Wilson loops in string theory in AdS.

hep-th↗