Konishi Operator Research Articles

Strong coupling results in the AdS 5 /CF T 4 correspondence from the numerical solution of the quantum spectral curve

In this paper, we solved numerically the Quantum Spectral Curve (QSC) equations corresponding to some twist-2 single trace operators with even spin from the $sl(2)$ sector of $AdS_5/CFT_4$ correspondence. We describe all technical details of the numerical method which are necessary to implement it in C++ language. In the $S=2,4,6,8$ cases, our numerical results confirm the analytical results, known in the literature for the first 4 coefficients of the strong coupling expansion for the anomalous dimensions of twist-2 operators. In the case of the Konishi operator, due to the high precision of the numerical data we could give numerical predictions to the values of two further coefficients, as well. The strong coupling behaviour of the coefficients $c_{a,n}$ in the power series representation of the ${\bf P}_{\!a}$-functions is also investigated. Based on our numerical data, in the regime, where the index of the coefficients is much smaller than $\lambda^{1/4}$, we conjecture that the coefficients have polynomial index dependence at strong coupling. This allows one to propose a strong coupling series representation for the ${\bf P}$-functions being valid far enough from the real short cut. In the paper the qualitative strong coupling behaviour of the ${\bf P}$-functions at the branch points is also discussed.

On soft theorems and form factors in N = 4 $$ \mathcal{N}=4 $$ SYM theory

Soft theorems for the form factors of 1/2-BPS and Konishi operator supermultiplets are derived at tree level in N=4 SYM theory. They have a form identical to the one in the amplitude case. For MHV sectors of stress tensor and Konishi supermultiplets loop corrections to soft theorems are considered at one loop level. They also appear to have universal form in soft limit. Possible generalization of the on-shell diagrams to the form factors based on leading soft behavior is suggested. Finally, we give some comments on inverse soft limit and integrability of form factors in the limit $q^2\to 0$

Cutting through form factors and cross sections of non-protected operators in N = 4 $$ \mathcal{N}=4 $$ SYM

We study the form factors of the Konishi operator, the prime example of non-protected operators in N=4 SYM theory, via the on-shell unitarity methods. Since the Konishi operator is not protected by supersymmetry, its form factors share many features with those in QCD, such as the occurrence of rational terms and of UV divergences that require renormalization. A subtle point is that this operator depends on the spacetime dimension. This requires a modification when calculating its form factors via unitarity methods. We derive a rigorous prescription that implements this modification to all loop orders and obtain the two-point form factor up to two-loop order and the three-point form factor to one-loop order. From these form factors, we construct an IR-finite cross section type quantity, namely the inclusive decay rate of the (off-shell) Konishi operator to any final (on-shell) state. Via the optical theorem, it is connected to the imaginary part of the two-point correlation function. We extract the Konishi anomalous dimension up to two-loop order from it.

Three-point correlators from string amplitudes: mixing and Regge spins

This paper has two parts. We first compute the leading contribution to the strong-coupling mixing between the Konishi operator and a double-trace operator composed of chiral primaries by using flat-space vertex operators for the string-duals of the operators. We then compute the three-point functions for protected or unprotected scalar operators with higher spin operators on the leading Regge trajectory. Here we see that the nontrivial spatial structures required by conformal invariance arise naturally from the form of the polarization tensors in the vertex operators. We find agreement with recent results extracted from Mellin amplitudes for four-point functions, as well as with earlier supergravity calculations. We also obtain some new results for other combinations of operators.

Quantum spectral curve at work: from small spin to strong coupling in N $$ \mathcal{N} $$ = 4 SYM

We apply the recently proposed quantum spectral curve technique to the study of twist operators in planar N=4 SYM theory. We focus on the small spin expansion of anomalous dimensions in the sl(2) sector and compute its first two orders exactly for any value of the 't Hooft coupling. At leading order in the spin S we reproduced Basso's slope function. The next term of order S^2 structurally resembles the Beisert-Eden-Staudacher dressing phase and takes into account wrapping contributions. This expansion contains rich information about the spectrum of local operators at strong coupling. In particular, we found a new coefficient in the strong coupling expansion of the Konishi operator dimension and confirmed several previously known terms. We also obtained several new orders of the strong coupling expansion of the BFKL pomeron intercept. As a by-product we formulated a prescription for the correct analytical continuation in S which opens a way for deriving the BFKL regime of twist two anomalous dimensions from AdS/CFT integrability.

Multiple zeta functions and double wrapping in planar [formula omitted] SYM

Using the FiNLIE solution of the AdS/CFT Y-system, we compute the anomalous dimension of the Konishi operator in planar N=4 SYM up to eight loops, i.e. up to the leading double wrapping order. At this order a non-reducible Euler–Zagier sum, ζ1,2,8, appears for the first time. We find that at all orders in perturbation, every spectral-dependent quantity of the Y-system is expressed through multiple Hurwitz zeta functions, hence we provide a Mathematica package to manipulate these functions, including the particular case of Euler–Zagier sums. Furthermore, we conjecture that only Euler–Zagier sums can appear in the answer for the anomalous dimension at any order in perturbation theory.We also resum the leading transcendentality terms of the anomalous dimension at all orders, obtaining a simple result in terms of Bessel functions. Finally, we demonstrate that exact Bethe equations should be related to an absence of poles condition that becomes especially non-trivial at double wrapping.

Three-point correlators of twist-2 operators in N=4 SYM at Born approximation

Abstract We calculate two different types of 3-point correlators involving twist-2 operators in the leading weak coupling approximation and all orders in N c in N=4 SYM theory. Each of three operators in the first correlator can be any component of twist-2 supermultiplet, though the explicit calculation was done for a particular component which is an SU(4) singlet. It is calculated in the leading, Born approximation for arbitrary spins j 1 , j 2 , j 3. The result significantly simplifies when at least one of the spins is large or equal to zero and the coordinates are restricted to the 2d plane spanned by two light-rays. The second correlator involves two twist-2 operators Tr(X∇ j1 X) + . . ., Tr(Z∇ j2 Z) + . . . and one Konishi operator $ \mathrm{Tr}{{\left[ {\overline{Z},\overline{X}} \right]}^2} $ . It vanishes in the lowest g 0 order and is computed at the leading g 2 approximation.

Six and seven loop Konishi from Lüscher corrections

Abstract In the present paper we derive six and seven loop formulas for the anomalous dimension of the Konishi operator in N=4 SYM from string theory using the technique of Lüscher corrections. We derive analytically the integrand using the worldsheet S-matrix and evaluate the resulting integral and infinite sum using a combination of high precision numerical integration and asymptotic expansion. We use this high precision numerical result to fit the integer coefficients of zeta values in the final analytical answer. The presented six and seven loop results can be used as a cross-check with FiNLIE on the string theory side, or with direct gauge theory computations. The seven loop level is the theoretical limit of this Lüscher approach as at eight loops double-wrapping corrections will appear.

Holographic three-point functions for short operators

We consider holographic three-point functions for operators dual to short string states at strong coupling in N=4 super Yang-Mills. We treat the states as point-like as they come in from the boundary but as strings in the interaction region in the bulk. The interaction position is determined by saddle point, which is equivalent to conservation of the canonical momentum for the interacting particles, and leads to conservation of their conformal charges. We further show that for large dimensions the rms size of the interaction region is small compared to the radius of curvature of the AdS space, but still large compared to the string Compton wave-length. Hence, one can approximate the string vertex operators as flat-space vertex operators with a definite momentum, which depends on the conformal and R-charges of the operator. We then argue that the string vertex operator dual to a primary operator is chosen by satisfying a twisted version of Q^L=Q^R, up to spurious terms. This leads to a unique choice for a scalar vertex operator with the appropriate charges at the first massive level. We then comment on some features of the corresponding three-point functions, including the application of these results to Konishi operators.

Solving the AdS/CFT Y-system

Abstract Using integrability and analyticity properties of the AdS5/CFT4 Y-system we reduce it to a finite set of nonlinear integral equations. The $ {{\mathbb{Z}}_4} $ symmetry of the underlying coset sigma model, in its quantum version, allows for a deeper insight into the analyticity structure of the corresponding Y-functions and T-functions, as well as for their analyticity friendly parameterization in terms of Wronskian determinants of Q-functions. As a check for the new equations, we reproduce the numerical results for the Konishi operator previously obtained from the original infinite Y-system.

Five-loop Konishi in [formula omitted] SYM

We present a new method for computing the Konishi anomalous dimension in N=4 SYM at weak coupling. It does not rely on the conventional Feynman diagram technique and is not restricted to the planar limit. It is based on the OPE analysis of the four-point correlation function of stress-tensor multiplets, which has been recently constructed up to six loops. The Konishi operator gives the leading contribution to the singlet SU(4) channel of this OPE. Its anomalous dimension is the coefficient of the leading single logarithmic singularity of the logarithm of the correlation function in the double short-distance limit, in which the operator positions coincide pairwise. We regularize the logarithm of the correlation function in this singular limit by a version of dimensional regularization. At any loop level, the resulting singularity is a simple pole whose residue is determined by a finite two-point integral with one loop less. This drastically simplifies the five-loop calculation of the Konishi anomalous dimension by reducing it to a set of known four-loop two-point integrals and two unknown integrals which we evaluate analytically. We obtain an analytic result at five loops in the planar limit and observe perfect agreement with the prediction based on integrability in AdS/CFT.

Hidden symmetry of four-point correlation functions and amplitudes in [formula omitted] SYM

We study the four-point correlation function of stress-tensor supermultiplets in N=4 SYM using the method of Lagrangian insertions. We argue that, as a corollary of N=4 superconformal symmetry, the resulting all-loop integrand possesses an unexpected complete symmetry under the exchange of the four external and all the internal (integration) points. This alone allows us to predict the integrand of the three-loop correlation function up to four undetermined constants. Further, exploiting the conjectured amplitude/correlation function duality, we are able to fully determine the three-loop integrand in the planar limit. We perform an independent check of this result by verifying that it is consistent with the operator product expansion, in particular that it correctly reproduces the three-loop anomalous dimension of the Konishi operator. As a byproduct of our study, we also obtain the three-point function of two half-BPS operators and one Konishi operator at three-loop level. We use the same technique to work out a compact form for the four-loop four-point integrand and discuss the generalisation to higher loops.

Leading quantum correction to energy of ‘short’ spiky strings

We consider semiclassical quantization of spiky strings spinning in the AdS3 part of AdS5 × S5 using an integrability-based (algebraic curve) method. In the ‘short-string’ (small-spin) limit the expansion of string energy starts with its flat-space expression. We compute the leading quantum string correction to ‘short’ spiky string energy and find the explicit form of the corresponding one-loop coefficient a01. It turns out to be rational and expressed in terms of the harmonic sums as functions of the number n of spikes. In the special case of n = 2 when the spiky string reduces to the single-folded spinning string, the coefficient a01 takes the value (−1/4) found in Gromov et al (2011 J. High Energy Phys. JHEP08(2011)046). We also consider a similar computation for the m-folded string and more general spiky string with an extra ‘winding’ number, finding similar expressions for a01. These results may be useful for a description of energies of higher excited states in the quantum AdS5 × S5 string spectrum, generalizing earlier discussions of the string counterparts of the Konishi operator.

On form factors in $ \mathcal{N} = 4 $ SYM

In this paper we study the form factors for the half-BPS operators $\mathcal{O}^{(n)}_I$ and the $\mathcal{N}=4$ stress tensor supermultiplet current $W^{AB}$ up to the second order of perturbation theory and for the Konishi operator $\mathcal{K}$ at first order of perturbation theory in $\mathcal{N}=4$ SYM theory at weak coupling. For all the objects we observe the exponentiation of the IR divergences with two anomalous dimensions: the cusp anomalous dimension and the collinear anomalous dimension. For the IR finite parts we obtain a similar situation as for the gluon scattering amplitudes, namely, apart from the case of $W^{AB}$ and $\mathcal{K}$ the finite part has some remainder function which we calculate up to the second order. It involves the generalized Goncharov polylogarithms of several variables. All the answers are expressed through the integrals related to the dual conformal invariant ones which might be a signal of integrable structure standing behind the form factors.

Konishi operator at intermediate coupling

Thermodynamic Bethe Ansatz equations for two-particle states from the sector proposed by Arutyunov, Suzuki and the author are solved numerically for the Konishi operator descendent up to 't Hooft's coupling λ ≈ 2046. The data obtained is used to analyze the properties of Y-functions and address the issue of the existence of the critical values of the coupling. In addition, we find a new integral representation for the BES dressing phase which substantially reduces the computational time.

6-loop anomalous dimension of a single impurity operator from AdS/CFT and multiple zeta values

Anomalous dimension of the simplest nontrivial single impurity operator in the beta=1/2 deformed theory is determined at six loops from the AdS/CFT correspondence. L\"uscher correction is evaluated at next-to-next-to-leading order (NNLO) in terms of multiple zeta values. The result can be simplified into the products of simple zeta functions and the same form of the correction is expected for the Konishi operator at six loops, too.

Operator mixing in [formula omitted] SYM: The Konishi anomaly re-re-visited

The supersymmetry transformation relating the Konishi operator to its lowest descendant in the 10 of SU ( 4 ) is not manifest in the N = 1 formulation of the theory but rather uses an equation of motion. On the classical level one finds one operator, the unintegrated chiral superpotential. In the quantum theory this term receives an admixture by a second operator, the Yang–Mills part of the Lagrangian. It has long been debated whether this “anomalous” contribution is affected by higher loop corrections. We present a first principles calculation at the second non-trivial order in perturbation theory using supersymmetric dimensional reduction as a regulator and renormalisation by Z-factors. Singular higher loop corrections to the renormalisation factor of the Yang–Mills term are required if the conformal properties of two-point functions are to be met. These singularities take the form determined in preceding work on rather general grounds. Moreover, we also find non-vanishing finite terms. The core part of the problem is the evaluation of a four-loop two-point correlator which is accomplished by the Laporta algorithm. Apart from several examples of the T 1 topology with two lines of non-integer dimension we need the first few orders in the ϵ expansion of three master integrals. The approach is self-contained in that all the necessary information can be derived from the power counting finiteness of some integrals.

Finite-size effect for four-loop Konishi of the β-deformed [formula omitted] SYM

We propose that certain twists of the su ( 2 | 2 ) S-matrix elements describe the β-deformation of N = 4 supersymmetric Yang–Mills theory. We compute the perturbative four-loop anomalous dimension of the Konishi operator of the deformed gauge theory from the Lüscher formula based on these twisted S-matrix elements. The result agrees exactly with the perturbative gauge theory computations.

Wrapping effects in supersymmetric gauge theories

AbstractSeveral perturbative computations of finite‐size effects, performed on the gauge side of the AdS/CFT correspondence by means of superspace techniques, are presented. First, wrapping effects are analyzed in the standard 𝒩 = 4 theory, by means of the calculation of the four‐loop anomalous dimension of the Konishi operator. Then, a similar computation at five loops is described. Afterwards, finite‐size effects are studied in the β‐deformed case, where thanks to the reduced number of supersymmetries the simpler class of single‐impurity operators can be considered, so that the leading corrections to the anomalous dimensions at generic order can be reduced to the computation of a class of integrals. Explicit results are given up to eleven loops. A further chapter is dedicated to the computation of the leading finite‐size effects on operators dual to open strings. In the end, some comments are made and proposals for future developments are discussed.

5-loop Konishi from linearized TBA and the XXX magnet

Using the linearized TBA equations recently obtained in [arXiv:1002.1711] we show analytically that the 5-loop anomalous dimension of the Konishi operator agrees with the result obtained previously from the generalized Luscher formulae. The proof is based on the relation between this linear system and the XXX model TBA equations.