scholarly journals Perturbative and nonperturbative studies of CFTs with MN global symmetry

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Johan Henriksson ◽  
Andreas Stergiou
Keyword(s):  
Fixed Points ◽  
Numerical Data ◽  
Three Dimensions ◽  
Global Symmetry ◽  
Conformal Field Theories ◽  
Conformal Field ◽  
Conformal Bootstrap ◽  
State Of Affairs ◽  
Perturbative Limit ◽  
Good Agreement

Fixed points in three dimensions described by conformal field theories with \ensuremath{M N}_{m,n} = O(m)^n\rtimes S_nMNm,n=O(m)n⋊Sn global symmetry have extensive applications in critical phenomena. Associated experimental data for m=n=2m=n=2 suggest the existence of two non-trivial fixed points, while the \varepsilonε expansion predicts only one, resulting in a puzzling state of affairs. A recent numerical conformal bootstrap study has found two kinks for small values of the parameters mm and nn, with critical exponents in good agreement with experimental determinations in the m=n=2m=n=2 case. In this paper we investigate the fate of the corresponding fixed points as we vary the parameters mm and nn. We find that one family of kinks approaches a perturbative limit as mm increases, and using large spin perturbation theory we construct a large mm expansion that fits well with the numerical data. This new expansion, akin to the large NN expansion of critical O(N)O(N) models, is compatible with the fixed point found in the \varepsilonε expansion. For the other family of kinks, we find that it persists only for n=2n=2, where for large mm it approaches a non-perturbative limit with \Delta_\phi\approx 0.75Δϕ≈0.75. We investigate the spectrum in the case \ensuremath{M N}_{100,2}MN100,2 and find consistency with expectations from the lightcone bootstrap.

scholarly journals Analytic and numerical bootstrap of CFTs with $O(m)\times O(n)$ global symmetry in 3D

2020 ◽  
Vol 9 (3) ◽  
Author(s):  
Johan Henriksson ◽  
Stefanos R. Kousvos ◽  
Andreas Stergiou
Keyword(s):  
Power Series ◽  
Fixed Points ◽  
Parameter Space ◽  
Field Theories ◽  
Global Symmetry ◽  
Conformal Field Theories ◽  
Conformal Field ◽  
Bootstrap Techniques ◽  
Perturbative Methods ◽  
Anomalous Dimensions

Motivated by applications to critical phenomena and open theoretical questions, we study conformal field theories with O(m)\times O(n)O(m)×O(n) global symmetry in d=3d=3 spacetime dimensions. We use both analytic and numerical bootstrap techniques. Using the analytic bootstrap, we calculate anomalous dimensions and OPE coefficients as power series in \varepsilon=4-dε=4−d and in 1/n1/n, with a method that generalizes to arbitrary global symmetry. Whenever comparison is possible, our results agree with earlier results obtained with diagrammatic methods in the literature. Using the numerical bootstrap, we obtain a wide variety of operator dimension bounds, and we find several islands (isolated allowed regions) in parameter space for O(2)\times O(n)O(2)×O(n) theories for various values of nn. Some of these islands can be attributed to fixed points predicted by perturbative methods like the \varepsilonε and large-nn expansions, while others appear to arise due to fixed points that have been claimed to exist in resummations of perturbative beta functions.

scholarly journals Bootstrapping mixed correlators in three-dimensional cubic theories II

2020 ◽  
Vol 8 (6) ◽  
Author(s):  
Stefanos R. Kousvos ◽  
Andreas Stergiou
Keyword(s):  
Condensed Matter ◽  
Three Dimensional ◽  
Global Symmetry ◽  
Energy Tensor ◽  
Conformal Field Theories ◽  
Cubic Symmetry ◽  
Conformal Field ◽  
Conformal Bootstrap ◽  
Perturbative Methods ◽  
Stress Energy

Conformal field theories (CFTs) with cubic global symmetry in 3D are relevant in a variety of condensed matter systems and have been studied extensively with the use of perturbative methods like the \varepsilonε expansion. In an earlier work, we used the nonperturbative numerical conformal bootstrap to provide evidence for the existence of a previously unknown 3D CFT with cubic symmetry, dubbed “Platonic CFT”. In this work, we make further use of the numerical conformal bootstrap to perform a three-dimensional scan in the space of scaling dimensions of three low-lying operators. We find a three-dimensional isolated allowed region in parameter space, which includes both the 3D (decoupled) Ising model and the Platonic CFT. The essential assumptions on the spectrum of operators used to provide the isolated allowed region include the existence of a stress-energy tensor and the irrelevance of certain operators (in the renormalization group sense).

scholarly journals Two-dimensional O(n) models and logarithmic CFTs

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Victor Gorbenko ◽  
Bernardo Zan
Keyword(s):  
Fixed Point ◽  
Fixed Points ◽  
Two Dimensional ◽  
Conformal Field Theories ◽  
Negative Norm ◽  
Conformal Field ◽  
Conformal Bootstrap ◽  
Bootstrap Approach ◽  
Continuous Range ◽  
Relevant Operator

Abstract We study O(n)-symmetric two-dimensional conformal field theories (CFTs) for a continuous range of n below two. These CFTs describe the fixed point behavior of self-avoiding loops. There is a pair of known fixed points connected by an RG flow. When n is equal to two, which corresponds to the Kosterlitz-Thouless critical theory, the fixed points collide. We find that for n generic these CFTs are logarithmic and contain negative norm states; in particular, the O(n) currents belong to a staggered logarithmic multiplet. Using a conformal bootstrap approach we trace how the negative norm states decouple at n = 2, restoring unitarity. The IR fixed point possesses a local relevant operator, singlet under all known global symmetries of the CFT, and, nevertheless, it can be reached by an RG flow without tuning. Besides, we observe logarithmic correlators in the closely related Potts model.

scholarly journals Bootstrap bounds on closed Einstein manifolds

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
James Bonifacio ◽  
Kurt Hinterbichler
Keyword(s):  
Compact Riemannian Manifold ◽  
Tree Level ◽  
Conformal Field Theories ◽  
Einstein Manifolds ◽  
Consistency Conditions ◽  
Conformal Field ◽  
Geometric Data ◽  
Conformal Bootstrap ◽  
Laplacian Operators ◽  
Kaluza Klein

Abstract A compact Riemannian manifold is associated with geometric data given by the eigenvalues of various Laplacian operators on the manifold and the triple overlap integrals of the corresponding eigenmodes. This geometric data must satisfy certain consistency conditions that follow from associativity and the completeness of eigenmodes. We show that it is possible to obtain nontrivial bounds on the geometric data of closed Einstein manifolds by using semidefinite programming to study these consistency conditions, in analogy to the conformal bootstrap bounds on conformal field theories. These bootstrap bounds translate to constraints on the tree-level masses and cubic couplings of Kaluza-Klein modes in theories with compact extra dimensions. We show that in some cases the bounds are saturated by known manifolds.

scholarly journals Bounds in 4D conformal field theories with global symmetry

2010 ◽  
Vol 44 (3) ◽  
pp. 035402 ◽  
Author(s):  
Riccardo Rattazzi ◽  
Slava Rychkov ◽  
Alessandro Vichi
Keyword(s):  
Field Theories ◽  
Global Symmetry ◽  
Conformal Field Theories ◽  
Conformal Field

scholarly journals Bootstrap experiments on higher dimensional CFTs

2018 ◽  
Vol 33 (07) ◽  
pp. 1850036 ◽  
Author(s):  
Yu Nakayama
Keyword(s):  
Empirical Relationship ◽  
Adjoint Representation ◽  
Field Theories ◽  
Conformal Field Theories ◽  
Time Dimension ◽  
Unitarity Bound ◽  
Conformal Field ◽  
Dimension Formula ◽  
Conformal Bootstrap ◽  
Higher Dimensional

Recent programs on conformal bootstrap suggest an empirical relationship between the existence of nontrivial conformal field theories and nontrivial features such as a kink in the unitarity bound of conformal dimensions in the conformal bootstrap equations. We report the existence of nontrivial kink-like behaviors in the unitarity bound of scalar operators in the adjoint representation of the [Formula: see text] symmetric conformal field theories. They have interesting properties: (1) the kink-like behaviors exist in [Formula: see text] dimensions; (2) the location of kink-like behaviors are when the unitarity bound hits the space–time dimension [Formula: see text]; (3) there exists a “conformal window” of [Formula: see text], where [Formula: see text] in [Formula: see text] and [Formula: see text] in [Formula: see text].

scholarly journals A roadmap for bootstrapping critical gauge theories: decoupling operators of conformal field theories in $d>2$ dimensions

2021 ◽  
Vol 11 (6) ◽  
Author(s):  
Yin-Chen He ◽  
Junchen Rong ◽  
Ning Su
Keyword(s):  
Gauge Group ◽  
Gauge Theories ◽  
Higher Dimensions ◽  
Equation Of Motion ◽  
Field Theories ◽  
Conformal Field Theories ◽  
Gauge Groups ◽  
Conformal Field ◽  
Conformal Bootstrap ◽  
Null Operator

We propose a roadmap for bootstrapping conformal field theories (CFTs) described by gauge theories in dimensions d>2d>2. In particular, we provide a simple and workable answer to the question of how to detect the gauge group in the bootstrap calculation. Our recipe is based on the notion of decoupling operator, which has a simple (gauge) group theoretical origin, and is reminiscent of the null operator of 2d2d Wess-Zumino-Witten CFTs in higher dimensions. Using the decoupling operator we can efficiently detect the rank (i.e. color number) of gauge groups, e.g., by imposing gap conditions in the CFT spectrum. We also discuss the physics of the equation of motion, which has interesting consequences in the CFT spectrum as well. As an application of our recipes, we study a prototypical critical gauge theory, namely the scalar QED which has a U(1)U(1) gauge field interacting with critical bosons. We show that the scalar QED can be solved by conformal bootstrap, namely we have obtained its kinks and islands in both d=3d=3 and d=2+\epsilond=2+ϵ dimensions.

scholarly journals ON SOLITON AUTOMORPHISMS IN MASSIVE AND CONFORMAL THEORIES

1999 ◽  
Vol 11 (03) ◽  
pp. 337-359 ◽  
Author(s):  
MICHAEL MÜGER
Keyword(s):  
Field Theories ◽  
Global Symmetry ◽  
Subsequent Paper ◽  
Quantum Field Theories ◽  
Conformal Field Theories ◽  
Conformal Field ◽  
Symmetry Transformations ◽  
Left And Right ◽  
Necessary And Sufficient ◽  
Quasilocal Algebra

For massive and conformal quantum field theories in 1+1 dimensions with a global gauge group we consider soliton automorphisms, viz. automorphisms of the quasilocal algebra which act like two different global symmetry transformations on the left and right spacelike complements of a bounded region. We give a unified treatment by providing a necessary and sufficient condition for the existence and Poincaré covariance of soliton automorphisms which is applicable to a large class of theories. In particular, our construction applies to the QFT models with the local Fock property — in which case the latter property is the only input from constructive QFT we need — and to holomorphic conformal field theories. In conformal QFT soliton representations appear as twisted sectors, and in a subsequent paper our results will be used to give a rigorous analysis of the superselection structure of orbifolds of holomorphic theories.

scholarly journals Multi-fixed point numerical conformal bootstrap: a case study with structured global symmetry

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Matthew T. Dowens ◽  
Chris A. Hooley
Keyword(s):  
Group Symmetry ◽  
Global Symmetry ◽  
Minimal Set ◽  
Conformal Field ◽  
Conformal Bootstrap ◽  
Critical Theories ◽  
Global Symmetry Group ◽  
Starting Point ◽  
Future Utility

Abstract In large part, the future utility of modern numerical conformal bootstrap depends on its ability to accurately predict the existence of hitherto unknown non-trivial conformal field theories (CFTs). Here we investigate the extent to which this is possible in the case where the global symmetry group has a product structure. We do this by testing for signatures of fixed points using a mixed-correlator bootstrap calculation with a minimal set of input assumptions. This ‘semi-blind’ approach contrasts with other approaches for probing more complicated groups, which ‘target’ known theories with additional spectral assumptions or use the saturation of the single-correlator bootstrap bound as a starting point. As a case study, we select the space of CFTs with product-group symmetry O(15) ⊗ O(3) in d = 3 dimensions. On the assumption that there is only one relevant scalar (ℓ = 0) singlet operator in the theory, we find a single ‘allowed’ region in our chosen space of scaling dimensions. The scaling dimensions corresponding to two known large-N critical theories, the Heisenberg and the chiral ones, lie on or very near the boundary of this region. The large-N antichiral point lies well outside the ‘allowed’ region, which is consistent with the expectation that the antichiral theory is unstable, and thus has an additional relevant scalar singlet operator. We also find a sharp kink in the boundary of the ‘allowed’ region at values of the scaling dimensions that do not correspond to the (N, M ) = (3, 15) instance of any large-N -predicted O(N ) ⊗ O(M ) critical theory.

scholarly journals Bootstrapping MN and tetragonal CFTs in three dimensions

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Andreas Stergiou
Keyword(s):  
Phase Transition ◽  
Rare Earth ◽  
Phase Transitions ◽  
Structural Phase ◽  
Earth Metal ◽  
Universality Class ◽  
Three Dimensions ◽  
Global Symmetry ◽  
Conformal Bootstrap ◽  
The Rare Earth

Conformal field theories (CFTs) with MN and tetragonal global symmetry in d=2+1d=2+1 dimensions are relevant for structural, antiferromagnetic and helimagnetic phase transitions. As a result, they have been studied in great detail with the \varepsilon=4-dε=4−d expansion and other field theory methods. The study of these theories with the nonperturbative numerical conformal bootstrap is initiated in this work. Bounds for operator dimensions are obtained and they are found to possess sharp kinks in the MN case, suggesting the existence of full-fledged CFTs. Based on the existence of a certain large-NN expansion in theories with MN symmetry, these are argued to be the CFTs predicted by the \varepsilonε expansion. In the tetragonal case no new kinks are found, consistently with the absence of such CFTs in the \varepsilonε expansion. Estimates for critical exponents are provided for a few cases describing phase transitions in actual physical systems. In two particular MN cases, corresponding to theories with global symmetry groups O(2)^2\rtimes S_2O(2)2⋊S2 and O(2)^3\rtimes S_3O(2)3⋊S3, a second kink is found. In the O(2)^2\rtimes S_2O(2)2⋊S2 case it is argued to be saturated by a CFT that belongs to a new universality class relevant for the structural phase transition of NbO_22 and paramagnetic-helimagnetic transitions of the rare-earth metals Ho and Dy. In the O(2)^3\rtimes S_3O(2)3⋊S3 case it is suggested that the CFT that saturates the second kink belongs to a new universality class relevant for the paramagnetic-antiferromagnetic phase transition of the rare-earth metal Nd.

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