Supersymmetric Critical Points Research Articles

Critical structure and emergent symmetry of Dirac fermion systems

Emergent symmetry in Dirac system means that the system acquires an enlargement of two basic symmetries at some special critical point. The continuous quantum criticality between the two symmetry broken phases can be described within the framework of Gross–Neveu–Yukawa (GNY) model. Using the first-order ε expansion in dimensions, we study the critical structure and emergent symmetry of the O(N)-GNY model with N f flavors of four-component Dirac fermions coupled strongly to an O(N) scalar field under a small O(N)-symmetry breaking perturbation. After determining the stable fixed point, we calculate the inverse correlation length exponent and the anomalous dimensions (bosonic and fermionic) for general N and N f . Further, we discuss the emergent-symmetry and the emergent supersymmetric critical point for on the basis of O(N)-GNY model. It turns out that the O(N)-GNY universality class is physically meaningful if and only if . On this premise, the small O(N)-symmetry breaking perturbation is always irrelevant in the O(N)-GNY universality class. Our studies show that the emergent symmetry in Dirac systems has an upper limit , depending on the flavor numbers N f . As a result, the emergent-O(4) and O(5) symmetries are possible to be found in Dirac systems with fermion flavor , and the emergent-O(4), O(5), O(6) and O(7) symmetries are expected to be found in the systems with fermion flavor . Our result suggests some richer transitions with emergent- symmetry, and so on. Interestingly, in the O(4)-GNY universality class, we find that there is a new supersymmetric critical point which is expected to be found in Dirac systems with fermion flavor .

Fermion-induced quantum critical point in the Landau-Devonshire model

Fluctuations can change the phase transition properties drastically. An example is the fermion-induced quantum critical point (FIQCP), in which fluctuations of the massless Dirac fermions turn a putative Landau-de Gennes first-order phase transition (FOPT) with a cubic boson interaction into a continuous one. However, for the Landau-Devonshire theory, which characterizes another very large class of FOPTs, its fate under the coupling with extra fluctuations has not been explored. Here, we discover a new type of FIQCP, in which the Dirac fermion fluctuations round the boson Landau-Devonshire FOPT into a continuous phase transition. By using the functional renormalization group analyses, we determine the condition for the appearance of this FIQCP. Moreover, we point out that the present FIQCP can be a supersymmetric critical point. We finally show that the low-temperature phase diagram can provide distinct experimental evidences to detect this FIQCP.

SO(8) supergravity and the magic of machine learning

Using de Wit-Nicolai D = 4 mathcal{N} = 8 SO(8) supergravity as an example, we show how modern Machine Learning software libraries such as Google’s TensorFlow can be employed to greatly simplify the analysis of high-dimensional scalar sectors of some M-Theory compactifications. We provide detailed information on the location, symmetries, and particle spectra and charges of 192 critical points on the scalar manifold of SO(8) supergravity, including one newly discovered mathcal{N} = 1 vacuum with SO(3) residual symmetry, one new potentially stabilizable non-supersymmetric solution, and examples for “Galois conjugate pairs” of solutions, i.e. solution-pairs that share the same gauge group embedding into SO(8) and minimal polynomials for the cosmological constant. Where feasible, we give analytic expressions for solution coordinates and cosmological constants.As the authors’ aspiration is to present the discussion in a form that is accessible to both the Machine Learning and String Theory communities and allows adopting our methods towards the study of other models, we provide an introductory overview over the relevant Physics as well as Machine Learning concepts. This includes short pedagogical code examples. In particular, we show how to formulate a requirement for residual Supersymmetry as a Machine Learning loss function and effectively guide the numerical search towards supersymmetric critical points. Numerical investigations suggest that there are no further supersymmetric vacua beyond this newly discovered fifth solution.

RG flows in 6D N = (1,0) SCFT from SO(4) half-maximal 7D gauged supergravity

We study $N=2$ seven-dimensional gauged supergravity coupled to three vector multiplets with $SO(4)$ gauge group. The resulting gauged supergravity contains 10 scalars consisting of the dilaton and 9 vector multiplet scalars parametrized by $SO(3,3)/SO(3)\times SO(3)$ coset manifold. The maximally supersymmetric $AdS_7$ vacuum with unbroken $SO(4)$ symmetry is identified with a $(1,0)$ SCFT in six dimensions. We find one new supersymmetric $AdS_7$ critical point preserving $SO(3)_{\textrm{diag}}\subset SO(3)\times SO(3)\sim SO(4)$ and study a holographic RG flow interpolating between the $SO(4)$ and the new $SO(3)$ supersymmetric critical points. The RG flow is driven by a vacuum expectation value of a dimension-four operator and describes a deformation of the UV $(1,0)$ SCFT to another supersymmetric fixed point in the IR. In addition, a number of non-supersymmetric critical points are identified, and some of them are stable with all scalar masses above the BF bound. RG flows to non-conformal $N=(1,0)$ Super Yang-Mills with $SO(2)\times SO(2)$ and $SO(2)$ symmetries are also investigated. Some of these flows have physically acceptable IR singularities since the scalar potential is bounded above. These provide physical RG flows from $(1,0)$ SCFT to non-conformal field theories in six dimensions.

Deformations of large N = (4, 4) 2D SCFT from 3D gauged supergravity

Supersymmetric and non-supersymmetric deformations of large $N=(4,4)$ SCFT with superconformal symmetry $D^1(2,1;\alpha)\times D^1(2,1;\alpha)$ are explored in the gravity dual described by a Chern-Simons $N=8$, $(SO(4)\times SO(4))\ltimes \mathbf{T}^{12}$ gauged supergravity in three dimensions. For $\alpha>0$, the gauged supergravity describes an effective theory of the maximal supergravity in nine dimensions on $AdS_3\times S^3\times S^3$ with the parameter $\alpha$ being the ratio of the two $S^3$ radii. We consider the scalar manifold of the supergravity theory of the form $SO(8,8)/SO(8)\times SO(8)$ and find a number of stable non-supersymmetric $AdS_3$ critical points for some values of $\alpha$. These correspond to non-supersymmetric IR fixed points of the UV $N=(4,4)$ SCFT dual to the maximally supersymmetric critical point. We study the associated RG flow solutions interpolating between these fixed points and the UV $N=(4,4)$ SCFT. Possible supersymmetric flows to non-conformal field theories are also investigated. Additionally, a half-supersymmetric domain wall within this gauged supergravity is obtained.

Emergence of supersymmetry on the surface of three-dimensional topological insulators

We propose two possible experimental realizations of a (2 + 1)-dimensional spacetime supersymmetry at a quantum critical point on the surface of three-dimensional topological insulators. The quantum critical point between the semi-metallic state with one Dirac fermion and the s-wave superconducting state on the surface is described by a supersymmetric conformal field theory within the ϵ-expansion. We predict the exact voltage dependence of the differential conductance at the supersymmetric critical point.

Holographic RG flows in six dimensional F(4) gauged supergravity

We study critical points of F (4) gauged supergravity in six dimensions coupled to three vector multiplets. Scalar fields are described by $ {{\mathbb{R}}^{+}}\times \frac{{\mathrm{SO}\left( {4,3} \right)}}{{\mathrm{SO}(4)\times \mathrm{SO}(3)}} $ coset space, and the gauge group is given by SO(3)R × SO(3) with SO(3)R being the R-symmetry. We identify new non-supersymmetric critical points of the scalar potential. One of these new critical points is shown to be stable with all scalar masses above the BF bound and should correspond to a new non-supersymmetric CFT in five dimensions. On the other hand, the maximally supersymmetric critical point with all scalars vanishing is dual to an SCFT5 arising from a near horizon geometry of the D4-D8 brane system in type I′ theory with an enhanced global symmetry E 1 ~ SU(2). We give a numerical RG flow solution interpolating between this SCFT and the new stable critical point. The flow describes a non-supersymmetric deformation driven by relevant operators of dimension 3. We identify the dual operators with the mass terms for hypermultiplet scalars in the dual field theory. The solution provides another example of holographic RG flows in AdS6/CFT5 correspondence.

Minimal stability in maximal supergravity

Recently, it has been shown that maximal supergravity allows for non-supersymmetric AdS critical points that are perturbatively stable. We investigate this phenomenon of stability without supersymmetry from the sGoldstino point of view. In particular, we calculate the projection of the mass matrix onto the sGoldstino directions, and derive the necessary conditions for stability. Indeed we find a narrow window allowing for stable SUSY breaking points. As a by-product of our analysis, we find that it seems impossible to perturb supersymmetric critical points into non-supersymmetric ones: there is a minimal amount of SUSY breaking in maximal supergravity.

Vacua of N = 10 three-dimensional gauged supergravity

We study scalar potentials and the corresponding vacua of N = 10 three-dimensional gauged supergravity. The theory contains 32 scalar fields parametrizing the exceptional coset space . The admissible gauge groups considered in this work involve both compact and non-compact gauge groups which are maximal subgroups of SO(10) × U(1) and E6( − 14), respectively. These gauge groups are given by SO(p) × SO(10 − p) × U(1) for p = 6, …, 10, SO(5) × SO(5), SU(4, 2) × SU(2), G2( − 14) × SU(2, 1) and F4( − 20). We find many AdS3 critical points with various unbroken gauge symmetries. The relevant background isometries associated with the maximally supersymmetric critical points at which all scalars vanish are also given. These correspond to the superconformal symmetries of the dual conformal field theories in two dimensions.

Vacua and RG flows in N = 9 three dimensional gauged supergravity

We study some vacua of N=9 three dimensional gauged supergravity. The theory contains sixteen scalar fields parametrizing the exceptional coset space ${F_{4(-20)}}{SO(9)}$. Various AdS supersymmetric and some non-supersymmetric vacua are found in both compact and non-compact gaugings with gauge groups $SO(p)\times SO(9-p)$ for $p=0, 1, 2, 3, 4$, $G_{2(-14)}\times SL(2)$ and $Sp(1,2)\times SU(2)$. We also study many RG flow solutions, both analytic and numerical, interpolating between supersymmetric critical points in this theory. All the flows considered here are driven by a relevant operator of dimension $\Delta={3}{2}$. This operator breaks conformal symmetry as well as supersymmetry and drives the CFT in the UV to another CFT in the IR with lower supersymmetries.

F-term uplifting and moduli stabilization consistent with Kähler invariance

An important ingredient in the construction of phenomenologically viable superstring models is the uplifting of Anti-de Sitter supersymmetric critical points in the moduli sector to metastable Minkowski or de Sitter vacua with broken supersymmetry. In all cases described so far, uplifting results in a displacement of the potential minimum away from the critical point and, if the uplifting is large, can lead to the disappearance of the minimum altogether. We propose a variant of F-term uplifting which exactly preserves supersymmetric critical points and shift symmetries at tree level. In spite of a direct coupling, the moduli do not contribute to supersymmetry breaking. We analyse the stability of the critical points in a toy one-modulus sector before and after uplifting, and find a simple stability condition depending solely on the amount of uplifting and not on the details of the uplifting sector. There is a region of parameter space, corresponding to the uplifting of local AdS {\em maxima} --or, more importantly, local minima of the Kahler function-- where the critical points are stable for any amount of uplifting. On the other hand, uplifting to (non- supersymmetric) Minkowski space is special in that all SUSY critical points, that is, for all possible compactifications, become stable or neutrally stable.

Emergence of supersymmetry at a critical point of a lattice model

Supersymmetry is a symmetry between a boson and a fermion. Although there is no apparent supersymmetry in nature, its mathematical consistency and appealing properties have led many people to believe that supersymmetry may exist in nature in the form of a spontaneously broken symmetry. In this paper, we explore an alternative possibility by which supersymmetry is realized in nature, that is, supersymmetry dynamically emerges in the low-energy limit of a nonsupersymmetric condensed matter system. We propose a $(2+1)$-dimensional lattice model which exhibits an emergent space-time supersymmetry at a quantum critical point. It is shown that there is only one relevant perturbation at the supersymmetric critical point in the $ϵ$ expansion and the critical theory is the two copies of the Wess-Zumino theory with four supercharges. Exact critical exponents are predicted.

K3×T2/Z2 orientifolds with fluxes, open string moduli and critical points

Abstract We extend the four-dimensional gauged supergravity analysis of type IIB vacua on K3×T 2 / Z 2 to the case where also D3 and D7 moduli, belonging to N =2 vector multiplets, are turned on. In this case, the overall special geometry does not correspond to a symmetric space, unless D3 or D7 moduli are switched off. In the presence of non-vanishing fluxes, we discuss supersymmetric critical points which correspond to Minkowski vacua, finding agreement with previous analysis. Finally, we point out that care is needed in the choice of the symplectic holomorphic sections of special geometry which enter the computation of the scalar potential.

A new supersymmetric compactification of chiral IIB supergravity

We present a new compactification of chiral, N=2 ten-dimensional supergravity down to five dimensions and show that it corresponds to the N=2 supersymmetric critical point of five-dimensional, N=8 gauged supergravity found in [1]. This solution presented here is of particular significance because it involves non-zero tensor gauge fields and, via the AdS/CFT correspondence, is dual to the non-trivial N=1 supersymmetric fixed point of N=4 Yang-Mills theory.

Critical points and phase transitions in 5d compactifications of M-theory

We study critical points of the BPS mass Z, the BPS string tension Z m , the black hole potential V and the gauged central charge potential P for M-theory compactified on Calabi-Yau three-folds. We first show that the stabilization equations for Z (determining the black hole entropy) take an extremely simple form in five dimensions as opposed to four dimensions. The stabilization equations for Z m are also very simple and determine the size of the infinite adS 3throat of the string. The black hole potential in general exhibits two classes of critical points: supersymmetric critical points which coincide with those of the central charge and non-supersymmetric critical points. We then generalize the discussion to the entire extended Kähler cone encompassing topologically different but birationally equivalent Calabi-Yau three-folds that are connected via flop transitions. We examine behavior of the four potentials to probe the nature of these phase transitions. We find that V and P are continuous but not smooth across the flop transition, while Z and its first two derivatives, as well as Z m and its first derivative, are continuous. This in turn implies that supersymmetric stabilization of Z and Z m for a given configuration takes place in at most one point throughout the entire extended Kähler cone. The corresponding black holes (or string states) interpolate between different Calabi-Yau three-folds. At the boundaries of the extended Kähler cone we observe that electric states become massless and/or magnetic strings become tensionless.

Critical points and phase transitions in 5d compactifications of M-theory

We study critical points of the BPS mass Z , the BPS string tension Z m , the black hole potential V and the gauged central charge potential P for M-theory compactified on Calabi-Yau three-folds. We first show that the stabilization equations for Z (determining the black hole entropy) take an extremely simple form in five dimensions as opposed to four dimensions. The stabilization equations for Z m are also very simple and determine the size of the infinite adS 3 throat of the string. The black hole potential in general exhibits two classes of critical points: supersymmetric critical points which coincide with those of the central charge and non-supersymmetric critical points. We then generalize the discussion to the entire extended Kähler cone encompassing topologically different but birationally equivalent Calabi-Yau three-folds that are connected via flop transitions. We examine behavior of the four potentials to probe the nature of these phase transitions. We find that V and P are continuous but not smooth across the flop transition, while Z and its first two derivatives, as well as Z m and its first derivative, are continuous. This in turn implies that supersymmetric stabilization of Z and Z m for a given configuration takes place in at most one point throughout the entire extended Kähler cone. The corresponding black holes (or string states) interpolate between different Calabi-Yau three-folds. At the boundaries of the extended Kähler cone we observe that electric states become massless and/or magnetic strings become tensionless.