Showing papers on "Superpotential published in 2017"

Are neutrino masses modular forms

Abstract: We explore a new class of supersymmetric models for lepton masses and mixing angles where the role of flavour symmetry is played by modular invariance. The building blocks are modular forms of level N and matter supermultiplets, both transforming in representations of a finite discrete group ΓN. In the simplest version of these models, Yukawa couplings are just modular forms and the only source of flavour symmetry breaking is the vacuum expectation value of a single complex field, the modulus. In the special case where modular forms are constant functions the whole construction collapses to a supersymmetric flavour model invariant under ΓN, the case treated so far in the literature. The framework has a number of appealing features. Flavon fields other than the modulus might not be needed. Neutrino masses and mixing angles are simultaneously constrained by the modular symmetry. As long as supersymmetry is exact, modular invariance determines all higher-dimensional operators in the superpotential. We discuss the general framework and we provide complete examples of the new construction. The most economical model predicts neutrino mass ratios, lepton mixing angles, Dirac and Majorana phases uniquely in terms of the modulus vacuum expectation value, with all the parameters except one within the experimentally allowed range. As a byproduct of the general formalism we extend the notion of non-linearly realised symmetries to the discrete case.

$ \mathcal{N}=1 $ deformations and RG flows of $ \mathcal{N}=2 $ SCFTs

Abstract: We study certain $$ \mathcal{N}=1 $$ preserving deformations of four-dimensional $$ \mathcal{N}=2 $$ superconformal field theories (SCFTs) with non-abelian flavor symmetry. The deformation is described by adding an $$ \mathcal{N}=1 $$ chiral multiplet transforming in the adjoint representation of the flavor symmetry with a superpotential coupling, and giving a nilpotent vacuum expectation value to the chiral multiplet which breaks the flavor symmetry. This triggers a renormalization group flow to an infrared SCFT. Remarkably, we find classes of theories flow to enhanced $$ \mathcal{N}=2 $$ supersymmetric fixed points in the infrared under the deformation. They include generalized Argyres-Douglas theories and rank-one SCFTs with non-abelian flavor symmetries. Most notably, we find renormalization group flows from the deformed conformal SQCDs to the (A 1 , A n ) Argyres-Douglas theories. From these “Lagrangian descriptions,” we compute the full superconformal indices of the (A 1 , A n ) theories and find agreements with the previous results. Furthermore, we study the cases, including the T N and R 0,N theories of class $$ \mathcal{S} $$ and some of rank-one SCFTs, where the deformation gives genuine $$ \mathcal{N}=1 $$ fixed points.

Supersymmetric Gauge Theories with Decoupled Operators and Chiral Ring Stability.

Abstract: We propose a general way to complete supersymmetric theories with operators below the unitarity bound, adding gauge-singlet fields that enforce the decoupling of such operators. This makes it possible to perform all usual computations, and to compactify on a circle. We concentrate on a duality between an N=1 SU(2) gauge theory and the N=2 A_{3} Argyres-Douglas theory, mapping the moduli space and chiral ring of the completed N=1 theory to those of the A_{3} model. We reduce the completed gauge theory to 3D, finding a 3D duality with N=4 supersymmetric QED (SQED) with two flavors. The naive dimensional reduction is instead N=2 SQED. Crucial is a concept of chiral ring stability, which modifies the superpotential and allows for a 3D emergent global symmetry.

B-branes and supersymmetric quivers in 2d

Abstract: We study 2d $\mathcal{N}=(0,2)$ supersymmetric quiver gauge theories that describe the low-energy dynamics of D1-branes at Calabi-Yau fourfold (CY$_4$) singularities. On general grounds, the holomorphic sector of these theories---matter content and (classical) superpotential interactions---should be fully captured by the topological $B$-model on the CY$_4$. By studying a number of examples, we confirm this expectation and flesh out the dictionary between B-brane category and supersymmetric quiver: the matter content of the supersymmetric quiver is encoded in morphisms between B-branes (that is, Ext groups of coherent sheaves), while the superpotential interactions are encoded in the $A_\infty$ algebra satisfied by the morphisms. This provides us with a derivation of the supersymmetric quiver directly from the CY$_4$ geometry. We also suggest a relation between triality of $\mathcal{N}=(0,2)$ gauge theories and certain mutations of exceptional collections of sheaves. 0d $\mathcal{N}=1$ supersymmetric quivers, corresponding to D-instantons probing CY$_5$ singularities, can be discussed similarly.

Emergence of Supersymmetric Quantum Electrodynamics.

Abstract: Supersymmetric (SUSY) gauge theories such as the minimal supersymmetric standard model play a fundamental role in modern particle physics, but have not been verified so far in nature. Here, we show that a SUSY gauge theory with dynamical gauge bosons and fermionic gauginos emerges naturally at the pair-density-wave (PDW) quantum phase transition on the surface of a correlated topological insulator hosting three Dirac cones, such as the topological Kondo insulator SmB_{6}. At the quantum tricritical point between the surface Dirac semimetal and nematic PDW phases, three massless bosonic Cooper pair fields emerge as the superpartners of three massless surface Dirac fermions. The resulting low-energy effective theory is the supersymmetric XYZ model, which is dual by mirror symmetry to N=2 supersymmetric quantum electrodynamics in 2+1 dimensions, providing a first example of emergent supersymmetric gauge theory in condensed matter systems. Supersymmetry allows us to determine certain critical exponents and the optical conductivity of the surface states at the strongly coupled tricritical point exactly, which may be measured in future experiments.

Three-forms in supergravity and flux compactifications

Abstract: We present a duality procedure that relates conventional four-dimensional matter-coupled $$\mathcal{N}=1$$ supergravities to dual formulations in which auxiliary fields are replaced by field strengths of gauge three-forms. The duality promotes specific coupling constants appearing in the superpotential to vacuum expectation values of the field strengths. We then apply this general duality to type IIA string compactifications on Calabi–Yau orientifolds with RR fluxes. This gives a new supersymmetric formulation of the corresponding effective four-dimensional theories which includes gauge three-forms.

Maximal supersymmetry and B-mode targets

Abstract: Extending the work of Ferrara and one of the authors [1], we present dynamical cosmological models of α-attractors with plateau potentials for 3α = 1, 2, 3, 4, 5, 6, 7. These models are motivated by geometric properties of maximally supersymmetric theories: M-theory, superstring theory, and maximal N = 8 supergravity. After a consistent truncation of maximal to minimal supersymmetry in a seven-disk geometry, we perform a two-step procedure: 1) we introduce a superpotential, which stabilizes the moduli of the seven-disk geometry in a supersymmetric minimum, 2) we add a cosmological sector with a nilpotent stabilizer, which breaks supersymmetry spontaneously and leads to a desirable class of cosmological attractor models. These models with n s consistent with observational data, and with tensor-to-scalar ratio r ≈ 10−2 − 10−3, provide natural targets for future B-mode searches. We relate the issue of stability of inflationary trajectories in these models to tessellations of a hyperbolic geometry.

Anti-D3 branes and moduli in non-linear supergravity

Abstract: Anti-D3 branes and non-perturbative effects in flux compactifications spontaneously break supersymmetry and stabilise moduli in a metastable de Sitter vacua. The low energy 4D effective field theory description for such models would be a supergravity theory with non-linearly realised supersymmetry. Guided by string theory modular symmetry, we compute this non-linear supergravity theory, including dependence on all bulk moduli. Using either a constrained chiral superfield or a constrained vector field, the uplifting contribution to the scalar potential from the anti-D3 brane can be parameterised either as an F-term or Fayet-Iliopoulos D-term. Using again the modular symmetry, we show that 4D non-linear supergravities that descend from string theory have an enhanced protection from quantum corrections by non-renormalisation theorems. The superpotential giving rise to metastable de Sitter vacua is robust against perturbative string-loop and α′ corrections.

Operator Dimensions from Moduli

Abstract: We consider the operator spectrum of a three-dimensional $$ \mathcal{N}=2 $$ superconformal field theory with a moduli space of one complex dimension, such as the fixed point theory with three chiral superfields X, Y, Z and a superpotential W = XYZ. By using the existence of an effective theory on each branch of moduli space, we calculate the anomalous dimensions of certain low-lying operators carrying large R-charge J. While the lowest primary operator is a BPS scalar primary, the second-lowest scalar primary is in a semi-short representation, with dimension exactly J + 1, a fact that cannot be seen directly from the XYZ Lagrangian. The third-lowest scalar primary lies in along multiplet with dimension J + 2−c −3 J −3 + O(J −4), where c −3 is an unknown positive coefficient. The coefficient c −3 is proportional to the leading superconformal interaction term in the effective theory on moduli space. The positivity of c −3 does not follow from supersymmetry, but rather from unitarity of moduli scattering and the absence of superluminal signal propagation in the effective dynamics of the complex modulus. We also prove a general lemma, that scalar semi-short representations form a module over the chiral ring in a natural way, by ordinary multiplication of local operators. Combined with the existence of scalar semi-short states at large J, this proves the existence of scalar semi-short states at all values of J. Thus the combination of $$ \mathcal{N}=2 $$ superconformal symmetry with the large-J expansion is more powerful than the sum of its parts.

Compactification of dualities with decoupled operators and $3d$ mirror symmetry

Abstract: We consider supersymmetric theories with operators below the unitarity bound. In order to embed the information of the decoupling of these operators, we reformulate the theories adding gauge-singlet fields. In this way it's possible to compute chiral rings and dimensionally reduce dualities involving decoupled operators. We concentrate on a duality between a certain $SU(2)$ gauge theory and the $A_3$ Argyres-Douglas model, found by Maruyoshi and Song. We reduce the duality to three dimensions, showing that $A_3$ Argyres-Douglas becomes $\mathcal{N}=4$ SQED with two flavors. The naive dimensional reduction instead flows to $\mathcal{N}=2$ SQED with two flavors. We check our claims at the level of chiral rings, sphere partition functions and mirror dual RG flows. Crucial in our analysis is a concept of chiral ring stability, which dinamically modifies the superpotential and allows for an accidental symmetry.

Anti-D3 branes and moduli in non-linear supergravity

Abstract: Anti-D3 branes and non-perturbative effects in flux compactifications spontaneously break supersymmetry and stabilise moduli in a metastable de Sitter vacua. The low energy 4D effective field theory description for such models would be a supergravity theory with non-linearly realised supersymmetry. Guided by string theory modular symmetry, we compute this non-linear supergravity theory, including dependence on all bulk moduli. Using either a constrained chiral superfield or a constrained vector field, the uplifting contribution to the scalar potential from the anti-D3 brane can be parameterised either as an F-term or Fayet-Iliopoulos D-term. Using again the modular symmetry, we show that 4D non-linear supergravities that descend from string theory have an enhanced protection from quantum corrections by non-renormalisation theorems. The superpotential giving rise to metastable de Sitter vacua is robust against perturbative string-loop and $\alpha'$ corrections.

Electric dipole moments in natural supersymmetry

Abstract: We discuss electric dipole moments (EDMs) in the framework of CP-violating natural supersymmetry (SUSY). Recent experimental results have significantly tightened constraints on the EDMs of electrons and of mercury, and substantial further progress is expected in the near future. We assess how these results constrain the parameter space of natural SUSY. In addition to our discussion of SUSY, we provide a set of general formulas for two-loop fermion EDMs, which can be applied to a wide range of models of new physics. In the SUSY context, the two-loop effects of stops and charginos respectively constrain the phases of A t μ and M 2 μ to be small in the natural part of parameter space. If the Higgs mass is lifted to 125 GeV by a new tree-level superpotential interaction and soft term with CP-violating phases, significant EDMs can arise from the two-loop effects of W bosons and tops. We compare the bounds arising from EDMs to those from other probes of new physics including colliders, b → sγ, and dark matter searches. Importantly, improvements in reach not only constrain higher masses, but require the phases to be significantly smaller in the natural parameter space at low mass. The required smallness of phases sharpens the CP problem of natural SUSY model building.

Starobinsky Inflation: From Non-SUSY To SUGRA Realizations

Abstract: We review the realization of Starobinsky-type inflation within induced-gravity supersymmetric ( SUSY ) and non-SUSY models. In both cases, inflation is in agreement with the current data and can be attained for sub-Planckian values of the inflation. The corresponding effective theories retain perturbative unitarity up to the Planck scale and the inflation mass is predicted to be . The supergravity embedding of these models is achieved by employing two gauge singlet chiral superfields, a superpotential that is uniquely determined by a continuous and a discrete symmetry and several (semi)logarithmic Kahler potentials that respect these symmetries. Checking various functional forms for the noninflation accompanying field in the Kahler potentials, we identify four cases which stabilize it without invoking higher order terms.

T-branes, monopoles and S-duality

Abstract: M2 branes probing T-brane backgrounds in M-theory with ADE surface singularities perceive deformations on their worldvolume superpotentials by monopole operators. The dynamics and moduli spaces of the resulting theories can be studied using a dual description involving conventional superpotential terms and (the dimensional reduction of) class S trinion theories. By using the S-dual description of N=2 SU(N) SQCD with 2N flavors in four dimensions, we are able to study T-branes corresponding to all minimal nilpotent orbits for the whole ADE series.

The Geometry of G$_2$, Spin(7), and Spin(8)-models

Abstract: We study the geometry of elliptic fibrations given by Weierstrass models resulting from Step 6 of Tate's algorithm. Such elliptic fibrations have a discriminant locus containing an irreducible component $S$, over which the generic fiber is of Kodaira type I$^*_0$. In string geometry, these geometries are used to geometrically engineer G$_2$, Spin($7$), and Spin($8$) gauge theories. We give sufficient conditions for the existence of crepant resolutions. When they exist, we give a complete description of all crepant resolutions and show explicitly how the network of flops matches the Coulomb branch of the associated gauge theories. We also compute the triple intersection numbers in each chamber. Physically, they correspond to the Chern-Simons levels of the gauge theory and depend on the choice of a Coulomb branch. We determine the representations associated with these elliptic fibrations by computing intersection numbers with fibral divisors and then interpreting them as weights of a representation. For a five-dimensional gauge theory, we compute the number of hypermultiplets in each representation by matching the triple intersection numbers with the superpotential of the theory. We also discuss anomaly cancellations of a six-dimensional supergravity theory obtained by a compactification of F-theory on an elliptically fibered Calabi--Yau threefold corresponding to a G$_2$, Spin($7$), or Spin($8$) gauge theory.

Surface operators, chiral rings, and localization in N=2 gauge theories

Abstract: We study half-BPS surface operators in supersymmetric gauge theories in four and five dimensions following two different approaches. In the first approach we analyze the chiral ring equations for certain quiver theories in two and three dimensions, coupled respectively to four- and five-dimensional gauge theories. The chiral ring equations, which arise from extremizing a twisted chiral superpotential, are solved as power series in the infrared scales of the quiver theories. In the second approach we use equivariant localization and obtain the twisted chiral superpotential as a function of the Coulomb moduli of the four- and five-dimensional gauge theories, and find a perfect match with the results obtained from the chiral ring equations. In the five-dimensional case this match is achieved after solving a number of subtleties in the localization formulas which amounts to choosing a particular residue prescription in the integrals that yield the Nekrasov-like partition functions for ramified instantons. We also comment on the necessity of including Chern-Simons terms in order to match the superpotentials obtained from dual quiver descriptions of a given surface operator.

The method of generating functions in exact scalar field cosmology

Abstract: Exact solutions construction in scalar fields cosmology is of growing interest. In this work we review the results which obtained with the help of one of the most effective method. Namely, the method of generating functions for exact solutions construction in the scalar field cosmology. We also included into debate the superpotential method which may be considered as the bridge to slow roll approximation equations. Basing on the review, we suggested classification for the generating functions and found connection for all of them with the superpotential.

E 8 orbits of IR dualities

Abstract: We discuss USp(2n) supersymmetric models with eight fundamental fields and a field in the antisymmetric representation. Turning on the most generic superpotentials, coupling pairs of fundamental fields to powers of the antisymmetric field while preserving an R symmetry, we give evidence for the statement that the models are connected by a large network of dualities which can be organized into orbits of the Weyl group of E8. We make also several curious observations about such models. In particular, we argue that a USp(2m) model with the addition of singlet fields and even rank m flows in the IR to a CFT with E7 × U(1) symmetry. We also discuss an infinite number of duals for the USp(2) theory with eight fundamentals and no superpotential.

Surface operators, chiral rings and localization in N $$ \mathcal{N} $$ =2 gauge theories

Abstract: We study half-BPS surface operators in supersymmetric gauge theories in four and five dimensions following two different approaches. In the first approach we analyze the chiral ring equations for certain quiver theories in two and three dimensions, coupled respectively to four- and five-dimensional gauge theories. The chiral ring equations, which arise from extremizing a twisted chiral superpotential, are solved as power series in the infrared scales of the quiver theories. In the second approach we use equivariant localization and obtain the twisted chiral superpotential as a function of the Coulomb moduli of the four- and five-dimensional gauge theories, and find a perfect match with the results obtained from the chiral ring equations. In the five-dimensional case this match is achieved after solving a number of subtleties in the localization formulas which amounts to choosing a particular residue prescription in the integrals that yield the Nekrasov-like partition functions for ramified instantons. We also comment on the necessity of including Chern-Simons terms in order to match the superpotentials obtained from dual quiver descriptions of a given surface operator.

Starobinsky-like inflation in no-scale supergravity Wess-Zumino model with Polonyi term

Abstract: We propose a simple modification of the no-scale supergravity Wess-Zumino model of Starobinsky-like inflation to include a Polonyi term in the superpotential. The purpose of this term is to provide an explicit mechanism for supersymmetry breaking at the end of inflation. We show how successful inflation can be achieved for a gravitino mass satisfying the strict upper bound m 3/2 < 103 TeV, with favoured values $$ {m}_{3/2}\lesssim \mathcal{O}(1) $$ TeV. The model suggests that SUSY may be discovered in collider physics experiments such as the LHC or the FCC.

Dubrovin's superpotential as a global spectral curve

Abstract: We apply the spectral curve topological recursion to Dubrovin’s universal Landau–Ginzburg superpotential associated to a semi-simple point of any conformal Frobenius manifold. We show that under some conditions the expansion of the correlation differentials reproduces the cohomological field theory associated with the same point of the initial Frobenius manifold.

Modular and duality properties of surface operators in N=2* gauge theories

Abstract: We calculate the instanton partition function of the four-dimensional $$ \mathcal{N}={2}^{\star } $$ SU(N) gauge theory in the presence of a generic surface operator, using equivariant localization. By analyzing the constraints that arise from S-duality, we show that the effective twisted superpotential, which governs the infrared dynamics of the two-dimensional theory on the surface operator, satisfies a modular anomaly equation. Exploiting the localization results, we solve this equation in terms of elliptic and quasi-modular forms which resum all non-perturbative corrections. We also show that our results, derived for monodromy defects in the four-dimensional theory, match the effective twisted superpotential describing the infrared properties of certain two-dimensional sigma models coupled either to pure $$ \mathcal{N}=2 $$ or to $$ \mathcal{N}={2}^{\star } $$ gauge theories.

E_8 orbits of IR dualities

Abstract: We discuss USp(2n) supersymmetric models with eight fundamental fields and a field in the antisymmetric representation. Turning on the most generic superpotentials, coupling pairs of fundamental fields to powers of the antisymmetric field while preserving an R symmetry, we give evidence for the statement that the models are connected by a large network of dualities which can be organized into orbits of the Weyl group of E_8. We make also several curious observations about such models. In particular, we argue that a USp(2m) model with the addition of singlet fields and even rank m flows in the IR to a CFT with E_7 U(1) symmetry. We also discuss an infinite number of duals for the USp(2) theory with eight fundamentals and no superpotential.

Operator Dimensions from Moduli

Abstract: We consider the operator spectrum of a three-dimensional ${\cal N} = 2$ superconformal field theory with moduli spaces of one complex dimension, such as the fixed point theory with three chiral superfields $X,Y,Z$ and a superpotential $W = XYZ$. By using the existence of an effective theory on each branch of moduli space, we calculate the anomalous dimensions of certain low-lying operators carrying large $R$-charge $J$. While the lowest primary operator is a BPS scalar primary, the second-lowest scalar primary is in a semi-short representation, with dimension exactly $J+1$, a fact that cannot be seen directly from the $XYZ$ Lagrangian. The third-lowest scalar primary lies in a long multiplet with dimension $J+2 - c_{-3} \, J^{-3} + O(J^{-4})$, where $c_{-3}$ is an unknown positive coefficient. The coefficient $c_{-3}$ is proportional to the leading superconformal interaction term in the effective theory on moduli space. The positivity of $c_{-3}$ does not follow from supersymmetry, but rather from unitarity of moduli scattering and the absence of superluminal signal propagation in the effective dynamics of the complex modulus. We also prove a general lemma, that scalar semi-short representations form a module over the chiral ring in a natural way, by ordinary multiplication of local operators. Combined with the existence of scalar semi-short states at large $J$, this proves the existence of scalar semi-short states at all values of $J$. Thus the combination of ${\cal N}=2$ superconformal symmetry with the large-$J$ expansion is more powerful than the sum of its parts.

Effective theories of flavor and the nonuniversal MSSM

Abstract: Flavor symmetries a la Froggatt-Nielsen provide a compelling way to explain the hierarchies of fermionic masses and mixing angles in the Yukawa sector. In supersymmetric (SUSY) extensions of the Standard Model where the mediation of SUSY breaking occurs at scales larger than the breaking of flavor, this symmetry must be respected not only by the Yukawas of the superpotential but also by the soft-breaking masses and trilinear terms. In this work we show that contrary to naive expectations, even starting with completely flavor blind soft breaking in the full theory at high scales, the low-energy sfermion mass matrices and trilinear terms of the effective theory, obtained upon integrating out the heavy mediator fields, are strongly nonuniversal. We explore the phenomenology of these SUSY flavor models after the latest LHC searches for new physics.

Scalar potentials with multi-scalar fields from quantum cosmology and supersymmetric quantum mechanics

Abstract: The multi-scalar field cosmology of the anisotropic Bianchi type-I model is used in order to construct a family of potentials that are the best suited to model the inflation phenomenon. We employ the quantum potential approach to quantum mechanics due to Bohm in order to solve the corresponding Wheeler-DeWitt equation; which in turn enables us to restrict sensibly the aforementioned family of potentials. Supersymmetric Quantum Mechanics (SUSYQM) is also employed in order to constrain the superpotential function, at the same time the tools from SUSY Quantum Mechanics are used to test the family of potentials in order to infer which is the most convenient for the inflation epoch. For completeness solutions to the wave function of the universe are also presented.

On the Effective Field Theory of Heterotic Vacua

Abstract: The effective field theory of heterotic vacua that realise R3;1 preserving N=1 supersymmetry are studied. The vacua in question admit large radius limits taking the form R3;1 x X, with X a smooth three-fold with vanishing first Chern class and a stable holomorphic gauge bundle E. In a previous paper we calculated the kinetic terms for moduli, deducing the moduli metric and Kahler potential. In this paper, we compute the remaining couplings in the effective field theory, correct to first order in a'. In particular, we compute the contribution of the matter sector to the Kahler potential, derive the Yukawa couplings and other quadratic fermionic couplings. From this we write down a Kahler potential K and superpotential W.

A Composite Axion from a Supersymmetric Product Group

Abstract: A global $U(1)_\text{PQ}$ symmetry is protected from gravitational effects in the s-confining $SU(N)^k$ product group theory with $A+4Q +N\overline{Q}$ matter. If the $SU(4)$ family symmetry is gauged and an appropriate tree-level superpotential is added, then the dynamically generated superpotential spontaneously breaks $SU(4)\times U(1)_\text{PQ} \rightarrow SU(3)_c$ and produces a QCD axion. Small values of the $CP$-violating $\theta$ parameter are then possible without any fine-tuning, as long as the product group is suitably large. By introducing a second copy of the s-confining $SU(N)$ product group also coupled to the gauged $SU(4)$, we find that values as small as $N=7$ are consistent with $\bar\theta<10^{-10}$, even under the pessimistic assumption that the dominant contribution to the axion quality is at tree level.

A composite axion from a supersymmetric product group

Abstract: A global U(1)PQ symmetry is protected from gravitational effects in the s-confining SU(N)k product group theory with $$ A + 4Q+N\overline{Q} $$ matter. If the SU(4) family symmetry is gauged and an appropriate tree-level superpotential is added, then the dynamically generated superpotential spontaneously breaks SU(4) × U(1)PQ → SU(3)c and produces a QCD axion. Small values of the CP -violating θ parameter are then possible without any fine-tuning, as long as the product group is suitably large. By introducing a second copy of the s-confining SU(N) product group also coupled to the gauged SU(4), we find that values as small as N = 7 are consistent with $$ \overline{\theta}<1{0}^{-10} $$ , even under the pessimistic assumption that the dominant contribution to the axion quality is at tree level.