Search

We consider a low-energy effective theory of p -branequaes in a D -dimensional spacetime, and impose two conditions: (1) the theory is scale-invariant, and (2) the electric–magnetic dual |$(D-p-4)$| -branes exist and they obey the same type of interactions to the p -branes. (We also assume other natural conditions such as Lorentz invariance but not string theory, supersymmetry, supergravity, and so on.) We then ask what values of p and D are consistent with these conditions. Using simple dimensional analysis, we find that only two solutions are possible: |$(p,D)=(2,11)$| and |$(p,D)=(2n-1,4n+2)$|⁠ , (⁠|$n=1,2,3,\cdots$|⁠). The first solution corresponds to M-theory, and the second solutions at |$n=1$| and |$n=2$| correspond to self-dual strings in little string theory and D3-branes in type IIB superstring theory, respectively, while the second solutions for |$n \ge 3$| are unknown but would be higher spin theories. Thus, quantum gravity (massless spin two theory) satisfying our two conditions would only be superstring theories, and the conditions would be strong enough to characterize superstring theories in quantum gravity. [ABSTRACT FROM AUTHOR]

We survey on-shell and off-shell higher derivative supergravities in dimensions 1 ≤ D ≤ 11. Various approaches to their construction, including the Noether procedure, (harmonic) superspace, superform method, superconformal tensor calculus, S -matrix and dimensional reduction, are summarized. Primarily the bosonic parts of the invariants and the supertransformations of the fermionic fields are provided. The process of going on-shell, solutions to the Killing spinor equations, typical supersymmetric solutions, and the role of duality symmetries in the context of R 4 , D 4 R 4 and D 6 R 4 invariants are reviewed. [ABSTRACT FROM AUTHOR]

We study the quantum dynamics of a system of n Abelian N = 1 vector multiplets coupled to 1 2 n n + 1 chiral multiplets which parametrise the Hermitian symmetric space Sp(2n, ℝ)/U(n). In the presence of supergravity, this model is super-Weyl invariant and possesses the maximal non-compact duality group Sp(2n, ℝ) at the classical level. These symmetries should be respected by the logarithmically divergent term (the "induced action") of the effective action obtained by integrating out the vector multiplets. In computing the effective action, one has to deal with non-minimal operators for which the known heat kernel techniques are not directly applicable, even in flat (super)space. In this paper we develop a method to compute the induced action in Minkowski superspace. The induced action is derived in closed form and has a simple structure. It is a higher-derivative superconformal sigma model on Sp(2n, ℝ)/U(n). The obtained N = 1 results are generalised to the case of N = 2 local supersymmetry: a system of n Abelian N = 2 vector multiplets coupled to N = 2 chiral multiplets XI parametrising Sp(2n, ℝ)/U(n). The induced action is shown to be proportional to ∫ d 4 x d 4 θ d 4 θ ¯ E K X X ¯ , where K X X ¯ is the Kähler potential for Sp(2n, ℝ)/U(n). We also apply our method to compute DeWitt's a2 coefficients in some non-supersymmetric theories with non-minimal operators. [ABSTRACT FROM AUTHOR]

We propose quantum gravitational constraints on effective four-dimensional theories with N = 1 supersymmetry. These Swampland constraints arise by demanding consistency of the worldsheet theory of a class of axionic, or EFT, strings whose existence follows from the Completeness Conjecture of quantum gravity. Modulo certain assumptions, we derive positivity bounds and quantization conditions for the axionic couplings to the gauge and gravitational sector at the two- and four-derivative level, respectively. We furthermore obtain general bounds on the rank of the gauge sector in terms of the gravitational couplings to the axions. We exemplify how these bounds rule out otherwise consistent effective supergravity theories as theories of quantum gravity. Our derivations of the quantum gravity bounds are tested and further motivated in concrete string theoretic settings. In particular, this leads to a sharper version of the bound on the gauge group rank in F-theory on elliptic four-folds with a smooth base, which improves the known geometrical Kodaira bounds. We furthermore provide a detailed derivation of the EFT string constraints in heterotic string compactifications including higher derivative corrections to the effective action and apply the bounds to M-theory compactifications on G2 manifolds. [ABSTRACT FROM AUTHOR]

A central problem in any quantum theory of gravity is to explain the emergence of the classical spacetime geometry in some limit of a more fundamental, microscopic description of nature. The gauge/gravity-correspondence provides a framework in which this problem can, in principle, be addressed. This is a holographic correspondence which relates a supergravity theory in five-dimensional Anti-deSitter space to a strongly coupled superconformal gauge theory on its 4-dimensional flat Minkowski boundary. In particular, the classical geometry should therefore emerge from some quantum state of the dual gauge theory. Here we confirm this by showing how the classical metric emerges from a canonical state in the dual gauge theory. In particular, we obtain approximations to the Sasaki-Einstein metric underlying the supergravity geometry, in terms of an explicit integral formula involving the canonical quantum state in question. In the special case of toric quiver gauge theories we show that our results can be computationally simplified through a process of tropicalization. It is an outstanding question in quantum gravity how to describe the emergence of classical spacetime geometry from a quantum state. Here, the authors propose a construction in the context of the gauge/gravity correspondence, producing the classical geometry from a quantum state at the boundary of spacetime. [ABSTRACT FROM AUTHOR]

We find large N gauge theories containing a large number of operators within a band of low conformal dimensions. One of such examples is the four-dimensional N = 1 supersymmetric SU(N) gauge theory with one adjoint and a pair of fundamental/anti-fundamental chiral multiplets. This theory flows to a superconformal theory in the infrared upon a superpotential coupling with gauge singlets. The gap in the low-lying spectrum scales as 1/N and the central charges scale as O(N1) contrary to the usual O(N2) scaling of ordinary gauge theory coming from the matrix degree of freedom. We find the AdS version of the Weak Gravity Conjecture (WGC) holds for this theory, although it cannot be holographically dual to supergravity. This supports the validity of WGC in a more general theory of quantum gravity. [ABSTRACT FROM AUTHOR]

In this paper, we study a class of symmetry reduced models of N = 1 super- gravity using self-dual variables. It is based on a particular Ansatz for the gravitino field as proposed by D'Eath et al. We show that the essential part of the constraint algebra in the classical theory closes. In particular, the (graded) Poisson bracket between the left and right supersymmetry constraint reproduces the Hamiltonian constraint. For the quantum theory, we apply techniques from the manifestly supersymmetric approach to loop quantum supergravity, which yields a graded analog of the holonomy-flux algebra and a natural state space. We implement the remaining constraints in the quantum theory. For a certain subclass of these models, we show explicitly that the (graded) commutator of the supersymmetry constraints exactly reproduces the classical Poisson relations. In particular, the trace of the commutator of left and right supersymmetry constraints reproduces the Hamilton constraint operator. Finally, we consider the dynamics of the theory and compare it to a quantization using standard variables and standard minisuperspace techniques. [ABSTRACT FROM AUTHOR]

Using a D = 1 supergravity framework I construct a super-Friedmann equation for an isotropic and homogenous universe including dynamical scalar fields. In the context of quantum theory this becomes an equation for a wave function of the universe of spinorial type, the Wheeler-DeWitt-Dirac equation. It is argued that a cosmological constant breaks a certain chiral symmetry of this equation, a symmetry in the Hilbert space of universe states, which could protect a small cosmological constant from being affected by large quantum corrections. [ABSTRACT FROM AUTHOR]

We initiate the classification of supersymmetric solutions of type II supergravity on R 1 , 2 × S 3 × M 4 . We find explicit local expressions for all backgrounds with either a single Killing spinor or two of equal norm, up to PDE's. We show that the only type II AdS × 4 S 3 solution is the known N = 4 AdS 4 background obtained from the near-horizon limit of intersecting D2–D6 branes. Various known branes and intersecting brane systems are recovered, and we obtain a novel class of R 1 , 2 × S 2 × S 3 solutions in IIA. [ABSTRACT FROM AUTHOR]

In this paper, we study noncommutative massive unquenched Chern–Simons matter theory using its gravity dual. We construct this novel background by applying a TsT-transformation on the known parent commutative solution. We discuss several aspects of this solution to the Type IIA supergravity equations of motion and, amongst others, check that it preserves 𝒩=1 supersymmetry. We then turn our attention to applications and investigate how dynamical flavor degrees of freedom affect numerous observables of interest. Our framework can be regarded as a key step toward the construction of holographic quantum Hall states on a noncommutative plane. [ABSTRACT FROM AUTHOR]

We study the constraints of spacetime supersymmetry for perturbative three- and two-dimensional Minkowski vacua of the critical heterotic string. Assuming a standard RNS construction of the spacetime supersymmetry generators and a compact unitary internal superconformal worldsheet theory, we describe the worldsheet structures associated to various spacetime supersymmetries. In three dimensions we show that there are no CFT surprises: each allowed spacetime supersymmetry is realized by a supergravity compactification. As a recent orbifold construction shows, in two dimensions there are more exotic possibilities, and we discuss how these fit into our analysis. [ABSTRACT FROM AUTHOR]

The ten-dimensional supergravity theory is a geometric low-energy effective theory and the equations of motion for its fields can be obtained from string theory by computing β functions. With d compact dimensions, an O ( d , d ; Z ) geometric structure can be added to it giving the supergravity theory with T-duality manifest. In this paper, this is constructed through the use of a suitable star product whose role is the one to implement the weak constraint on the fields and the gauge parameters in order to have a closed gauge symmetry algebra. The consistency of the action here proposed is based on the orthogonality of the momenta associated with fields in their triple star products in the cubic terms defined for d ≥ 1 . This orthogonality holds also for an arbitrary number of star products of fields for d = 1 . Finally, we extend our analysis to the double sigma model, non-commutative geometry and open string theory. [ABSTRACT FROM AUTHOR]

Models of geometric flows pertaining to R 2 scale invariant (super) gravity theories coupled to conformally invariant matter fields are investigated. Related to this work are supersymmetric scalar manifolds that are isomorphic to the Kählerian spaces M n = S U ( 1 , 1 + k ) ∕ U ( 1 ) × S U ( 1 + k ) as generalizations of the non-supersymmetric analogs with S O ( 1 , 1 + k ) ∕ S O ( 1 + k ) manifolds. For curved superspaces with geometric evolution of physical objects, a complete supersymmetric theory has to be elaborated on nonholonomic (super) manifolds and bundles determined by non-integrable superdistributions with additional constraints on (super) field dynamics and geometric evolution equations. We also consider generalizations of Perelman’s functionals using such nonholonomic variables which result in the decoupling of geometric flow equations and Ricci soliton equations with supergravity modifications of the R 2 gravity theory. As such, it is possible to construct exact non-homogeneous and locally anisotropic cosmological solutions for various types of (super) gravity theories modeled as modified Ricci soliton configurations. Such solutions are defined by employing the general ansatz encompassing coefficients of generic off-diagonal metrics and generalized connections that depend generically on all spacetime coordinates. We consider nonholonomic constraints resulting in diagonal homogeneous configurations encoding contributions from possible nonlinear parametric geometric evolution scenarios, off-diagonal interactions and anisotropic polarization/modification of physical constants. In particular, we analyze small parametric deformations when the underlying scale symmetry is preserved and the nontrivial anisotropic vacuum corresponds to generalized de Sitter spaces. Such configurations may mimic quantum effects whenever transitions to flat space are possible. Our approach allows us to generate solutions with scale violating terms induced by geometric flows, off-diagonal interactions and supersymmetric modifications of effective potentials. We study reconstructing the formalism for (super) geometric flows and modified gravity cosmological scenarios. We also analyze the conditions under which such modified mimetic type theories and solutions reproduce the Starobinsky inflationary models in the double scalar approach. [ABSTRACT FROM AUTHOR]

We present a new formulation of quantum holonomy theory, which is a candidate for a non-perturbative and background independent theory of quantum gravity coupled to matter and gauge degrees of freedom. The new formulation is based on a Hilbert space representation of the [ABSTRACT FROM AUTHOR]

I discuss the role of quantum effects in the phenomenology of effective supergravity theories from compactification of the weakly coupled heterotic string. An accurate incorporation of these effects requires a regularization procedure that respects local supersymmetry and BRST invariance and that retains information associated with the cut-off scale, which has physical meaning in an effective theory. I briefly outline the Pauli–Villars regularization procedure, describe some applications, and comment on what remains to be done to fully define the effective quantum field theory. [ABSTRACT FROM AUTHOR]

This work considers an extension of the Standard Model (SM) Higgs sector by a real, scalar singlet field, including applicability to a dark matter (DM) model with the addition of a Yukawa coupling to a fermionic dark matter candidate. The collider signatures and constraints on the mixed two-Higgs scenario are determined, including limits from Higgs production signals and exclusion searches, as well as constraints arising from the Higgs total and invisible widths. As there is overwhelming Higgs data which is consistent with a SM scenario, the case in which an additional scalar has evaded detection is further explored in the context of Higgs precision measurement. The discovery reach and prospective signatures of the model at a proposed linear collider are investigated, with particular focus on the Higgs triple coupling, and di-Higgs production processes. [ABSTRACT FROM AUTHOR]

We study the inclusive production of a Higgs boson in association with a high- p photon at the LHC, detailing the leading-order features of the main processes contributing to the Hγ final state. Requiring an extra hard photon in Higgs production upsets the cross-section hierarchy for the dominant channels. The Hγ inclusive production comes mainly from photons radiated in vector-boson fusion (VBF), which accounts for about 2/3 of the total rate, for p > 30 GeV, at leading order. On the other hand, radiating a high- p photon in the main top-loop Higgs channel implies an extra parton in the final state, which suppresses the production rate by a further α power. As a result, the Hγ production via top loops at the LHC has rates comparable with the ones arising from either the $$ Ht\overline{t} $$ production or the HW ( Z)γ associated production. Then, in order of decreasing cross section, comes the single-top-plus-Higgs channel, followed in turn by the heavy-flavor fusion processes $$ b\overline{b}\to H\gamma $$ and $$ c\overline{c}\to H\gamma $$. The Hγ production via electroweak loops has just a minor role. At larger c.m. energies, the $$ Ht\overline{t}\gamma $$ channel surpasses the total contribution of top-loop processes. In particular, requiring p > 30 GeV at $$ \sqrt{S}\simeq 100 $$ TeV, $$ Ht\overline{t}\gamma $$ accounts for about 1 /4 of the inclusive Hγ production at leading order, about half of the total being due to VBF production. [ABSTRACT FROM AUTHOR]

We present a version of the twin Higgs mechanism with vector-like top partners. In this setup all gauge anomalies automatically cancel, even without twin leptons. The matter content of the most minimal twin sector is therefore just two twin tops and one twin bottom. The LHC phenomenology, illustrated with two example models, is dominated by twin glueball decays, possibly in association with Higgs bosons. We further construct an explicit four-dimensional UV completion and discuss a variety of UV completions relevant for both vector-like and fraternal twin Higgs models. [ABSTRACT FROM AUTHOR]

We study global symmetry groups of six-dimensional superconformal field theories (SCFTs). In the Coulomb branch we use field theoretical arguments to predict an upper bound for the global symmetry of the SCFT. We then analyze global symmetry groups of F-theory constructions of SCFTs with a one-dimensional Coulomb branch. While in the vast majority of cases, all of the global symmetries allowed by our Coulomb branch analysis can be realized in F-theory, in a handful of cases we find that F-theory models fail to realize the full symmetry of the theory on the Coulomb branch. In one particularly mysterious case, F-theory models realize several distinct maximal subgroups of the predicted group, but not the predicted group itself. [ABSTRACT FROM AUTHOR]

We study Einstein-Born-Infeld gravity and construct the dyonic (A)dS planar black holes in general even dimensions, that carry both the electric charge and magnetic fluxes along the planar space. In four dimensions, the solution can be constructed with also spherical and hyperbolic topologies. We study the black hole thermodynamics and obtain the first law. We also classify the singularity structure. [ABSTRACT FROM AUTHOR]

We review the construction of a duality-invariant higher-derivative theory based on a doubled metric. This theory incorporates the corrections needed in the Green-Schwarz anomaly cancellation mechanism. We note recent progress in elucidating the structure of the theory. This article is largely based on the plenary talk given by B. Zwiebach at 'The String Theory Universe', 21st European String Workshop, Leuven, September 7-11, 2015. [ABSTRACT FROM AUTHOR]

Starting with the F ˆ / G supercoset model corresponding to the AdS n × S n superstring one can define the λ -model of arXiv:1409.1538 either as a deformation of the F ˆ / F ˆ gauged WZW model or as an integrable one-parameter generalisation of the non-abelian T-dual of the AdS n × S n superstring sigma model with respect to the whole supergroup F ˆ . Here we consider the case of n = 2 and find the explicit form of the 4d target space background for the λ -model for the PSU ( 1 , 1 | 2 ) / SO ( 1 , 1 ) × SO ( 2 ) supercoset. We show that this background represents a solution of type IIB 10d supergravity compactified on a 6-torus with only metric, dilaton Φ and the RR 5-form (represented by a 2-form F in 4d) being non-trivial. This implies that the λ -model is Weyl invariant at the quantum level and thus defines a consistent superstring sigma model. The supergravity solution we find is different from the one in arXiv:1410.1886 which should correspond to a version of the λ -model where only the bosonic subgroup of F ˆ is gauged. Still, the two solutions have equivalent scaling limit of arXiv:1504.07213 leading to the isometric background for the metric and e Φ F which is related to the η -deformed AdS 2 × S 2 sigma model of arXiv:1309.5850. Similar results are expected in the AdS 3 × S 3 and AdS 5 × S 5 cases. [ABSTRACT FROM AUTHOR]