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We present a proposal to relate the de Sitter conjecture (dSC) with the time dependence of fluxes via the covariant entropy bound (CEB). By assuming an early phase of accelerated expansion where the CEB is satisfied, we take into account a contribution from time-dependent flux compactification to the four-dimensional entropy which establishes a bound on the usual slow-roll parameters ηH and ∈H. We also show an explicit calculation of entropy from a toroidal flux compactification, from a transition amplitude of time-dependent fluxes which allows us to determine the conditions on which the bounds on the slow-roll parameters are in agreement to the dSC. [ABSTRACT FROM AUTHOR]

We consider a particular example of dynamical compactification of an anisotropic 7 + 1 dimensional Universe in Einstein–Gauss–Bonnet gravity. Starting from rather general totally anisotropic initial conditions a Universe in question evolves towards a product of two isotropic subspaces. The first subspace expands isotropically, the second represents an "inner" isotropic subspace with stabilized size. The dynamical evolution does not require fine-tuning of initial conditions, though it is possible for a particular range of coupling constants. The corresponding condition have been found analytically and have been confirmed using numerical integration of equations of motion. [ABSTRACT FROM AUTHOR]

In this work we consider quotients of elliptically fibered Calabi-Yau threefolds by freely acting discrete groups and the associated physics of F-theory compactifications on such backgrounds. The process of quotienting a Calabi-Yau geometry produces not only new genus one fibered manifolds, but also new effective 6-dimensional physics. These theories can be uniquely characterized by the much simpler covering space geometry and the symmetry action on it. We use this method to construct examples of F-theory models with an array of discrete gauge groups and non-trivial monodromies, including an example with ℤ6 discrete symmetry. [ABSTRACT FROM AUTHOR]

Intersecting D-brane models and their T-dual magnetic compactifications yield attractive models of particle physics where magnetic flux plays a twofold role, being the source of fermion chirality as well as supersymmetry breaking. A potential problem of these models is the appearance of tachyons which can only be avoided in certain regions of moduli space and in the presence of Wilson lines. We study the effective four-dimensional field theory for an orientifold compactification of type IIA string theory and the corresponding toroidal compactification of type I string theory. After determining the Kaluza-Klein and Landau-level towers of massive states in different sectors of the model, we evaluate their contributions to the one-loop effective potential, summing over all massive states, and we relate the result to the corresponding string partition functions. We find that the Wilson- line effective potential has only saddle points, and the theory is therefore driven to the tachyonic regime. There tachyon condensation takes place and chiral fermions acquire a mass of the order of the compactification scale. We also find evidence for a tachyonic behaviour of the volume moduli. More work on tachyon condensation is needed to clarify the connection between supersymmetry breaking, a chiral fermion spectrum and vacuum stability. [ABSTRACT FROM AUTHOR]

Abstract We revisit the number-theory dark matter scenario where one of the light chiral fermions required by the anomaly cancellation conditions of U(1) B-L explains dark matter. Focusing on some of the integer B-L charge assignments, we explore a new region of the parameter space where there appear two light fermions and the heavier one becomes a dark matter of mass ≲ O (10) keV or O (10) MeV. The dark matter radiatively decays into neutrino and photon, which can explain the tantalizing hint of the 3.55 keV X-ray line excess. Interestingly, the other light fermion can erase the AdS vacuum around the neutrino mass scale in a compactification of the standard model to 3D. This will make the standard model consistent with the AdS-WGC statement that stable non-supersymmetric AdS vacua should be absent. [ABSTRACT FROM AUTHOR]

Abstract Particle physics models with Peccei–Quinn (PQ) symmetry breaking as a consequence of supersymmetry (SUSY) breaking are attractive in that they solve the strong CP problem with a SUSY DFSZ-like axion, link the SUSY breaking and PQ breaking intermediate mass scales and can resolve the SUSY μ problem with a naturalness-required weak scale μ term whilst soft SUSY breaking terms inhabit the multi-TeV regime as required by LHC sparticle mass limits and the Higgs mass measurement. On the negative ledger, models based on global symmetries suffer a generic gravity spoliation problem. We present two models based on the discrete R -symmetry Z 24 R —which may emerge from compactification of 10-d Lorentzian spacetime in string theory—where the μ term and dangerous proton decay and R -parity violating operators are either suppressed or forbidden while a gravity-safe PQ symmetry emerges as an accidental approximate global symmetry leading to a solution to the strong CP problem and a weak-scale/natural value for the μ term. [ABSTRACT FROM AUTHOR]

Abstract Magnetized orbifolds play an important role in compactifications of string theories and higher-dimensional field theories to four dimensions. Magnetic flux leads to chiral fermions, it can be a source of supersymmetry breaking and it is an important ingredient of moduli stabilization. Flux quantization on orbifolds is subtle due to the orbifold singularities. Generically, Wilson line integrals around these singularities are non-trivial, which can be interpreted as localized flux. As a consequence, flux densities on orbifolds can take the same values as on tori. We determine the transition functions for the flux vector bundle on the orbifold T 2 ∕ Z 2 and the related twisted boundary conditions of zero-mode wave functions. We also construct "untwisted" zero-mode functions that are obtained for singular vector fields related to the Green's function on a torus, and we discuss the connection between zeros of the wave functions and localized flux. Twisted and untwisted zero-mode functions are related by a singular gauge transformation. [ABSTRACT FROM AUTHOR]

Abstract The gravitational Szekeres differential system is completely integrable with two rational first integrals and an additional analytical first integral. We describe the dynamics of the Szekeres system when one of these two rational first integrals is negative, showing that all the orbits come from the infinity of R 4 and go to infinity. Highlights • The 4 D Szekeres system provides exact solutions of a kind of Einstein equations. • This system has two rational first integrals F and H. • We prove that if F < 0 then all the orbits come from and go to infinity. [ABSTRACT FROM AUTHOR]

Abstract We evaluate the entanglement entropy of strips for boosted D3-black-branes compactified along the lightcone coordinate. The bulk theory describes 3-dimensional a = 3 θ = 1 Lifshitz theory on the boundary. The area of small strips is evaluated perturbatively up to second order, where the leading term has a logarithmic dependence on strip width l , whereas entropy of the excitations is found to be proportional to l 4. The entanglement temperature falls off as 1 / l 3 on expected lines. The size of the subsystem has to be bigger than typical 'Lifshitz scale' in the theory. At second order, the redefinition of temperature (or strip width) is required so as to meaningfully describe the entropy corrections in the form of a first law of entanglement thermodynamics. [ABSTRACT FROM AUTHOR]

Abstract We prove a version of the Weak Gravity Conjecture for 6d F-theory or heterotic string compactifications with 8 supercharges. This sharpens our previous analysis by including massless scalar fields. The latter are known to modify the Weak Gravity Conjecture bound in two a priori independent ways: First, the extremality condition of a charged black hole is modified, and second, the test particles required to satisfy the Weak Gravity Conjecture are subject to additional Yukawa type interactions. We argue on general grounds that at weak coupling, the two types of effects are equivalent for a tower of asymptotically massless charged test particles predicted by the Swampland Distance Conjecture. We then specialize to F-theory compactified on elliptic Calabi–Yau three-folds and prove that the precise numerical bound on the charge-to-mass ratio is satisfied at weak coupling. This amounts to an intriguing coincidence of two a priori different notions of extremality, namely one based on the balance of gauge, gravitational and scalar forces for extremal (non-BPS) black holes, and the other encoded in the modular properties of certain Jacobi forms. In the presence of multiple abelian gauge group factors, the elliptic genus counting these states is a lattice quasi-Jacobi form of higher rank, and we exemplify this in a model with two abelian gauge group factors. [ABSTRACT FROM AUTHOR]

Abstract We introduce a class of F-theory vacua which may be viewed as a specialization of the so-called E 6 fibration, and construct a weak coupling limit associated with such vacua which we view as the 'square' of the Sen limit. We find that while Sen's limit is naturally viewed as an orientifold theory, the universal tadpole relation which equates the D3 charge between the associated F-theory compactification and the limit we construct suggests that perhaps the limiting theory is in fact an oriented theory compactified on the base of the F-theory elliptic fibration. [ABSTRACT FROM AUTHOR]

It is believed that in SU(N) Yang-Mills theory observables are N -branched functions of the topological θ angle. This is supposed to be due to the existence of a set of locally-stable candidate vacua, which compete for global stability as a function of θ. We study the number of θ vacua, their interpretation, and their stability properties using systematic semiclassical analysis in the context of adiabatic circle compactification on ℝ³ × S1. We find that while observables are indeed N-branched functions of θ, there are only ≈ N/2 locally-stable candidate vacua for any given θ. We point out that the different θ vacua are distinguished by the expectation values of certain magnetic line operators that carry non-zero GNO charge but zero 't Hooft charge. Finally, we show that in the regime of validity of our analysis YM theory has spinodal points as a function of θ, and gather evidence for the conjecture that these spinodal points are present even in the ℝ4 limit. [ABSTRACT FROM AUTHOR]

We discuss a number of problems associated with the circle compactification of the bosonic tensile ambitwistor string with the asymmetric vacuum choice. By considering the spectrum and physical state conditions, we show that the circle radius plays a role as a tuning parameter which determines the low energy effective field theory. At the self dual point, we construct the current operators and compute OPEs between them. While the final outcome remains as yet inconclusive, several new results are obtained. Through the current algebra analysis we show that there is a subsector of the massless states where the gauge symmetry is enhanced to I S O ( 2 ) L × S U ( 2 ) R . Using the fact that the one loop partition function is not modular invariant, we show that tensile ambitwistor string partition function is exactly the same as a field theory partition function. Our result proves that despite the existence of winding modes, which is a typical characteristic of a string, the tensile ambitwistor string behaves as a point particle theory. [ABSTRACT FROM AUTHOR]

We construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. The corresponding action in four dimensions is similar to the action of K-essence theories. This approach is applied to anisotropic cosmological Bianchi type VI(h=-1) model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. The classical Einstein field equations give us a hidden symmetry, corresponding to the equality between two radii B=C, which permits us to solve exactly the equations of motion. One relation between the scale factors (A,C) via the solutions is found. With this hidden symmetry, then we solve the FRW model, finding that the scale factor goes to B radii. Also the corresponding Wheeler-DeWitt (WDW) equation in the context of Standard Quantum Cosmology is solved, building a wavepacket when the scalar fields have a hyperbolic behavior, obtaining some qualitative results when we analyze the projection plane to the wall formed by the probability density. Bohm’s formalism for this cosmological model is revisited too. [ABSTRACT FROM AUTHOR]

We investigate de Sitter solutions of N = 1 supergravity with an F-term scalar potential near a no-scale Minkowski point, as they may in particular arise from flux compactifications in string theory. We show that a large class of such solutions has a universal tachyon with η ≤ -4/3 at positive vacuum energies, thus forbidding meta-stable de Sitter vacua and slow-roll inflation. The tachyon aligns with the sgoldstino in the Minkowski limit, whereas the sgoldstino itself is generically stable in the de Sitter vacuum due to mass mixing effects. We specify necessary conditions for the superpotential and the Kähler potential to avoid the instability. Our result may also help to explain why the program of classical de Sitter hunting has remained unsuccessful, while constructions involving instantons or non-geometric fluxes have led to various examples of meta-stable de Sitter vacua. [ABSTRACT FROM AUTHOR]

We consider four-dimensional N = 1 supergravity models of a kind appearing in string flux compactifications. It has been recently shown that, by using double three-form multiplets instead of ordinary chiral multiplets, one can promote to dynamical variables (part of) the quantized numbers appearing in the flux-induced superpotential. We show that double three-form multiplets naturally transform under symplectic dualities associated with the special Kähler structure that characterizes their scalar sector. Furthermore, we discuss how to couple membranes which carry arbitrary 'electric-magnetic' charges. The complete action is supersymmetric, kappa-symmetric and duality covariant. As an application, we derive the flow equations for BPS domain walls sourced by membranes and give simple analytic examples of their solution. [ABSTRACT FROM AUTHOR]

We propose a 6d model with a SUSY SU(5) gauge symmetry. After compactification, it explains the origin of the S4 Family Symmetry with CSD3 vacuum alignment, as well as SU(5) breaking with doublet-triplet splitting. The model naturally accounts for all quark and lepton (including neutrino) masses and mixings, incorporating the highly predictive Littlest Seesaw structure. It spontaneously breaks CP symmetry, resulting in successful CP violation in the quark and lepton sectors, while solving the Strong CP problem. It also explains the Baryon Asymmetry of the Universe (BAU) through leptogenesis, with the leptogenesis phase directly linked to the Dirac and Majorana phases. [ABSTRACT FROM AUTHOR]

We present a model to study the effects from external magnetic field, chemical potential and finite size on the phase structures of a massive four- and six-fermion interacting systems. These effects are introduced by a method of compactification of coordinates, a generalization of the standard Matsubara prescription. Through the compactification of the z-coordinate and of imaginary time, we describe a heated system with the shape of a film of thickness L, at temperature β−1 undergoing first- or second-order phase transition. We have found a strong dependence of the temperature transition on the coupling constants λ and η. Besides inverse magnetic catalysis and symmetry breaking for both kinds of transition, we have found an inverse symmetry breaking phenomenon with respect to first-order phase transition [ABSTRACT FROM AUTHOR]

Using Nisnevich coverings and a Hilbert stack of stacky points, we prove étale dévissage results for non-representable étale and quasi-finite flat coverings. We give applications to absolute noetherian approximation of algebraic stacks and compact generation of derived categories. [ABSTRACT FROM AUTHOR]

Abstract: We classify N = 2 Minkowski4 solutions of IIB supergravity with an S U ( 2 ) R symmetry geometrically realized by an S2‐foliation in the remaining six dimensions. For the various cases of the classification, we reduce the supersymmetric system of equations to PDEs. These cases often accommodate systems of intersecting branes and half‐maximally supersymmetric AdS5, 6, 7 solutions when they exist. As an example, we analyze the AdS6 case in more detail, reducing the supersymmetry equations to a single cylindrical Laplace equation. We also recover an already known linear dilaton background dual to the (1, 1) Little String Theory (LST) living on NS5‐branes, and we find a new Minkowski5 linear dilaton solution from brane intersections. Finally, we also discuss some simple Minkowski4 solutions based on compact conformal Calabi‐Yau manifolds. [ABSTRACT FROM AUTHOR]

In this paper, a miniaturised multi-beam-controlled circular eight-port beamforming network for long-range ultra-highfrequency radio-frequency identification (UHF RFID) hemispheric beam-coverage systems (e.g. unmanned aircraft systems) is proposed. For multi-beam control and compact implementation, the proposed eight-port feeding network consists of an integrated beam-control block with a two-stage RF switch block, 12 quadrature hybrid couplers, and 12 90° phase shifters, and was designed and fabricated on a circular three-layer 1.2 mm FR-4 substrate. The diameter of the fabricated network is ~0.47 λ0 at 915 MHz. The measured maximum insertion loss, and amplitude and phase imbalances of the fabricated network at the authorised UHF RFID frequency band (902-928 MHz) are ~4.5 dB, ± 1.3 dB, and ± 17.5°, respectively. An eight-element dipole antenna array with the proposed feeding network shows feasibility of hemispheric beam coverage by generating multiple beams simultaneously regarding port controls. Beam coverages, where the simulated realised gain is higher than 3 dBi, are ~180° and 130° at ϕ = 90 and 0°, respectively. [ABSTRACT FROM AUTHOR]

In this paper we show that the number of all 1/2-BPS branes in string theory compactified on a torus can be derived by universal wrapping rules whose formulation we present. These rules even apply to branes in less than ten dimensions whose ten-dimensional origin is an exotic brane. In that case the wrapping rules contain an additional combinatorial factor that is related to the highest dimension in which the ten-dimensional exotic brane, after compactification, can be realized as a standard brane. We show that the wrapping rules also apply to cases with less supersymmetry. As a specific example, we discuss the compactification of IIA/IIB string theory on ( T/ ℤ) × T. [ABSTRACT FROM AUTHOR]

6d superconformal field theories (SCFTs) are the SCFTs in the highest possible dimension. They can be geometrically engineered in F-theory by compactifying on non-compact elliptic Calabi-Yau manifolds. In this paper we focus on the class of SCFTs whose base geometry is determined by −2 curves intersecting according to ADE Dynkin diagrams and derive the corresponding mirror Calabi-Yau manifold. The mirror geometry is uniquely determined in terms of the mirror curve which has also an interpretation in terms of the Seiberg-Witten curve of the four-dimensional theory arising from torus compactification. Adding the affine node of the ADE quiver to the base geometry, we connect to recent results on SYZ mirror symmetry for the A case and provide a physical interpretation in terms of little string theory. Our results, however, go beyond this case as our construction naturally covers the D and E cases as well. [ABSTRACT FROM AUTHOR]

A generic feature of string compactifications is the presence of many scalar fields, called moduli. Moduli are usually displaced from their post-inflationary minimum during inflation. Their relaxation to the minimum could lead to the production of oscillons: localised, long-lived, non-linear excitations of the scalar fields. Here we discuss under which conditions oscillons can be produced in string cosmology and illustrate their production and potential phenomenology with two explicit examples: the case of an initially displaced volume modulus in the KKLT scenario and the case of a displaced blow-up Kähler modulus in the Large Volume Scenario (LVS). One, in principle, observable consequence of oscillon dynamics is the production of gravitational waves which, contrary to those produced from preheating after high scale inflation, could have lower frequencies, closer to the currently observable range. We also show that, for the considered parameter ranges, oscillating fibre and volume moduli do not develop any significant non-perturbative dynamics. Furthermore, we find that the vacua in the LVS and the KKLT scenario are stable against local overshootings of the field into the decompatification region, which provides an additional check on the longevity of these metastable configurations. [ABSTRACT FROM AUTHOR]

Using a one-way Monte Carlo algorithm from several different starting points, we get an approximation to the distribution of toric threefold bases that can be used in four-dimensional F-theory compactification. We separate the threefold bases into 'resolvable' ones where the Weierstrass polynomials ( f, g) can vanish to order (4 , 6) or higher on codimension-two loci and the 'good' bases where these (4 , 6) loci are not allowed. A simple estimate suggests that the number of distinct resolvable base geometries exceeds 10, with over 10 'good' bases, though the actual numbers are likely much larger. We find that the good bases are concentrated at specific 'end points' with special isolated values of h that are bigger than 1,000. These end point bases give Calabi-Yau fourfolds with specific Hodge numbers mirror to elliptic fibrations over simple threefolds. The non-Higgsable gauge groups on the end point bases are almost entirely made of products of E, F, G and SU(2). Nonetheless, we find a large class of good bases with a single non-Higgsable SU(3). Moreover, by randomly contracting the end point bases, we find many resolvable bases with h( B) ∼ 50-200 that cannot be contracted to another smooth threefold base. [ABSTRACT FROM AUTHOR]

We show that F-theory compactifications with abelian gauge factors generally exhibit a non-trivial global gauge group structure. The geometric origin of this structure lies with the Shioda map of the Mordell-Weil generators. This results in constraints on the $$ \mathfrak{u}(1) $$ charges of non-abelian matter consistent with observations made throughout the literature. In particular, we find that F-theory models featuring the Standard Model algebra actually realise the precise gauge group [SU(3) × SU(2) × U(1)]/ ℤ . Furthermore, we explore the relationship between the gauge group structure and geometric (un-)higgsing. In an explicit class of models, we show that, depending on the global group structure, an $$ \mathfrak{s}\mathfrak{u}(2)\oplus \mathfrak{u}(1) $$ gauge theory can either unhiggs into an SU(2) × SU(2) or an SU(3) × SU(2) theory. We also study implications of the charge constraints as a criterion for the F-theory 'swampland'. [ABSTRACT FROM AUTHOR]

Nonlinear realizations of the group are discussed from the point of view of symmetries. Dynamical symmetry breaking is introduced. One linear and one quadratic model in curvature are constructed. Coherent states of the Klauder-Perelomov type are defined for both cases taking into account the coset geometry. A new spontaneous compactification mechanism is defined in the subspace invariant under the stability subgroup. The physical implications of the symmetry rupture in the context of nonlinear realizations and direct gauging are analyzed and briefly discussed. [ABSTRACT FROM AUTHOR]

In string compactifications, frequently the anomalous U(1) gauge symmetry appears which belongs to $$E_8 \times E_8'$$ of the heterotic string. This anomalous U(1) gauge boson obtains mass at the compactification scale ( $$\approx 10^{18\,}\,\text {GeV}$$ ) by absorbing one pseudoscalar (corresponding to the model-independent axion) from the second rank antisymmetric tensor field $$B_{MN}$$ . Below the compactification scale a global symmetry $$U(1)_{\mathrm{anom}}$$ results whose charge $$Q_\mathrm{anom}$$ is the original gauge U(1) charge. This is the most natural global symmetry, realizing the 'invisible' axion. This global symmetry $$U(1)_{\mathrm{anom}}$$ is suitable for a flavor symmetry. In the simplest compactification model with the flipped SU(5) grand unification, all the low energy parameters are calculated in terms of the vacuum expectation values of the standard model singlets. [ABSTRACT FROM AUTHOR]

We study moduli stabilization of the F-theory compactified on an elliptically fibered Calabi–Yau fourfold. Our setup is based on the mirror symmetry framework including brane deformations. The complex structure moduli dependence of the resulting 4D N = 1 effective theory is determined by the associated fourfold period integrals. By turning on appropriate G -fluxes, we explicitly demonstrate that all the complex structure moduli fields can be stabilized around the large complex structure point of the F-theory fourfold. [ABSTRACT FROM AUTHOR]

Type IIb supergravity compactifications on five-dimensional Einstein manifolds realize holographic duals to four-dimensional conformal field theories. Black holes in such geometries are dual to thermal states in these CFTs. When black holes become sufficiently small in (global) , they are expected to suffer Gregory-Laflamme instability with respect to localization on . Previously, the instability was demonstrated for gravitational dual of SYM, where . We extend stability analysis to arbitrary . We point out that the quasinormal mode equation governing the instabilities is universal. The precise onset of the instability is -sensitive, as it is governed by the lowest nonvanishing eigenvalue of its Laplacian. [ABSTRACT FROM AUTHOR]

We perform a refined count of BPS states in the compactification of M-theory on $${K3 \times T^2}$$ , keeping track of the information provided by both the $${SU(2)_L}$$ and $${SU(2)_R}$$ angular momenta in the SO(4) little group. Mathematically, this four variable counting function may be expressed via the motivic Donaldson-Thomas counts of $${K3 \times T^2}$$ , simultaneously refining Katz, Klemm, and Pandharipande's motivic stable pairs counts on K3 and Oberdieck-Pandharipande's Gromov-Witten counts on $${K3 \times T^2}$$ . This provides the first full answer for motivic curve counts of a compact Calabi-Yau threefold. Along the way, we develop a Hodge-elliptic genus for Calabi-Yau manifolds-a new counting function for BPS states that interpolates between the Hodge polynomial and the elliptic genus of a Calabi-Yau. [ABSTRACT FROM AUTHOR]

Assuming $$\mathbf {O}(D,D)$$ covariant fields as the 'fundamental' variables, double field theory can accommodate novel geometries where a Riemannian metric cannot be defined, even locally. Here we present a complete classification of such non-Riemannian spacetimes in terms of two non-negative integers, $$(n,\bar{n})$$ , $$0\le n+\bar{n}\le D$$ . Upon these backgrounds, strings become chiral and anti-chiral over n and $$\bar{n}$$ directions, respectively, while particles and strings are frozen over the $$n+\bar{n}$$ directions. In particular, we identify (0, 0) as Riemannian manifolds, (1, 0) as non-relativistic spacetime, (1, 1) as Gomis-Ooguri non-relativistic string, $$(D{-1},0)$$ as ultra-relativistic Carroll geometry, and ( D, 0) as Siegel's chiral string. Combined with a covariant Kaluza-Klein ansatz which we further spell, (0, 1) leads to Newton-Cartan gravity. Alternative to the conventional string compactifications on small manifolds, non-Riemannian spacetime such as $$D=10$$ , (3, 3) may open a new scheme for the dimensional reduction from ten to four. [ABSTRACT FROM AUTHOR]

A class of $$\mathrm{AdS}_2\times \Sigma _2$$ , with $$\Sigma _2$$ being a two-sphere or a hyperbolic space, solutions within four-dimensional $$N=4$$ gauged supergravity coupled to three-vector multiplets with dyonic gauging is identified. The gauged supergravity has a non-semisimple $$SO(3)\ltimes ({\mathbf {T}}^3,\hat{{\mathbf {T}}}^3)$$ gauge group and can be obtained from a consistent truncation of 11-dimensional supergravity on a tri-sasakian manifold. The maximally symmetric vacua contain $$\mathrm{AdS}_4$$ geometries with $$N=1,3$$ supersymmetry corresponding to $$N=1$$ and $$N=3$$ superconformal field theories (SCFTs) in three dimensions. We find supersymmetric solutions of the form $$\mathrm{AdS}_2\times \Sigma _2$$ preserving two supercharges. These solutions describe twisted compactifications of the dual $$N=1$$ and $$N=3$$ SCFTs and should arise as near horizon geometries of dyonic black holes in asymptotically $$\mathrm{AdS}_4$$ space-time. Most solutions have hyperbolic horizons although some of them exhibit spherical horizons. These provide a new class of $$\mathrm{AdS}_2\times \Sigma _2$$ geometries with known M-theory origin. [ABSTRACT FROM AUTHOR]

The notion of a G -uniform function was introduced by Jan de Vies in order to prove that, if G is a locally compact Hausdorff group, then any completely regular G -space admits a G -compactification. In this paper, for a locally compact Hausdorff group G , we establish analogs of the well known Urysohn Lemma and Tietze Extension Theorem for G -uniform functions. We examine also the extension problem for vector-valued G -uniform maps. [ABSTRACT FROM AUTHOR]

In light of the present LHC Run II at √ s = 13 TeV, a SM-like string model is studied. Specifically, a singlet S scalar-extended SM given in terms of four stacks of intersecting D6-branes in a type IIA superstring compactification producing a large gauge symmetry is examined. The scales involved are dealt with. According to the dark matter relic density, the mass of the scalar dark matter beyond the SM m ≲ 10 GeV and the corresponding Higgs portal couplings λ ≲ 10 have been obtained. [ABSTRACT FROM AUTHOR]

We discuss the effect of the dynamics of D-branes on moduli stabilization in type IIB string theory compactifications, with reference to a concrete toy model of orientifold compactification with fractional D3-branes and anti-D3-branes at orbifold fixed points. The resulting attractive forces between anti-D3-branes and D3-branes, together with the repulsive forces between anti-D3-branes and O3-planes, can affect the stability of the compact space. There are no complex structure moduli in orientifold, which should thus capture some generic features of more general settings where all complex structure moduli are stabilized by three-form fluxes. The simultaneous presence of branes and anti-branes brings along the breaking of supersymmetry. Non-BPS combinations of this type are typical of 'brane supersymmetry breaking' and are a necessary ingredient in the KKLT scenario for stabilizing the remaining Kähler moduli. The conclusion of our analysis is that, while mutual D-brane interactions sometimes help Kähler moduli stabilization, this is not always the case. [ABSTRACT FROM AUTHOR]

We utilize machine learning to study the string landscape. Deep data dives and conjecture generation are proposed as useful frameworks for utilizing machine learning in the landscape, and examples of each are presented. A decision tree accurately predicts the number of weak Fano toric threefolds arising from reflexive polytopes, each of which determines a smooth F-theory compactification, and linear regression generates a previously proven conjecture for the gauge group rank in an ensemble of $$ \frac{4}{3}\times 2.96\times {10}^{755} $$ F-theory compactifications. Logistic regression generates a new conjecture for when E arises in the large ensemble of F-theory compactifications, which is then rigorously proven. This result may be relevant for the appearance of visible sectors in the ensemble. Through conjecture generation, machine learning is useful not only for numerics, but also for rigorous results. [ABSTRACT FROM AUTHOR]