首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
During inflation, the geometry of spacetime is described by a (quasi‐)de Sitter phase. Inflationary observables are determined by the underlying (softly broken) de Sitter isometry group which acts like a conformal group on : when the fluctuations are on super‐Hubble scales, the correlators of the scalar fields are constrained by conformal invariance. Heavy fields with mass m larger than the Hubble rate H correspond to operators with imaginary dimensions in the dual Euclidean three‐dimensional conformal field theory. By making use of the dS/CFT correspondence we show that, besides the Boltzmann suppression expected from the thermal properties of de Sitter space, the generic effect of heavy fields in the inflationary correlators of the light fields is to introduce power‐law suppressed corrections of the form . This can be seen, for instance, at the level of the four‐point correlator for which we provide the correction due to a massive scalar field exchange.  相似文献   

2.
We derive the mass formulae for , matter‐coupled Supergravity for broken (and unbroken) Supersymmetry in curved space‐time. These formulae are applicable to De Sitter configurations as is the case for inflation. For unbroken Supersymmetry in anti‐de Sitter (AdS) one gets the mass relations modified by the AdS curvature. We compute the mass relations both for the potential and its derivative non‐vanishing.  相似文献   

3.
We first review the Coset Space Dimensional Reduction (CSDR) programme and present the best model constructed so far based on the , 10‐dimensional E8 gauge theory reduced over the nearly‐Kähler manifold with the additional use of the Wilson flux mechanism. Then we present the corresponding programme in the case that the extra dimensions are considered to be fuzzy coset spaces and the best model that has been constructed in this framework too. In both cases the best model appears to be the trinification GUT .  相似文献   

4.
We study various aspects of wormholes that are made traversable by an interaction beween the two asymptotic boundaries. We concentrate on the case of nearly‐ gravity and discuss a very simple mechanical picture for the gravitational dynamics. We derive a formula for the two sided correlators that includes the effect of gravitational backreaction, which limits the amount of information we can send through the wormhole. We emphasize that the process can be viewed as a teleportation protocol where the teleportee feels nothing special as he/she goes through the wormhole. We discuss some applications to the cloning paradox for old black holes. We point out that the same formula we derived for gravity is also valid for the simple SYK quantum mechanical theory, around the thermofield double state. We present a heuristic picture for this phenomenon in terms of an operator growth model. Finally, we show that a similar effect is present in a completely classical chaotic system with a large number of degrees of freedom.  相似文献   

5.
We provide a model‐independent argument indicating that for a black hole of entropy N the non‐thermal deviations from Hawking radiation, per each emission time, are of order , as opposed to . This fact abolishes the standard a priory basis for the information paradox.  相似文献   

6.
Non‐geometric flux‐scaling vacua provide promising starting points to realize axion monodromy inflation via the F‐term scalar potential. We show that these vacua can be uplifted to Minkowski and de Sitter by adding an ‐brane or a D‐term containing geometric and non‐geometric fluxes. These uplifted non‐supersymmetric models are analyzed with respect to their potential to realize axion monodromy inflation self‐consistently. Admitting rational values of the fluxes, we construct examples with the required hierarchy of mass scales.  相似文献   

7.
In the study of stationary solutions in extended supergravities with symmetric scalar manifolds, the nilpotent orbits of a real symmetric pair play an important role. In this paper we discuss two approaches to determine the nilpotent orbits of a real symmetric pair. We apply our methods to an explicit example, and thereby classify the nilpotent orbits of acting on the fourth tensor power of the natural 2‐dimensional ‐module. This makes it possible to classify all stationary solutions of the so‐called STU‐supergravity model.  相似文献   

8.
The standard model has for massless quarks and leptons “miraculously” no triangle anomalies due to the fact that the sum of all possible traces — where and are the generators of one, of two or of three of the groups and U (1) — over the representations of one family of the left handed fermions and anti‐fermions (and separately of the right handed fermions and anti‐fermions), contributing to the triangle currents, is equal to zero. 1 - 4 It is demonstrated in this paper that this cancellation of the standard model triangle anomaly follows straightforwardly if the and are the subgroups of the orthogonal group , as it is in the spin‐charge‐family theory. 5 - 22 We comment on the anomaly cancellation, which works if handedness and charges are related “by hand”.  相似文献   

9.
The Nonsymmetric Kaluza–Klein (Jordan–Thiry) Theory leads to a model of a modified acceleration that can fit an anomalous acceleration experienced by the Pioneer 10 and 11 spacecraft. The future positions of those spacecrafts are predicted using distorted hyperbolic orbit. A connection between an anomalous acceleration and a Hubble constant is solved in the theory together with a relation to a cosmological constant in CDMΛ model. In the paper we consider an exact solution of a point mass motion in the Solar System under an influence of an anomalous acceleration. We find two types of orbits: periodic and chaotic. Both orbits are bounded. This means there is no possibility to escape from the Solar System. Some possibilities to avoid this conclusion are considered. We resolve also a coincidence between an anomalous acceleration and the cosmological constant using a paradigm of modern cosmology. Relativistic effects and a cosmological drifting of a gravitational constant are considered. The model of an anomalous acceleration does not cause any contradiction with Solar System observations. We give a full statistical analysis of the model. We consider also a full formalism of the Nonsymmetric Jordan–Thiry Theory for the problem and present a relativistic model of an anomalous acceleration. We consider the model for General Relativity approximation, i.e. (). In this model there are no contradictions with General Relativity tests in the Solar System. Pioneer 10/11 spacecrafts will come back in 106 years (a time scale of our periodic solutions is 106 years). Moreover, almost relativistic or relativistic spacecrafts can escape from the Solar System. We consider also a model of a relativistic acceleration which is more complicated, with taken into account.  相似文献   

10.
We compute the Hodge numbers for the quotients of complete intersection Calabi‐Yau three‐folds by groups of orders divisible by 4. We make use of the polynomial deformation method and the counting of invariant Kähler classes. The quotients studied here have been obtained in the automated classification of V. Braun. Although the computer search found the freely acting groups, the Hodge numbers of the quotients were not calculated. The freely acting groups, G, that arise in the classification are either or contain , , or as a subgroup. The Hodge numbers for the quotients for which the group G contains or have been computed previously. This paper deals with the remaining cases, for which or . We also compute the Hodge numbers for 99 of the 166 CICY's which have quotients.  相似文献   

11.
A new class is introduced of M2‐branes solutions of d=11 supergravity that include internal fluxes obeying Englert equation in 7‐dimensions. A simple criterion for the existence of Killing spinors in such backgrounds is established. Englert equation is viewed as the generalization to d=7 of Beltrami equation defined in d=3 and it is treated accordingly. All 2‐brane solutions of minimal d=7 supergracity can be uplifted to d=11 and have supersymmetry. It is shown that the simple group PSL(2, 7) is crystallographic in d=7 having an integral action on the A7 root lattice. By means of this point‐group and of the T7 torus obtained quotiening with the A7 root lattice we were able to construct new M2 branes with Englert fluxes and . In particular we exhibit here an solution depending on 4‐parameters and admitting a large non abelian discrete symmetry, namely . The dual field theories have the same symmetries and have complicated non linear interactions.  相似文献   

12.
This article explores possible embeddings of the Standard Model gauge group and its matter representations into F‐theory. To this end we construct elliptic fibrations with gauge group as suitable restrictions of a ‐fibration with rank‐two Mordell‐Weil group. We analyse the five inequivalent toric enhancements to gauge group along two independent divisors W3 and W2 in the base. For each of the resulting smooth fibrations, the representation spectrum generically consists of a bifundamental , three types of representations and five types of representations (plus conjugates), in addition to charged singlet states. The precise spectrum of zero‐modes in these representations depends on the 3‐form background. We analyse the geometrically realised Yukawa couplings among all these states and find complete agreement with field theoretic expectations based on their U(1) charges. We classify possible identifications of the found representations with the Standard Model field content extended by right‐handed neutrinos and extra singlets. The linear combination of the two abelian gauge group factors orthogonal to hypercharge acts as a selection rule which, depending on the specific model, can forbid dangerous dimension‐four and ‐five proton decay operators.  相似文献   

13.
The model of Quantum Associative Memories (QAM) we propose here consists in simplifying and generalizing that of Rigui Zhou et al. 1 which uses the quantum matrix with the binary decision diagram put forth by David Rosenbaum 2 and the Abrams and Lloyd's nonlinear search algorithm 3 . Our model gives the possibility to retrieve one of the sought states in multi‐values retrieving scheme when a measurement is done on the first register in time complexity. It is better than Grover's algorithm and its modified form which need steps when they are used as the retrieval algorithm. n is the number of qubits of the first register and m the number of x values for which . As the nonlinearity makes the system highly susceptible to the noise, an analysis of the influence of the single qubit noise channels on the Nonlinear Search Algorithm of our model of QAM shows a fidelity of about 0.7 whatever the number of qubits existing in the first register, thus demonstrating the robustness of our model.  相似文献   

14.
15.
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 algebra, which is generated by holonomy‐diffeomorphisms on a 3‐dimensional manifold and by canonical translation operators on the underlying configuration space over which the holonomy‐diffeomorphisms form a non‐commutative ‐algebra. A proof that the state that generates the representation exist is left for later publications.  相似文献   

16.
We consider the Beltrami equation for hydrodynamics and we show that its solutions can be viewed as instanton solutions of a more general system of equations. The latter are the equations of motion for an sigma model on 4‐dimensional worldvolume (which is taken locally HyperKähler) with a 4‐dimensional HyperKähler target space. By means of the 4D twisting procedure originally introduced by Witten for gauge theories and later generalized to 4D sigma‐models by Anselmi and Fré, we show that the equations of motion describe triholomophic maps between the worldvolume and the target space. Therefore, the classification of the solutions to the 3‐dimensional Beltrami equation can be performed by counting the triholomorphic maps. The counting is easily obtained by using several discrete symmetries. Finally, the similarity with holomorphic maps for sigma on Calabi‐Yau space prompts us to reformulate the problem of the enumeration of triholomorphic maps in terms of a topological sigma model.  相似文献   

17.
We study heterotic backgrounds with non‐trivial H‐flux and non‐vanishing expectation values of fermionic bilinears, often referred to as gaugino condensates. The gaugini appear in the low energy action via the gauge‐invariant three‐form bilinear . For Calabi‐Yau compactifications to four dimensions, the gaugino condensate corresponds to an internal three‐form that must be a singlet of the holonomy group. This condition does not hold anymore when an internal H‐flux is turned on and effects are included. In this paper we study flux compactifications to three and four‐dimensions on G‐structure manifolds. We derive the generic conditions for supersymmetric solutions. We use integrability conditions and Lichnerowicz type arguments to derive a set of constraints whose solution, together with supersymmetry, is sufficient for finding backgrounds with gaugino condensate.  相似文献   

18.
We derive the analog of the large N Gross‐Taylor holomorphic string expansion for the refinement of q‐deformed Yang‐Mills theory on a compact oriented Riemann surface. The derivation combines Schur‐Weyl duality for quantum groups with the Etingof‐Kirillov theory of generalized quantum characters which are related to Macdonald polynomials. In the unrefined limit we reproduce the chiral expansion of q‐deformed Yang‐Mills theory derived by de Haro, Ramgoolam and Torrielli. In the classical limit , the expansion defines a new β‐deformation of Hurwitz theory wherein the refined partition function is a generating function for certain parameterized Euler characters, which reduce in the unrefined limit to the orbifold Euler characteristics of Hurwitz spaces of holomorphic maps. We discuss the geometrical meaning of our expansions in relation to quantum spectral curves and β‐ensembles of matrix models arising in refined topological string theory.  相似文献   

19.
In this paper we argue that a firewall is simply a manifestation of an inconsistent truncation of non‐perturbative effects that unitarize the semiclassical black hole. Namely, we show that a naive truncation of quantum corrections to the Hawking spectrum at order , inexorably leads to a “localised” divergent energy density near the black hole horizon. Nevertheless, in the same approximation, a distant observer only sees a discretised spectrum and concludes that unitarity is achieved by effects. This is due to the fact that instead, the correct quantum corrections to the Hawking spectrum go like . Therefore, while at a distance far away from the horizon, where , quantum corrections are perturbative, they do diverge close to the horizon, where . Nevertheless, these “corrections” nicely re‐sum so that correlations functions are smooth at the would‐be black hole horizon. Thus, we conclude that the appearance of firewalls is just a signal of the breaking of the semiclassical approximation at the Page time, even for large black holes.  相似文献   

20.
We study ‐dimensional half‐maximal flux backgrounds using exceptional field theory. We define the relevant generalised structures and also find the integrability conditions which give warped half‐maximal MinkowskiD and AdSD vacua. We then show how to obtain consistent truncations of type II / 11‐dimensional SUGRA which break half the supersymmetry. Such truncations can be defined on backgrounds admitting exceptional generalised structures, where , and N is the number of vector multiplets obtained in the lower‐dimensional theory. Our procedure yields the most general embedding tensors satisfying the linear constraint of half‐maximal gauged SUGRA. We use this to prove that all half‐maximal warped AdSD and MinkowskiD vacua of type II / 11‐dimensional SUGRA admit a consistent truncation keeping only the gravitational supermultiplet. We also show to obtain heterotic double field theory from exceptional field theory and comment on the M‐theory / heterotic duality. In five dimensions, we find a new SO(5, N ) double field theory with a ‐dimensional extended space. Its section condition has one solution corresponding to 10‐dimensional supergravity and another yielding six‐dimensional SUGRA.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号