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The D-term inflation in supergravity, in the braneworld Randall Sundrum II (RSII) context, has been proposed to solve some problems related to the four-dimensional inflation model. That scenario is based on a modification of the Friedmann equation by the addition of the fifth dimension, which corresponds to an energy, called brane tension λ. Therefore, we propose the investigation of the brane effect on the reheating epoch. In this context, we have analyzed the process of reheating and focused on the variation of the temperature value Tre. We found that it depends on all parameters, and the value found is in the range Tre ∼ (7.5 × 108−8 × 1010) GeV, which is consistent with the thermal leptogenesis (Tre ≥ 108 GeV).

We analyse the consequences of a new gauge invariant Fayet-Iliopoulos (FI) term proposed recently to a class of inflation models driven by supersymmetry breaking with the inflaton being the superpartner of the goldstino. We first show that charged matter fields can be consistently added with the new term, as well as the standard FI term in supergravity in a K\"ahler frame where the $U(1)$ is not an R-symmetry. We then show that the slow-roll conditions can be easily satisfied with inflation driven by a D-term depending on the two FI parameters. Inflation starts at initial conditions around the maximum of the potential where the $U(1)$ symmetry is restored and stops when the inflaton rolls down to the minimum describing the present phase of our Universe. The resulting tensor-to-scalar ratio of primordial perturbations can be even at observable values in the presence of higher order terms in the K\"ahler potential., Comment: 19 pages, 7 figures

We discuss the possibility that inflation is driven by supersymmetry breaking with the superpartner of the goldstino (sgoldstino) playing the role of the inflaton. Imposing an R-symmetry allows to satisfy easily the slow-roll conditions, avoiding the so-called [Formula: see text]-problem, and leads to an interesting class of small field inflation models, characterized by an inflationary plateau around the maximum of the scalar potential near the origin, where R-symmetry is restored with the inflaton rolling down to a minimum describing the present phase of the Universe. Inflation can be driven by either an [Formula: see text]- or a [Formula: see text]-term, while the minimum has a positive tuneable vacuum energy. The models agree with cosmological observations and in the simplest case predict a rather small tensor-to-scalar ratio of primordial perturbations.

We consider ${\cal N}=1$ supersymmetric Born-Infeld actions that have a second non-linear supersymmetry. We focus on the model proposed by Bagger and Galperin and show that the breaking of the second supersymmetry is sourced by the new Fayet-Iliopoulos D-term. Interpreting such an action as the effective theory of a space-filling (anti) D3-brane leads to an expression for the new Fayet-Iliopoulos parameter in terms of the brane tension and $\alpha'$., Comment: 35 pages; v2: comments and references added, to appear on JHEP; v3: minor corrections

We propose a new model of single-field D-term inflation in supergravity, where the inflation is driven by a single modulus field which transforms non-linearly under the U(1) gauge symmetry. One of the notable features of our modulus D-term inflation scenario is that the global U(1) remains unbroken in the vacuum and hence our model is not plagued by the cosmic string problem which can exclude most of the conventional D-term inflation models proposed so far due to the CMB observations., Comment: 15 pages, 5 figures

We propose a new mechanism of (geometric) moduli stabilisation in type IIB/F-theory four-dimensional compactifications on Calabi-Yau manifolds, in the presence of 7-branes, that does not rely on non-perturbative effects. Complex structure moduli and the axion-dilaton system are stabilised in the standard way, without breaking supersymmetry, using 3-form internal fluxes. K\"ahler class moduli stabilisation utilises perturbative string loop corrections, together with internal magnetic fields along the D7-branes world-volume leading to Fayet-Iliopoulos D-terms in the effective supergravity action. The main ingredient that makes the stabilisation possible at a de Sitter vacuum is the logarithmic dependence of the string loop corrections in the large two-dimensional transverse volume limit of the 7-branes., Comment: 15 pages, 2 figures

We construct a supergravity-Maxwell theory with a novel embedding of the Fayet-Iliopoulos D-term, leading to spontaneous supersymmetry breaking. The gauging of the R-symmetry is not required and a gravitino mass is allowed for a generic vacuum. When matter couplings are introduced, an uplift through a positive definite contribution to the scalar potential is obtained. We observe a notable similarity to the $\overline{D3}$ uplift constructions and we give a natural description in terms of constrained multiplets., 23 pages, version 3, new appendix on electric-magnetic duality and updated references

Recently proposed exceptional field theories (EFTs) making manifest the duality $E_{n(n)}$ symmetry, first observed as nonlinearly realized symmetries of the maximal $d=3,4,...,9$ supergravity ($n=11-d$) and containing 11D and type IIB supergravity as sectors, were formulated in enlarged spacetimes. In the case of $E_{7(7)}$ EFT such an enlarged spacetime can be identified with the bosonic body of the $d=4$ central charge superspace $\Sigma^{(60|32)}$, the ${\cal N}=8$ $d=4$ superspace completed by 56 additional bosonic coordinates associated to central charges of the maximal $d=4$ supersymmetry algebra. In this paper we show how the hypothesis on the relation of all the known $E_{n(n)}$ EFTs, including $n=8$, with supersymmetry leads to the conjecture on existence of 11D exceptional field theory living in 11D tensorial central charge superspace $\Sigma^{(528|32)}$ and underlying all the $E_{n(n)}$ EFTs with $n=2,...,8$, and probably the double field theory (DFT). We conjecture the possible form of the section conditions of such an 11D EFT and show that quite generic solutions of these can be generated by superparticle models the ground states of which preserve from one half to all but one supersymmetry. The properties of these superparticle models are briefly discussed. We argue that, upon quantization, their quantum states should describe free massless non-conformal higher spin fields in D=11. We also discuss some relevant representations of the M-theory superalgebra which, in the present context, describes supersymmetry of the 11D EFT., Comment: 33 pages. V2: references added. V3: 42 pages. Minor corrections. New sections 3.3 and 5 added. Published in NPB

The supersymmetric extension of “Starobinsky” R + α R 2 models of inflation is particularly simple in the “new minimal” formalism of supergravity, where the inflaton has no scalar superpartners. This paper is devoted to matter couplings in such supergravity models. We show how in the new minimal formalism matter coupling presents certain features absent in other formalisms. In particular, for the large class of matter couplings considered in this paper, matter must possess an R-symmetry, which is gauged by the vector field which becomes dynamical in the “new minimal” completion of the R + α R 2 theory. Thus, in the dual formulation of the theory, where the gauge vector is part of a massive vector multiplet, the inflaton is the superpartner of the massive vector of a nonlinearly realized R-symmetry. The F-term potential of this theory is of no-scale type, while the inflaton potential is given by the D-term of the gauged R-symmetry. The absolute minimum of the potential is always exactly supersymmetric, so in this class of models if realistic vacua exist, they must be always metastable. We also briefly comment on possible generalizations of the examples discussed here and we exhibit some features of higher-curvature supergravity coupled to matter in the “old minimal” formalism.

We revisit the D-term inflation and amend it with ghost-free higher derivative couplings of chiral superfields to super-curvature. These couplings realize a more generic inflationary phase in supergravity. After pointing out that a consistent embedding of these specific higher derivatives is known to exist only in the new-minimal supergravity, we show how a potential for the scalar component may arise due to a Fayet-Iliopoulos D-term. We then turn to inflationary cosmology and explicitly discuss different types of potentials, which capture properties of the common scenarios. These models thanks to the derivative coupling: i) naturally evade the supergravity $\eta$-problem, ii) drive inflation for a wider range of parameter values, and iii) predict lower values for the tensor-to-scalar ratio., Comment: plain text, 12 pages, PLB Journal version

We study a supergravity D-term chaotic inflationary model, in the context of the braneworld scenario, in particular we consider the Randall—Sundrum model type 2. Using the latest release from the combination of WMAP9, eCMB, BAO, and H0, we show that the inflation observables depend only on the number of e-folds N. We also derive all known spectrum inflationary parameters, which are widely consistent with WMAP9 data for a particular choice of values N specially for the scalar spectral index ns and the ratio r. However, the running of the scalar spectral index dns/dlnk is now excluded from the range given by the latest observational measurements.

We study the decoupling limit of a superheavy sgoldstino field in spontaneously broken N=1 supergravity. Our approach is based on K\"ahler superspace, which, among others, allows direct formulation of N=1 supergravity in the Einstein frame and correct identifications of mass parameters. Allowing for a non-renormalizable K\"ahler potential in the hidden sector, the decoupling limit of a superheavy sgoldstino is identified with an infinite negative K\"ahler curvature. Constraints that lead to non-linear realizations of supersymmetry emerge as consequence of the equations of motion of the goldstino superfield when considering the decoupling limit. Finally, by employing superspace Bianchi identities, we identify the real chiral superfield, which will be the superconformal symmetry breaking chiral superfield that enters the conservation of the Ferrra-Zumino multiplet in the field theory limit of N=1 supergravity., Comment: 15 pages, version to be published in Phys. Lett. B

Hybrid inflation, driven by a Fayet-Iliopoulos (FI) D term, is an intriguing inflationary model. In its usual formulation, it however suffers from several shortcomings. These pertain to the origin of the FI mass scale, the stability of scalar fields during inflation, gravitational corrections in supergravity, as well as to the latest constraints from the cosmic microwave background. We demonstrate that these issues can be remedied if D-term inflation is realized in the context of strongly coupled supersymmetric gauge theories. We suppose that the D term is generated in consequence of dynamical supersymmetry breaking. Moreover, we assume canonical kinetic terms in the Jordan frame as well as an approximate shift symmetry along the inflaton direction. This provides us with a unified picture of D-term inflation and high-scale supersymmetry breaking. The D term may be associated with a gauged U(1)_B-L, so that the end of inflation spontaneously breaks B-L in the visible sector., Comment: 5 pages + references, 1 figure. v2: slightly extended discussion, updated references, matches version published in PRD

I discuss a general class of models where the inflation is driven by supersymmetry breaking with the superpartner of the goldstino (sgoldstino) playing the role of the inflaton. Imposing an R-symmetry allows to satisfy easily the slow-roll conditions, avoiding the so-called [Formula: see text]-problem, and leads to two different classes of small field inflation models; they are characterized by an inflationary plateau around the maximum of the scalar potential, where R-symmetry is either restored or spontaneously broken, with the inflaton rolling down to a minimum describing the present phase of our universe. Inflation can be driven by either an F- or a D-term, while the minimum has a positive tuneable vacuum energy. The models agree with cosmological observations and in the simplest case predict a tensor-to-scalar ratio of primordial perturbations [Formula: see text] and an inflation scale [Formula: see text].

This is an overview of the all-years research activity in supersymmetry in the Markov-Ogievetsky group at the Bogoliubov Laboratory of Theoretical Physics. It started shortly after the discovery of supersymmetry and is lasting for more than 30 years. In this survey the main emphasis is made on the superspace geometric approaches and unconstrained superfield formulations. Alongside such milestones as the geometric formulation of supergravity and the harmonic superspace approach to extended supersymmetry, some other developments largely contributed by the Dubna theorists are briefly accounted for.

The superspace formulation for four-dimensional N = 2 matter-coupled supergravity recently developed in [S.M. Kuzenko, U. Lindstrom, M. Rocek, G. Tartaglino-Mazzucchelli, 4D N = 2 supergravity and projective superspace, arXiv: 0805.4683 ] makes use of a new type of conformal compensator with infinitely many off-shell degrees of freedom: the so-called covariant weight-one polar hypermultiplet. In the present note we prove the duality of this formulation to the known minimal ( 40 + 40 ) off-shell realization for N = 2 Poincare supergravity involving the improved tensor compensator. Within the latter formulation, we present new off-shell matter couplings realized in terms of covariant weight-zero polar hypermultiplets. We also elaborate upon the projective superspace description of vector multiplets in N = 2 conformal supergravity. An alternative superspace representation for locally supersymmetric chiral actions is given. We present a model for massive improved tensor multiplet with both “electric” and “magnetic” types of mass terms.

We review a model of D-term dominated chaotic inflation in supergravity. The F-flat direction present in this model is lifted by the dominant D-term, which leads to chaotic inflation and subsequent reheating. The leptogenesis scenario via the inflaton decay in this D-term chaotic inflation scenario is also discussed.

As a step towards formulating projective superspace techniques for supergravity theories with eight supercharges, this work is devoted to field theory in five-dimensional N = 1 anti-de Sitter superspace AdS 5 | 8 = SU ( 2 , 2 | 1 ) / SO ( 4 , 1 ) × U ( 1 ) which is a maximally symmetric curved background. We develop the differential geometry of AdS 5 | 8 and describe its isometries in terms of Killing supervectors. Various off-shell supermultiplets in AdS 5 | 8 × S 2 are defined, and supersymmetric actions are constructed both in harmonic and projective superspace approaches. Several families of supersymmetric theories are presented including nonlinear sigma-models, Chern–Simons theories and vector–tensor dynamical systems. Using a suitable coset representative, we make use of the coset construction to develop an explicit realization for one half of the superspace AdS 5 | 8 as a trivial fiber bundle with fibers isomorphic to four-dimensional Minkowski superspace.

We investigated a simple D-term inflation with taking account of higher order corrections in the Kähler potential. These terms may solve the cosmic string problem in D-term inflation model. The mass per unit length of cosmic strings formed after inflation can be suppressed enough. In addition, the change of the potential slope leads simultaneously a more tilted scalar spectral index ns ≃ 0.96 – 0.97 than that in the model without these corrections.

In this note, we review our construction of de Sitter vacua in type IIB flux compactifications, in which moduli stabilization and D-term uplifting can be combined consistently with the supergravity constraints. Here, the closed string fluxes fix the dilaton and the complex structure moduli while perturbative quantum corrections to the K\"ahler potential stabilize the volume Kahler modulus in an AdS_4-vacuum. Then, magnetized D7-branes provide consistent supersymmetric D-term uplifting towards dS_4. Based on hep-th/0602253., Comment: 8 pages, 1 figure, LaTeX, Contribution to the proceedings of the RTN project "Constituents, Fundamental Forces and Symmetries of the Universe" conference in Napoli, October 9-13, 2006

The simple chaotic inflation is highly consistent with the BICEP2 experiment, and no-scale supergravity can be realized naturally in various string compactifications. Thus, we construct a chaotic inflation model in no-scale supergravity inspired from Type IIB string compactification with an anomalous U(1)_X gauged symmetry. We introduce two moduli T_1 and T_2 which transform non-trivially under U(1)_X, and some pairs of fundamental quarks charged under the SU(N) x U(1)_X gauge group. The non-trivial transformations of moduli under U(1)_X lead to a moduli-dependent Fayet-Iliopoulos (FI) term. The modulus T_2 and the real component of T_1 are stabilized by the non-perturbative effect from quark condensation and the U(1)_X D-term. In particular, the stabilization from the anomalous U(1)_X D-term with moduli-dependent FI term is crucial for inflation since it gives heavy mass to the real component of the modulus T_1 while keeping its axionic part light. Choosing the proper parameters, we obtain a global Minkowski vacuum where the imaginary part of T_1 has a quadratic potential for chaotic inflation., Revtex4, 17 pages, 2 figures

We show that the anomaly-mediated supersymmetry breaking via the Kahler and sigma-model anomalies is suppressed by conformal dynamics in the supersymmetry breaking sector., Comment: 8 pages

An inflationary stage dominated by a $D$-term avoids the slow-roll problem of inflation in supergravity and may emerge in theories with a non-anomalous or anomalous U(1) gauge symmetry. The most intriguing and commonly invoked possibility is that the Fayet-Iliopoulos $D$-term triggering inflation is the one emerging in superstring theories. We discuss the complications one has to face when trying to build up a successful $D$-term inflationary scenario in superstring models. In particular, we show that the ``vacuum shifting'' phenomenon of string theories is usually very efficient even in the early Universe, thus preventing inflation from taking place. On the other hand, when $D$-term inflation is free to occur, the presence of a plethora of fields and several non-anomalous additional abelian symmetries in string theories may help in reconciling the value of the Fayet-Iliopoulos $D$-term required by the COBE normalization with the value predicted by string theories. We also show that in superstring $D$-term inflation gravitinos are likely to pose no cosmological problem., Comment: 19 pages, LaTeX file

We study an N=(4,4) supersymmetric gauged linear sigma model which gives rise to the nonlinear sigma model for multi-centered KK-monopoles. We find a new T-duality transformation of the model even in the presence of F-terms. Performing T-duality, we find the gauged linear sigma model whose IR limit describes the exotic 522-brane with B-field., Comment: 18 pages, typos correcred

We present the mechanism of the dynamical supersymmetry breaking at the metastable vacuum recently uncovered in the N=1 U(N) supersymmetric gauge theory that contains adjoint superfields and that is specified by Kahler and non-canonical gauge kinetic functions and a superpotential whose tree vacua preserve N=1 supersymmetry. The overall U(1) serves as the hidden sector and no messenger superfield is required. The dynamical supersymmetry breaking is triggered by the non-vanishing D term coupled to the observable sector, and is realized by the self-consistent Hartree-Fock approximation of the NJL type while it eventually brings us the non-vanishing F term as well. It is shown that theoretical analysis is resolved as a variational problem of the effective potential for three kinds of background fields, namely, the complex scalar, and the two order parameters D and F of supersymmetry, the last one being treated perturbatively. We determine the stationary point and numerically check the consistency of such treatment as well as the local stability of the scalar potential. The coupling to the N = 1 supergravity is given and the gravitino mass formula is derived., Comment: 33 pages, 2 figures

We complete the N=1 superfield action for the generic system of vector multiplets and hypermultiplets coupled to 5D supergravity, which is based on the superconformal formulation. Especially we clarify the gravitational couplings to the bulk matters at linear order in the gravitational superfields. They consist of four N=1 superfields, two of which are Z_2-odd when the fifth dimension is compactified on S^1/Z_2. This formulation provides a powerful tool to calculate quantum effects, keeping the N=1 off-shell structure., Comment: 36 pages, typos corrected

The dual version of 10D supergravity (SUGRA) is analyzed in the superspace approach. The standard set of constraints on the fundamental superfields is used, making it possible to consider the theory on the mass shell. There is an additional degree of freedom in the theory that consists in the presence of the 3-form superfield Zabc, which is not determined by the equations of motion for fundamental fields. The Z field is the ghost-free and is restricted by linear homogeneous equations. The derivation of these equations is the main result of the present paper. The Z field describes the Green-Schwarz anomaly compensating terms in dual SUGRA.

In this short note we discuss quantization of the Fayet-Iliopoulos parameter in supergravity theories. We argue that in supergravity, the Fayet-Iliopoulos parameter determines a lift of the group action to a line bundle, and such lifts are quantized. Just as D-terms in rigid N=1 supersymmetry are interpreted in terms of moment maps and symplectic reductions, we argue that in supergravity the quantization of the Fayet-Iliopoulos parameter has a natural understanding in terms of linearizations in geometric invariant theory (GIT) quotients, the algebro-geometric version of symplectic quotients., Comment: 21 pages, utarticle class; v2: typos and tex issue fixed

We construct the complete superspace action ℒ of chiral D=10, N=2 supergravity. The self-duality condition on the field strength Fa1 - a5 is derived as an equation of motion in superspace. The space-time restriction of ℒ is not supersymmetric, since the self-duality condition does not follow from the space-time variational equations. However, supersymmetry can be restored via the introduction of a Lagrange multiplier term.

We study the magnitude of D-components in a generic supersymmetric field theory. There exists F-component whose vacuum expectation value is comparable to or higher than that of D-component, in the absence of the Fayet-Iliopoulos term, the large hierarchy in the charge spectrum and strongly interacting higher-dimensional couplings in the Kahler potential, if contributions from terms other than the F- and D-terms are negligible., Article, PROGRESS OF THEORETICAL PHYSICS. 125(3):509-520 (2011)

The fermionic sectors of the Lagrangians of 16/16 supergravity coupled to a chiral matter field—in the formalism of the superspace of Wess-Zumino—are studied.

We study the possibility to describe multiple M0-brane system in the frame of superembedding approach. The simplest framework is provided by the maximally supersymmetric non-Abelian SU(N) Yang-Mills supermultiplet on the d=1 N=16 superspace the embedding of which to the target D=11 supergravity superspace is determined by the so-called superembedding equation, characteristic of the worldline superspace of a single M0-brane. We use it to obtain a covariant generalization of the Matrix model equations describing the multiple M0-system in flat target superspace., 14 pages, LaTeX, no figures. V2. Misprints corrected, to appear in Phys. Lett. B.

Motivated by recent discussions, we revisit the issue of whether globally supersymmetric theories with non-zero Fayet-Iliopoulos terms may be consistently coupled to supergravity. In particular, we examine claims that a fundamental inconsistency arises due to the conflicting requirements which are imposed on the $R$-symmetry properties of the theory by the supergravity framework. We also prove that certain kinds of Fayet-Iliopoulos contributions to the supercurrent supermultiplets of theories with non-zero Fayet-Iliopoulos terms fail to exist. A key feature of our discussion is an explicit comparison between results from the chiral (or ``old minimal'') and linear (or ``new minimal'') formulations of supergravity, and the effects within each of these formalisms that are induced by the presence of non-zero Fayet-Iliopoulos terms., Comment: Comments: 69 pages, LaTeX, 2 figures, 7 tables. Significant new material on conformal-compensator formalisms added, previous results clarified and extended, references added

Starting from an investigation of D=10, N=1 superspace geometry, we identify realization of spacetime conformal symmetry on the superspace supergravity superfields. It is shown that the requirement of k -symmetry of the Green-Schwarz action is consistent with this conformal D=10, N=1 superspace supergravity theory. The relationship with the third-rank and seventh-rank field strength formulations is also clarified.

We draw attention to a close analogy between curvature-squared terms and the three-form gauge potential in superspace and discuss the supersymmetric extensions of gravitational Chern-Simons and Euler forms, with comments on the corresponding Green-Schwarz mechanisms.

Demanding analyticity along supersymmetric lines in superspace defined by pure spinors yields the essential on-shell constraints of ten-dimensional supersymmetric Yang-Mills. A similar procedure in loop superspace yields the constraints of on-shell ten-dimensional supergravity.

The concept of a harmonic N=2 superspace with additional coordinates related to the SU(2)/U(1) sphere is introduced. This concept leads to an adequate geometric description of the N=2 theories of matter, the Yang-Mills theory, and supergravity in terms of superfields without coupling. A new effect has been discovered: the unboundedness of the number of gauge and auxiliary degrees of freedom.

The structure of superunified theories in superspace is discussed from the point of view of local gauge invariance. It is shown that the same two requirements which lead to the correct description of gravity determine the structure of these theories. In particular, all the transformation laws of the fields follow from geometry.

A brief review of the recent progress in gauge supersymmetry and the development of its connection with superspace formulations of supergravity is given. The equivalence of the metric approach and the supervierbein approach for super gravity mass-shell spaces is given. Recent progress in gauge supersymmetry includes the establishment of a rigorous theorem (including all quantum connections) on the existence of a residual preserved group, field content of gauge supersymmetry and finiteness of one and two loop connections to propagators for N ≥ 2, where 4N is the dimensionality of the fermionic part of superspace.

Superspace, as an extension of Minkowski space-time with spinning degrees of freedom is reviewed. Superspace techniques useful for the construction of globally and locally supersymmetric field theories are discussed.

The superfield formulation of the two-dimensional (4, 0) supergravity is developed using the harmonic superspace techniques. The different sets of constraints are given and their solutions are expressed in terms of an SU(2) self-dual torsion superfield and harmonic prepotentials. The pure auxiliary (4, 0) Einstein action generalizing the (2, 0) one is written down and the most general (4, 0) matter couplings are given.

A superfield method for the derivation of the low-energy effective action in supergravity theories, employing the chiral superspace in the N = 1 case, and the harmonic superspace in the N = 2 case, is proposed. It is applied to demonstrate the existence of couplings, leading to hierarchically large masses of the scalar particles and to a Higgs-mixing term in the low-energy theory.

We reveal the model-independent geometric content of spontaneous breakdown of local supersymmetry in N = 1 supergravities (conformal and minimal Einstein ones) by constructing nonlinear realizations of their underlying superspace gauge group. A general method of implementing such realizations consistently with the intrinsic superspace geometry of supergravity theories is proposed and its relevance to the description of spontaneous symmetry breaking in the theories of similar nature (strings, membranes,…) is pointed out. We define superspaces adequate to the nonlinear realizations constructed and find the explicit relation between them and conventional curved N = 1 superspaces. The implications of this relationship for the N = 1 supergravity actions with spontaneously broken supersymmetry are discussed.

It is shown that racetrack inflation can be implemented in a moduli stabilisation scenario with a supersymmetric uplifting D-term. The resulting model is completely described by an effective supergravity theory, in contrast to the original racetrack models. We study the inflationary dynamics and show that the gaugino condensates vary during inflation. The resulting spectral index is n_s = 0.95 as in the original racetrack inflation model. Hence extra fields do not appear to alter the predictions of the model. An equivalent, simplified model with just a single field is presented., Comment: 14 pages, 5 figures

We extend previous work on the minimal D-term inflation model modified by Right-Handed (RH) sneutrino fields to include additional inflaton-sector SUGRA corrections and two-field inflation effects. We show that SUGRA corrections simultaneously allow n_{s} to be within 3-year WMAP limits and the cosmic string contribution to the CMB power spectrum to be less than 5%. For gauge coupling g < 1, the CMB contribution from cosmic strings is predicted to be at least 1% while the spectral index is predicted to be less than 0.968 for a CMB string contribution less than 5%. Treating the inflaton-RH sneutrino system as a two-field inflation model, we show that the time-dependence of the RH sneutrino field strongly modifies the single-field results for values of RH sneutrino mass m_{\Phi} > 0.1 H. The running spectral index is \alpha = -0.0002 when m_{\Phi} < 0.1 H but increases to positive values as m_{\Phi}/H increases, with \alpha > 0.008 for m_{\Phi} > 1.0 H., Comment: 22 pages LaTeX, 14 eps figures, to be published in Physical Review D

Even though the chaotic inflation is one of the most popular inflation models for its simple dynamics and compelling resolutions to the initial condition problems, its realization in supergravity has been considered a challenging task. We discuss how the chaotic inflation dominated by the D-term can be induced in supergravity, which would give a new perspective on the inflation model building in supergravity., Comment: 5 pages, to appear in Phys. Rev. D

In this note, which is based on hep-th/0611111, we review the stability of the static, positive deficit angle D-term string solutions of D=4, N=1 supergravity with a constant Fayet-Iliopoulos term. We prove the semi-classical stability of this class of solutions using standard positive energy theorem techniques. In particular, we discuss how the negative deficit angle D-term string, which also solves the Killing spinor equations, violates the dominant energy condition and so is excluded from our arguments., Comment: 9 pages, contribution to the proceedings of the RTN project `Constituents, Fundamental Forces and Symmetries of the Universe' conference in Napoli, October 9 - 13, 2006

We present a D-term hybrid inflation model, embedded in supergravity with moduli stabilisation. Its novel features allow us to overcome the serious challenges of combining D-term inflation and moduli fields within the same string-motivated theory. One salient point of the model is the positive definite uplifting D-term arising from the moduli stabilisation sector. By coupling this D-term to the inflationary sector, we generate an effective Fayet-Iliopoulos term. Moduli corrections to the inflationary dynamics are also obtained. Successful inflation is achieved for a limited range of parameter values with spectral index compatible with the WMAP3 data. Cosmic D-term strings are also formed at the end of inflation; these are no longer Bogomol'nyi-Prasad-Sommerfeld (BPS) objects. The properties of the strings are studied., 30 pages, table added