arXiv subjects

Gianguido Dall'Agata

Publications and source records attributed to Gianguido Dall'Agata.

At least 19 recordsLinked to original sources

arXiv2025

Supersymmetry-breaking compactifications on Riemann-flat manifolds

We consider compactifications of higher-dimensional supergravities on Riemann-flat manifolds of dimension d ($3 \le d \le 7$) that fully break supersymmetry at the classical level on a resulting D-dimensional Minkowski space. We systematically discuss consistency conditions, the Kaluza-Klein (KK) spectrum and harmonics, and the resulting one-loop effective potential $V_1$, focusing for illustration on maximal supergravity and d=3, in particular on the $T^3/Z_3$ and on the Hantzsche-Wendt manifolds. We show how the KK spectrum is organized in multiplets of the broken supersymmetry, derive new universal supertrace mass relations valid at each KK level and obtain an analytic finite expression for $V_1$ after resumming the contributions of all KK levels. In all examples $V_1$ is negative definite and scales with inverse powers of some internal radii. We extensively comment, when applicable, on the relation with the Scherk-Schwarz mechanism and with supersymmetry-breaking string compactifications on freely acting symmetric orbifolds. We also finally clarify the assumptions and constraints for Scherk-Schwarz reductions to correspond to twisted tori compactifications.

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arXiv2024

One-loop effective potential in Scherk-Schwarz compactifications of pure d=5 supergravities

We perform a systematic analysis of the one-loop effective potential of pure $d=5$ supergravities, with supersymmetry fully broken by a Scherk-Schwarz compactification on the circle, as a function of the radial modulus. We discuss the precise correspondence between the effective potential $V_1$ in the full compactified theory and its counterpart $V_{1,red}$ in the reduced theory. We confirm that $V_1$ is finite for any $N>0$, in contrast to $V_{1,red}$. We find that for broken $N=8$ supergravity $V_1$ is negative definite even after accounting for the Kaluza-Klein states. We outline a program for future work where the study of a different kind of Scherk-Schwarz compactifications, still at the field theory level but with at least three extra dimensions, could lead to qualitatively new results.

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arXiv2023

Gauged D=4 N=4 Supergravity

We present the full Lagrangian and supersymmetry transformation rules for the gauged D=4, N=4 (half-maximal) supergravity coupled to an arbitrary number of vector multiplets. Using the embedding tensor formulation, the final results are universal and valid in arbitrary symplectic frames. We also analyze the conditions for the critical points of the scalar potential and specify the full spectrum of the quadratic fluctuations about Minkowski vacua. This allows us also to exclude the appearance of quadratic divergences in the 1-loop corrections to the scalar potential for any Minkowski vacuum fully breaking supersymmetry. We also provide some interesting byproducts of our analysis, like the field equations and the quadratic constraints for the fermion shifts characterizing the gauging (also known as T-tensor identities).

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arXiv2023

Simple Supergravity

We present a short overview of the structure and couplings of supergravity theories at the component level. We do so with as little technical machinery as possible, working directly with the physical on-shell fields and using explicit computations and geometrical reasoning to arrive at the result, highlighting the new properties of supersymmetry in the context of a gravitational theory.

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arXiv2022

Weak gravity versus scale separation

We give evidence that fully supersymmetric Anti-de Sitter vacua of extended supergravity with a residual gauge group containing an abelian factor cannot be scale separated as a consequence of the weak gravity conjecture. We prove this for N=2 and N=8 supergravity and we explain how our argument applies also to vacua with partially broken, but extended residual supersymmetry. We finally discuss possible loopholes and especially how certain N=1 models can evade our reasoning. Our results suggest that N=0,1 supersymmetry at the lagrangian level might be the most promising chances to obtain a truly four-dimensional effective description of quantum gravity.

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arXiv2022

Anti-brane uplift instability from goldstino condensation

We investigate the possible appearance of composite states of the goldstino in models with four-dimensional non-linear supersymmetry and we provide a description of their dynamics in terms of a Kähler potential and a superpotential. Our analysis shows that the critical point corresponding to the Volkov-Akulov model is unstable. Similarly, we find that the uplifted stable de Sitter critical point of the KKLT model is shifted and acquires a tachyonic instability. Our findings indicate the existence of a potentially dangerous instability shared by all anti-brane uplifts.

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arXiv2021

The unbearable lightness of charged gravitini

We prove that charged gravitini cannot have parametrically small or vanishing Lagrangian mass in de Sitter vacua of extended supergravity while respecting the magnetic weak gravity conjecture. This places large classes of de Sitter solutions of gauged supergravity in the swampland, including all known stable solutions of the N=2 theory. We illustrate this result by analyzing a variety of de Sitter critical points of N=2 matter-coupled supergravity that also include new stable de Sitter solutions. Our results provide concrete evidence that (quasi) de Sitter with charged light gravitini should belong to the swampland, which also strongly resonates with the festina lente bound.

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arXiv2020

Covariant formulation of BPS black holes and the scalar weak gravity conjecture

In this note we analyze the BPS black hole equations in extended supergravities and we find two interesting relations involving first and second derivatives of combinations of the central charges. One relation is a new identity that solely relies on the geometric properties of the scalar manifolds of extended supergravity theories. The other relation is a generalization of a scalar weak gravity conjecture relation conjectured by Palti and uses properties of the underlying black hole solution. We also provide for the first time an explicit covariant construction of the BPS squared action for such solutions.

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arXiv2019

Warm dark energy

Motivated by some of the recent swampland conjectures, we study the implementation for the late time acceleration of the Universe of a mechanism developed by Anber and Sorbo in the context of primordial inflation, in which an axion field can slowly roll in a steep potential due to additional friction provided by its coupling to some U(1) gauge field. We first study the realization of this mechanism in N = 2 supergravity models resulting from string compactifications on Calabi--Yau manifolds. We then study the transition between matter domination and the axion domination, and show that indeed the backreaction of the produced gauge field can sufficiently slow the motion of the axion, so to produce the present accelerated era. We finally study the transition from a pre-inflationary matter or radiation domination to primordial inflation. In the regime that we could explore numerically, the evolution is characterized by stages of faster axion roll (and consequent bursts of gauge field amplification) intermitted by stages of slower roll, with a pattern that "oscillates'' about the steady state Anber and Sorbo solution, but that does not appear to relax to it.

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arXiv2019

Uplifts of maximal supergravities and transitions to non-geometric vacua

We describe a new procedure to obtain consistent backgrounds that uplift vacua and deformations of various maximal gauged supergravities by taking a known solution and performing singular limits along the moduli space of the corresponding 4-dimensional theory. We then apply this procedure to the S^3 x H^{2,2} background that provides the uplift of 4-dimensional Minkowski vacua of maximal supergravity with gauge group [SO(4) x SO(2,2)] $\ltimes$ R^{16}. We find that the newly generated vacua are generally only locally geometric and correspond to asymmetric orbifolds, Q-flux backgrounds or combinations thereof. We also provide the uplift to eleven dimensions of all the four-parameter Cremmer-Scherk-Schwarz gaugings.

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arXiv2018

On the off-shell formulation of N=2 supergravity with tensor multiplets

We revisit the construction of N=2 superconformal multiplets using rheonomic superspace techniques. We apply the result to the derivation of off-shell Poincaré supersymmetric models where a tensor multiplet couples to gravity and to an arbitrary number of vector multiplets. We also analyze gaugings involving the tensor field.

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arXiv2018

Chromo-Natural inflation in Supergravity

We present supergravity realizations of chromo-natural inflationary models. We show that by using superpotentials with "imaginary" holomorphic functions of the inflaton one can obtain effective theories of inflation that are also consistent truncations of the original supergravity models.

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arXiv2016

Constrained superfields in Supergravity

We analyze constrained superfields in supergravity. We investigate the consistency and solve all known constraints, presenting a new class that may have interesting applications in the construction of inflationary models. We provide the superspace Lagrangians for minimal supergravity models based on them and write the corresponding theories in component form using a simplifying gauge for the goldstino couplings.

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arXiv2015

Minimal scalar-less matter-coupled supergravity

We build the minimal supergravity model where the nilpotent chiral goldstino superfield is coupled to a chiral matter superfield, realising a different non-linear representation through a mixed nilpotency constraint. The model describes the spontaneous breaking of local supersymmetry in the presence of a generically massive Majorana fermion, but in the absence of elementary scalars. The sign and the size of the cosmological constant, the spectrum and the four-fermion interactions are controlled by suitable parameters.

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arXiv2015

Uplifting non-compact gauged supergravities

We provide the M-theory uplift of de Sitter vacua of SO(5,3) and SO(4,4) gaugings of maximal supergravity in 4 dimensions. We find new non-compact backgrounds that are squashed hyperboloids with non-trivial flux for the 3-form potential. The uplift requires a new non-linear ansatz for the 11-dimensional metric and for the 3-form potential that reduces to the known one leading to the 7-sphere solution in the case of the SO(8) gauging.

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arXiv2014

On sgoldstino-less supergravity models of inflation

We go a step further in the search for a consistent and realistic supergravity model of large-field inflation by building a class of models with the following features: during slow-roll, all the scalar fields other than the inflaton are frozen by large inflaton-dependent masses or removed from the spectrum; at the end of inflation, supersymmetry is spontaneously broken with naturally vanishing classical vacuum energy. We achieve this by combining some geometrical properties of the Kaehler potential with the consistent use of a single nilpotent chiral superfield, in one-to-one correspondence with the supersymmetry-breaking direction in field space at the vacuum.

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arXiv2014

Symplectic Deformations of Gauged Maximal Supergravity

We identify the space of symplectic deformations of maximal gauged supergravity theories. Coordinates of such space parametrize inequivalent supergravity models with the same gauge group. We apply our procedure to the SO(8) gauging, extending recent analyses. We also study other interesting cases, including Cremmer-Scherk-Schwarz models and gaugings of groups contained in SL(8,R) and in SU*(8).

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arXiv2014

A Search for an N=2 Inflaton Potential

We consider N=2 supergravity theories that have the same spectrum as the R+R^2 supergravity, as predicted from the off-shell counting of degrees of freedom. These theories describe standard N=2 supergravity coupled to one or two long massive vector multiplets. The central charge is not gauged in these models and they have a Minkowski vacuum with N=2 unbroken supersymmetry. The gauge symmetry, being non-compact, is always broken. $α$-deformed inflaton potentials are obtained, in the case of a single massive vector multiplet, with $α=1/3$ and $2/3$. The $α=1$ potential (i.e. the Starobinsky potential) is also obtained, but only at the prize of having a single massive vector and a residual unbroken gauge symmetry. The inflaton corresponds to one of the Cartan fields of the non-compact quaternionic-K{ä}hler cosets.

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