Pietro Galli

University of Milan, Milano, Lombardy, Italy

Are you Pietro Galli?

Claim your profile

Publications (11)40.31 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: We extend previous investigations on the construction of extremal supersymmetric and non-supersymmetric solutions in the H-FGK formalism to "unconventional" solutions with anharmonic terms. We show how the use of "fake" charge vectors equivariant under duality transformations simplifies and clarifies the task of identification of the attractors of the theory.
    Journal of High Energy Physics 05/2013; · 5.62 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We apply the H-FGK formalism to the study of some properties of the general class of black holes in N=2 supergravity in four dimensions that correspond to the harmonic and hyperbolic ansatze and obtain explicit extremal and non-extremal solutions for the t^3 model with and without a quantum correction. Not all solutions of the corrected model (quantum black holes), including in particular a solution with a single q_1 charge, have a regular classical limit.
    Journal of High Energy Physics 12/2012; 2013(4). · 5.62 Impact Factor
  • Source
    Pietro Galli, Kevin Goldstein, Jan Perz
    [Show abstract] [Hide abstract]
    ABSTRACT: We investigate the stabilisation equations for sufficiently general, yet regular, extremal (supersymmetric and non-supersymmetric) and non-extremal black holes in four-dimensional N=2 supergravity using both the H-FGK approach and a generalisation of Denef's formalism. By an explicit calculation we demonstrate that the equations necessarily contain an anharmonic part, even in the static, spherically symmetric and asymptotically flat case.
    Journal of High Energy Physics 11/2012; 2013(3). · 5.62 Impact Factor
  • Source
    Pietro Galli, Patrick Meessen, Tomas Ortin
    [Show abstract] [Hide abstract]
    ABSTRACT: We show that the representation of black-hole solutions in terms of the variables H^M which are harmonic functions in the supersymmetric case is non-unique due to the existence of a local symmetry in the effective action. This symmetry is a continuous (and local) generalization of the discrete Freudenthal transformations initially introduced for the black-hole charges and can be used to rewrite the physical fields of a solution in terms of entirely different-looking functions.
    Journal of High Energy Physics 11/2012; 2013(5). · 5.62 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Methods similar to those used for obtaining supersymmetric black hole solutions can be employed to find also non-supersymmetric solutions. We briefly review some of them, with the emphasis on the non-extremal deformation ansatz of [1].
    Fortschritte der Physik 09/2012; 60(9-10):1026-1029. · 0.98 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This is an overview for non-specialists of some of the progress in research on black holes in String and Supergravity theories, mostly focused on the search and study of explicit classical solutions describing them.
    07/2012;
  • [Show abstract] [Hide abstract]
    ABSTRACT: We review a generic recipe for deforming extremal black holes into non-extremal black holes, introduced in [1], which allows to construct general non-extremal black hole solutions from general supersymmetric solutions. We also relate the deformation procedure directly to the equations of motion, by means of the H-FGK formalism [2], providing additional support of the Ansätz.
    07/2012;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We propose a generic recipe for deforming extremal black holes into non-extremal black holes and we use it to find and study the non-extremal black-hole solutions of several N=2,d=4 supergravity models (SL(2,R)/U(1), CPn and STU with four charges). In all the cases considered, the non-extremal family of solutions smoothly interpolates between all the different extremal limits, supersymmetric and not supersymmetric. This fact can be used to find explicitly extremal non-supersymmetric solutions in the cases in which the attractor mechanism does not completely fix the values of the scalars on the event horizon and they still depend on the boundary conditions at spatial infinity. We compare (supersymmetry) Bogomol'nyi bounds with extremality bounds, we find the first-order flow equations for the non-extremal solutions and the corresponding superpotential, which gives in the different extremal limits different superpotentials for extremal black holes. We also compute the "entropies" (areas) of the inner (Cauchy) and outer (event) horizons, finding in all cases that their product gives the square of the moduli-independent entropy of the extremal solution with the same electric and magnetic charges.
    Journal of High Energy Physics - J HIGH ENERGY PHYS. 05/2011; 7.
  • Source
    Pietro Galli, Jan Perz
    [Show abstract] [Hide abstract]
    ABSTRACT: Using the superpotential approach we generalize Denef's method of deriving and solving first-order equations describing multicenter extremal black holes in four-dimensional N = 2 supergravity to allow non-supersymmetric solutions. We illustrate the general results with an explicit example of the stu model. Comment: 17 pages, v2: some clarifications added
    Journal of High Energy Physics 09/2009; · 5.62 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We derive a generalised form of flow equations for extremal static and rotating non-BPS black holes in four-dimensional ungauged N = 2 supergravity coupled to vector multiplets. For particular charge vectors, we give stabilisation equations for the scalars, analogous to the BPS case, describing full known solutions. Based on this, we propose a generic ansatz for the stabilisation equations, which surprisingly includes ratios of harmonic functions. KeywordsBlack Holes in String Theory–Supergravity Models
    Journal of High Energy Physics 2011(6):1-28. · 5.62 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We propose a generic recipe for deforming extremal black holes into non-extremal black holes and we use it to find and study the static non-extremal black-hole solutions of several N = 2, d = 4 supergravity models $ \left( {{{{{\text{SL}}\left( {2,\mathbb{R}} \right)}} \left/ {{{\text{U}}(1)}} \right.}} \right. $ , $ {\overline {\mathbb{C}\mathbb{P}}^n} $ and STU with four charges). In all the cases considered, the non-extremal family of solutions smoothly interpolates between all the different extremal limits, supersymmetric and not supersymmetric. This fact can be used to explicitly find extremal non-supersymmetric solutions also in the cases in which the attractor mechanism does not completely fix the values of the scalars on the event horizon and they still depend on the boundary conditions at spatial infinity. We compare (supersymmetry) Bogomol’nyi bounds with extremality bounds, we find the first-order flow equations for the non-extremal solutions and the corresponding super-potential, which gives in the different extremal limits different superpotentials for extremal black holes. We also compute the entropies (areas) of the inner (Cauchy) and outer (event) horizons, finding in all cases that their product gives the square of the moduli-independent entropy of the extremal solution with the same electric and magnetic charges.
    Journal of High Energy Physics 2011(7). · 5.62 Impact Factor