1,720,981 research outputs found
Brane induced supersymmetry breaking and de Sitter supergravity
Get PDFAbstract: We obtain a four-dimensional supergravity with spontaneously broken super-symmetry allowing for de Sitter vacua by coupling a superspace action of minimal N = 1, D = 4 supergravity to a locally supersymmetric generalization of the Volkov-Akulov goldstino action describing the dynamics of a space-filling non-BPS 3-brane in N = 1, D = 4 superspace. To the quadratic order in the goldstino field the obtained action coincides with earlier constructions of supergravities with nilpotent superfields, while matching the higher-order contributions will require a non-linear redefinition of fields. In the unitary gauge, in which the goldstino field is set to zero, the action coincides with that of Volkov and Soroka. We also show how a nilpotency constraint on a chiral curvature superfield emerges in this formulation
Variant 4D supergravities and membranes
Get PDFWe review the dynamical generation of coupling constants in supergravity by means of gauge three-forms. The latter are introduced as components of particular variant chiral multiplets and can be coupled to membranes preserving local supersymmetry. We present generic N = 1, D = 4 supergravity models with variant multiplets and study domain wall solutions that interpolate between vacua with different values of the cosmological constant.Work of I.B. was supported in part by the Spanish MINECO/FEDER (ERDF) EU grant FPA 2015-66793-P, by the Basque Government Grant IT-979-16, and the Basque Country University program UFI 11/55. F.F. is supported from the KU Leuven C1 grant ZKD1118 C16/16/005. S.L. is grateful for hospitality to Istituto de Fisica Teorica UAM-CSIC, Madrid, where this work was completed. Work of D.S. was supported in part by the Russian Science Foundation grant 1442-00047 in association with Lebedev Physical Institute and by the Australian Research Council project No. DP160103633
Trirefringence and the M5-brane
Get PDFThe Hamiltonian formulation for nonlinear chiral 2-form electrodynamics in
six-dimensional Minkowski spacetime is used to show that small-amplitude
plane-wave perturbations of a generic uniform constant `magnetic' background
exhibit trirefringence: all three independent wave-polarisations have distinct
dispersion relations. While two coincide for Lorentz invariant theories, all
three coincide uniquely for the chiral 2-form theory on the worldvolume of the
M5-brane of M-theory. We argue that this is because, in this M-theory context,
the waves propagate in a planar M5-M2-M2 bound-state preserving 16
supersymmetries. We also show how our results imply analogous results for
nonlinear electrodynamics in a Minkowski spacetime of five and four dimensions.Comment: 14 pages, v4 includes minor clarifications to v
Three-forms, dualities and membranes in four-dimensional supergravity
Get PDFAbstract 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
Superstring at the boundary of open supermembrane interacting with D=4 supergravity and matter supermultiplets
Get PDF[EN] We present the complete supersymmetric and κ-symmetric action for the 4-
dimensional interacting system of open supermembrane, dynamical supergravity and 3-
form matter multiplets. The cases of a single 3-form matter multiplet and a quite generic
model with a number of nonlinear interacting double 3-form multiplets are considered. In
all cases the fermionic parameter of the κ-symmetry is subject to two apparently different
projection conditions which suggests that the ground state of the system, in particular a
domain junction, might preserve at most 1/4 of the spacetime supersymmetry.
The boundary term of the open supermembrane action, needed to preserve the κ-
symmetry, has the meaning of the action of a superstring. The Wess-Zumino term of
this superstring action is expressed in terms of real linear superfield playing the role of
St¨uckelberg field for the 3-form gauge symmetry. This indicates that this symmetry is
broken spontaneously by the superstring at the boundary of supermembrane.The author is thankful to Sergei Kuzenko and especially to Dima Sorokin for useful conversations and for collaboration at early stages of this work which was supported in part by the Spanish MINECO/FEDER (ERDF EU) grant PGC2018-095205-B-I00, by the Basque Government Grant IT-979-16, and by the Basque Country University program UFI 11/55
Superstring in doubled superspace
No full textAbstractThe covariant and kappa-symmetric action for superstring in direct product of two flat D=10 N=1 superspaces is presented. It is given by the sum of supersymmetric generalization of two copies of chiral boson actions constructed with the use of the Pasti–Sorokin–Tonin (PST) technique. The chirality of 8 ‘left’ bosons and 8 ‘left’ fermions and the anti-chirality of their ‘right’ counterparts are obtained as gauge fixed version of the equations of motion, so that the physical degrees of freedom are essentially those of the II Green–Schwarz superstring. Our action is manifestly T-duality invariant as the fields describing oscillating and winding modes enter it on equal footing
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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