Search results for "Superstring"
showing 10 items of 28 documents
N=2 Super-Higgs, N=1 Poincare' Vacua and Quaternionic Geometry
2002
In the context of N=2 supergravity we explain the occurrence of partial super-Higgs with vanishing vacuum energy and moduli stabilization in a model suggested by superstring compactifications on type IIB orientifolds with 3-form fluxes. The gauging of axion symmetries of the quaternionic manifold, together with the use of degenerate symplectic sections for special geometry, are the essential ingredients of the construction.
Lorentz harmonics and superfield action. D=10, N=1 superstring
2000
We propose a new version of the superfield action for a closed D=10, N=1 superstring where the Lorentz harmonics are used as auxiliary superfields. The incorporation of Lorentz harmonics into the superfield action makes possible to obtain superfield constraints of the induced worldsheet supergravity as equations of motion. Moreover, it becomes evident that a so-called 'Wess-Zumino part' of the superfield action is basically a Lagrangian form of the generalized action principle. We propose to use the second Noether theorem to handle the essential terms in the transformation lows of hidden gauge symmetries, which remove dynamical degrees of freedom from the Lagrange multiplier superfield.
Twistor string as tensionless superstring
2007
6 pages.-- PACS nrs.: 11.30.Pb, 11.25.-w, 11.10.Kk, 12.60.Jv.-- ISI Article Identifier: 000247103400009.-- ArXiv pre-print available at: http://arxiv.org/abs/hep-th/0702133
Oh, wait, O8 de Sitter may be unstable!
2021
We analyze the stability of four-dimensional de Sitter vacua constructed by compactifying massive Type IIA supergravity in the presence of two O8 sources [1]. When embedded in String Theory the first source has a clear interpretation as an O8$_-$ plane, but the second one could correspond to either an O8$_+$ plane or to an O8$_-$ plane with 16 D8-branes on top. We find that this latter solution has a tachyonic instability, corresponding to the D8-branes moving away from the O8$_-$ plane. We comment on the possible ways of distinguishing between these sources.
D=4 supergravity dynamically coupled to superstring in a superfield Lagrangian approach
2003
We elaborate a full superfield description of the interacting system of dynamical D=4, N=1 supergravity and dynamical superstring. As far as minimal formulation of the simple supergravity is used, such a system should contain as well the tensor (real linear) multiplet which describes the dilaton and the two-superform gauge field whose pull-back provides the Wess-Zumino term for the superstring. The superfield action is given by the sum of the Wess-Zumino action for D=4, N=1 superfield supergravity, the superfield action for the tensor multiplet in curved superspace and the Green-Schwarz superstring action. The latter includes the coupling to the tensor multiplet both in the Nambu-Goto and i…
Gauged extended supergravity without cosmological constant: No-scale structure and supersymmetry breaking
2002
We consider the interplay of duality symmetries and gauged isometries of supergravity models giving N-extended, spontaneously broken supergravity with a no-scale structure. Some examples, motivated by superstring and M-theory compactifications are described.
Superembedding Approach and S-Duality. A unified description of superstring and super-D1-brane
2001
It is proved that a basic superembedding equation for the 2-dimensional worldsheet superspace $\S^{(2|8+8)}$ embedded into D=10 type IIB superspace $M^{(10|16+16)}$ provides a universal, S-duality invariant description of a fundamental superstring and super-D1-brane. We work out generalized action principle, obtain superfield equations of motion for both these objects and find how the S-duality transformations relate the superfield equations of superstring and super-D1-brane. The superembedding of 6-dimensional worldsheet superspace $\S^{(6|16)}$ into the D=10 type IIB superspace will probably provide a similar universal description for the set of type IIB super-NS5-brane, super-D5-brane an…
On the chirality of the SM and the fermion content of GUTs
2015
The Standard Model (SM) is a chiral theory, where right- and left-handed fermion fields transform differently under the gauge group. Extra fermions, if they do exist, need to be heavy otherwise they would have already been observed. With no complex mechanisms at work, such as confining interactions or extra-dimensions, this can only be achieved if every extra right-handed fermion comes paired with a left-handed one transforming in the same way under the Standard Model gauge group, otherwise the new states would only get a mass after electroweak symmetry breaking, which would necessarily be small (similar to 100 GeV). Such a simple requirement severely constrains the fermion content of Grand…
Kaluza-Klein origin for the superstring tension
1992
The natural configuration space of a string in a background antisymmetric tensor potential is not loop space, but a principal U(1) bundle over loop space. This allows a Kaluza-Klein--like interpretation of the string tension as momentum along the U(1) fiber, and a similar interpretation is possible for a {ital p}-dimensional object. The higher-dimensional'' action incorporating this momentum as a dynamical variable is given for a {ital p}-dimensional supersymmetric extended object, in a general supergravity background. Its relevance, for a flat background, to classical anomalies'' in the supersymmetry algebra is explained.
Supersymmetry currents and WZ-like terms in (supersymmetry)2 models
1990
Abstract Using the superfield formulation of the N = 1 spinning superparticle model as an example, the superfield currents associated with the target space supersymmetry are given, and the component expression of the corresponding superalgebra is found to describe a graded “doubling” of the Poincare superalgebra. Further, it is shown how the torsion-like term in the spinning super-particle model can be obtained from the form associated with the Green-Schwarz WZ term for the superstring, and a possible way of introducing extended spinning supersymmetric objects is discussed.