835 research outputs found
Maximal supergravity in D=10: forms, Borcherds algebras and superspace cohomology
We give a very simple derivation of the forms of supergravity from
supersymmetry and SL(2,\bbR) (for IIB). Using superspace cohomology we show
that, if the Bianchi identities for the physical fields are satisfied, the
(consistent) Bianchi identities for all of the higher-rank forms must be
identically satisfied, and that there are no possible gauge-trivial Bianchi
identities () except for exact eleven-forms. We also show that the
degrees of the forms can be extended beyond the spacetime limit, and that the
representations they fall into agree with those predicted from Borcherds
algebras. In IIA there are even-rank RR forms, including a non-zero
twelve-form, while in IIB there are non-trivial Bianchi identities for
thirteen-forms even though these forms are identically zero in supergravity. It
is speculated that these higher-rank forms could be non-zero when higher-order
string corrections are included.Comment: 15 pages. Published version. Some clarification of the tex
IIA/IIB Supergravity and Ten-forms
We perform a careful investigation of which p-form fields can be introduced
consistently with the supersymmetry algebra of IIA and/or IIB ten-dimensional
supergravity. In particular the ten-forms, also known as "top-forms", require a
careful analysis since in this case, as we will show, closure of the
supersymmetry algebra at the linear level does not imply closure at the
non-linear level. Consequently, some of the (IIA and IIB) ten-form potentials
introduced in earlier work of some of us are discarded. At the same time we
show that new ten-form potentials, consistent with the full non-linear
supersymmetry algebra can be introduced. We give a superspace explanation of
our work. All of our results are precisely in line with the predictions of the
E(11) algebra.Comment: 17 page
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A survey of 557 GHz water vapor emission in the NGC 1333 molecular cloud
Using NASA\u27s Submillimeter Wave Astronomy Satellite (SWAS), we have examined the production of water in quiescent and shocked molecular gas through a survey of the 556.936 GHz 110-101 transition of ortho-H2O in the NGC 1333 molecular core. These observations reveal broad emission lines associated with the IRAS 2, IRAS 4, IRAS 7, and HH 7-11 outflows. Toward three positions we detect narrow (Δv ~ 2-3 km s-1) emission lines clearly associated with the ambient gas. The SWAS observations, with a resolution of ~4\u27, are supplemented with observations from the Infrared Space Observatory (ISO) and by an unbiased survey of a ~17\u27 × 15\u27 area, with ~50\u27\u27 resolution, in the low-J transitions of CO, 13CO, C18O, N2H+, CH3OH, and SiO. Using these combined data sets, with consistent assumptions, we find beam-averaged ortho-H2O abundances of greater than 10-6 relative to H2 for all four outflows. A comparison of SWAS and ISO water data is consistent with nondissociative shock models, provided the majority of the ortho-H2O (110-101) emission arises from cool postshock material with enhanced abundances. In the ambient gas the ortho-H2O abundance is found to lie between 0.1 × 10-7 and 1 × 10-7 relative to H2 and is enhanced when compared to cold prestellar molecular cores. A comparison of the water emission with tracers of dense condensations and shock chemistry finds no clear correlation. However, the water emission appears to be associated with the presence of luminous external heating sources that power the reflection nebula and the photodissociation region (PDR). Simple PDR models are capable of reproducing the water and high-J 13CO emission, suggesting that a PDR may account for the excitation of water in low-density undepleted gas, as suggested by Spaans & van Dishoeck
The general gaugings of maximal d=9 supergravity
We use the embedding tensor method to construct the most general maximal
gauged/massive supergravity in d=9 dimensions and to determine its extended
field content. Only the 8 independent deformation parameters (embedding tensor
components, mass parameters etc.) identified by Bergshoeff \textit{et al.} (an
SL(2,R) triplet, two doublets and a singlet can be consistently introduced in
the theory, but their simultaneous use is subject to a number of quadratic
constraints. These constraints have to be kept and enforced because they cannot
be used to solve some deformation parameters in terms of the rest. The
deformation parameters are associated to the possible 8-forms of the theory,
and the constraints are associated to the 9-forms, all of them transforming in
the conjugate representations. We also give the field strengths and the gauge
and supersymmetry transformations for the electric fields in the most general
case. We compare these results with the predictions of the E11 approach,
finding that the latter predicts one additional doublet of 9-forms, analogously
to what happens in N=2, d=4,5,6 theories.Comment: Latex file, 43 pages, reference adde
Sigma models with off-shell N=(4,4) supersymmetry and noncommuting complex structures
We describe the conditions for extra supersymmetry in N=(2,2) supersymmetric
nonlinear sigma models written in terms of semichiral superfields. We find that
some of these models have additional off-shell supersymmetry. The (4,4)
supersymmetry introduces geometrical structures on the target-space which are
conveniently described in terms of Yano f-structures and Magri-Morosi
concomitants. On-shell, we relate the new structures to the known
bi-hypercomplex structures.Comment: 20 pages; v2: significant corrections, clarifications, and
reorganization; v3: discussion of supersymmetry vs twisted supersymmetry
added, relevant signs corrected
Evidence for the classical integrability of the complete AdS(4) x CP(3) superstring
We construct a zero-curvature Lax connection in a sub-sector of the
superstring theory on AdS(4) x CP(3) which is not described by the
OSp(6|4)/U(3) x SO(1,3) supercoset sigma-model. In this sub-sector worldsheet
fermions associated to eight broken supersymmetries of the type IIA background
are physical fields. As such, the prescription for the construction of the Lax
connection based on the Z_4-automorphism of the isometry superalgebra OSp(6|4)
does not do the job. So, to construct the Lax connection we have used an
alternative method which nevertheless relies on the isometry of the target
superspace and kappa-symmetry of the Green-Schwarz superstring.Comment: 1+26 pages; v2: minor typos corrected, acknowledgements adde
Free Differential Algebras and Pure Spinor Action in IIB Superstring Sigma Models
In this paper we extend to the case of IIB superstring sigma models the
method proposed in hep-th/10023500 to derive the pure spinor approach for type
IIA sigma models. In particular, starting from the (Free) Differential Algebra
and superspace parametrization of type IIB supergravity, extended to include
the BRST differential and all the ghosts, we derive the BRST transformations of
fields and ghosts as well as the standard pure spinor constraints for the
ghosts related to supersymmetry. Moreover, using the method first
proposed by us, we derive the pure spinor action for type IIB superstrings in
curved supergravity backgrounds (on shell), in full agreement with the action
first obtained by Berkovits and Howe.Comment: 24 page
Off-shell supergravity-matter couplings in three dimensions
We develop the superspace geometry of N-extended conformal supergravity in
three space-time dimensions. General off-shell supergravity-matter couplings
are constructed in the cases N=1,2,3,4.Comment: 73 pages; V5: typos in eqs. (3.4b), (3.17) and (4.24) correcte
Heterotic Black Horizons
We show that the supersymmetric near horizon geometry of heterotic black
holes is either an AdS_3 fibration over a 7-dimensional manifold which admits a
G_2 structure compatible with a connection with skew-symmetric torsion, or it
is a product R^{1,1} * S^8, where S^8 is a holonomy Spin(7) manifold,
preserving 2 and 1 supersymmetries respectively. Moreover, we demonstrate that
the AdS_3 class of heterotic horizons can preserve 4, 6 and 8 supersymmetries
provided that the geometry of the base space is further restricted. Similarly
R^{1,1} * S^8 horizons with extended supersymmetry are products of R^{1,1} with
special holonomy manifolds. We have also found that the heterotic horizons with
8 supersymmetries are locally isometric to AdS_3 * S^3 * T^4, AdS_3 * S^3 * K_3
or R^{1,1} * T^4 * K_3, where the radii of AdS_3 and S^3 are equal and the
dilaton is constant.Comment: 35 pages, latex. Minor alterations to equation (3.11) and section
4.1, the conclusions are not affecte
Bi-harmonic superspace for N=4 d=4 super Yang-Mills
We develop N=4 d=4 bi-harmonic superspace and use it to derive a novel form
for the low-energy effective action in N=4 super Yang-Mills theory. We solve
the N=4 supergauge constraints in this superspace in terms of analytic
superfields. Using these superfields, we construct a simple functional that
respects N=4 supersymmetry and scale invariance. In components, it reproduces
all on-shell terms in the four-derivative part of the N=4 SYM effective action;
in particular, the F^4/X^4 and Wess-Zumino terms. The latter comes out in a
novel SO(3) x SO(3)-invariant form.Comment: 1+19 pages; minor corrections, references adde
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