11,423 research outputs found
Higher Derivative F-terms in N=2 Strings
We study a special class of higher derivative F-terms of the form
where W is the N=2 gravitational superfield and
is the chiral projector applied to a non-holomorphic function of the
heterotic dilaton vector superfield. We analyze these couplings in the
heterotic theory on , where it is found they satisfy an anomaly
equation as the well studied terms. We recognize that, near a point
of SU(2) enhancement, a given generating function of the leading singularity of
the reproduces the free energy of a c=1 string at an arbitrary radius
R. According to the N=2 heterotic-type II duality in 4d, we then study these
couplings near a conifold singularity, using its local description in terms of
intersecting D-5-branes. In this context, it turns out that there exists, among
the other states involved, a vector gauge field reproducing the heterotic
leading singularity structure.Comment: 19 pages, latex file, no figure
Nonholomorphic N=2 terms in N=4 SYM: 1-Loop Calculation in N=2 superspace
The effective action of N=2 gauge multiplets in general includes
higher-dimension UV finite nonholomorphic corrections integrated with the full
N=2 superspace measure. By adding a hypermultiplet in the adjoint
representation we study the effective action of N=4 SYM. The nonanomalous SU(4)
R-symmetry of the classical N=4 theory must be also present in the on-shell
effective action, and therefore we expect to find similar nonholomorphic terms
for each of the scalars in the hypermultiplet. The N=2 path integral
quantization formalism developed in projective superspace allows us to compute
these hypermultiplet nonholomorphic terms directly in N=2 superspace. The
corresponding gauge multiplet expression can be successfully compared with the
result inferred from a N=1 calculation in the abelian subsector.Comment: 12 pages, LaTex, includes 4 .eps figures, sign convention in path
integral definition changed, sign of nonholomorphic potential change
On N=2 low energy effective actions
We propose a Wilsonian action compatible with special geometry and higher
dimension N=2 corrections, and show that the holomorphic contribution F to the
low energy effective action is independent of the infrared cutoff. We further
show that for asymptotically free SU(2) super Yang-Mills theories, the infrared
cutoff can be tuned to cancel leading corrections to F. We also classify all
local higher-dimensional contributions to the N=2 superspace effective action
that produce corrections to the Kahler potential when reduced to N=1
superspace.Comment: 9 pages, Late
The Gaugings of Maximal D=6 Supergravity
We construct the most general gaugings of the maximal D=6 supergravity. The
theory is (2,2) supersymmetric, and possesses an on-shell SO(5,5) duality
symmetry which plays a key role in determining its couplings. The field content
includes 16 vector fields that carry a chiral spinor representation of the
duality group. We utilize the embedding tensor method which determines the
appropriate combinations of these vectors that participate in gauging of a
suitable subgroup of SO(5,5). The construction also introduces the magnetic
duals of the 5 two-form potentials and 16 vector fields.Comment: 34 pages, latex, reference added, typo's corrected and minor
improvements mad
Tensor hierarchies, Borcherds algebras and E11
Gauge deformations of maximal supergravity in D=11-n dimensions generically
give rise to a tensor hierarchy of p-form fields that transform in specific
representations of the global symmetry group E(n). We derive the formulas
defining the hierarchy from a Borcherds superalgebra corresponding to E(n).
This explains why the E(n) representations in the tensor hierarchies also
appear in the level decomposition of the Borcherds superalgebra. We show that
the indefinite Kac-Moody algebra E(11) can be used equivalently to determine
these representations, up to p=D, and for arbitrarily large p if E(11) is
replaced by E(r) with sufficiently large rank r.Comment: 22 pages. v2: Published version (except for a few minor typos
detected after the proofreading, which are now corrected
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
Consistent truncation of d = 11 supergravity on AdS_4 x S^7
We study the system of equations derived twenty five years ago by B. de Wit
and the first author [Nucl. Phys. B281 (1987) 211] as conditions for the
consistent truncation of eleven-dimensional supergravity on AdS_4 x S^7 to
gauged N = 8 supergravity in four dimensions. By exploiting the E_7(7)
symmetry, we determine the most general solution to this system at each point
on the coset space E_7(7)/SU(8). We show that invariants of the general
solution are given by the fluxes in eleven-dimensional supergravity. This
allows us to both clarify the explicit non-linear ansatze for the fluxes given
previously and to fill a gap in the original proof of the consistent
truncation. These results are illustrated with several examples.Comment: 41 pages, typos corrected, published versio
Strong Couplings of X(3872)_{J=1,2} and a New Look at J/psi Suppression in Heavy Ion Collisions
We define and compute from data the strong couplings of the X(3872) with both
of the possible quantum numbers assignments J^{PC}=1^{++},2^{-+}. We use these
to compute cross sections for J/psi resonance scattering into D Dbar*. As an
application of the results obtained we revise the calculation of the J/psi
absorption in a hot hadron gas to confront with recent RHIC observations in
Au-Au collisions.Comment: 23 pages, 18 figures, 4 table
Volume Stabilization and the Origin of the Inflaton Shift Symmetry in String Theory
The main problem of inflation in string theory is finding the models with a
flat potential, consistent with stabilization of the volume of the compactified
space. This can be achieved in the theories where the potential has (an
approximate) shift symmetry in the inflaton direction. We will identify a class
of models where the shift symmetry uniquely follows from the underlying
mathematical structure of the theory. It is related to the symmetry properties
of the corresponding coset space and the period matrix of special geometry,
which shows how the gauge coupling depends on the volume and the position of
the branes. In particular, for type IIB string theory on K3xT^2/Z with D3 or D7
moduli belonging to vector multiplets, the shift symmetry is a part of
SO(2,2+n) symmetry of the coset space [SU(1,1)/ U(1)]x[SO(2,2+n)/(SO(2)x
SO(2+n)]. The absence of a prepotential, specific for the stringy version of
supergravity, plays a prominent role in this construction, which may provide a
viable mechanism for the accelerated expansion and inflation in the early
universe.Comment: 12 page
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