4,161 research outputs found
N=8 BPS black holes preserving 1/8 supersymmetry
In the context of N=8 supergravity we consider BPS black-holes that preserve
1/8 supersymmetry. It was shown in a previous paper that, modulo U-duality
transformations of E_{7(7)} the most general solution of this type can be
reduced to a black-hole of the STU model. In this paper we analize this
solution in detail, considering in particular its embedding in one of the
possible Special K\"ahler manifold compatible with the consistent truncations
to N=2 supergravity, this manifold being the moduli space of the T^6/Z^3
orbifold, that is: SU(3,3)/SU(3)*U(3). This construction requires a crucial use
of the Solvable Lie Algebra formalism. Once the group-theoretical analisys is
done, starting from a static, spherically symmetric ans\"atz, we find an exact
solution for all the scalars (both dilaton and axion-like) and for gauge
fields, together with their already known charge-dependent fixed values, which
yield a U-duality invariant entropy. We give also a complete translation
dictionary between the Solvable Lie Algebra and the Special K\"ahler formalisms
in order to let comparison with other papers on similar issues being more
immediate. Although the explicit solution is given in a simplified case where
the equations turn out to be more manageable, it encodes all the features of
the more general one, namely it has non-vanishing entropy and the scalar fields
have a non-trivial radial dependence.Comment: 29+1 pages, 1 Latex file; a misprint in the entropy formula,
eq.(5.14), correcte
More Anomalies from Fractional Branes
In this note we show how the anomalies of both pure and matter coupled N=1,2
supersymmetric gauge theories describing the low energy dynamics of fractional
branes on orbifolds can be derived from supergravity.Comment: 11 pages, latex; v2: minor typos fixe
N=2 four-dimensional gauge theories from fractional branes
This is a pedagogical and extended version of the results published in Refs.
[1,2] and presented by the authors in various talks during the last year. We
discuss the type II D-branes (both regular and fractional) of the orbifold
R^{1,5}*R^4/Z_2, we determine their corresponding supergravity solution and
show how this can be used to study the properties of N=2 super Yang-Mills.
Supergravity is able to reproduce the perturbative moduli space of the gauge
theory, while it does not encode the non-perturbative corrections. The short
distance region of space-time, which corresponds to the infrared region of the
gauge theory, is excised by an enhancon mechanism, and more states should be
included in the low energy effective action in order to enter inside the
enhancon and recover the instanton corrections. (To be published on a Memorial
Volume commemorating Michael Marinov)Comment: 44 pages, AMS-LaTeX, no figure
Overview on Rural Poverty in Developed Countries
Despite the long tradition of intervention, rural poverty is still an important issue to face in the economic and social growth of developed countries. Often hidden for many reason recalled in the paper, rural poverty is transmitted by the cumulative negative effects of vicious circle of labour market, demography, education and remoteness. Agricultural and rural policy with social policy has reached important result for reducing rural poverty in developed countries, especially promoting diversification of rural area and sustainability approach to the production. The paper underlines the role of coordination between top-down and place-based policies, as well as the indicators for adapting policies and having successful intervention, shortly discussing some examples of good practices
Fractional Branes and N=1 Gauge Theories
We discuss fractional D3-branes on the orbifold C^3/Z_2*Z_2. We study the
open and the closed string spectrum on this orbifold. The corresponding N=1
theory on the brane has, generically, a U(N_1)*U(N_2)*U(N_3)*U(N_4) gauge group
with matter in the bifundamental. In particular, when only one type of brane is
present, one obtains pure N=1 Yang-Mills. We study the coupling of the branes
to the bulk fields and present the corresponding supergravity solution, valid
at large distances. By using a probe analysis, we are able to obtain the
Wilsonian beta-function for those gauge theories that possess some chiral
multiplet. Although, due to the lack of moduli, the probe technique is not
directly applicable to the case of pure N=1 Yang-Mills, we point out that the
same formula gives the correct result also for this case.Comment: 21 pages, AMS-LaTeX, v2: references added and typos correcte
D-branes, Orientifolds and K-theory
The complete D-brane spectrum in ZZ[squared] orientifolds is computed. Stable non-BPS D-branes with both integral and torsion charges are found. The relation to K-theory is discussed and a new K-theory relevant to orientifolds is suggested
Closed string exchanges on in a background B-field
In an earlier work it was shown that the IR singularities arising in the
nonplanar one loop two point function of a noncommutative gauge
theory can be reproduced exactly from the massless closed string exchanges. The
noncommutative gauge theory is realised on a fractional brane localised
at the fixed point of the orbifold. In this paper we identify the
contributions from each of the closed string modes. The sum of these adds upto
the nonplanar two-point function.Comment: 27 page
Supersymmetry breaking at the end of a cascade of Seiberg dualities
We study the IR dynamics of the cascading non-conformal quiver theory on N
regular and M fractional D3 branes at the tip of the complex cone over the
first del Pezzo surface. The horizon of this cone is the irregular
Sasaki-Einstein manifold Y^{2,1}. Our analysis shows that at the end of the
cascade supersymmetry is dynamically broken.Comment: 12 pages, 2 figures, minor changes, typos correcte
The Trispectrum in the Effective Field Theory of Large Scale Structure
We compute the connected four point correlation function (the trispectrum in
Fourier space) of cosmological density perturbations at one-loop order in
Standard Perturbation Theory (SPT) and the Effective Field Theory of Large
Scale Structure (EFT of LSS). This paper is a companion to our earlier work on
the non-Gaussian covariance of the matter power spectrum, which corresponds to
a particular wavenumber configuration of the trispectrum. In the present
calculation, we highlight and clarify some of the subtle aspects of the EFT
framework that arise at third order in perturbation theory for general
wavenumber configurations of the trispectrum. We consistently incorporate
vorticity and non-locality in time into the EFT counterterms and lay out a
complete basis of building blocks for the stress tensor. We show predictions
for the one-loop SPT trispectrum and the EFT contributions, focusing on
configurations which have particular relevance for using LSS to constrain
primordial non-Gaussianity.Comment: 25+3 pages, 7 figure
- …