Publications (62)142.27 Total impact

Article: The Slow Gravitino
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ABSTRACT: When the supersymmetry breaking sector is a fluid background, Lorentz invariance is broken spontaneously. The superHiggs mechanism leads to a gravitino Lagrangian with Lorentz symmetry violating terms. We analyse the resulting field equations and constraints. We identify the physical spin 3/2 and spin 1/2 helicity states, derive their equations of motion and construct the propagator. The violation of Lorentz symmetry implies that the longitudinal mode has a nonrelativistic dispersion relation, whose speed is lower than the speed of light. We briefly comment on possible implications to gravitino cosmology and phenomenology.07/2014;  [Show abstract] [Hide abstract]
ABSTRACT: We examine the possibilities for constructing models with Dirac gaugino masses and unification of gauge couplings. We identify one promising model, and discuss to what extent it can have a "natural SUSY" spectrum. We then determine the lowenergy constraints upon it, and propose a constrained set of boundary conditions at the unification scale. We describe the implementation of these boundary conditions in the spectrumgenerator generator \SARAH and we perform a first exploration of the parameter space, specifically searching for points where the spectrum is relatively light. It is shown that the pattern of the masses of SUSY states is very different compared to any expectations from the constrained MSSM.03/2014;  [Show abstract] [Hide abstract]
ABSTRACT: We review the emergence and fate of goldstinos in different frameworks. First, we consider a superHiggs mechanism when supersymmetry breaking is induced by neither an Fterm nor a Dterm but related to a more general stress energymomentum tensor. This allows us to build a novel Lagrangian that describes the propagation of a spin3/2 state in a fluid. Then we briefly review the ubiquitous pseudogoldstinos when breaking supersymmetry in an extra dimension. We remind that the fermion (gravitino or gaugino) soft masses can be tuned to be of Diractype. Finally, we briefly connect the latter to the study of models with Diractype gaugino masses and stress the advantage of having both an F and a Dterm sizable contributions for the hierarchies of softterms as well as for minimizing Rsymmetry breaking.The European Physical Journal Conferences 02/2014; 71.  [Show abstract] [Hide abstract]
ABSTRACT: We consider a scenario where supersymmetry is broken at a high energy scale, out of reach of the LHC, but leaves a few fermionic states at the TeV scale. The particle content of the lowenergy effective theory is similar to that of Split Supersymmetry. However, the gauginos and higgsinos are replaced by fermions carrying the same quantum numbers but having different couplings, which we call fake gauginos and fake higgsinos. We study the prediction for the lightHiggs mass in this Fake Split SUSY Model (FSSM). We find that, in contrast to Split or highscale supersymmetry, a 126 GeV Higgs boson is easily obtained even for arbitrarily high values of the supersymmetry scale. For a supersymmetry scale greater than roughly 100 PeV, the Higgs mass is almost independent of the supersymmetry scale and the stop mixing parameter, while the observed value is achieved for tan beta between 1.3 and 1.8 depending on the gluino mass.12/2013; 
Article: The SuperHiggs Mechanism in Fluids
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ABSTRACT: Supersymmetry is spontaneously broken when the field theory stressenergy tensor has a nonzero vacuum expectation value. In local supersymmetric field theories the massless gravitino and goldstino combine via the superHiggs mechanism to a massive gravitino. We study this mechanism in fourdimensional fluids, where the vacuum expectation value of the stressenergy tensor breaks spontaneously both supersymmetry and Lorentz symmetry. We consider both constant as well as spacetime dependent ideal fluids. We derive a formula for the gravitino mass in terms of the fluid velocity, energy density and pressure. We discuss some of the phenomenological implications.10/2013; 
Article: Dirac Gauginos and the 125 GeV Higgs
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ABSTRACT: We investigate the mass, production and branching ratios of a 125 GeV Higgs in models with Dirac gaugino masses. We give a discussion of naturalness, and describe how deviations from the Standard Model in the key Higgs search channels can be simply obtained. We then perform parameter scans using a SARAH package upgrade, which produces SPheno code that calculates all relevant quantities, including electroweak precision and flavour constraint data, to a level of accuracy previously impossible for this class of models. We study three different variations on the minimal Dirac gaugino extension of the (N)MSSM.Journal of High Energy Physics 11/2012; 2013(6). · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We review the status of lowscale string theories and large extradimensions. After an overview on different string realizations, we discuss some of the main important problems and we summarize present bounds on the size of possible extradimensions from collider experiments.International Journal of Modern Physics A 01/2012; 15(27). · 1.13 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: This proceeding is based on arXiv:1105.0591 [hepth] where we consider breaking of supersymmetry in intersecting Dbrane configurations by slight deviation of the angles from their supersymmetric values. We compute the masses generated by radiative corrections for the adjoint scalars on the brane worldvolumes. In the open string channel, the string twopoint function receives contributions only from the infrared limits of N~4 and N~2 supersymmetric configurations, via messengers and their KaluzaKlein excitations, and leads at leading order to tachyonic directions.01/2012; 
Article: Dirac Gauginos: A User Manual
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ABSTRACT: The issue of a Majorana, Dirac or pseudoDirac mass for gauginos must not be reduced to a question of an extension of the Minimal Supersymmetric Standard Model by extra states, parameters and phenomenological implications. On the contrary, it is intimately related to the fundamental issue of the realization of new symmetries in nature, Rsymmetries. We present here a very dense compilation of the main features of models with (pseudo)Dirac gauginos.Fortschritte der Physik 06/2011; · 0.98 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We consider breaking of supersymmetry in intersecting Dbrane configurations by slight deviation of the angles from their supersymmetric values. We compute the masses generated by radiative corrections for the adjoint scalars on the brane worldvolumes. In the open string channel, the string twopoint function receives contributions only from the infrared and the ultraviolet limits. The latter is due to treelevel closed string uncanceled NSNS tadpoles, which we explicitly reproduce from the effective BornInfeld action. On the other hand, the infrared region reproduces the oneloop mediation of supersymmetry breaking in the effective gauge theory, via messengers and their KaluzaKlein excitations. In the toroidal setup considered here, it receives contributions only from broken N=4 and N=2 supersymmetric configurations, and thus always leads at leading order to a tachyonic direction, in agreement with effective field theory expectations.Journal of High Energy Physics 05/2011; 8. · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We consider the extension of the Minimal Supersymmetric Standard Model by Dirac masses for the gauginos. We study the possibility that the same singlet that pairs up with the bino, to form a Dirac fermion, is used to generate mu and Bmu terms through its vacuum expectation value. For this purpose, we assume that, in the Higgs potential, the necessary Rsymmetry breaking originates entirely from a superpotential term cubic in the singlet and discuss the implications for the spectrum of the model.04/2011;  [Show abstract] [Hide abstract]
ABSTRACT: We consider the extension of the Minimal Supersymmetric Standard Model by Dirac masses for the gauginos. We study the possibility that the same singlet S that pairs up with the bino, to form a Dirac fermion, is used to generate μ and Bμ terms through its vacuum expectation value. For this purpose, we assume that, in the Higgs potential, the necessary Rsymmetry breaking originates entirely from a superpotential term κ3S3 and discuss the implications for the spectrum of the model.Nuclear Physics B 01/2011; 851(3):445461. · 4.33 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We investigate the building of models with Dirac gauginos and perturbative gauge coupling unification. Here, in contrast to the MSSM, additional fields are required for unification, and these can naturally play the role of the messengers of supersymmetry breaking. We present a framework within which such models can be constructed, including the constraints that the messenger sector must satisfy; and the renormalisation group equations for the soft parameters, which differ from those of the MSSM. For illustration, we provide the spectrum at the electroweak scale for explicit models whose gauge couplings unify at the scale predicted by heterotic strings.Nuclear Physics B 03/2010; · 4.33 Impact Factor 
Article: Disordered Extra Dimensions
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ABSTRACT: A very large extra dimension may contain many localized branes. We discuss the possibility to formulate such models as a spin system where each spin indicates the supersymmetry direction preserved by the corresponding brane. In the evolution of the universe, the extra dimensions might have ended into a vacuum made of patches with different orientation of the spins, responsible for the observed breaking of supersymmetry. We discuss the limit where the separation of these patches is by very thin defects described as localization of gravitino masses. Comment: 15 pages, no figure. Typos corrected. References added. Version accepted for publication.New Journal of Physics 02/2010; · 4.06 Impact Factor 
Article: Dirac gauginos and kinetic mixing
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ABSTRACT: We present formulae for the calculation of Dirac gaugino masses at leading order in the supersymmetry breaking scale using the methods of analytic continuation in superspace and demonstrate a link with kinetic mixing, even for nonabelian gauginos. We illustrate the result through examples in field and string theory. We discuss the possibility that the singlet superfield that gives the U(1) gaugino a Dirac mass may be a modulus, and some consequences of the Dterm coupling to the scalar component. We give examples of possible effects in colliders and astroparticle experiments if the modulus scalar constitutes decaying dark matter.Nuclear Physics B 08/2009; · 4.33 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We consider the minimal supersymmetric extension of the Standard Model allowing both Dirac and Majorana gauginos. The Dirac masses are obtained by pairing up extra chiral multiplets: a singlet S for U(1)_Y, a triplet T for SU(2) and an octet O for SU(3) with the respective gauginos. The electroweak symmetry breaking sector is modified by the couplings of the new fields S and T to the Higgs doublets. We discuss two limits: i) both the adjoint scalars are decoupled with the main effect being the modification of the Higgs quartic coupling; ii) the singlet remaining light, and due to its direct coupling to sfermions, providing a new contribution to the soft masses and inducing new decay/production channels. We discuss the LSP in this scenario; after mentioning the possibility that it may be a Dirac gravitino, we focus on the case where it is identified with the lightest neutralino, and exhibit particular values of the parameter space where the relic density is in agreement with WMAP data. This is illustrated for different scenarios where the LSP is either a bino (in which case it can be a Dirac fermion) or binohiggsino/wino mixtures. We also point out in each case the peculiarity of the model with respect to dark matter detection experiments. Comment: 43 pages, 5 figures; one reference added. Corresponds to published version in JCAPJournal of Cosmology and Astroparticle Physics 05/2009; · 6.04 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We extend the formulation by Meade, Seiberg and Shih of general gauge mediation of supersymmetry breaking to include Dirac masses for the gauginos. These appear through mixing of the visible sector gauginos with additional states in adjoint representations. We illustrate the method by reproducing the existing results in the literature for the gaugino and sfermion masses when preserving Rsymmetry. We then explain how the generation of same sign masses for the two propagating degrees of freedom in the adjoint scalars can be achieved. We end by commenting on the use of the formalism for describing U(1) mixing.Nuclear Physics B 11/2008; · 4.33 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We compute the twopoint functions for chiral matter states in toroidal intersecting D6brane models. In particular, we provide the techniques to calculate Moebius strip diagrams including the worldsheet instanton contribution.Nuclear Physics B 06/2008; · 4.33 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: This collection of studies on new physics at the LHC constitutes the report of the supersymmetry working group at the Workshop `Physics at TeV Colliders', Les Houches, France, 2007. They cover the wide spectrum of phenomenology in the LHC era, from alternative models and signatures to the extraction of relevant observables, the study of the MSSM parameter space and finally to the interplay of LHC observations with additional data expected on a similar time scale. The special feature of this collection is that while not each of the studies is explicitely performed together by theoretical and experimental LHC physicists, all of them were inspired by and discussed in this particular environment.03/2008; 
Article: BraneWorlds PseudoGoldstinos
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ABSTRACT: We consider a spacetime with extra dimensions containing sectors, branes and bulk, that communicate only through gravitational interactions. In each sector, if considered separately, supersymmetry could be spontaneously broken, leading to the appearance of Goldstinos. However, when taken all together, only certain combinations of the latter states turn out to be true ``would be Goldstinos'', eaten by the gravitinos. The other (orthogonal) combinations, we call pseudoGoldstinos, remain in the low energy spectrum. We discuss explicitly how this happen in the simplest setup of fivedimensional space compactified on S^1/Z_2 . Our results divide into two parts that can be considered separately. First, we build an extension of the bulk fivedimensional supergravity, by a set of new auxiliary fields, that allows coupling it to branes where supersymmetry is spontaneously broken. Second, we discuss in details the super Higgs mechanism in the R_\xi and unitary gauges, in the presence of both of a bulk ScherkSchwarz mechanism and brane localized Fterms. This leads us to compute the gravitino mass and provide explicit formulae for the pseudoGoldstinos spectrum.Nuclear Physics B 07/2007; · 4.33 Impact Factor
Publication Stats
2k  Citations  
142.27  Total Impact Points  
Top Journals
Institutions

2011

Polytech ParisUPMC
Lutetia Parisorum, ÎledeFrance, France


2010

Deutsches ElektronenSynchrotron
Hamburg, Hamburg, Germany


2007–2009

Pierre and Marie Curie University  Paris 6
Lutetia Parisorum, ÎledeFrance, France


1998–2006

CERN
 Physics Department (PH)
Genève, Geneva, Switzerland


2003

Université de Neuchâtel
 Institut de physique (IPH)
Neuenburg, Neuchâtel, Switzerland


1999

Texas A&M University
 Department of Physics and Astronomy
College Station, Texas, United States


1996

Abdus Salam International Centre for Theoretical Physics
Trst, Friuli Venezia Giulia, Italy


1992

École Polytechnique
 Centre de Physique Théorique
Paliseau, ÎledeFrance, France
