Karim Benakli - Academia.edu (original) (raw)
Papers by Karim Benakli
Supersymmetry and Electroweak Breaking by Extra Dimensions
Acta Physica Polonica Series B
ABSTRACT
New Journal of Physics, 2001
We identify a class of chiral models where the one-loop effective potential for Higgs scalar fiel... more We identify a class of chiral models where the one-loop effective potential for Higgs scalar fields is finite without any requirement of supersymmetry. It corresponds to the case where the Higgs fields are identified with the components of a gauge field along compactified extra dimensions. We present a six dimensional model with gauge group U (3) × U (3) and quarks and leptons accomodated in fundamental and bi-fundamental representations. The model can be embedded in a D-brane configuration of type I string theory and, upon compactification on a T 2 /Z 2 orbifold, it gives rise to the standard model with two Higgs doublets. * On leave of absence from CPHT, Ecole Polytechnique, UMR du CNRS 7644.
Journal of High Energy Physics, 2014
When the supersymmetry breaking sector is a fluid background, Lorentz invariance is broken sponta... more When the supersymmetry breaking sector is a fluid background, Lorentz invariance is broken spontaneously. The super-Higgs 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 non-relativistic dispersion relation, whose speed is lower than the speed of light. We briefly comment on possible implications to gravitino cosmology and phenomenology. a kbenakli@lpthe.jussieu.fr b darme@lpthe.jussieu.fr c yaronoz@post.tau.ac.il
Brane-worlds pseudo-Goldstinos
We propose a class of models with gauge mediation of supersymmetry breaking, inspired by simple b... more We propose a class of models with gauge mediation of supersymmetry breaking, inspired by simple brane constructions, where R-symmetry is very weakly broken. The gauge sector has an extended N=2 supersymmetry and the two electroweak Higgses form an N=2 hypermultiplet, while quarks and leptons remain in N=1 chiral multiplets. Supersymmetry is broken via the D-term expectation value of a secluded
Journal of High Energy Physics, 2014
We consider a scenario where supersymmetry is broken at a high energy scale, out of reach of the ... more 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 low-energy 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 light-Higgs mass in this Fake Split SUSY Model (FSSM). We find that, in contrast to Split or high-scale supersymmetry, a 126 GeV Higgs boson is easily obtained even for arbitrarily high values of the supersymmetry scale M S . For M S 10 8 GeV, the Higgs mass is almost independent of the supersymmetry scale and the stop mixing parameter, while the observed value is achieved for tan β between 1.3 and 1.8 depending on the gluino mass.
Journal of High Energy Physics, 2001
We compute the tree-level four-point scattering amplitudes in string models where matter fields l... more We compute the tree-level four-point scattering amplitudes in string models where matter fields live on D-brane intersections. Extracting the contribution of massless modes, we are left with dimension-six four-fermion operators which in general receive contributions from three different sources: exchange of massive Kaluza-Klein excitations, winding modes and string oscillator states. We compute their coefficients and extract new bounds on the string scale in the brane-world scenario. This is contrasted with the situation where matter fields arise from open strings with both ends confined on the same collection of D-branes, in which case the exchange of massive string modes leads to dimension-eight operators that have been studied in the past. When matter fields live on brane intersections, the presence of dimension-six operators increases the lower bound on the string scale to 2-3 TeV, independently of the number of large extra dimensions.
Physics Letters B, 2006
We show how splitting supersymmetry reconciles a class of intersecting brane models with unificat... more We show how splitting supersymmetry reconciles a class of intersecting brane models with unification. The gauge sector in these models arises in multiplets of extended supersymmetry while matter states are in N = 1 representations. A deformation of the angles between the branes gives large masses to squarks and sleptons, as well as supersymmetry breaking contributions to other string states. The latter generate at one-loop heavy Dirac masses for Winos and gluinos and can induce a mass term for the Higgsino doublets. We find that this scenario is compatible with gauge coupling unification at high scale for both cases where the gauge sector is N = 2 and N = 4 supersymmetric. Moreover a neutralino, combination of neutral Higgsinos and Binos, is a natural candidate for dark matter. * On leave of absence from CPHT, Ecole Polytechnique, UMR du CNRS 7644
Nuclear Physics B, 2000
We propose a way to generate the electroweak symmetry breaking radiatively in nonsupersymmetric t... more We propose a way to generate the electroweak symmetry breaking radiatively in nonsupersymmetric type I models with string scale in the TeV region. By identifying the Higgs field with a tree-level massless open string state, we find that a negative squared mass term can be generated at one loop. It is finite, computable and typically a loop factor smaller than the string scale, that acts as an ultraviolet cutoff in the effective field theory. When the Higgs open string has both ends confined on our world brane, its mass is predicted to be around 120 GeV, i.e. that of the lightest Higgs in the minimal supersymmetric model for large tan β and m A . Moreover, the string scale turns out to be one to two orders of magnitude higher than the weak scale. We also discuss possible effects of higher order string threshold corrections that might increase the string scale and the Higgs mass.
Nuclear Physics B, 2002
We study a class of type I string models with supersymmetry broken on the world-volume of some D-... more We study a class of type I string models with supersymmetry broken on the world-volume of some D-branes and vanishing tree-level potential. Despite the non-supersymmetric spectrum, supersymmetry is non-linearly realized on these D-branes, while it is spontaneously broken in the bulk by Scherk-Schwarz boundary conditions. These models can easily accommodate 3-branes with interesting gauge groups and chiral fermions. We also study the effective field theory and in particular we compute the four-fermion couplings of the localized Goldstino with the matter fermions on the brane. * On leave of absence from CPHT, Ecole Polytechnique, UMR du CNRS 7644. 1 The parameter C f is related to the parametrisation of other authors by C f = − α 4 [17] = C f f 2 [18].
Nuclear Physics B, 2006
We study string realizations of split extended supersymmetry, recently proposed in hep-ph/0507192... more We study string realizations of split extended supersymmetry, recently proposed in hep-ph/0507192. Supersymmetry is broken by small (ǫ) deformations of intersection angles of D-branes giving tree-level masses of order m 2 0 ∼ ǫM 2 s , where M s is the string scale, to localized scalars. We show through an explicit one-loop string amplitude computation that gauginos acquire hierarchically smaller Dirac masses m D 1/2 ∼ m 2 0 /M s . We also evaluate the one-loop Higgsino mass, µ, and show that, in the absence of tree-level contributions, it behaves as µ ∼ m 4 0 /M 3 s . Finally we discuss an alternative suppression of scales using large extra dimensions. The latter is illustrated, for the case where the gauge bosons appear in N = 4 representations, by an explicit string model with Standard Model gauge group, three generations of quarks and leptons and gauge coupling unification. * On leave of absence from CPHT, Ecole Polytechnique, UMR du CNRS 7644
Brane-worlds pseudo-Goldstinos
Nuclear Physics B, 2008
... Second, we discuss in details the super-Higgs mechanism in the R ξ and unitary gauges, in the... more ... Second, we discuss in details the super-Higgs mechanism in the R ξ and unitary gauges, in the presence of both of a bulk ScherkSchwarz mechanism and brane localized F-terms. ... The generalized ScherkSchwarz mechanism, as introduced by Bagger et al. ...
Comptes Rendus Physique, 2003
Transverse (submillimeter) and longitudinal (TeV) extra dimensions can help in dealing with the H... more Transverse (submillimeter) and longitudinal (TeV) extra dimensions can help in dealing with the Higgs hierarchy problem. On the one hand large transverse dimensions can lower the fundamental scale of quantum gravity from the Planck scale to the TeV range. On the other hand longitudinal dimensions can provide genuine extra-dimensional symmetries (higher dimensional gauge symmetry and/or supersymmetry) to protect the Higgs mass against ultraviolet sensitivity. In this article we review recent developments along these directions.
Physics Letters B, 1994
Perturbative breaking of supersymmetry in four-dimensional string theories predict in general the... more Perturbative breaking of supersymmetry in four-dimensional string theories predict in general the existence of new large dimensions at the TeV scale. Such large dimensions lie in a domain of energies accessible to particle accelerators. Their main signature is the production of Kaluza-Klein excitations which can be detected at future colliders. We study this possibility for hadron colliders (TEVATRON, LHC) and e + e − colliders (LEP-200, NLC-500). * Laboratoire Propre du CNRS UPR A.0014
Supersymmetry and Electroweak Breaking by Extra Dimensions
Acta Physica Polonica Series B
ABSTRACT
New Journal of Physics, 2001
We identify a class of chiral models where the one-loop effective potential for Higgs scalar fiel... more We identify a class of chiral models where the one-loop effective potential for Higgs scalar fields is finite without any requirement of supersymmetry. It corresponds to the case where the Higgs fields are identified with the components of a gauge field along compactified extra dimensions. We present a six dimensional model with gauge group U (3) × U (3) and quarks and leptons accomodated in fundamental and bi-fundamental representations. The model can be embedded in a D-brane configuration of type I string theory and, upon compactification on a T 2 /Z 2 orbifold, it gives rise to the standard model with two Higgs doublets. * On leave of absence from CPHT, Ecole Polytechnique, UMR du CNRS 7644.
Journal of High Energy Physics, 2014
When the supersymmetry breaking sector is a fluid background, Lorentz invariance is broken sponta... more When the supersymmetry breaking sector is a fluid background, Lorentz invariance is broken spontaneously. The super-Higgs 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 non-relativistic dispersion relation, whose speed is lower than the speed of light. We briefly comment on possible implications to gravitino cosmology and phenomenology. a kbenakli@lpthe.jussieu.fr b darme@lpthe.jussieu.fr c yaronoz@post.tau.ac.il
Brane-worlds pseudo-Goldstinos
We propose a class of models with gauge mediation of supersymmetry breaking, inspired by simple b... more We propose a class of models with gauge mediation of supersymmetry breaking, inspired by simple brane constructions, where R-symmetry is very weakly broken. The gauge sector has an extended N=2 supersymmetry and the two electroweak Higgses form an N=2 hypermultiplet, while quarks and leptons remain in N=1 chiral multiplets. Supersymmetry is broken via the D-term expectation value of a secluded
Journal of High Energy Physics, 2014
We consider a scenario where supersymmetry is broken at a high energy scale, out of reach of the ... more 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 low-energy 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 light-Higgs mass in this Fake Split SUSY Model (FSSM). We find that, in contrast to Split or high-scale supersymmetry, a 126 GeV Higgs boson is easily obtained even for arbitrarily high values of the supersymmetry scale M S . For M S 10 8 GeV, the Higgs mass is almost independent of the supersymmetry scale and the stop mixing parameter, while the observed value is achieved for tan β between 1.3 and 1.8 depending on the gluino mass.
Journal of High Energy Physics, 2001
We compute the tree-level four-point scattering amplitudes in string models where matter fields l... more We compute the tree-level four-point scattering amplitudes in string models where matter fields live on D-brane intersections. Extracting the contribution of massless modes, we are left with dimension-six four-fermion operators which in general receive contributions from three different sources: exchange of massive Kaluza-Klein excitations, winding modes and string oscillator states. We compute their coefficients and extract new bounds on the string scale in the brane-world scenario. This is contrasted with the situation where matter fields arise from open strings with both ends confined on the same collection of D-branes, in which case the exchange of massive string modes leads to dimension-eight operators that have been studied in the past. When matter fields live on brane intersections, the presence of dimension-six operators increases the lower bound on the string scale to 2-3 TeV, independently of the number of large extra dimensions.
Physics Letters B, 2006
We show how splitting supersymmetry reconciles a class of intersecting brane models with unificat... more We show how splitting supersymmetry reconciles a class of intersecting brane models with unification. The gauge sector in these models arises in multiplets of extended supersymmetry while matter states are in N = 1 representations. A deformation of the angles between the branes gives large masses to squarks and sleptons, as well as supersymmetry breaking contributions to other string states. The latter generate at one-loop heavy Dirac masses for Winos and gluinos and can induce a mass term for the Higgsino doublets. We find that this scenario is compatible with gauge coupling unification at high scale for both cases where the gauge sector is N = 2 and N = 4 supersymmetric. Moreover a neutralino, combination of neutral Higgsinos and Binos, is a natural candidate for dark matter. * On leave of absence from CPHT, Ecole Polytechnique, UMR du CNRS 7644
Nuclear Physics B, 2000
We propose a way to generate the electroweak symmetry breaking radiatively in nonsupersymmetric t... more We propose a way to generate the electroweak symmetry breaking radiatively in nonsupersymmetric type I models with string scale in the TeV region. By identifying the Higgs field with a tree-level massless open string state, we find that a negative squared mass term can be generated at one loop. It is finite, computable and typically a loop factor smaller than the string scale, that acts as an ultraviolet cutoff in the effective field theory. When the Higgs open string has both ends confined on our world brane, its mass is predicted to be around 120 GeV, i.e. that of the lightest Higgs in the minimal supersymmetric model for large tan β and m A . Moreover, the string scale turns out to be one to two orders of magnitude higher than the weak scale. We also discuss possible effects of higher order string threshold corrections that might increase the string scale and the Higgs mass.
Nuclear Physics B, 2002
We study a class of type I string models with supersymmetry broken on the world-volume of some D-... more We study a class of type I string models with supersymmetry broken on the world-volume of some D-branes and vanishing tree-level potential. Despite the non-supersymmetric spectrum, supersymmetry is non-linearly realized on these D-branes, while it is spontaneously broken in the bulk by Scherk-Schwarz boundary conditions. These models can easily accommodate 3-branes with interesting gauge groups and chiral fermions. We also study the effective field theory and in particular we compute the four-fermion couplings of the localized Goldstino with the matter fermions on the brane. * On leave of absence from CPHT, Ecole Polytechnique, UMR du CNRS 7644. 1 The parameter C f is related to the parametrisation of other authors by C f = − α 4 [17] = C f f 2 [18].
Nuclear Physics B, 2006
We study string realizations of split extended supersymmetry, recently proposed in hep-ph/0507192... more We study string realizations of split extended supersymmetry, recently proposed in hep-ph/0507192. Supersymmetry is broken by small (ǫ) deformations of intersection angles of D-branes giving tree-level masses of order m 2 0 ∼ ǫM 2 s , where M s is the string scale, to localized scalars. We show through an explicit one-loop string amplitude computation that gauginos acquire hierarchically smaller Dirac masses m D 1/2 ∼ m 2 0 /M s . We also evaluate the one-loop Higgsino mass, µ, and show that, in the absence of tree-level contributions, it behaves as µ ∼ m 4 0 /M 3 s . Finally we discuss an alternative suppression of scales using large extra dimensions. The latter is illustrated, for the case where the gauge bosons appear in N = 4 representations, by an explicit string model with Standard Model gauge group, three generations of quarks and leptons and gauge coupling unification. * On leave of absence from CPHT, Ecole Polytechnique, UMR du CNRS 7644
Brane-worlds pseudo-Goldstinos
Nuclear Physics B, 2008
... Second, we discuss in details the super-Higgs mechanism in the R ξ and unitary gauges, in the... more ... Second, we discuss in details the super-Higgs mechanism in the R ξ and unitary gauges, in the presence of both of a bulk ScherkSchwarz mechanism and brane localized F-terms. ... The generalized ScherkSchwarz mechanism, as introduced by Bagger et al. ...
Comptes Rendus Physique, 2003
Transverse (submillimeter) and longitudinal (TeV) extra dimensions can help in dealing with the H... more Transverse (submillimeter) and longitudinal (TeV) extra dimensions can help in dealing with the Higgs hierarchy problem. On the one hand large transverse dimensions can lower the fundamental scale of quantum gravity from the Planck scale to the TeV range. On the other hand longitudinal dimensions can provide genuine extra-dimensional symmetries (higher dimensional gauge symmetry and/or supersymmetry) to protect the Higgs mass against ultraviolet sensitivity. In this article we review recent developments along these directions.
Physics Letters B, 1994
Perturbative breaking of supersymmetry in four-dimensional string theories predict in general the... more Perturbative breaking of supersymmetry in four-dimensional string theories predict in general the existence of new large dimensions at the TeV scale. Such large dimensions lie in a domain of energies accessible to particle accelerators. Their main signature is the production of Kaluza-Klein excitations which can be detected at future colliders. We study this possibility for hadron colliders (TEVATRON, LHC) and e + e − colliders (LEP-200, NLC-500). * Laboratoire Propre du CNRS UPR A.0014