Добірка наукової літератури з теми "Unconventional Supersymmetry"

An unconventional version of supersymmetry leads to the following highly teatable predictions: (1) the Higgs boson has an R-parity of -1, so it can only be produced as one member of a pair of superpartners. (2) The only superpartners are scalar bosons, so neutralinos etc. do not exist. (3) The most likely candidate for cold dark matter is therefore a sneutrino. (4) The Higgs and other bosonic superpartners have an unconventional equation of motion. These predictions are associated with new interpretations of Yukawa couplings, supersymmetry, gauge fields, and Lorentz invariance.

It has been argued in previous works by the authors that nodal excitations in (2 + 1)-dimensional doped antiferromagnets might exhibit, in the spin-charge separation framework and at specific regions of the parameter space, a supersymmetry between spinons and holons. This supersymmetry has been elevated to a N = 2 extended supersymmetry of composite operators of spinon and holons, corresponding to the effective "hadronic" degrees of freedom. In this work we elaborate further on this idea by describing in some detail the dynamics of a specific composite model corresponding to an Abelian Higgs model (SQED). The Abelian nature of the gauge group seems to be necessitated both by the composite structure used, and also by electric charge considerations for the various composites. We demonstrate the passage from a pseudogap to an unconventional superconducting phase, which notably is an exact non-perturbative analytic result, due to the underlying N = 2 supersymmetric Abelian gauge theory. We believe that these considerations may provide a first step towards a non-perturbative understanding of the phase diagrams of strongly-correlated electron systems.

In supersymmetric extensions of the Standard Model, the observed particles come in fermion–boson pairs necessary for the realization of supersymmetry (SUSY). In spite of the expected abundance of super-partners for all the known particles, not a single supersymmetric pair has been reported to date. Although a hypothetical SUSY breaking mechanism, operating at high energy inaccessible to current experiments cannot be ruled out, this reduces SUSY’s predictive power and it is unclear whether SUSY, in its standard form, can help reducing the remaining puzzles of the standard model (SM). Here we argue that SUSY can be realized in a different way, connecting spacetime and internal bosonic symmetries, combining bosonic gauge fields and fermionic matter particles in a single gauge field, a Lie superalgebra-valued connection. In this unconventional representation, states do not come in SUSY pairs, avoiding the doubling of particles and fields and SUSY is not a fully off-shell invariance of the action. The resulting systems are remarkably simple, closely resembling a standard quantum field theory and SUSY still emerges as a contingent symmetry that depends on the features of the vacuum/ground state. We illustrate the general construction with two examples: (i) A 2 + 1 dimensional system based on the osp(2,2|2) superalgebra, including Lorentz and u(1) generators that describe graphene; (ii) a supersymmetric extension of 3 + 1 conformal gravity with an SU(2,2|2) connection that describes a gauge theory with an emergent chiral symmetry breaking, coupled to gravity. The extensions to higher odd and even dimensions, as well as the extensions to accommodate more general internal symmetries are also outlined.

We discuss the possibility to absorb all anomalies in the supersymmetry algebra of the N=(1,1) Wess–Zumino model in d=1+1 by a local counterterm. This counterterm corresponds to the change of the vacuum parameter [Formula: see text] in the model and the transition to an unconventional but admissible renormalization scheme. It does not modify the physical consequences such as BPS saturation, and thus the situation is rather different from gauge theory where local counterterms are required to absorb spurious gauge anomalies.

We exploit an index theorem and a high degree of symmetry to understand unusual quantum Hall effects of the n = 0 Landau level in graphene. The high symmetry such as the pseudospin symmetry of Fermi points in a graphene sheet cannot couple to an external magnetic field. In the absence of the magnetic field, the index theorem provides a relation between the zero-energy state of the graphene sheet and the topological deformation of the compact lattice. Under the topological deformation, the zero-energy state emerges naturally without the Zeeman splitting at the Fermi points in the graphene sheet. This results in the fact that the pseudospin is an exact symmetry. In the case of nonzero energy, the up-spin and down-spin states have the exact high symmetry of spin, forming the pseudospin singlet pairing. We describe the peculiar and unconventional quantum Hall effects of the n = 0 Landau level in graphene on the basis of the index theorem and the high degree of symmetry.

AbstractWe consider algebraic varieties canonically associated with any Lie superalgebra, and study them in detail for super-Poincaré algebras of physical interest. They are the locus of nilpotent elements in (the projectivized parity reversal of) the odd part of the algebra. Most of these varieties have appeared in various guises in previous literature, but we study them systematically here, from a new perspective: As the natural moduli spaces parameterizing twists of a super-Poincaré-invariant physical theory. We obtain a classification of all possible twists, as well as a systematic analysis of unbroken symmetry in twisted theories. The natural stratification of the varieties, the identification of strata with twists, and the action of Lorentz and R-symmetry are emphasized. We also include a short and unconventional exposition of the pure spinor superfield formalism, from the perspective of twisting, and demonstrate that it can be applied to construct familiar multiplets in four-dimensional minimally supersymmetric theories. In all dimensions and with any amount of supersymmetry, this technique produces BRST or BV complexes of supersymmetric theories from the Koszul complex of the maximal ideal over the coordinate ring of the nilpotence variety, possibly tensored with any equivariant module over that coordinate ring. In addition, we remark on a natural connection to the Chevalley–Eilenberg complex of the supertranslation algebra, and give two applications related to these ideas: a calculation of Chevalley–Eilenberg cohomology for the (2, 0) algebra in six dimensions, and a degenerate BV complex encoding the type IIB supergravity multiplet.

Non-critical String Cosmologies are offered as an alternative to Standard Big Bang Cosmology. The new features encompassed within the dilaton dependent non-critical terms affect the dynamics of the Universeś evolution in an unconventional manner being in agreement with the cosmological data. Non-criticality is responsible for a late transition to acceleration at redshifts z =0.2. The role of the uncoupled rolling dilaton to relic abundance calculations is discussed. The uncoupled rolling dilaton dilutes the neutralino relic densities in supersymmetric theories by factors of ten, relaxing considerably the severe WMAP Dark Matter constraints, while at the same time leaves almost unaffected the baryon density in agreement with primordial Nucleosynthesis.

In this Thesis, we propose to analyze three different aspects of Fundamental Physics.The first part is devoted to the detailed study of what is called "unconventional supersymmetry" in three and four dimensions for Abelian and non-Abelian internal groups. We show the dynamical content of the odd-dimensional theory, counting at the same time the local degrees of freedom for some particular sectors of the phase space. In the non-Abelian three-dimensional case, some black hole solutions are presented, including their Killing spinors. In four dimensions, the supersymmetry is broken explicitly and a standard Dirac Lagrangian coupled with the electromagnetic field and the background geometry is obtained.In the second part, the dynamical content for the free and gauge coupled massless Rarita-Schwinger theory is presented. We are able to do that through the Dirac's Hamiltonian formalism and the Faddeev-Jackiw method, showing at the same time the symmetries of the theory. It is shown that in the gauge extended theory, which includes extra fermionic fields to restore the fermionic symmetries of the free case, the anticommutator of the Rarita-Schwinger field in the canonical quantization is not positive definite in general.As the graphene has been proposed as an on ``table-top laboratory" for some Quantum Gravity scenarios, in the third part of this Thesis we clarify some subtle features of strained graphene in order to manage properly this material. We show particularly that the pseudo-magnetic field induced by the in-plane strain tensor field cannot emerge from a Quantum Field Theory in curved spacetime approach (bottom-up approach) but from the detailed analysis of the tight-binding Hamiltonian of pi electrons in graphene (top-down approach) instead.
Dans cette Thèse, nous nous proposons d'analyser trois aspects différents de la Physique Fondamentale.La première partie est consacrée à l'éude détaillée de ce qu'on appelle "supersymétrie non conventionnelle" à trois et quatre dimensions pour des groupes internes abéliens et non abéliens. Nous montrons le contenu dynamique de la théorie de la dimension impaire, comptant en même temps les degrés de liberté locaux pour certains secteurs particuliers de l'espace des phases. Dans le cas tridimensionnel non-abélien, certaines solutions de trous noirs sont présentées, y compris leurs spinors de Killing. En quatre dimensions, la supersymétrie est brisée explicitement et un Lagrangien de Dirac standard couplé à l'électromagnétisme et à la géométrie d'arriére-plan est obtenu.Dans la deuxième partie, le contenu dynamique de la théorie de Rarita-Schwinger libre et couplée à un champ de jauge sans masse est présenté. Nous sommes en mesure de le faire par le formalisme Hamiltonien de Dirac et la méthode dite de Faddeev-Jackiw, en montrant en même temps les symétries de la théorie. Il est démontré que dans la théorie étendue de jauge, qui comprend des champs fermioniques supplémentaires pour restaurer les symétries fermioniques du cas libre, l'anticommutator du champ Rarita-Schwinger dans la quantification canonique n'est pas définiti positif en général.Comme le graphène a été proposé comme un "laboratoire de table" pour certains scénarios de gravité quantique, dans la troisième partie de cette Thèse, nous clarifions certaines caractéristiques subtiles du graphène sous tension afin de gérer correctement ce matériel. Nous montrons en particulier que le champ pseudo-magnétique induit par le champ tensoriel de déformation dans le plan ne peut pas émerger d'une théorie de champ quantique dans un espace courbe (approche bottom-up), mais bien à partir de l'analyse détaillée de l'Hamiltonien tight-binding des pi électrons dans le graphène (approche top-down).
En esta Tesis se propone analizar tres aspectos diferentes de la Física Fundamental.La primera parte está dedicada al estudio detallado de lo que ha pasado a llamarse "supersimetría no convencional" en tres y cuatro dimensiones para grupos internos abelianos y no abelianos. Se muestra el contenido dinámico en dimensiones impares de la teoría, contando al mismo tiempo los grados de libertad locales para ciertos sectores del espacio de fases. En el caso tridimensional no abeliano, se presentan algunas soluciones de agujeros negros, incluyendo sus espinores de Killing. En cuatro dimensiones, la supersimetría está rota explícitamente y se obtiene un lagrangiano estándar de Dirac acoplado con el campo electromagnético y la geometría de fondo.En la segunda parte, se presenta el contenido dinámico de la teoría de Rarita-Schwinger libre y con acoplamiento gauge. Esto se puede hacer a través del formalismo hamiltoniano de Dirac y el método de Faddeev-Jackiw, mostrando al mismo tiempo las simetrías de la teoría. Se observa que en la teoría gauge extendida, la cual incluye campos fermiónicos extra para restaurar la simetría fermiónica del caso libre, el anticonmutador del campo de Rarita-Schwinger no es definido positivo en la cuantización canónica.Ya que el grafeno se ha propuesto como una "mesa de laboratorio" para algunos escenarios de gravedad cuántica, en la tercera parte de esta Tesis se clarifican algunas características sutiles del grafeno extendido con el objetivo de manejar debidamente el material. Se muestra particularmente que el campo seudo-magnético inducido por el campo de tensión planar no puede emerger de una teoría cuántica de campos en espacios curvos (abordaje top-down), sino de un análisis detallado del hamiltoniano tight-binding de los electrones pi en el grafeno (abordaje bottom-up).
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

Nous étudions dans un premier temps deux théories supersymétriques basées sur la présence de Gauginos de Dirac à travers deux scénarios à la phénoménologie bien distincte. La première, dite de "Fake Split SUSY", se caractérise par un spectre de particules scindé entre une partie à l'échelle électrofaible et l'autre plus lourde. Ces modèles prédisent avec une grande précision la masse du boson de Higgs et sont compatibles avec de nombreux résultats de cosmologie, au prix d'un spectre très peu naturel. La seconde présente un scénario supersymétrique dont l'un des bosons scalaire pourrait être identifié avec la résonance à 750 GeV observée au LHC. Dans un second temps, nous analysons deux comportements non-conventionnels du graviton et de son partenaire supersymétrique, le gravitino. Lorsque la symétrie de Lorentz est brisée par la présence d'un fluide, nous montrons que la pseudo-particule générée par cette brisure, le phonino, devient la composante longitudinale du gravitino et se propage suivant une relation de dispersion non relativiste que nous étudions en détails. Finalement, nous explorons des théories de gravité étendue dans lesquelles, en sus du Lagrangien d'Hilbert-Einstein, nous ajoutons des opérateurs construits à partir de produits de tenseurs de Riemann. En présence d'un fluide, nous prouvons qu'un graviton peut se propager "prestement", une notion reliée celle de vitesse superluminale
We will first focus on supersymmetric theories with Dirac Gaugino masses. We investigate two advantages of such models. First, the possibility to reconcile the measured Higgs mass with an arbitrary large scale of supersymmetry breaking. Second, we show how the scalar singlet present in such models is a sound candidate for a resonance explaining the 750 GeV diphoton excess observed by the LHC experiments. In a second part, we start by discussing the propagation of a massive spin 3/2 state in a fluid (for instance the gravitino when supergravity is coupled to a background fluid). We show that the degrees of freedom corresponding to different helicities travel with different velocities. We then discuss the separate issue of graviton speed in extended gravity theories where the usual Einstein-Hilbert Lagrangian is supplemented by various higher order terms constructed from Riemann tensors