1,720,976 research outputs found
Topological effective field theories for Dirac fermions from index theorem
No full textDirac fermions have a central role in high energy physics but it is well known that they emerge also as quasiparticles in several condensed matter systems supporting topological order.
We present a general method for deriving the topological effective actions of (3+1) massless Dirac fermions living on general backgrounds and coupled with vector and axial--vector gauge fields. The first step of our strategy is standard (in the Hermitian case) and consists in connecting
the determinants of Dirac operators with the corresponding analytical indices
through the zeta-function regularization. Then, we introduce a suitable splitting of the heat kernel that naturally
selects the purely topological part of the determinant (i.e. the topological effective action). This topological effective action is expressed in terms of gauge fields using the Atiyah-Singer index theorem which computes the analytical index in topological terms. The main new result of this paper is to provide a consistent extension of this method to the non Hermitian case where a well-defined determinant does not exist.
Quantum systems supporting relativistic fermions can thus be topologically classified on the basis of their response to the presence of (external or emergent) gauge fields
through the corresponding topological effective field theories
Super-Quantum Mechanics in the Integral Form Formalism
No full textWe reformulate super-quantum mechanics in the context of inte-gral forms. This framework allows to interpolate between different actionsfor the same theory, connected by different choices of picture changingoperators (PCO). In this way we retrieve component and superspace ac-tions and prove their equivalence. The PCO are closed integral formsand can be interpreted as super-Poincar ́e duals of bosonic submanifoldsembedded into a supermanifold. We use them to construct Lagrangiansthat are top integral forms, and therefore can be integrated on the wholesupermanifold. TheD=1,N=1andtheD=1,N= 2 cases are stud-ied, in a flat and in a curved supermanifold. In this formalism, we alsoconsider coupling with gauge fields, Hilbert space of quantum states, andobservables
Integral representations on supermanifolds: super Hodge duals, PCOs and Liouville forms
No full textWe present a few types of integral transforms and integral representations that are very useful for extending to supergeometry many familiar concepts of differential geometry. Among them we discuss the construction of the super Hodge dual, the integral representation of picture changing operators of string theories and the construction of the super-Liouville form of a symplectic supermanifold
Classical solutions of CPn non linear Ï\u83 -models; an algebraic geometrical description
No full textString Sigma Models on Curved Supermanifolds
No full textWe use the techniques of integral forms to analyze the easiest example of two-dimensional sigma models on a supermanifold. We write the action as an integral of a top integral form over a D = 2 supermanifold, and we show how to interpolate between different superspace actions. Then, we consider curved supermanifolds, and we show that the definitions used for flat supermanifolds can also be used for curved supermanifolds. We prove it by first considering the case of a curved rigid supermanifold and then the case of a generic curved supermanifold described by a single superfield E
In difesa della legge n.219 del 2017 («Norme in materia di consenso informato e di disposizioni anticipate di trattamento»)
No full textL'Autore analizza la legge n. 219 del 2017, ponendo in evidenza la necessità di una sua completa attuazione nell'eterogeneo panorama nazionale
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