Almost-Commutative Geometry, massive Neutrinos and the Orientability Axiom in KO-Dimension 6

In recent publications Alain Connes [1] and John Barrett [2] proposed to change the KO-dimension of the internal space of the standard model in its noncommutative representation [3] from zero to six. This apparently minor modification allowed to resolve the fermion doubling problem [4], and the introduction of Majorana mass terms for the right-handed neutrino. The price which had to be paid was that at least the orientability axiom of noncommutative geometry [5,6] may not be obeyed by the underlying geometry. In this publication we review three internal geometries, all three failing to meet the orientability axiom of noncommutative geometry. They will serve as examples to illustrate the nature of this lack of orientability. We will present an extension of the minimal standard model found in [7] by a right-handed neutrino, where only the sub-representation associated to this neutrino is not orientable

A Dark Sector Extension of the Almost-Commutative Standard Model

We consider an extension of the Standard Model within the frame work of Noncommutative Geometry. The model is based on an older model [St09] which extends the Standard Model by new fermions, a new U(1)-gauge group and, crucially, a new scalar field which couples to the Higgs field. This new scalar field allows to lower the mass of the Higgs mass from ~170 GeV, as predicted by the Spectral Action for the Standard Model, to a value of 120-130 GeV. The short-coming of the previous model lay in its inability to meet all the constraints on the gauge couplings implied by the Spectral Action. These shortcomings are cured in the present model which also features a "dark sector" containing fermions and scalar particles

Gauge unification in noncommutative geometry

Gauge unification is widely considered to be a desirable feature for extensions of the standard model. Unfortunately the standard model itself does not exhibit a unification of its running gauge couplings but it is required by grand unified theories as well as the noncommutative version of the standard model [2]. We will consider here the extension of the noncommutative standard model by vector doublets as proposed in [6]. Two consequences of this modification are: 1. the relations of the coupling constants at unification energy are altered with respect to the well known relation from grand unified theories. 2. The extended model allows for unification of the gauge couplings at ~10^(13) GeV

Almost-Commutative Geometries Beyond the Standard Model III: Vector Doublets

We will present a new extension of the standard model of particle physics in its almostcommutative formulation. This extension has as its basis the algebra of the standard model with four summands [11], and enlarges only the particle content by an arbitrary number of generations of left-right symmetric doublets which couple vectorially to the U(1)_YxSU(2)_w subgroup of the standard model. As in the model presented in [8], which introduced particles with a new colour, grand unification is no longer required by the spectral action. The new model may also possess a candidate for dark matter in the hundred TeV mass range with neutrino-like cross section

Almost-Commutative Geometries Beyond the Standard Model II: New Colours

We will present an extension of the standard model of particle physics in its almost-commutative formulation. This extension is guided by the minimal approach to almost-commutative geometries employed in [13], although the model presented here is not minimal itself. The corresponding almost-commutative geometry leads to a Yang-Mills-Higgs model which consists of the standard model and two new fermions of opposite electro-magnetic charge which may possess a new colour like gauge group. As a new phenomenon, grand unification is no longer required by the spectral action.Comment: Revised version for publication in J.Phys.A with corrected Higgs masse

Fixing the leak: unemployment incidence before and after the 2006 reform of unemployment benefits in Germany

From 2002-2004, the German government passed several laws that curtailed the generosity of the unemployment compensation system. One of the most ambitious changes was a considerable reduction in unemployment benefit entitlement lengths for older unemployed, which was effective during 2006 and 2007. We apply a difference-in-differences approach to show that the highly disputed reform induced a considerable decline in unemployment incidence among older workers. It thus sealed an important leak in the unemployment insurance system. Furthermore, we find a strong anticipation effect; unemployment entries of elderly workers peaked during the months preceding the reform. --unemployment incidence,policy evaluation,administrative data

Fixing the leak: Unemployment incidence before and after the 2006 reform of unemployment benefits in Germany

"From 2002 - 2004, the German government passed several laws that curtailed the generosity of the unemployment compensation system. One of the most ambitious changes was a considerable reduction in unemployment benefit entitlement lengths for older unemployed, which was effective during 2006 and 2007. We apply a difference-in-differences approach to show that the highly disputed reform induced a considerable decline in unemployment incidence among older workers. It thus sealed an important leak in the unemployment insurance system. Furthermore, we find a strong anticipation effect; unemployment entries of elderly workers peaked during the months preceding the reform." (Author's abstract, IAB-Doku) ((en))ältere Arbeitnehmer, arbeitsmarktpolitische Maßnahme, Arbeitslosengeld, Leistungsbezug - Dauer, Wirkungsforschung