Inflation and flat directions in modular invariant superstring effective theories

The potential during inflation must be very flat in, at least, the direction of the inflaton. In renormalizable global supersymmetry, flat directions are ubiquitous, but they are not preserved in a generic supergravity theory. It is known that at least some of them are preserved in no-scale supergravity, and simple generalizations of it. We here study a more realistic generalization, based on string-derived supergravity, using the linear supermultiplet formalism for the dilaton. We consider a general class of hybrid inflation models, where a Fayet-Illiopoulos $D$ term drives some fields to large values. The potential is dominated by the $F$ term, but flatness is preserved in some directions. This allows inflation, with the dilaton stabilized in its domain of attraction, and some moduli stabilized at their vacuum values. Another modulus may be the inflaton.Comment: 19 pages, REVTEX, further typos, refs fixe

Three Generations in the Fermionic Construction

We obtain three generation SU(3)_c X SU(2)_L X U(1)_Y string models in all of the exactly solvable (0,2) constructions sampled by fermionization. None of these examples, including those that are symmetric abelian orbifolds, rely on the Z_2 X Z_2 orbifold underlying the NAHE basis. We present the first known three generation models for which the hypercharge normalization, k_1, takes values smaller than that obtained from an SU(5) embedding, thus lowering the effective gauge coupling unification scale. All of the models contain fractional electrically charged and vectorlike exotic matter that could survive in the light spectrum.Comment: harvmac, 51 page

Composite model with neutrino large mixing

We suggest a simple composite model that induces the large flavor mixing of neutrino in the supersymmetric theory. This model has only one hyper-color in addition to the standard gauge group, which makes composite states of preons. In this model, {\bf 10} and {\bf 1} representations in SU(5) grand unified theory are composite states and produce the mass hierarchy. This explains why the large mixing is realized in the lepton sector, while the small mixing is realized in the quark sector. This model can naturally solve the atmospheric neutrino problem. We can also solve the solar neutrino problem by improving the model.Comment: 20 pages, Latex, no figure

One-Loop Pauli-Villars Regularization of Supergravity I: Canonical Gauge Kinetic Energy

It is shown that the one-loop coefficients of on-shell operators of standard supergravity with canonical gauge kinetic energy can be regulated by the introduction of Pauli-Villars chiral and abelian gauge multiplets, subject to a condition on the matter representations of the gauge group. Aspects of the anomaly structure of these theories under global nonlinear symmetries and an anomalous gauge symmetry are discussed.Comment: 46 pages, full postscript also available from http://phyweb.lbl.gov/theorygroup/papers/preprints.html/41981.ps . Misprints and errors in equations present in the original version have been correcte

Leptophobic Z′Z' in stringy flipped SU(5)

We show that leptophobic $Z'$ gauge bosons occur naturally in flipped SU(5) and may shift $R_b$ in an interesting way without upsetting the good values of $\Gamma_{had}$ and $R_c$. Within a string-derived version of the model, we study three possible scenarios and the constraints imposed on model building that would allow the new symmetry to remain unbroken down to low energies. Such $Z'$ gauge boson has generation non-universal couplings to quarks that violate parity maximally in the up-quark sector, and may contribute significantly to spin asymmetries in polarized $pp$ scattering experiments now being prepared for RHIC.Comment: 22 pages, LaTeX, 3 figures (included). Final version to appear in Phys. Rev. D. Includes discussion on how to avoid potential FCNC problems and updated data on R_b and R_

Neoliberalism and Pedagogical Practices of Alienation: A Case Study Research on the Integrated Curriculum in Greek Primary Education

In this article, we present insights from an ethnographic research that investigated the concept of citizenship in primary schools in Greece. We explored children’s experiences of citizenship in school approaching citizenship as a set of habits that prescribe what is considered ‘legitimate’ in the public sphere. We focused on structures and agents inside and outside the school classroom and the way they may interfere with pedagogical practices and relationships. This work reveals a vicious circle of asymmetrical relationships and hierarchical structures between the society and the school that entrap teachers in assessment-oriented pedagogical practices. We argue that the emergent loyalty of the educational system to traditional pedagogical approaches premised on competition fosters pupils’ incomprehension of the importance of social solidarity. It also contributes to their withdrawal from the public sphere, undermining the transformative potential of education. With the use of a diverse sample, we highlight the shortcomings of the integrated curriculum introduced in 2001, in successfully promoting critical thinking and participatory learner-centred pedagogy, and we discuss the implications for the transformative potential of education arising from the adherence to the implementation of European education policy that is discerned in the text of the newly introduced Curriculum of the ‘New School’