History of Supersymmetric Extensions of the Standard Model

We recall the many obstacles which seemed, long ago, to prevent supersymmetry from possibly being a fundamental symmetry of Nature. We also present their solutions, leading to the construction of the supersymmetric extensions of the Standard Model. Finally we discuss briefly the early experimental searches for Supersymmetry.Comment: 40 pages, 10 figures, 3 Table

“‘Relentless Geography’: Los Angeles’ Imagined Cartographies in Karen Tei Yamashita’s Tropic of Orange,”

What would a map of Los Angeles drawn from the ground up look like? In his groundbreaking work The Production of Space (1974), Henri Lefebvre argues that the conceived space of urban planners is fundamentally distinct from lived space, which cannot be mapped out. In her impressive city-wide narrative, Karen Tei Yamashita’s Tropic of Orange (1997) demonstrates the effects of imposing conceived space upon the lived space of inner city Los Angeles residents, and what happens when the counter-model of space being lived by a city’s inhabitants rebels. Yamashita’s text mirrors this disjuncture between represented and lived space through the use of narrative surrealism. Space is magically reconfigured in the city, shrinking the uninhabited Downtown and expanding over-populated yet underrepresented neighborhoods, literally shifting geographically until its mapping matches the social space of those on the ground rather than those who map it from above. Literary criticism on the novel to date has largely interpreted Tropic of Orange as a commentary on the effects of globalization; not enough attention has been paid to the novel’s surreal expansion of Los Angeles’ inner city. Using Lefebvre’s “science of space,” anchored by Los Angeles’ city planning schemas, I argue that Yamashita offers a different map, one perceived by the subsets of LA’s population that fall through the cracks of the city’s grid. Tropic of Orange’s unorthodox formal structure, when combined with its narrative surrealism, creates a differential space in the text, transforming the novel into the Los Angeles imagined by its anonymous users

Topological defects and misfit strain in magnetic stripe domains of lateral multilayers with perpendicular magnetic anisotropy

Stripe domains are studied in perpendicular magnetic anisotropy films nanostructured with a periodic thickness modulation that induces the lateral modulation of both stripe periods and inplane magnetization. The resulting system is the 2D equivalent of a strained superlattice with properties controlled by interfacial misfit strain within the magnetic stripe structure and shape anisotropy. This allows us to observe, experimentally for the first time, the continuous structural transformation of a grain boundary in this 2D magnetic crystal in the whole angular range. The magnetization reversal process can be tailored through the effect of misfit strain due to the coupling between disclinations in the magnetic stripe pattern and domain walls in the in-plane magnetization configuration

λ\lambda-symmetries for discrete equations

Following the usual definition of $\lambda$-symmetries of differential equations, we introduce the analogous concept for difference equations and apply it to some examples.Comment: 10 page

Controlled nucleation of topological defects in the stripe domain patterns of Lateral multilayers with Perpendicular Magnetic Anisotropy: competition between magnetostatic, exchange and misfit interactions

Magnetic lateral multilayers have been fabricated on weak perpendicular magnetic anisotropy amorphous Nd-Co films in order to perform a systematic study on the conditions for controlled nucleation of topological defects within their magnetic stripe domain pattern. A lateral thickness modulation of period $w$ is defined on the nanostructured samples that, in turn, induces a lateral modulation of both magnetic stripe domain periods $\lambda$ and average in-plane magnetization component $M_{inplane}$. Depending on lateral multilayer period and in-plane applied field, thin and thick regions switch independently during in-plane magnetization reversal and domain walls are created within the in-plane magnetization configuration coupled to variable angle grain boundaries and disclinations within the magnetic stripe domain patterns. This process is mainly driven by the competition between rotatable anisotropy (that couples the magnetic stripe pattern to in-plane magnetization) and in-plane shape anisotropy induced by the periodic thickness modulation. However, as the structural period $w$ becomes comparable to magnetic stripe period $\lambda$, the nucleation of topological defects at the interfaces between thin and thick regions is hindered by a size effect and stripe domains in the different thickness regions become strongly coupled.Comment: 10 pages, 7 figures, submitted to Physical Review