Natural Scherk-Schwarz Theories of the Weak Scale

Natural supersymmetric theories of the weak scale are under growing pressure given present LHC constraints, raising the question of whether untuned supersymmetric (SUSY) solutions to the hierarchy problem are possible. In this paper, we explore a class of 5-dimensional natural SUSY theories in which SUSY is broken by the Scherk-Schwarz mechanism. We pedagogically explain how Scherk-Schwarz elegantly solves the traditional problems of 4-dimensional SUSY theories (based on the MSSM and its many variants) that usually result in an unsettling level of fine-tuning. The minimal Scherk-Schwarz set up possesses novel phenomenology, which we briefly outline. We show that achieving the observed physical Higgs mass motivates extra structure that does not significantly affect the level of tuning (always better than $\sim 10\%$) and we explore three qualitatively different extensions: the addition of extra matter that couples to the Higgs, an extra $U(1)^\prime$ gauge group under which the Higgs is charged and an NMSSM-like solution to the Higgs mass problem.Comment: 36 pages + appendix, 12 figure

Unlawfully Present Aliens, Driver’s Licenses, and Other State-Issued ID: Select Legal Issues

[Excerpt] This report provides an overview of key legal issues raised by state laws regarding the denial or issuance of driver’s licenses and other forms of ID to unlawfully present aliens. It also addresses the legal issues raised by local governments issuing ID cards to unlawfully present aliens, as well as by state and local approaches to recognizing foreign-issued ID documents

Signaling Concerns about Fairness: Cooperation under Uncertain Social Preferences

This paper investigates incomplete information and signaling about players?inequity aversion in the simultaneous and sequential-move prisoner?s dilemma game. We first evaluate the role of incomplete information according to: (1) whether uncertainty helps select the effcient equilibrium outcome, and (2) whether more cooperation can be sustained under incomplete than under complete information. We then examine the possibility of information transmission among individuals in a signaling game. A separating equilibrium can be supported in which players with high concerns about fairness bear the cost of cooperating in order to reveal their type to opponents, thus promoting cooperation in subsequent periods. We also fi?nd a pooling equilibrium in which a player unconcerned about inequity aversion initially cooperates in order to mislead the uninformed player. This misleading strategy induces cooperation from the uninformed player in the subsequent stage of the game, moment at which the unconcerned player takes the opportunity to defect. This "backstabbing" equilibrium helps explain frequently observed behavior in ?finitely-repeated experiments.Prisoner?s Dilemma; Inequity aversion; Incomplete Information; Signaling

Light Collimation and Focussing by a Thin Flat Metallic Slab

We present experimental and theoretical work showing that a flat metallic slab can collimate and focus light impinging on the slab from a punctual source. The effect is optimised when the radiation is around the bulk, not at the surface, plasma frequency. And the smaller the imaginary part of the permittivity is, the better the collimation. Experiments for Ag in the visible as well as calculations are presented. We also discuss the interesting case of the Aluminium whose imaginary part of the permittivity is very small at the plasma frequency in UV radiation. Generalization to other materials and radiations are also discussed.Comment: 6 pages, 3 figures. To be published on Optics Lette

Source Galerkin Calculations in Scalar Field Theory

In this paper, we extend previous work on scalar $\phi^4$ theory using the Source Galerkin method. This approach is based on finding solutions $Z[J]$ to the lattice functional equations for field theories in the presence of an external source $J$. Using polynomial expansions for the generating functional $Z$, we calculate propagators and mass-gaps for a number of systems. These calculations are straightforward to perform and are executed rapidly compared to Monte Carlo. The bulk of the computation involves a single matrix inversion. The use of polynomial expansions illustrates in a clear and simple way the ideas of the Source Galerkin method. But at the same time, this choice has serious limitations. Even after exploiting symmetries, the size of calculations become prohibitive except for small systems. The calculations in this paper were made on a workstation of modest power using a fourth order polynomial expansion for lattices of size $8^2$,$4^3$,$2^4$ in $2D$, $3D$, and $4D$. In addition, we present an alternative to the Galerkin procedure that results in sparse matrices to invert.Comment: 31 pages, latex, figures separat

The net effect: using social media data to understand the impact of a conference on social networks

The research uses social media data from Twitter to develop a methodology for understanding the effects of events and conferences. Key findings: Social media data offers a rich source of information to understand the effects of events on networking. Attending events is associated with a much higher rate of growth in Twitter connections among event participants than with people outside the event. Many of the connections formed at events are between people who already have a mutual connection on Twitter, indicating that they are more likely to have met in the longer-term. However, there are also connections between people that are further apart in the Twitter network before the event. This is particularly true for international connections. Within conferences one can see social networking behaviour consistent with commercial incentives e.g. consultants connecting with potential clients (but not with each other), or people connecting along language lines