Opportunity cost and prudentiality : a representative-agent model of futures clearinghouse behavior

Includes bibliographic references (p. 31-38)

Lidar Electro-Optic Beam Switch with a Liquid Crystal Variable Retarder

A document discusses a liquid crystal variable retarder, an electro-optic element that changes the polarization of an optical beam in response to a low-voltage electronic signal. This device can be fabricated so that the element creates, among other states, a half-wave of retardance that can be reduced to a very small retardance. When aligned to a polarized source, this can act to rotate the polarization by 90 in one state, but generate no rotation in the other state. If the beam is then incident on a polarization beam splitter, it will efficiently switch from one path to the other when the voltage is applied. The laser beam switching system has no moving parts, improving reliability over mechanical switching. It is low cost, tolerant of high laser power density, and needs only simple drive electronics, minimizing the required system resources

Higgs boson interactions in supersymmetric theories with large tan beta

We show that radiative corrections to the Higgs potential in supersymmetric theories with large tan beta generically lead to large differences in the light Higgs boson decay branching fractions compared to those of the standard model Higgs boson. In contrast, the light Higgs boson production rates are largely unaffected. We identify W h associated production followed by Higgs boson decays to photons or to leptons via W W* as potential experimental probes of these theories.Comment: 11 pages, 4 figure

Confronting Electroweak Fine-tuning with No-Scale Supergravity

Applying No-Scale Supergravity boundary conditions at a heavy unification scale to the Flipped $SU(5)$ grand unified theory with extra TeV-scale vector-like multiplets, $i.e.$ No-Scale ${\cal F}$-$SU(5)$, we express the $Z$-boson mass $M_Z$ as an explicit function of the boundary gaugino mass $M_{1/2}$, $M_Z^2 = M_Z^2 (M_{1/2}^2)$, with implicit dependence upon a dimensionless ratio $c$ of the supersymmetric Higgs mixing parameter $\mu$ and $M_{1/2}$. Setting the top Yukawa coupling consistent with $m_t = 174.3$ GeV at $M_Z = 91.2$ GeV, the value of $c$ naturally tends toward $c \simeq 1$, which indirectly suggests underlying action of the Giudice-Masiero mechanism. Proportional dependence of all model scales upon the unified gaugino mass $M_{1/2}$ in the No-Scale ${\cal F}$-$SU(5)$ model suggests one possible mechanism of confronting the electroweak fine tuning problem.Comment: Physics Letters B version; 8 Pages, 7 Figures, 1 Tabl

The importance of tau leptons for supersymmetry searches at the Tevatron

Supersymmetry is perhaps most effectively probed at the Tevatron through production and decay of weak gauginos. Most of the analyses of weak gaugino observables require electrons or muons in the final state. However, it is possible that the gauginos will decay primarily to tau leptons, thus complicating the search for supersymmetry. The motivating reasons for high tau multiplicity final states are discussed in three approaches to supersymmetry model building: minimal supergravity, gauge mediated supersymmetry breaking, and more minimal supersymmetry. The concept of ``e/mu/tau candidate'' is introduced, and an observable with three e/mu/tau candidates is defined in analog to the trilepton observable. The maximum mass reach for supersymmetry is then estimated when gaugino decays to tau leptons have full branching fraction.Comment: 9 pages, latex, 2 figures. Presented at the D0 New Phenomena Workshop, UC Davis, 26-28 March 199

Opportunity cost and prudentiality : an analysis of futures clearinghouse behavior

Margin deposits, which serve as collateral to protect the clearinghouse, are typically the most important tool for risk management. The authors develop a model that explains how creating a futures clearinghouse may allow traders simultaneously to reduce both the risk of default and the total amount of margin that members post. Optimal margin levels are determined by the need to balance the deadweight costs of default against the opportunity cost of holding additional margin. Both costs are a consequence of market participants'imperfect access to capital markets. The simultaneous reduction in default risk and in the opportunity cost of margin deposits is possible because the creation of the clearinghouse facilitates multilateral netting. The authors characterize the conditions under which multilateral netting will dominate bilateral netting. They also show that it is credible for the clearinghouse to expel members who default, further reducing the risk of default. Finally, they show that it may (but need not) be optimal for the clearinghouse to monitor the financial condition of its members. If monitoring occurs, it will reduce the amount of margin required, but need not affect the probability of default. The empirical tests run by the authors indicate that the opportunity cost of margin plays an important role in determining margin. The relationship between volatility and margins indicates that participants face an upward-sloping opportunity cost for margin, which appears to more than offset the effects that monitoring and expulsion would be expected to have on margin setting.Environmental Economics&Policies,Banks&Banking Reform,International Terrorism&Counterterrorism,Economic Theory&Research,Insurance&Risk Mitigation