Probing Form Factors in Top Quark Pair Production at e−e+e^-e^+ Colliders

We describe how to probe new physics through large CP violation effects and non--standard Z-t-t couplings via the scattering process e^-e^+ -> t tbar. [Talk presented at the Workshop on Physics and Experiments with Linear $e^+e^-$ Colliders, Waikoloa, Hawaii, 26-30 April 1993.]Comment: 4 pages, TeXsis, MSUTH 93/0

Acute kidney injury in the elderly: predisposition to chronic kidney disease and vice versa.

There have been considerable advances in the past few years in our understanding of how chronic kidney disease (CKD) predisposes to acute kidney injury (AKI) and vice versa. This review shows, however, that few studies have focused on the elderly or conducted stratified analysis by age. It does appear that elderly patients with estimated glomerular filtration rate (eGFR) 45-59 ml/min/1.73 m(2) are at higher risk for AKI compared with their counterparts with eGFR >60 ml/min/1.73 m(2). This is a similar relationship to that seen in younger patients, although effect size appears smaller. As the incidence of AKI has been increasing over the past several years, the proportion of elderly patients surviving after AKI has also been increasing. Since AKI heightens the risk for the development and acceleration of CKD, this implies significant public health concerns with regard to the absolute number of elderly persons developing incident CKD

B-meson signatures of a Supersymmetric U(2) flavor model

We discuss B-meson signatures of a Supersymmetric U(2) flavor model, with relatively light (electroweak scale masses) third generation right-handed scalars. We impose current B and K meson experimental constraints on such a theory, and obtain expectations for B->X_s gamma, B->X_s glue, B->X_s l+ l-, B->phi K_s, B_s-B_sbar mixing, and the dilepton asymmetry in B_s. We show that such a theory is compatible with all current data, and furthermore, could reconcile the apparent deviations from Standard Model predictions that have been found in some experiments.Comment: 37 pages, 21 figures, RevTeX4; v.2 - minor modifications to improve readability. Published versio

Non-Fermi liquid states in the pressurized CeCu2(Si1−xGex)2CeCu_2(Si_{1-x}Ge_x)_2 system: two critical points

In the archetypal strongly correlated electron superconductor CeCu$_2$Si$_2$ and its Ge-substituted alloys CeCu$_2$(Si$_{1-x}$Ge$_{x}$)$_2$ two quantum phase transitions -- one magnetic and one of so far unknown origin -- can be crossed as a function of pressure \cite{Yuan 2003a}. We examine the associated anomalous normal state by detailed measurements of the low temperature resistivity ($\rho$) power law exponent $\alpha$. At the lower critical point (at $p_{c1}$, $1\leq\alpha\leq 1.5$) $\alpha$ depends strongly on Ge concentration $x$ and thereby on disorder level, consistent with a Hlubina-Rice-Rosch scenario of critical scattering off antiferromagnetic fluctuations. By contrast, $\alpha$ is independent of $x$ at the upper quantum phase transition (at $p_{c2}$, $\alpha\simeq 1$), suggesting critical scattering from local or Q=0 modes, in agreement with a density/valence fluctuation approach.Comment: 4 pages, including 4 figures. New results added. Significant changes on the text and Fig.

On The Orbital Evolution of Jupiter Mass Protoplanet Embedded in A Self-Gravity Disk

We performed a series of hydro-dynamic simulations to investigate the orbital migration of a Jovian planet embedded in a proto-stellar disk. In order to take into account of the effect of the disk's self gravity, we developed and adopted an \textbf{Antares} code which is based on a 2-D Godunov scheme to obtain the exact Reimann solution for isothermal or polytropic gas, with non-reflecting boundary conditions. Our simulations indicate that in the study of the runaway (type III) migration, it is important to carry out a fully self consistent treatment of the gravitational interaction between the disk and the embedded planet. Through a series of convergence tests, we show that adequate numerical resolution, especially within the planet's Roche lobe, critically determines the outcome of the simulations. We consider a variety of initial conditions and show that isolated, non eccentric protoplanet planets do not undergo type III migration. We attribute the difference between our and previous simulations to the contribution of a self consistent representation of the disk's self gravity. Nevertheless, type III migration cannot be completely suppressed and its onset requires finite amplitude perturbations such as that induced by planet-planet interaction. We determine the radial extent of type III migration as a function of the disk's self gravity.Comment: 19 pages, 13 figure

Curvature and Acoustic Instabilities in Rotating Fluid Disks

The stability of a rotating fluid disk to the formation of spiral arms is studied in the tightwinding approximation in the linear regime. The dispersion relation for spirals that was derived by Bertin et al. is shown to contain a new, acoustic instability beyond the Lindblad resonances that depends only on pressure and rotation. In this regime, pressure and gravity exchange roles as drivers and inhibitors of spiral wave structures. Other instabilities that are enhanced by pressure are also found in the general dispersion relation by including higher order terms in the small parameter 1/kr for wavenumber k and radius r. These instabilities are present even for large values of Toomre's parameter Q. Unstable growth rates are determined in four cases: a self-gravitating disk with a flat rotation curve, a self-gravitating disk with solid body rotation, a non-self-gravitating disk with solid body rotation, and a non-self-gravitating disk with Keplerian rotation. The most important application appears to be as a source of spiral structure, possibly leading to accretion in non-self-gravitating disks, such as some galactic nuclear disks, disks around black holes, and proto-planetary disks. All of these examples have short orbital times so the unstable growth time can be small.Comment: 30 pages, 5 figures, scheduled for ApJ 520, August 1, 199