Energy dependence of the freeze out eccentricity from the azimuthal dependence of HBT at STAR

Non-central heavy ion collisions create an out-of-plane-extended participant zone that expands toward a more round state as the system evolves. The recent RHIC Beam Energy Scan at sqrt{s_{NN}} of 7.7, 11.5, and 39 GeV provide an opportunity to explore the energy dependence of the freeze out eccentricity. The new low energy data from STAR complements high statistics data sets at sqrt{s_{NN}} of 62.4 and 200 GeV. Hanbury-Brown-Twiss (HBT) interferometry allows to determine the size of pion emitting source regions. The dependence of the HBT radius parameters on azimuthal angle relative to the reaction plane have been extracted. These dependencies can be related to the freeze out eccentricity. The new results from STAR are consistent with a monotonically decreasing freeze out eccentricity and constrain any minimum, suggested by previously available data, to lie in the range between 11.5 and 39 GeV. Of several models UrQMD appears to best predict the STAR and AGS data.Comment: 4 pages, 2 figures, Proceedings for the XXII International Conference on Ultra-relativistic Nucleus-Nucleus Collisions (Quark Matter 2011), 22-28 May 2011, Annecy, Franc

Probable or Improbable Universe? Correlating Electroweak Vacuum Instability with the Scale of Inflation

Measurements of the Higgs boson and top quark masses indicate that the Standard Model Higgs potential becomes unstable around $\Lambda_I \sim 10^{11}$ GeV. This instability is cosmologically relevant since quantum fluctuations during inflation can easily destabilize the electroweak vacuum if the Hubble parameter during inflation is larger than $\Lambda_I$ (as preferred by the recent BICEP2 measurement). We perform a careful study of the evolution of the Higgs field during inflation, obtaining different results from those currently in the literature. We consider both tunneling via a Coleman-de Luccia or Hawking-Moss instanton, valid when the scale of inflation is below the instability scale, as well as a statistical treatment via the Fokker-Planck equation appropriate in the opposite regime. We show that a better understanding of the post-inflation evolution of the unstable AdS vacuum regions is crucial for determining the eventual fate of the universe. If these AdS regions devour all of space, a universe like ours is indeed extremely unlikely without new physics to stabilize the Higgs potential; however, if these regions crunch, our universe survives, but inflation must last a few e-folds longer to compensate for the lost AdS regions. Lastly, we examine the effects of generic Planck-suppressed corrections to the Higgs potential, which can be sufficient to stabilize the electroweak vacuum during inflation.Comment: 26 pages, 7 figures. Clarifications added. Matches published version in JHE

The neuropsychological endophenotype of specific language impairments and autism spectrum disorders: Category or continuum?

The primary goal of this investigation was to illuminate variables of the specific language impairment (SLI) and autism spectrum disorders (ASD) neuropsychological endophenotypes and to clarify the nature of overlap between SLI and ASD. Group differences in cognitive functioning, epidemiological factors including proband comorbidity and health problems, and familial data in 39 SLI children and 89 ASD children who presented for clinical evaluation at Henry Ford Health System in Detroit were examined by retrospective chart review. Cognitive data revealed that ASD probands performed more poorly on tests of perceptual-motor functioning and had higher rates of pragmatic language deficits than SLI probands. In addition, ASD probands had higher rates of pragmatic speech problems than SLI probands. Proband comorbidity and health problem group differences were noted in several areas. SLI probands had higher rates of learning disorders, asthma, and stomach/digestion problems than the ASD probands. ASD probands had higher rates of mental retardation (MR) than the SLI probands. Familial group differences were noted in parental education levels and family history of psychopathology. SLI parents were less likely to have obtained a high school diploma or GED than ASD parents. SLI probands had higher rates of first-degree maternal relatives with learning disorders than ASD probands. ASD probands had higher rates of first-degree maternal relatives with ASD and thought disorders than SLI probands. In addition to significant findings between the diagnostic groups, differences between severity levels were also found. The severe groups performed more poorly on tests of academic functioning and visual attention than mild-moderate groups. In addition, the severe groups had higher rates of verbal communication content problems than the mild-moderate groups. In terms of comorbidity, the mild-moderate groups had higher rates of learning disorders and ADHD than the severe groups. The severe groups had higher MR rates than the mild-moderate groups. Finally, familial data indicated that the mild-moderate groups had higher rates of parents employed in business/finance and engineering/science than the severe groups. Overall, these findings provide valuable information on factors present in SLI and ASD neuropsychological endophenotypes and increase understanding on the nature of overlap between the two disorders

A knowledge-based system for construction site level facilities layout

Author name used in this publication: K. W. ChauSeries: Lecture notes in computer science2001-2002 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe