Minimal Flavor Violation and the Scale of Supersymmetry Breaking

In this paper we explore the constraints from B-physics observables in SUSY models of Minimal Flavor Violation, in the large tan beta regime, for both low and high scale supersymmetry breaking scenarios. We find that the rare B-decays b -> s gamma and B_s -> mu+ mu- can be quite sensitive to the scale M at which supersymmetry breaking is communicated to the visible sector. In the case of high scale supersymmetry breaking, we show that the additional gluino contribution to the b -> s gamma and B_s -> mu+ mu- rare decay rates can be significant for large tan beta, mu and M_3. The constraints on B_u -> tau nu are relatively insensitive to the precise scale of M. We also consider the additional constraints from the present direct Higgs searches at the Tevatron in the inclusive H/A -> tau tau channel, and the latest CDMS direct dark matter detection experiments. We find that altogether the constraints from B-physics, Higgs physics and direct dark matter searches can be extremely powerful in probing regions of SUSY parameter space for low M_A and large tan beta, leading to a preference for models with a lightest CP-even Higgs mass close to the current experimental limit. We find interesting regions of parameter space that satisfy all constraints and can be probed by Higgs searches at the Tevatron and the LHC and by direct dark matter searches in the near future.Comment: 24 pages, 6 figures. Added citations. Published in PR

Direct gaze modulates face recognition in young infants

From birth, infants prefer to look at faces that engage them in direct eye contact. In adults, direct gaze is known to modulate the processing of faces, including the recognition of individuals. In the present study, we investigate whether direction of gaze has any effect on face recognition in four-month-old infants. Four-month infants were shown faces with both direct and averted gaze, and subsequently given a preference test involving the same face and a novel one. A novelty preference during test was only found following initial exposure to a face with direct gaze. Further, face recognition was also generally enhanced for faces with both direct and with averted gaze when the infants started the task with the direct gaze condition. Together, these results indicate that the direction of the gaze modulates face recognition in early infancy

The Nuclear Activity of the Galaxies in the Hickson Compact Groups

In order to investigate the nuclear activity of galaxies residing in compact groups of galaxies, we present results of our optical spectroscopic program made at Okayama Astrophysical Observatory. We have performed optical spectroscopy of 69 galaxies which belong to 31 Hickson Compact Groups (HCGs) of Galaxies. Among them, three galaxies have discordant redshifts. Further, spectral quality is too poor to classify other three galaxies. Therefore, we describe our results for the remaining 63 galaxies. Our main results are summarized below. (1) We have found in our sample; 28 AGN, 16 HII nuclei, and 19 normal galaxies which show no emission line. We used this HCG sample for statistical analyses. (2) Comparing the frequency distributions of activity types between the HCGs and the field galaxies whose data are taken from Ho, Filippenko, & Sargent (382 field galaxies), we find that the frequency of HII nuclei in the HCGs is significantly less than that in the field. However, this difference may be due to selection bias that our HCG sample contains more early-type galaxies than the field, because it is known that HII nuclei are rarer in early-type galaxies than in later ones. (3) Applying correction this morphological bias to the HCG sample, we find that there is no statistically significant difference in the frequency of occurrence of emission-line galaxies between the HCGs and the field. This implies that the dense galaxy environment in the HCGs does not affect triggering both the AGN activity and the nuclear starburst. We discuss some implications on the nuclear activity in the HCG galaxies.Comment: 33 pages (3 aasms4 LaTeX files), 5 figures (5 Postscript files: excluded Figure 1), Accepted for publication in The Astronomical Journa

Standard model explanation of a CDF dijet excess in Wjj

We demonstrate the recent observation of a peak in the dijet invariant mass of the Wjj signal observed by the CDF Collaboration can be explained as the same upward fluctuation observed by CDF in single-top-quark production. In general, both t-channel and s-channel single-top-quark production produce kinematically induced peaks in the dijet spectrum. Since CDF used a Monte Carlo simulation to subtract the single-top backgrounds instead of data, a peak in the dijet spectrum is expected. The D0 Collaboration has a small upward fluctuation in their published t-channel data; and hence we predict they would see at most a small peak in the dijet invariant mass spectrum of Wjj if they follow the same procedure as CDF.Comment: 3 pg., 2 figs, revtex, minor clarifications, to appear in Phys. Rev.

The Irreducible String and an Infinity of Additional Constants of Motion in a Deposition-Evaporation Model on a Line

We study a model of stochastic deposition-evaporation with recombination, of three species of dimers on a line. This model is a generalization of the model recently introduced by Barma {\it et. al.} (1993 {\it Phys. Rev. Lett.} {\bf 70} 1033) to $q\ge 3$ states per site. It has an infinite number of constants of motion, in addition to the infinity of conservation laws of the original model which are encoded as the conservation of the irreducible string. We determine the number of dynamically disconnected sectors and their sizes in this model exactly. Using the additional symmetry we construct a class of exact eigenvectors of the stochastic matrix. The autocorrelation function decays with different powers of $t$ in different sectors. We find that the spatial correlation function has an algebraic decay with exponent 3/2, in the sector corresponding to the initial state in which all sites are in the same state. The dynamical exponent is nontrivial in this sector, and we estimate it numerically by exact diagonalization of the stochastic matrix for small sizes. We find that in this case $z=2.39\pm0.05$.Comment: Some minor errors in the first version has been correcte

Assessment of potentially toxic trace element contamination in urban allotment soils and their uptake by onions: A preliminary case study from Sheffield, England

Toxic trace element (TTE) contamination in urban soils may pose potential health risks, especially in cities with previous industrial activities. This study aimed to investigate soil contamination in urban allotments in Sheffield, the uptake of TTEs in autumn and spring sown onions (Allium cepa), and their potential risks on human health via consumption of the crops. Paired soil and plant samples were taken in triplicates from four private allotments to assess potentially elevated levels of lead (Pb), zinc (Zn), copper (Cu), arsenic (As), and chromium (Cr). These elements in soils exceeded the ambient background levels for England. Both Pb and As exceeded some UK and EU soil tolerable limits. Concentration factors (CF) were calculated as the ratio of trace element in the plant as compared to that in the soil, and uptake rates were in the order Zn>Cu>Cr>Pb>As. Concentrations were higher for most TTEs in spring sown onions (SSO), and had significantly higher CF (p < 0.05) for Pb and Cr than autumn sown onions (ASO), whereas the opposite was true for As. Toxic elements in plants did not exceed FAO/WHO intake limits when considering TTE content per plant and consumption rates. Human health risk assessment calculations using target hazard quotients (THQ) and hazard indexes (HI) indicated that consuming onions alone did not pose an immediate health risk

High energy parton-parton amplitudes from lattice QCD and the stochastic vacuum model

Making use of the gluon gauge-invariant two-point correlation function, recently determined by numerical simulation on the lattice in the quenched approximation and the stochastic vacuum model, we calculate the elementary (parton-parton) amplitudes in both impact-parameter and momentum transfer spaces. The results are compared with those obtained from the Kr\"{a}mer and Dosch ansatz for the correlators. Our main conclusion is that the divergences in the correlations functions suggested by the lattice calculations do not affect substantially the elementary amplitudes. Phenomenological and semiempirical information presently available on elementary amplitudes is also referred to and is critically discussed in connection with some theoretical issues.Comment: Text with 11 pages in LaTeX (twocolumn form), 10 figures in PostScript (psfig.tex used). Replaced with changes, Fig.1 modified, two references added, some points clarified, various typos corrected. Version to appear in Phys. Rev.

Ab initio vibrations in nonequilibrium nanowires

We review recent results on electronic and thermal transport in two different quasi one-dimensional systems: Silicon nanowires (SiNW) and atomic gold chains. For SiNW's we compute the ballistic electronic and thermal transport properties on equal footing, allowing us to make quantitative predictions for the thermoelectric properties, while for the atomic gold chains we evaluate microscopically the damping of the vibrations, due to the coupling of the chain atoms to the modes in the bulk contacts. Both approaches are based on a combination of density-functional theory, and nonequilibrium Green's functions.Comment: 16 pages, to appear in Progress in Nonequilibrium Green's Functions IV (PNGF4), Eds. M. Bonitz and K. Baltzer, Glasgow, August 200