Birth Kick Distributions and the Spin-Kick Correlation of Young Pulsars

Evidence from pulsar wind nebula symmetry axes and radio polarization observations suggests that pulsar motions correlate with the spin directions. We assemble this evidence for young isolated pulsars and show how it can be used to quantitatively constrain birth kick scenarios. We illustrate by computing several plausible, but idealized, models where the momentum thrust is proportional to the neutrino cooling luminosity of the proto-neutron star. Our kick simulations include the effects of pulsar acceleration and spin-up and our maximum likelihood comparison with the data constrains the model parameters. The fit to the pulsar spin and velocity measurements suggests that: i) the anisotropic momentum required amounts to ~10% of the neutrino flux, ii) while a pre-kick spin of the star is required, the preferred magnitude is small 10-20rad/s, so that for the best-fit models iii) the bulk of the spin is kick-induced with $\bar \Omega$ ~120rad/s and iv) the models suggest that the anisotropy emerges on a timescale $\tau$ ~1-3s.Comment: 37 pages, 13 figures, ApJ accepte

Supersymmetric b→sγb \rightarrow s \gamma with Large Chargino Contributions

Supersymmetric (SUSY) theories are often thought to give large branching ratios for $b \rightarrow s \gamma$ from charged Higgs loops. We show that in many cases chargino loop contributions can cancel those of the Higgs, and SUSY can give $B(b \rightarrow s \gamma)$ at or below the \SM\ prediction. We show this occurs because the large stop mass splittings usually found in SUSY break a GIM mechanism suppression. These effects are strongly enhanced by large $\tan\beta$, so that $B(b \rightarrow s \gamma)$ is very sensitive to the value of $\tan\beta$, contrary to what has been claimed. We also note that the supergravity relation $B_0 = A_0-1$ is somewhat disfavored over the general case.Comment: TRI-PP-93-66. 12pp (Plain LATEX)+4 fig not incl. PostScript file of figs available (~3MB), contact Corrie Kost [email protected]. Request hardcopy or FAX of figures through [email protected]

The Optical Polarisation of the Vela Pulsar revisited

In this work we present a revised measurement of the phase-averaged optical polarisation of the Vela pulsar (PSR B0833-45), for which only one value has been published so far (Wagner & Seifert 2000). Our measurement has been obtained through an accurate reanalysis of archival polarisation observations obtained with the FORS instrument at the VLT. We have measured a phase-averaged linear polarisation degree P=9.4% +/- 4% and a position angle 146 +/- 11 deg, very close to the ones of the axis of symmetry of the X-ray arcs and jets detected by Chandra and of the pulsar proper motion.We have compared the measured phase-averaged optical polarisation with the expectations of different pulsars' magnetosphere models. We have found that all models consistently predict too large values of the phase-averaged linear polarization with respect to the observed one. This is probably a consequence of present models' limitations which neglect the contributions of various depolarisation effects. Interestingly, for the outer gap model we have found that, assuming synchrotron radiation for the optical emission, the observed polarisation position angle also implies an alignment between the pulsar rotational axis and the axis of symmetry of the X-ray arcs and jets.Comment: 8 pages, 4 figure

Supersymmetric Time Reversal Violation in Semileptonic Decays of Charged Mesons

We provide a general analysis of time reversal violation arising from misalignment between quark and squark mass eigenstates. In particular, we focus on the possibility of large enhancement effects due to the top quark mass. For semileptonic decays of the charged mesons, $K^+ \rightarrow \pi^0 \mu^+ \nu_{\mu}$, $D^+ \rightarrow \overline{K}^0 \mu^+ \nu_{\mu}$, and $B^+ \rightarrow \overline{D}^0 \tau^+ \nu_{\tau}$, the transverse polarization of the lepton $P^{\bot}_l$ is a $T$-odd observable that is of great experimental interest. It is noted that under favorable choice of parameters, $P^{\bot}_{\mu}$ in $K^+_{\mu3}$ decay can be detectable at the ongoing KEK experiment and it holds a promising prospect for discovery at the proposed BNL experiment. Furthermore, $P^{\bot}_{\tau}$ in $B^{\pm}$ decay could well be within the reach of $B$ factories, but $P^{\bot}_{\mu}$ in $D^{\pm}$ decay is not large enough for detection at the proposed $\tau$-charm factory.Comment: LaTex, 14 pages, 2 figures, minor changes, version to appear in Phys. Lett.

MutDB: update on development of tools for the biochemical analysis of genetic variation

Understanding how genetic variation affects the molecular function of gene products is an emergent area of bioinformatic research. Here, we present updates to MutDB (http://www.mutdb.org), a tool aiming to aid bioinformatic studies by integrating publicly available databases of human genetic variation with molecular features and clinical phenotype data. MutDB, first developed in 2002, integrates annotated SNPs in dbSNP and amino acid substitutions in Swiss-Prot with protein structural information, links to scores that predict functional disruption and other useful annotations. Though these functional annotations are mainly focused on nonsynonymous SNPs, some information on other SNP types included in dbSNP is also provided. Additionally, we have developed a new functionality that facilitates KEGG pathway visualization of genes containing SNPs and a SNP query tool for visualizing and exporting sets of SNPs that share selected features based on certain filters

Gauged flavour symmetry for the light generations

We study the phenomenology of a model where an SU(2)^3 flavour symmetry acting on the first two generation quarks is gauged and Yukawa couplings for the light generations are generated by a see-saw mechanism involving heavy fermions needed to cancel flavour-gauge anomalies. We find that, in constrast to the SU(3)^3 case studied in the literature, most of the constraints related to the third generation, like electroweak precision bounds or B physics observables, can be evaded, while characteristic collider signatures are predicted.Comment: 16 pages, 3 figure

Flavor SU(3) symmetry and QCD factorization in B→PPB \to PP and PVPV decays

Using flavor SU(3) symmetry, we perform a model-independent analysis of charmless $\bar B_{u,d} (\bar B_s) \to PP, ~PV$ decays. All the relevant topological diagrams, including the presumably subleading diagrams, such as the QCD- and EW-penguin exchange diagrams and flavor-singlet weak annihilation ones, are introduced. Indeed, the QCD-penguin exchange diagram turns out to be important in understanding the data for penguin-dominated decay modes. In this work we make efforts to bridge the (model-independent but less quantitative) topological diagram or flavor SU(3) approach and the (quantitative but somewhat model-dependent) QCD factorization (QCDF) approach in these decays, by explicitly showing how to translate each flavor SU(3) amplitude into the corresponding terms in the QCDF framework. After estimating each flavor SU(3) amplitude numerically using QCDF, we discuss various physical consequences, including SU(3) breaking effects and some useful SU(3) relations among decay amplitudes of $\bar B_s \to PV$ and $\bar B_d \to PV$.Comment: 47 pages, 3 figures, 28 table

TeV Scale Implications of Non Commutative Space time in Laboratory Frame with Polarized Beams

We analyze $e^{+}e^{-}\rightarrow \gamma\gamma$, $e^{-}\gamma \rightarrow e^{-}\gamma$ and $\gamma\gamma \rightarrow e^{+}e^{-}$ processes within the Seiberg-Witten expanded noncommutative scenario using polarized beams. With unpolarized beams the leading order effects of non commutativity starts from second order in non commutative(NC) parameter i.e. $O(\Theta^2)$, while with polarized beams these corrections appear at first order ($O(\Theta)$) in cross section. The corrections in Compton case can probe the magnetic component($\vec{\Theta}_B$) while in Pair production and Pair annihilation probe the electric component($\vec{\Theta}_E$) of NC parameter. We include the effects of earth rotation in our analysis. This study is done by investigating the effects of non commutativity on different time averaged cross section observables. The results which also depends on the position of the collider, can provide clear and distinct signatures of the model testable at the International Linear Collider(ILC).Comment: 22 pages, 19 figures, new comments and references added, few typos corrected, Published in JHE

Risk factors for hospital admission with RSV bronchiolitis in England: a population-based birth cohort study.

OBJECTIVE: To examine the timing and duration of RSV bronchiolitis hospital admission among term and preterm infants in England and to identify risk factors for bronchiolitis admission. DESIGN: A population-based birth cohort with follow-up to age 1 year, using the Hospital Episode Statistics database. SETTING: 71 hospitals across England. PARTICIPANTS: We identified 296618 individual birth records from 2007/08 and linked to subsequent hospital admission records during the first year of life. RESULTS: In our cohort there were 7189 hospital admissions with a diagnosis of bronchiolitis, 24.2 admissions per 1000 infants under 1 year (95%CI 23.7-24.8), of which 15% (1050/7189) were born preterm (47.3 bronchiolitis admissions per 1000 preterm infants (95% CI 44.4-50.2)). The peak age group for bronchiolitis admissions was infants aged 1 month and the median was age 120 days (IQR = 61-209 days). The median length of stay was 1 day (IQR = 0-3). The relative risk (RR) of a bronchiolitis admission was higher among infants with known risk factors for severe RSV infection, including those born preterm (RR = 1.9, 95% CI 1.8-2.0) compared with infants born at term. Other conditions also significantly increased risk of bronchiolitis admission, including Down's syndrome (RR = 2.5, 95% CI 1.7-3.7) and cerebral palsy (RR = 2.4, 95% CI 1.5-4.0). CONCLUSIONS: Most (85%) of the infants who are admitted to hospital with bronchiolitis in England are born at term, with no known predisposing risk factors for severe RSV infection, although risk of admission is higher in known risk groups. The early age of bronchiolitis admissions has important implications for the potential impact and timing of future active and passive immunisations. More research is needed to explain why babies born with Down's syndrome and cerebral palsy are also at higher risk of hospital admission with RSV bronchiolitis