Long Distance Contribution to s→dγs \to d\gamma and Implications for Ω−→Ξ−γ,Bs→Bd∗γ\Omega^-\to \Xi ^-\gamma, B_s \to B_d^*\gamma and b→sγb \to s\gamma

We estimate the long distance (LD) contribution to the magnetic part of the $s \to d\gamma$ transition using the Vector Meson Dominance approximation $(V=\rho,\omega,\psi_i)$. We find that this contribution may be significantly larger than the short distance (SD) contribution to $s \to d\gamma$ and could possibly saturate the present experimental upper bound on the $\Omega^-\to \Xi^-\gamma$ decay rate, $\Gamma^{\rm MAX}_{\Omega^-\to \Xi^-\gamma} \simeq 3.7\times10^{-9}$eV. For the decay $B_s \to B^*_d\gamma$, which is driven by $s \to d\gamma$ as well, we obtain an upper bound on the branching ratio $BR(B_s \to B_d^*\gamma)<3\times10^{-8}$ from $\Gamma^{\rm MAX}_{\Omega^-\to \Xi^-\gamma}$. Barring the possibility that the Quantum Chromodynamics coefficient $a_2(m_s)$ be much smaller than 1, $\Gamma^{\rm MAX}_{\Omega^-\to \Xi^-\gamma}$ also implies the approximate relation $\frac{2}{3} \sum_i \frac{g^2_{\psi_i}(0)}{m^2_{\psi_i}} \simeq \frac{1}{2} \frac{g^2_\rho(0)}{m^2_\rho} + \frac{1}{6}\frac{g^2_\omega(0)}{m^2_\omega}$. This relation agrees quantitatively with a recent independent estimate of the l.h.s. by Deshpande et al., confirming that the LD contributions to $b \to s\gamma$ are small. We find that these amount to an increase of $(4\pm2)\%$ in the magnitude of the $b \to s \gamma$ transition amplitude, relative to the SD contribution alone.Comment: 16 pages, LaTeX fil

Social Network Evolution during Long-term Migration: A comparison of three case studies in the South Wales region

Ten years after Poland joined the European Union (EU), a sizable number of the once considered short-term migrants that entered the United Kingdom (UK) post-2004 have remained. From the literature, it is known that when initially migrating, social networks, composed of family and friends, are used to facilitate migration. Later, migrants’ social networks may evolve to include local, non-ethnic members of the community. Through these networks, migrants may access new opportunities within the local economy. They also serve to socialise newcomers in the cultural modalities of life in the destination country. However, what if migrants’ social networks do not evolve or evolve in a limited manner? Is cultural integration still possible under these conditions? Using data collected from three case studies in the South Wales region –Cardiff, Merthyr Tydfil & Llanelli- from 2008-2012, the aim of this article is to compare Polish migrants’ social network usage, or lack thereof, over time. This comparison will be used to understand how these social networks can be catalysts and barriers for cultural integration. The findings point to the migrants’ varied use of their local social networks, which is dependent upon their language skill acquisition and their labour market mobility in the destination country

Radiation exposure prior to traumatic brain injury induces responses that differ as a function of animal age

Purpose: Uncontrolled radiation exposure due to radiological terrorism, industrial accidents or military circumstances is a continuing threat for the civilian population. Age plays a major role in the susceptibility to radiation; younger children are at h