Signatures of Extra Gauge Bosons in the Littlest Higgs Model with T-parity at Future Colliders

We study the collider signatures of a T-odd gauge boson $W_{H}$ pair production in the Littlest Higgs Model with T-parity (LHT) at Large Hadron Collider (LHC) and Linear Collider (LC). At the LHC, we search for the $W_{H}$ boson using its leptonic decay, i.e. $pp\to W_{H}^{+}W_{H}^{-}\to A_{H}A_{H}\ell^{+}\nu_{\ell}\ell^{\prime-}\bar{\nu}_{\ell^{\prime}}$, which gives rise to a collider signature of \ell^{+}\ell^{\prime-}+\met. We demonstrate that the LHC not only has a great potential of discovering the $W_{H}$ boson in this channel, but also can probe enormous parameter space of the LHT. Due to four missing particles in the final state, one cannot reconstruct the mass of $W_{H}$ at the LHC. But such a mass measurement can be easily achieved at the LC in the process of $e^{+}e^{-}\to W_{H}^{+}W_{H}^{-}\to A_{H}A_{H}W^{+}W^{-}\to A_{H}A_{H}jjjj$. We present an algorithm of measuring the mass and spin of the $W_{H}$ boson at the LC. Furthermore, we illustrate that the spin correlation between the $W$ boson and its mother particle ($W_{H}$) can be used to distinguish the LHT from other new physics models.Comment: version to appear in PRD (a few references added

Prenatal Methylmercury Exposure through Rice Consumption in Rural China

Background: Methylmercury is one of the most toxic forms of mercury, which severely afflicts the developing fetus. Methylmercury exposure occurs not only through fish consumption but also through rice consumption. However, rice does not contain the same beneficial micronutrients that fish/shellfish has. Therefore, prenatal methylmercury exposure through maternal rice consumption may potentially increase adverse health effects on the developing fetus. Objectives: The purpose of this dissertation was to investigate the magnitude of prenatal methylmercury exposure through rice consumption and the relationship between maternal mercury biomarkers and birth outcomes. Methods: A total of 398 pregnant women were recruited at parturition in a rural area of southern China, where rice was a staple food and mercury contamination was considered minimal. Total mercury and/or methylmercury concentrations were measured in maternal hair and blood, in rice samples from each participant’s home, and in freshwater fish tissue purchased from local markets. Additional fish/shellfish mercury levels were obtained from a literature review. Neonatal weight, length and head circumference were recorded shortly after birth and then converted to: birth weight z score, birth length z score, head circumference z score, and ponderal index (birth weight/birth length3). Results: The geometric means of hair total mercury, hair methylmercury, and blood total mercury were 0.41 µg/g, 0.27 µg/g, and 1.3 µg/L, respectively, which were comparable to other pregnant cohorts with low-level mercury exposure mainly through fish/shellfish consumption. All three mercury biomarkers were significantly correlated with rice methylmercury intake, but not fish/shellfish methylmercury in take. After adjusting for covariates, both hair total mercury and hair methylmercury were negatively related with birth weight z score. An inverse relationship was also observed between blood total mercury and ponderal index. In contrast, the rela tionships between mercury biomarkers and other outcome measures were inverse but non-significant. Conclusions: Our findings confirm the presence of low-level prenatal methylmercury exposure occurring in this cohort, and indicated that rice intake contributed to the prenatal methylmercury exposure, more so than fish/shellfish intake. Also, inverse linear relationships between prenatal methylmercury exposure and birth weight and ponderal index were observe

Resummation Effects in the Search of SM Higgs Boson at Hadron Colliders

We examine the soft-gluon resummation effects, including the exact spin correlations among the final state particles, in the search of the Standard Model Higgs boson, via the process $gg\to H\to WW/ZZ \to 4 leptons, at the Tevatron and the LHC. A comparison between the resummation and the Next-to-Leading order (NLO) calculation is performed after imposing various kinematics cuts suggested in the literature for the Higgs boson search. For the$H\to ZZ$mode, the resummation effects increase the acceptance of the signal events by about 25various kinematics distributions of the final state leptons. For the$H\to WW$ mode, the acceptance rates of the signal events predicted by the resummation and NLO calculations are almost the same, but some of the predicted kinematical distributions are quite different. Thus, to precisely determine the properties of the Higgs boson at hadron colliders, the soft-gluon resummation effects have to be taken into account.Comment: The version to appear in PR

Generalized Area Spectral Efficiency: An Effective Performance Metric for Green Wireless Communications

Area spectral efficiency (ASE) was introduced as a metric to quantify the spectral utilization efficiency of cellular systems. Unlike other performance metrics, ASE takes into account the spatial property of cellular systems. In this paper, we generalize the concept of ASE to study arbitrary wireless transmissions. Specifically, we introduce the notion of affected area to characterize the spatial property of arbitrary wireless transmissions. Based on the definition of affected area, we define the performance metric, generalized area spectral efficiency (GASE), to quantify the spatial spectral utilization efficiency as well as the greenness of wireless transmissions. After illustrating its evaluation for point-to-point transmission, we analyze the GASE performance of several different transmission scenarios, including dual-hop relay transmission, three-node cooperative relay transmission and underlay cognitive radio transmission. We derive closed-form expressions for the GASE metric of each transmission scenario under Rayleigh fading environment whenever possible. Through mathematical analysis and numerical examples, we show that the GASE metric provides a new perspective on the design and optimization of wireless transmissions, especially on the transmitting power selection. We also show that introducing relay nodes can greatly improve the spatial utilization efficiency of wireless systems. We illustrate that the GASE metric can help optimize the deployment of underlay cognitive radio systems.Comment: 11 pages, 8 figures, accepted by TCo