A note on state-space representations of locally stationary wavelet time series

In this note we show that the locally stationary wavelet process can be decomposed into a sum of signals, each of which follows a moving average process with time-varying parameters. We then show that such moving average processes are equivalent to state space models with stochastic design components. Using a simple simulation step, we propose a heuristic method of estimating the above state space models and then we apply the methodology to foreign exchange rates data

NLO Higgs boson production via gluon fusion matched with shower in POWHEG

We present a next-to-leading order calculation of Higgs boson production via gluon fusion interfaced to shower Monte Carlo programs, implemented according to the POWHEG method. A detailed comparison with MC@NLO and PYTHIA is carried out for several observables, for the Tevatron and LHC colliders. Comparisons with next-to-next-to-leading order results and with resummed ones are also presented.Comment: Version accepted for publication by JHEP. One more figure added to Sec 4.1.2 and two more explanatory figures and comments added to Sec 4.3 on p_T distribution

Probing annihilations and decays of low-mass galactic dark matter in IceCube DeepCore array: Track events

The deployment of DeepCore array significantly lowers IceCube's energy threshold to about 10 GeV and enhances the sensitivity of detecting neutrinos from annihilations and decays of light dark matter. To match this experimental development, we calculate the track event rate in DeepCore array due to neutrino flux produced by annihilations and decays of galactic dark matter. We also calculate the background event rate due to atmospheric neutrino flux for evaluating the sensitivity of DeepCore array to galactic dark matter signatures. Unlike previous approaches, which set the energy threshold for track events at around 50 GeV (this choice avoids the necessity of including oscillation effect in the estimation of atmospheric background event rate), we have set the energy threshold at 10 GeV to take the full advantage of DeepCore array. We compare our calculated sensitivity with those obtained by setting the threshold energy at 50 GeV. We conclude that our proposed threshold energy significantly improves the sensitivity of DeepCore array to the dark matter signature for $m_{\chi}< 100$ GeV in the annihilation scenario and $m_{\chi}<300$ GeV in the decay scenario.Comment: 19 pages, 5 figures; match the published versio

Momentum Correlations of Charmed Pairs Produced in π−−Cu\pi^{-}-Cu Interactions at 230 GeV/c

We study the production characteristics of 557 pairs of charmed hadrons produced in $\pi^{-}-Cu$\ interactions at 230~GeV/c using a momentum estimator for charmed hadrons with missing decay products. We find, the mean value of the transverse momentum squared of the charmed pairs is $=(1.98\pm 0.11\pm 0.09)\;$ GeV$^2$/c$^2$, the mean rapidity difference is $=0.54\pm 0.02\pm 0.24$, and the mean effective mass is $=(4.45\pm 0.03\pm 0.13)\;$ GeV/c$^2$. Comparing these results with the next-to-leading order QCD predictions we find an agreement for the \yd\ and \mef, whilst the measured mean value of \pts\ is significantly larger than the predicted value.Comment: 10 pages, LaTeX, 4 (pages) postscript figure

Lightside Atmospheric Revitalization System

The system was studied as a replacement to the present baseline LiOH system for extended duration shuttle missions. The system consists of three subsystems: a solid amine water desorbed regenerable carbon dioxide removal system, a water vapor electrolysis oxygen generating system, and a Sabatier reactor carbon dioxide reduction system. The system is designed for use on a solar powered shuttle vehicle. The majority of the system's power requirements are utilized on the Sun side of each orbit, when solar power is available

Improving NLO-parton shower matched simulations with higher order matrix elements

In recent times the algorithms for the simulation of hadronic collisions have been subject to two substantial improvements: the inclusion, within parton showering, of exact higher order tree level matrix elements (MEPS) and, separately, next-to-leading order corrections (NLOPS). In this work we examine the key criteria to be met in merging the two approaches in such a way that the accuracy of both is preserved, in the framework of the POWHEG approach to NLOPS. We then ask to what extent these requirements may be fulfilled using existing simulations, without modifications. The result of this study is a pragmatic proposal for merging MEPS and NLOPS events to yield much improved MENLOPS event samples. We apply this method to W boson and top quark pair production. In both cases results for distributions within the remit of the NLO calculations exhibit no discernible changes with respect to the pure NLOPS prediction; conversely, those sensitive to the distribution of multiple hard jets assume, exactly, the form of the corresponding MEPS results.Comment: 38 pages, 17 figures. v2: added citations and brief discussion of related works, MENLOPS prescription localized in a subsection. v3: cited 4 more MEPS works in introduction

Supersymmetric QCD corrections to single top quark production at hadron colliders

We present the calculations of the supersymmetric QCD corrections to the total cross sections for single top production at the Fermilab Tevatron and the CERN Large Hadron Collider in the minimal supersymmetric standard model. Our results show that for the s-channel and t-channel, the supersymmetric QCD corrections are at most about 1%, but for the associated production process, the supersymmetric QCD corrections increase the total cross sections significantly, which can reach about 6% for most values of the parameters, and the supersymmetric QCD corrections should be taken into consideration in the future high precision experimental analysis for top physics.Comment: 33 pages, 19 figures, version to appear in Phys.Rev.

Computational and experimental investigation of mixing in microchannels

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.Mixing is a key process for the successful of all chemical or biochemical reactions, so effective micromixers represent essential components for micro total analysis systems (μTAS) or lab-on-a-chip. In the present study a combined computational and experimental approach was adopted to evaluate how the efficiency of a Y-mixer can be enhanced by modifying its downstream geometry. Three different geometries were studied and compared: Y-straight channel, Y-sine channel and Y-wrinkled wall channel. For each of them the influence of perfusing flow rates and channel cross section aspect ratio was investigated. Physical prototypes were built using a simple technique based on a xerographic process, and their mixing performance was experimentally evaluated. Computational models of the designed micromixers were generated: the Navier-Stokes equations for an incompressible Newtonian fluid and the advection-diffusion equation were solved with an uncoupled approach by means of the finite volume method. The computational and experimental results were critically compared, revealing Y-wrinkled wall mixer as the best performer among those considered and suggesting criteria of possible improvements and optimization

Tau Neutrino Astronomy in GeV Energies

We point out the opportunity of the tau neutrino astronomy for the neutrino energy E ranging between 10 GeV and 10^3 GeV. In this energy range, the intrinsic tau neutrino production is suppressed relative to the intrinsic muon neutrino production. Any sizable tau neutrino flux may thus arise because of the \nu_{\mu}\to \nu_{\tau} neutrino oscillations only. It is demonstrated that, in the presence of the neutrino oscillations, consideration of the neutrino flavor dependence in the background atmospheric neutrino flux leads to the drastically different prospects between the observation of the astrophysical muon neutrinos and that of the astrophysical tau neutrinos. Taking the galactic-plane neutrino flux as the targeted astrophysical source, we have found that the galactic-plane tau neutrino flux dominates over the atmospheric tau neutrino flux for E > 10 GeV. Hence, the galactic-plane can at least in principle be seen through the tau neutrinos with energies just greater than 10 GeV. In a sharp contrast, the galactic-plane muon neutrino flux is overwhelmed by its atmospheric background until E > 10^6 GeV.Comment: major revision of text and two new figures, to appear in PR

Detecting an Invisibly Decaying Higgs Boson at a Hadron Supercollider

We demonstrate that an invisibly decaying Higgs boson with Standard Model coupling strength to top--anti-top can be detected at the LHC for masses up to about 250 GeV.Comment: 7 pages, requires phyzzx.tex and tables.tex, revised to convert results from SSC to LHC and include additional top quark mass cases, full postscript file including embedded figure available via anonymous ftp at ucdhep.ucdavis.edu as [anonymous.gunion]hinvisible_revised.ps, preprint UCD-93-2