Light Higgs Studies for the CLIC CDR

The Higgs boson is the most anticipated discovery at the LHC, which can only partially explore its true nature. Thus one of the most compelling arguments to build a future linear collider is to investigate properties of the Higgs boson, especially to test the predicted linear dependence of the branching ratios on the mass of the final state. At a 3TeV CLIC machine the Higgs boson production cross section is relatively large and allows for a precision measurement of the Higgs branching ratio to pairs of b and c quarks, and even to muons. The cross section times branching ratio of the decays $H\rightarrow b\bar{b}$, $H\rightarrow c\bar{c}$ and $H\rightarrow \mu^{+}\mu^{-}$ can be measured with a statistical uncertainty of approximately 0.22%, 3.2% and 15%, respectively

Flavour Tagging at CLIC

We present the performance of the LCFI flavour tagging package in a realistic CLIC environment. The application is demonstrated on the examples of the measurement of the cross section times branching ratio of light Higgs decays to b and c quarks at 3 TeV, a study of heavy Higgs decays at 3 TeV and of top pair production at 500 GeV. All studies are based on full detector simulation with a realistic account of the machine- induced background at CLIC.Comment: LCWS 2011 proceeding

Measurement of the Cross Section Times Branching Ratio of Light Higgs Decays at CLIC

The investigation of the properties of a Higgs boson, especially a test of the predicted linear dependence of the branching ratios on the mass of the final state, is currently one of the most compelling arguments for building a linear collider. We demonstrate that the large Higgs boson production cross section at a 3 TeV CLIC machine allows for a precision measurement of the Higgs branching ratios. The cross section times branching ratio of the decays H \rightarrow b^{-}b, H \rightarrow cc^{-} and H \rightarrow {\mu}{\mu} can be measured with a statistical uncertainty of 0.22%, 3.2% and 15%, respectively.Comment: LCWS 2011 Proceeding

A Study of the Impact of High Cross Section ILC Processes on the SiD Detector Design

The SiD concept is one of two proposed detectors to be mounted at the interaction region of the International Linear Collider (ILC). A substantial ILC background arises from low transverse momentum $\mathrm{e}^{+}\mathrm{e}^{-}$ pairs created by the interaction of the colliding beams' electromagnetic fields. In order to provide hermeticity and sensitivity to beam targeting parameters, a forward Beamline Calorimeter (BeamCal) is being designed that will provide coverage down to 5 mrad from the outgoing beam trajectory, and intercept the majority of this pair background. Using the SiD simulation framework, the effect of this pair background on the SiD detector components, especially the vertex detector (VXD) and forward electromagnetic calorimeter (FCAL), is explored. In the case of the FCAL, backgrounds from Bhabha and two-photon processes are also considered. The consequence of several variants of the BeamCal geometry and ILC interaction region configuration are considered for both the vertex detector and BeamCal performance

Measurement of the Higgs boson mass and e+e−→ZHe^+e^- \to ZH cross section using Z→μ+μ−Z \to \mu^+\mu^- and Z→e+e−Z \to e^+ e^- at the ILC

This paper presents a full simulation study of the measurement of the production cross section ($\sigma_{\mathrm{ZH}}$) of the Higgsstrahlung process $\mathrm{e^{+}e^{-}\rightarrow ZH}$ and the Higgs boson mass ($M_{\mathrm{H}}$) at the International Linear Collider (ILC), using events in which a Higgs boson recoils against a Z boson decaying into a pair of muons or electrons. The analysis is carried out for three center-of-mass energies $\sqrt{s}$ = 250, 350, and 500 GeV, and two beam polarizations $\mathrm{e_{L}^{-}e_{R}^{+}}$ and $\mathrm{e_{R}^{-}e_{L}^{+}}$, for which the polarizations of $\mathrm{e^{-}}$ and $\mathrm{e^{+}}$ are $\left(P\mathrm{e^{-}},P\mathrm{e^{+}}\right)$ =($-$80\%, +30\%) and (+80\%, $-$30\%), respectively. Assuming an integrated luminosity of 250 $\mathrm{fb^{-1}}$ for each beam polarization at $\sqrt{s}$ = 250 GeV, where the best lepton momentum resolution is obtainable, $\sigma_{\mathrm{ZH}}$ and $M_{\mathrm{H}}$ can be determined with a precision of 2.5\% and 37 MeV for $\mathrm{e_{L}^{-}e_{R}^{+}}$ and 2.9\% and 41 MeV for $\mathrm{e_{R}^{-}e_{L}^{+}}$, respectively. Regarding a 20 year ILC physics program, the expected precisions for the $\mathrm{HZZ}$ coupling and $M_{\mathrm{H}}$ are estimated to be 0.4\% and 14 MeV, respectively. The event selection is designed to optimize the precisions of $\sigma_{\mathrm{ZH}}$ and $M_{\mathrm{H}}$ while minimizing the bias on the measured $\sigma_{\mathrm{ZH}}$ due to discrepancy in signal efficiencies among Higgs decay modes. For the first time, model independence has been demonstrated to a sub-percent level for the $\sigma_{\mathrm{ZH}}$ measurement at each of the three center-of-mass energies. The results presented show the impact of center-of-mass energy and beam polarization on the evaluated precisons and serve as a benchmark for the planning of the ILC run scenario.Comment: arXiv admin note: substantial text overlap with arXiv:1601.0648

Prospects for the Measurement of the Higgs Yukawa Couplings to b and c quarks, and muons at CLIC

The investigation of the properties of the Higgs boson, especially a test of the predicted linear dependence of the branching ratios on the mass of the final state is going to be an integral part of the physics program at colliders at the energy frontier for the foreseeable future. The large Higgs boson production cross section at a 3TeV CLIC machine allows for a precision measurement of the Higgs branching ratios. The cross section times branching ratio of the decays H->bb, H->cc and H->{\mu}{\mu} of a Standard Model Higgs boson with a mass of 120 GeV can be measured with a statistical uncertainty of 0.23%, 3.1% and 15%, respectively, assuming an integrated luminosity of 2 ab-1.Comment: 6 pages, 4 figure

An Early Transcriptional Analysis of Fracture Hematoma in Rat

Among other stressors, age and mechanical constraints significantly influence regeneration cascades in bone healing. Here, our aim was to identify genes and, through their functional annotation, related biological processes that are influenced by an interaction between the effects of mechanical fixation stability and age. Therefore, at day three post-osteotomy, chip-based whole- genome gene expression analyses of fracture hematoma tissue were performed for four groups of Sprague-Dawley rats with a 1.5-mm osteotomy gap in the femora with varying age (12 vs. 52 weeks - biologically challenging) and external fixator stiffness (mechanically challenging). From 31099 analysed genes, 1103 genes were differentially expressed between the six possible combinations of the four groups and from those 144 genes were identified as statistically significantly influenced by the interaction between age and fixation stability. Functional annotation of these differentially expressed genes revealed an association with extracellular space, cell migration or vasculature development. The chip-based whole-genome gene expression data was validated by q-RT-PCR at days three and seven post-osteotomy for MMP-9 and MMP-13, members of the mechanosensitive matrix metalloproteinase family and key players in cell migration and angiogenesis. Furthermore, we observed an interaction of age and mechanical stimuli in vitro on cell migration of mesenchymal stromal cells. These cells are a subpopulation of the fracture hematoma and are known to be key players in bone regeneration. In summary, these data correspond to and might explain our previously described biomechanical healing outcome after six weeks in response to fixation stiffness variation. In conclusion, our data highlight the importance of analysing the influence of risk factors of fracture healing (e.g. advanced age, suboptimal fixator stability) in combination rather than alone

Performance of Julia for High Energy Physics Analyses

We argue that the Julia programming language is a compelling alternative to implementations in Python and C++ for common data analysis workflows in high energy physics. We compare the speed of implementations of different workflows in Julia with those in Python and C++. Our studies show that the Julia implementations are competitive for tasks that are dominated by computational load rather than data access. For work that is dominated by data access, we demonstrate an application with concurrent file reading and parallel data processing.Comment: 16 pages, 4 pages, 1 table, 3 code listing