Calculation of the three-dimension, supersonic, inviscid, steady flow past an arrow-winged airframe, part 1

A detailed description of the procedure used to compute three dimensional, supersonic, inviscid, steady flows past airframes is given. No limitations are imposed on the geometry of the airplane. Suitable computational grids are generated by automatic conformal mappings. The equations of motion, with pressure, entropy, and velocity direction as basic unknowns, are written and discretized in the computational space. Special rules to approximate derivatives are given. Boundary points are treated by a modified method of characteristics

Experiments on initial and boundary conditions

Effects of three different models for the treatment of subsonic boundary conditions, applied to the problem of flow in a channel with a bump, are discussed. A preliminary discussion of the numerical treatment of the corners is presented

An old integration scheme for compressible flows revisited, refurbished and put to work

A scheme for integrating the Euler equations of compressible flow in any hyperbolic case is presented. The scheme relies on the concept of characteristics but is strictly a finite difference scheme. Improvements in accuracy and physical consistence due to the scheme are discussed and results of its application to complex flows are shown

Grid generation using classical techniques

A brief historical review of conformal mapping and its applications to problems in fluid mechanics and electromagnetism is presented. The use of conformal mapping as a grid generator is described. The philosophy of the 'closed form' approach and its application to a Neumann problem is discussed. Karman-Trefftz mappings and grids for ablated, three dimensional bodies are also discussed

Numerical studies of 2-dimensional flows

A formulation of the lambda scheme for the analysis of two dimensional inviscid, compressible, unsteady transonic flows is presented. The scheme uses generalized Riemann variables to determine the appropriate two point, one sided finite difference approximation for each derivative in the unsteady Euler equations. These finite differences are applied at the predictor and corrector levels with shock updating at each level. The weaker oblique shocks are captured, but strong near normal shocks are fitted into the flow using the Rankine-Hugoniot relations. This code is demonstrated with a numerical example of a duct flow problem with developing normal and oblique shock waves. The technique is implemented in a code which has been made efficient by streamlining to a minimal number of operations and by eliminating branch statements. The scheme is shown to provide an accurate analysis of the flow, including formation, motions, and interactions of shocks; the results obtained on a relatively coarse mesh are comparable to those obtained by other methods on much finer meshes

Fast Euler solver for steady, 1-dimensional flows

A numerical technique to solve the Euler equations for steady, one dimensional flows is presented. The technique is essentially implicit, but is structured as a sequence of explicit solutions for each Riemann variable separately. Each solution is obtained by integrating in the direction prescribed by the propagation of the Riemann variables. The technique is second-order accurate. It requires very few steps for convergence, and each step requires a minimal number of operations. Therefore, it is three orders of magnitude more efficient than a standard time-dependent technique. The technique works very well for transonic flows and provides shock fitting with errors as small as 0.001. Results are presented for subsonic problems. Errors are evaluated by comparison with exact solutions

Dependence of the leptonic decays of H^- on the neutrino mixing angles theta_{13} and theta_{23} in models with neutrinophilic charged scalars

In the Higgs Triplet Model and the neutrinophilic Two-Higgs-Doublet Model the observed neutrinos obtain mass from a vacuum expectation value which is much smaller than the vacuum expectation value of the Higgs boson in the Standard Model. Both models contain a singly charged Higgs boson (H^-) whose Yukawa coupling is directly related to the neutrino mass (i.e. a "neutrinophilic charged Higgs"). The partial decay widths of H^- into a charged lepton and a neutrino (H^- to l^- nu) depend identically on the neutrino masses and mixings in the two models. We quantify the impact of the recent measurement of sin^2(2theta_{13}), which plays a crucial role in determining the magnitude of the branching ratio of H^- to e^- nu for the case of a normal neutrino mass ordering if the lightest neutrino mass m_0 < 10^{-3} eV. We also discuss the sizeable dependence of H^- to mu^- nu and H^- to tau^- nu on sin^2(theta_{23}), which would enable information to be obtained on sin^2(theta_{23}) and the sign of \Delta m^2_{31} if these decays are measured. Such information would help neutrino oscillation experiments to determine the CP-violating phase \delta.Comment: 17 pages, 6 figure

Light charged Higgs boson with dominant decay to quarks and its search at LHC and future colliders

The possibility of a light charged Higgs boson $H^\pm$ that decays predominantly to quarks ($cs$ and/or $cb$) and with a mass in the range 80 GeV $\le m_{H^\pm} \le 90$ GeV is studied in the context of Three-Higgs-Doublet Models (3HDMs). At present the Large Hadron Collider (LHC) has little sensitivity to this scenario, and currently the best constraints are from LEP2 and Tevatron searches. The branching ratio of $H^\pm\to cb$ can be dominant in two of the five types of 3HDM, and we determine the parameter space where this occurs. The decay $H^\pm\to cb$ has recently been searched for at the LHC for the first time, and with increased integrated luminosity one would expect sensitivity to the region 80 GeV $\le m_{H^\pm} \le 90$ GeV due to the smaller backgrounds with respect to $H^\pm\to cs$ decays.Comment: 25 pages, 17 figure

Strong and Electro-Weak Supersymmetric Corrections to Single Top Processes at the Large Hadron Collider

We present the one-loop corrections originating from Quantum Chromo-Dynamics (QCD) and Electro-Weak (EW) interactions of Supersymmetric (SUSY) origin within the Minimal Supersymmetric Standard Model (MSSM) to the single-top processes bq -> tq' and qbar q' -> tbar b. We illustrate their impact onto top quark observables accessible at the Large Hadron Collider (LHC) in the 't+jet' final state, such as total cross section, several differential distributions and left-right plus forward-backward asymmetries. We find that in many instances these effects can be observable for planned LHC energies and luminosities, quite large as well as rather sensitive to several MSSM parameters.Comment: 22 pages, 10 figures; added a brief comment on the dependence of results on the value of top mass; corrected typo

Intrinsic scatter of caustic masses and hydrostatic bias: An observational study

All estimates of cluster mass have some intrinsic scatter and perhaps some bias with true mass even in the absence of measurement errors for example caused by cluster triaxiality and large scale structure. Knowledge of the bias and scatter values is fundamental for both cluster cosmology and astrophysics. In this paper we show that the intrinsic scatter of a mass proxy can be constrained by measurements of the gas fraction because masses with higher values of intrinsic scatter with true mass produce more scattered gas fractions. Moreover, the relative bias of two mass estimates can be constrained by comparing the mean gas fraction at the same (nominal) cluster mass. Our observational study addresses the scatter between caustic (i.e., dynamically estimated) and true masses, and the relative bias of caustic and hydrostatic masses. For these purposes, we used the X-ray Unbiased Cluster Sample, a cluster sample selected independently from the intracluster medium content with reliable masses: 34 galaxy clusters in the nearby ($0.050<z<0.135$) Universe, mostly with $14<\log M_{500}/M_\odot \lesssim 14.5$, and with caustic masses. We found a 35\% scatter between caustic and true masses. Furthermore, we found that the relative bias between caustic and hydrostatic masses is small, $0.06\pm0.05$ dex, improving upon past measurements. The small scatter found confirms our previous measurements of a highly variable amount of feedback from cluster to cluster, which is the cause of the observed large variety of core-excised X-ray luminosities and gas masses.Comment: A&A, in press, minor language changes from previous versio