Conventional searches for the charged Higgs boson using its production in association with Standard Model (SM) quarks is notoriously weak in the mid-tanB range. Hoping to find an alternate channel to fill this gap, the production of the charged Higgs boson in association with supersymmetric squarks is studied. Using Monte Carlo generators the production at the LHC is simulated within the non universal Higgs mass model (NUHM). If the six parameters of the model (m0, m1/2, A0, tanB, u, mA) induce small masses of the stop, sbottom and charged Higgs, the production cross section can be of the order pb. Through scans of the input parameter the cross section is maximized, with the requirement that the stop decays directly to a neutralino - simplifying detection, in the point (m0, m1/2, A0, tanB, u, mA) = (190, 187, -1147, 179, 745, 13.2) where the cross section is 559 fb. The production is compared to the irreducible backgrounds stop, stop, t, tbar and t, tbar + 2 jets. The former poses no severe constraints and can be easily removed using appropriate cuts. The latter, SM background, has a cross section almost 1000 times larger and strong cuts must be imposed to suppress it. Neglecting hadronization and systematic effects, we show that a 5 sigma discovery is possible at 133 fb-1. In this range, mH+ = 194 GeV and tanB = 13.2, other channels have little or no prospects of detecting the charged Higgs and the studied process shows good prospects for complementing charged Higgs searches at the LHC in the mid-tanB range.

In the ATLAS experiment software plays a central role in data taking, reconstruction, and analysis. This thesis presents a set of analysis algorithms written for the ATLAS software framework Athena, towards H+ searches in the τ+jets channel. Data recorded by the ATLAS experiment for 900 GeV proton-proton collisions from 2009 and 7 TeV proton-proton collisions from 2010 are analyzed with these algorithms and compared to Monte Carlo. A search for top quarks is performed on 36 pb-1 of data, and the results are found to agree well with Monte Carlo.

No description available.

A search for a light charged Higgs boson decaying into cs is presented using data recorded in pp collisions at √s = 7 TeV. The analysis uses a data sample corresponding to an integrated luminosity of 35.3 pb⁻¹ collected by the ATLAS detector at the LHC between June and November 2010. The search is based on the semi-leptonic tt channel searching for the process t → H⁺b where H⁺ → cs⁻. The invariant mass distribution of the dijet system consistent with the hadronic decay of a W⁺ is used to search for a secondary bump from hadronic H⁺ decays. With no observation of the charged Higgs signal, 95% confidence level upper limits on the decay branching ratio of top quarks to charged Higgs bosons are set as a function of the charged Higgs boson mass.

This thesis will examine the interactions of a cloud of charged vortex rings (CVRs) in the low temperature limit in helium-II (0.2 < T < 0.8 K) in a cubic cell containing a quasi-uniform electric field. A model of geometric collisions between vortex rings is proposed to explain the observed critical density of CVRs given by nR^3 ~ 3 cm^{-1} R where n is the CVR number density and R is the average CVR radius. This model was simulated in a simplified situation where two perfectly circular parent CVRs collide geometrically to create two perfectly circular daughter CVRs, conserving momentum and charge and dissipating a random amount of energy. The simulations are in qualitative and quantitative agreement with experiment.For an intense injection of CVRs into a strong electric field the CVRs quickly reconnect with one another to form a tangle of charged vortex loops. These loops move as one quasi-connected unit, it was found that the charged tangle's response to forcing was given by a law of the form t3 ~ (QE)^{-1/3} where t3 is the charged tangle time of flight, Q is the charge of the tangle and E is the applied electric field. Simulations of the displacement current induced in two electrodes in the cell were run in order to glean some information as to the transverse distribution of charge in the tangle, which was found to be approximately constant with time of flight and injected charge.

No description available.

We formulate a variational method to obtain the binding energies of a charged particle in presence of an electric dipole and a magnetic field aligned along the dipole. First, we test the method by obtaining the critical dipole moment for a point dipole, as well as a finite dipole in the absence of a magnetic field. A few larger dipole moments supporting a zero energy bound state are also obtained. Adding a magnetic field of ~ 20 - 100 T, we show that for a rigid and stationary dipole of moment 2.54 D, the electron binding energy increases by 15% - 66%. Our approach also shows the absence of a critical dipole moment in presence of an aligned magnetic field. / Thesis / Master of Science (MSc)

<p dir="ltr">The Mu2e experiment is searching for Beyond-Standard-Model, Charged Lepton Flavor Violation (CLFV) in the muon capture reaction μ⁻+ Al → e⁻ + Al. To compare the accessible energy scale of this experiment, the Large Hadron Collider (LHC) is capable of observing new physics at the few TeV mass scale. However, by searching for μ-to-e conversion at a branching ratio sensitivity of 10⁻¹⁷, Mu2e will probe for new physics at mass scales up to 10³ ∼ 10⁴TeV, far beyond the reach of any planned accelerator and surpassing the current world’s best limit by 10⁴ times. In addition, there is no competing Standard Model process that produces this decay to a branching ratio level < 10⁻⁵⁴. To report a reliable result, the number of stopped muons will be normalized to 10% precision utilizing two γ-ray transitions and one x-ray atomic transition. The first, directly proportional to the CLFV signal, is the 1808.7 keV γ-ray emitted promptly in the muon capture process. The second, the 2p→1s atomic transition of muonic aluminum, is the 346.8 keV x-ray line. The third, is the 844 keV γ-ray from the β-decay process. These signals need to be measured in the presence of an energy flux background of 3.2 x 10⁸TeV/sec, consisting of muons, electrons, neutrons, x-rays and γ-rays. Here, two com- 11 photon counting detectors are used in the luminosity measurement. One of them, the LaBr₃ detector, is capable of high rate operation up to and above 800 kcps and energy resolution of 0.7%, producing highly accurate statistical measurements. The other, the HPGe detector is capable of energy resolution of 0.1%, with limited rate capability ∼ 70 kcps, yet producing measurements having low systematic error. Once signals are found within the background, corrections must be understood and applied including: geometric factors, detector efficiency, branching ratio of the observed physics pro- cesses, signal loss due to propagation to the detector, interfering lines, event loss due to pile-up, event loss due to algorithm miscalculation, time evolution of the signal, and others. The normalization measurement will be reported out in real time every 5 to 10 minutes, and a comprehensive off-line analysis will be undertaken using merged data sets.</p>

Incident 0.5 to 2.5 MeV charged particle beams were used to ionize the inner-shells of selected targets and study their subsequent emission of characteristic x-rays. ⁹Be⁺ ions were used to examine K-shell x-ray production from thin F, Na, Al, Si, P, Cl, and K targets, L-shell x-ray production from thin Cu, An, Ge, Br, Zr and Ag targets, and M-shell x-ray production from thin Pr, Nd, Eu, Dy, Ho, Hf, W, Au, Pb and Bi targets. L-shell x-ray production cross sections were also measured for ²⁷Al⁺ ions incident upon Ni, Cu, Zn, As, Zr, and Pd targets. M-shell x-ray production cross sections were measure for ²⁷Al⁺ and ⁴⁰Ar⁺ ions incident upon Pr, Nd, Gd, Dy, Lu, Hf, Au, Pb, Bi, and U targets. These measurements were performed using the 2.5 MV Van de Graaff accelerator at North Texas State University. The x-rays were detected with a Si(Li) detector whose efficiency was determined by fitting a theoretical photon absorption curve to experimentally measure values. The x-ray yields were normalized to the simultaneously measured Rutherford backscattered (RBS) yields which resulted in an x-ray production cross section per incident ion. The RBS spectrum was obtained using a standard surface barrier detector calibrated for to account for the "pulse height defect." The experimental results are compared to the predictions of both the first Born and ECPSSR theories; each of which is composed of two parts, the direct ionization (DI) of the target electron to the continuum and the capture (EC) of the target electron to the projectile. The first Born describes DI by the Plane-Wave-Born-Approximation (PWBA) and EC by the Oppenheimer-Brinkman-Kramers treatment of Nikolaev (OBKN). ECPSSR expands upon the first Born by using perturbed (PSS) and relativistic (R) target electron wave functions in addition to considering the energy loss (E) of the projectile in the target and its deviation from straight line trajectory (Coulomb deflection (C)). The measurements presented show that the first Born theories overestimate the measured results rather significantly for all experiments using the ⁹Be beams to examine the inner shell x-rays, while the ECPSSR predictions fir the measured data much better. For incident ²⁷Al and ⁴⁰Ar ions, the measured results are not predicted by the theories. The first Born generally over-predicts the data for low target atomic numbers while under-predicting at high atomic numbers. The ECPSSR theory greatly under-predicts the results (factors of 10³ to 10²⁰). Reasons for this behavior are discussed as well as suggestions for future experiments.

The ATLAS experiment at the LHC is searching for evidence of charged Higgs bosons, without yet finding it. This report investigates the possibility of reconstructing charged Higgs bosons using multi-jet final states (pp -&gt; [b]tH+ -&gt; [b]bbbql\nu) with focus on fully hadronic H^+ -&gt; hW decays using a simulation of 500k events with m_{H+} = 250 GeV. After optimizing TMVA (Toolkit for Multivariate Analysis) input variables for BDT (Boosted Decision Trees), the mass of H+ was recreated with an efficiency of up to 26,7% (correct combinations).