Threshold Improved QCD Corrections for Stop-Antistop production at Hadron colliders

I present improved predictions for the total hadronic cross section of stop-antistop production at hadron colliders including next-to-next-to-leading-order threshold corrections and approximated Coulomb corrections. The results are based on soft corrections, which are logarithmically enhanced near threshold. I present analytic formulas for the NNLO scaling functions at threshold and explicit numbers for the total hadronic cross sections for the Tevatron and the LHC. Finally I discuss the systematic error, the scale uncertainty and the PDF error of the hadronic cross section.Comment: 19 pages, 6 figure

Constraints on Neutralino masses and mixings from Cosmology and Collider Physics

Bounds on cross section measurements of chargino pair production at LEP yield a bound on the chargino mass. If the GUT relation is assumed, the lightest neutralino must be heavier than \approx 45 -50\GeV. If no GUT relation is assumed, no lower bound on the neutralino mass exists. I derive mass bounds on the lightest neutralino from relic density measurements for relativistic and non-relativistic neutralinos and I derive bounds on the selectron mass from the observed limits on the cross section of the neutralino pair production process e^+e^-\to \x{1}\x{2} at LEP, if the lightest neutralino is massless. I further discuss radiative neutralino production and its background at the future ILC. Finally, I present a method to determine the neutralino couplings to right and left handed selectrons and Z bosons from cross section measurements of radiative neutralino production and neutralino pair production at the ILC.Comment: PhD-Thesis, 101 page

Coaching Style Preferences of Division I College and Professional Softball Players

The purpose of this study was to describe the coaching style and leader behavior preferences of softball players. The Leadership Scale for Sports (LSS; Chelladurai & Saleh, 1980) was administered to Division I college softball players and professional softball players from the National Professional Fastpitch league (NPF). Sixty-four softball players completed the Leadership Scale for Sport questionnaire (preference version), 52 Division I college softball players and 12 professional softball players from the NPF. Descriptive statistics revealed that softball players prefer Training and Instruction, Democratic Behavior, and Positive Feedback; players did not prefer Autocratic Behavior or Social Support. Follow-up univariate ANOVAs indicated that Autocratic Behavior was significantly different for Division I college softball players and professional softball players. Pairwise comparisons showed professional softball players significantly preferred Autocratic Behavior to Division I softball players; however, no statistical significance was found when examining coaching style preferences with relation to age and years of experience. Two one-way ANOVAs followed the trend that professional softball players preferred autocratic coaching behavior while Division I college softball players preferred democratic coaching behavior. Thus, female softball players, overall, prefer a democratic coaching style, training and instruction, and positive feedback; however, professional softball athletes significantly prefer autocratic coaching behaviors while Division I college players do not prefer autocratic coaching styles. Age and years of experience were not statistically significant when determining coaching preference, however, a power analysis is needed to reveal the optimal sample size to establish significance

The top-quark's running mass

We discuss the direct determination of the running top-quark mass from measurements of the total cross section of hadronic top-quark pair-production. The theory predictions in the MSbar scheme are very stable under scale variations and show rapid apparent convergence of the perturbative expansion. These features are explained by studying the underlying parton dynamics.Comment: 6 pages, 2 figures; to appear in Proceedings of the 9th International Symposium on Radiative Corrections, RADCOR 2009, Ascona, Switzerland, October 200

Measurement of radiative neutralino production

We perform the first experimental study with full detector simulation for the radiative production of neutralinos at the linear collider, at sqrt{s} = 500 GeV and realistic beam polarizations. We consider all relevant backgrounds, like the Standard Model background from radiative neutrino production. The longitudinal polarized beams enhance the signal and simultaneously reduce the background, such that statistical errors are significantly reduced. We find that the photon spectrum from the signal process can be well isolated. The neutralino mass and the cross section can be measured at a few per-cent level, with the largest systematic uncertainties from the measurement of the beam polarization and the beam energy spectrum.Comment: 6 pages, 2 figures, to appear in the proceedings of the 2011 International Workshop on Future Linear Colliders (LCWS11), Sept. 26-30, Granada, Spai

Accurate photonic temporal mode analysis with reduced resources

The knowledge and thus characterization of the temporal modes of quantum light fields is important in many areas of quantum physics ranging from experimental setup diagnosis to fundamental-physics investigations. Recent results showed how the auto-correlation function computed from continuous-wave homodyne measurements can be a powerful way to access the temporal mode structure. Here, we push forward this method by providing a deeper understanding and by showing how to extract the amplitude and phase of the temporal mode function with reduced experimental resources. Moreover, a quantitative analysis allows us to identify a regime of parameters where the method provides a trustworthy reconstruction, which we illustrate experimentally

Decoherence-protected memory for a single-photon qubit

The long-lived, efficient storage and retrieval of a qubit encoded on a photon is an important ingredient for future quantum networks. Although systems with intrinsically long coherence times have been demonstrated, the combination with an efficient light-matter interface remains an outstanding challenge. In fact, the coherence times of memories for photonic qubits are currently limited to a few milliseconds. Here we report on a qubit memory based on a single atom coupled to a high-finesse optical resonator. By mapping and remapping the qubit between a basis used for light-matter interfacing and a basis which is less susceptible to decoherence, a coherence time exceeding 100 ms has been measured with a time-independant storage-and-retrieval efficiency of 22%. This demonstrates the first photonic qubit memory with a coherence time that exceeds the lower bound needed for teleporting qubits in a global quantum internet.Comment: 3 pages, 4 figure