W+−H+W^+-H^+ Interference and Partial Width Asymmetry in Top and Antitop Decays

We re-examine the question of a possible difference in the partial decay widths of $t$ and $\overline t$, induced by an intermediate scalar boson $H^+$ with $CP$-violating couplings. The interference of $W^+$ and $H^+$ exchanges is analysed by constructing the $2\times 2$ propagator matrix of the $W^+-H^+$ system, and determining its absorptive part in terms of fermion loops. Results are obtained for the partial rate difference in the channels $t\to bl^+\nu_l$ and $t\to bc\overline s$, which fulfil explicitly the constraints of $CPT$ invariance. These results are contrasted with those in previous work.Comment: 14 pages, report PITHA 94/1

Energy Spectra and Energy Correlations in the Decay H→ZZ→μ+μ−μ+μ−H\to ZZ\to \mu^+\mu^-\mu^+\mu^-

It is shown that in the sequential decay $H\to ZZ\to (f_1\bar{f_1})+ (f_2\bar{f_2})$, the energy distribution of the final state particles provides a simple and powerful test of the $HZZ$ vertex. For a standard Higgs boson, the energy spectrum of any final fermion, in the rest frame of $H$, is predicted to be $d\Gamma /dx\sim 1+\beta^4-2(x-1)^2$, with $\beta = \sqrt{1-4m^2_Z/m^2_H}$ and $1-\beta \le x=4E/m_H\le 1+\beta$. By contrast, the spectrum for a pseudoscalar Higgs is $d\Gamma /dx \sim \beta^2+(x-1)^2$. There are characteristic energy correlations between $f_1$ and $f_2$ and between $f_1$ and $\bar{f_2}$. These considerations are applied to the ``gold--plated'' reaction $H\to ZZ\to \mu^+\mu^-\mu^+\mu^-$, including possible effects of CP--violation in the $HZZ$ coupling. Our formalism also yields the energy spectra and correlations of leptons in the decay $H\to W^+W^-\to l^+\nu_ll^- \bar{\nu_l}$.Comment: 14 pages + 4 figure

Master of Science

thesisThe Wasatch Mountains are a unique place to study deposition of ions in snow because of proximity to Salt Lake City, UT, home to 1.1 million people, and Great Salt Lake, the world' fourth largest closed-basin saline lake. Prior study at low elevations of the Wasatch Mountains and in Salt Lake City indicates very high deposition (>1 mmol L-1) of chloride nitrate, sulfate, sodium and calcium ions in snow and rime during winter temperature inversions. At peak snowpack, concentrations (?eq L-1) and ecosystem loading (meq m-2) of major ion species (Cl-, NO3-, SO42-, H+, NH4+, Na+, Mg2+, K+, and Ca2+) were measured at five sites in 2008 and 16 sites in 2009 in the Wasatch Mountains. Concentrations and loading of these ion species in snow were up to an order of magnitude higher than previously observed and were likely derived from salts that precipitated from Great Salt Lake as its elevation decreased. Great Salt Lake has very high salinity dominated by concentrations of chloride, sulfate, sodium and magnesium. Moderately strong correlations existed between concentrations of these ions in snow and distance from Great Salt Lake, suggesting it as a major source of ion deposition in the Wasatch Mountains. Concentrations and ecosystem loading of nitrate in snow were lower than expected, but total winter inorganic nitrogen deposition (NO3- and NH4+) was similar to observations at Niwot Ridge in the Rocky Mountains of Colorado. In general, concentrations of ions in snow decreased with elevation while ecosystem loading of ions increased with elevation due to greater snow accumulation

Large Extra Dimension Effects on the Spin Configuration of the Top Quark Pair at e^+ e^- Colliders

Large extra dimension effects on the spin configuration of the top quark pair at the $e^+ e^-\to t\bar{t}$ process are studied. It is shown that the TeV scale quantum gravity effects cause significant deviations from the Standard Model predictions for the spin configuration in the off-diagonal basis: they lead to substantial cross sections of the like-spin states of the top quark pair, which vanish in the SM; they weaken the pure dominance of the processes, the Up-Down (Down-Up) spin states for the left-handed (right-handed) beam. In addition it is shown that the angular cut $-0.5<\cos\theta<0$ is very effective to determine the sign of the quantum gravity corrections.Comment: A discussion on the angular distribution is added with a tabl

Energy correlation and asymmetry of secondary leptons in H→ttˉH\to t\bar t and H→W+W−H\to W^+W^-

We study the energy correlation of charged leptons produced in the decay of a heavy Higgs particle $H\to t\bar t\to bl^+\nu_l\bar bl^-\bar{\nu}_l$ and $H\to W^+W^-\to l^+\nu_ll^-\bar{\nu}_l.$ The possible influence of $CP$--violation in the $Ht\bar t$ and $HW^+W^-$ vertices on the energy spectrum of the secondary leptons is analyzed. The energy distribution of the charged leptons in the decay $H\to W^+W^-\to l^+\nu_ll^-\bar{\nu}_l$ is sensitive to the $CP$--parity of the Higgs particle and yields a simple criterion for distinguishing scalar Higgs from pseudoscalar Higgs.Comment: 12 pages, + 4 uuencoded figures. report PITHA 94/2

Detaching from the negative by reappraisal: the role of right superior frontal gyrus (BA9/32)

The ability to reappraise the emotional impact of events is related to long-term mental health. Self-focused reappraisal (REAPPself), i.e., reducing the personal relevance of the negative events, has been previously associated with neural activity in regions near right medial prefrontal cortex, but rarely investigated among brain-damaged individuals. Thus, we aimed to examine the REAPPself ability of brain-damaged patients and healthy controls considering structural atrophies and gray matter intensities, respectively. Twenty patients with well-defined cortex lesions due to an acquired circumscribed tumor or cyst and 23 healthy controls performed a REAPPself task, in which they had to either observe negative stimuli or decrease emotional responding by REAPPself. Next, they rated the impact of negative arousal and valence. REAPPself ability scores were calculated by subtracting the negative picture ratings after applying REAPPself from the ratings of the observing condition. The scores of the patients were included in a voxel-based lesion-symptom mapping (VLSM) analysis to identify deficit related areas (ROI). Then, a ROI group-wise comparison was performed. Additionally, a whole-brain voxel-based-morphometry (VBM) analysis was run, in which healthy participant's REAPPself ability scores were correlated with gray matter intensities. Results showed that (1) regions in the right superior frontal gyrus (SFG), comprising the right dorsolateral prefrontal cortex (BA9) and the right dorsal anterior cingulate cortex (BA32), were associated with patient's impaired down-regulation of arousal, (2) a lesion in the depicted ROI occasioned significant REAPPself impairments, (3) REAPPself ability of controls was linked with increased gray matter intensities in the ROI regions. Our findings show for the first time that the neural integrity and the structural volume of right SFG regions (BA9/32) might be indispensable for REAPPself. Implications for neurofeedback research are discussed.Fil: Falquez, Rosalux. University of Heidelberg; AlemaniaFil: Couto, Juan Blas Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Ibáñez Barassi, Agustín Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Freitag, Martin T.. German Cancer Research Center; AlemaniaFil: Berger, Moritz. German Cancer Research Center; AlemaniaFil: Arens, Elisabeth A.. University of Heidelberg; AlemaniaFil: Lang, Simone. University of Heidelberg; AlemaniaFil: Barnow, Sven. University of Heidelberg; Alemani

A Nyström method for a class of integral equations on the real line with applications to scattering by diffraction gratings and rough surfaces

We propose a Nystr¨om/product integration method for a class of second kind integral equations on the real line which arise in problems of two-dimensional scalar and elastic wave scattering by unbounded surfaces. Stability and convergence of the method is established with convergence rates dependent on the smoothness of components of the kernel. The method is applied to the problem of acoustic scattering by a sound soft one-dimensional surface which is the graph of a function f, and superalgebraic convergence is established in the case when f is infinitely smooth. Numerical results are presented illustrating this behavior for the case when f is periodic (the diffraction grating case). The Nystr¨om method for this problem is stable and convergent uniformly with respect to the period of the grating, in contrast to standard integral equation methods for diffraction gratings which fail at a countable set of grating periods

Spin Asymmetries In Diffractive J/ΨJ/\Psi Leptoproduction

In this report we calculate the cross section and $A_{ll}$ asymmetry for the diffractive $J/\Psi$ leptoproduction. We study dependences of the asymmetry on the structure of the Pomeron-proton couplingComment: 4 pages, latex, two PS figures, presented at the International Workshop "Symmetry and Spin" PRAHA'9