98 research outputs found
QCD Corrections to t anti-b H^- Associated Production in e^+ e^- Annihilation
We calculate the QCD corrections to the cross section of e^+ e^- -> t anti-b
H^- and its charge-conjugate counterpart within the minimal supersymmetric
extension of the Standard Model. This process is particularly important if m_t
b H^+ and e^+ e^- -> H^+ H^- are
not allowed kinematically. Large logarithmic corrections that arise in the
on-mass-shell scheme of quark mass renormalization, especially from the t
anti-b H^- Yukawa coupling for large values of tan(beta), are resummed by
adopting the modified minimal-subtraction scheme, so that the convergence
behavior of the perturbative expansion is improved. The inclusion of the QCD
corrections leads to a significant reduction of the theoretical uncertainties
due to scheme and scale dependences.Comment: 21 pages (Latex), 8 figures (Postscript); detailed discussion of
scheme and scale dependences adde
On MSSM charged Higgs boson production in association with an electroweak W boson at electron positron colliders
We present a calculation of the cross section for the process e+ e- --> W+/-
H-/+ in the minimal supersymmetric standard model (MSSM) and the Two Higgs
Doublet Model (THDM). We study the basic features of the MSSM prediction for
some distinctive parameter scenarios. We find large effects from virtual
squarks for scenarios with large mixing in the stop sector which can lead to a
cross section vastly different from a THDM with identical Higgs sector
parameters. We investigate this interesting behaviour in more detail by
thoroughly scanning the MSSM parameter space for regions of large cross
section. For a charged Higgs boson too heavy to be pair-produced at such a
machine, it turns out that a large MSSM cross section with a good chance of
observation is linked to a squark mass scale below 600 GeV and a considerable
amount of mixing in either the stop and sbottom sector.Comment: 25 pages, 10 figures (two in colour). Substantially improved on the
MSSM parameter restrictions taken into account. Added some reference
Remediation of fluency: Word specific or generalised training effects?
The present study examines whether reading fluency benefits more from repeated reading of a limited set of words or from practicing reading with many different words. A group of 37 reading delayed Dutch children repeatedly read the same 20 words with limited exposure duration, whereas another group of 37 poor readers received the same reading exercises with 400 different words. Results demonstrated that improvements in accuracy and speed of trained words were larger for the repeated reading group than for the children who had only practiced with these words once. No difference in generalisation of effects to untrained neighbour and control words was found between the two conditions. Furthermore, rapid naming skill was unrelated to improvements in reading fluency and transfer effects in both training conditions. Results demonstrate that the practical value of repeated reading lies in its word specific training effects. © Springer 2006
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