3,076 research outputs found
Radiative and non radiative muon capture on the proton in heavy baryon chiral perturbation theory
We have evaluated the amplitude for muon capture by a proton, mu + p --> n +
nu, to O(p^3) within the context of heavy baryon chiral perturbation theory
(HBChPT) using the new O(p^3) Lagrangian of Ecker and Mojzis (E&M). We obtain
expressions for the standard muon capture form factors and determine three of
the coefficients of the E&M Lagrangian, namely, b_7, b_{19}, and b_{23}. We
describe progress on the next step, a calculation of the radiative muon capture
process, mu + p --> n + nu + gamma.Comment: Talk at the 15th Int. Conf. on Few-Body Problems in Physics, 22-26
July, 1997, Groningen, The Netherlands, to be published in the proceedings; 5
pages, LaTeX, using espcrc1.st
Development of a systematic approach to conversion of the ileoanal pouch into continent ileostomy
Based on practical experience, a systematic approach to conversion of ileal J-pouches into continent ileostomies is developed by defining three types of conversion surgery, each with two subtypes. Type 1 refers to conversion without pouch reconstruction, type 2 to partial pouch reconstruction, and type 3 to complete pouch reconstruction. The subdivisions (a and b) take into account whether the afferent loop of the former pelvic pouch (a) or a higher ileal/jejunal segment of the small intestine (b) is used in conversion and/or reconstruction. The six resulting surgical variants are shown in schematic illustrations with accompanying descriptions of technical details to provide the specialized surgeon with comprehensive technical guidance
Die Bedeutung von Metakognitionen für das Verständnis und die Psychotherapie von Zwang
The Importance of Metacognitions in the Understanding and Treatment of Obsessive Compulsive Disorder The present article discusses three cognitive approaches of Obsessive Compulsive Disorder (OCD): (1) Beck's theory of content-specificity, (2) Salkovskis' cognitive-behavioural approach and (3) Wells' more recent theory of metacognitions. Wells' approach is explained in more detail: the so called Self-Regulatory Executive Function model is presented as well as special aspects of thinking in OCD, for example the self-referential status of thinking, thinking in object mode and aspects of `thought-action fusion'. The relevance of Wells' metacognitive approach for the development and the maintenance of OCD is discussed. Furthermore, proposals are made on how to include these issues in the psychotherapy of OCD
Sensitivity to new physics: a_e vs. a_mu
At present it is generally believed that ``new physics'' effects contribute
to leptonic anomalous magnetic moment, a_l, via quantum loops only and they are
proportional to the squared lepton mass, (m_l)^2. An alternative mechanism for
a contribution by new physics is proposed. It occurs at the tree level and
exhibits a linear rather than quadratic dependence on m_l. This leads to a much
larger sensitivity of a_e to the new physics than was expected so far.Comment: 4 pages, 2 figure
Final State Interactions and CP Violation in
Using chiral perturbation theory we calculate the imaginary parts of the form factors that arise from and
rescattering. We discuss their influence on CP violating variables in .Comment: ; 12 pages, 2 figures, TeX format; uses epsf.tex, tables.tex, and
phyzzx.te
Relating the scalar flavour-changing neutral couplings to the CKM matrix
We build a class of two-Higgs-doublet models in which the flavour-changing
couplings of the neutral scalars are related in an exact way to elements of the
quark mixing matrix. In this framework, we explore the different possibilities
for CP violation and find some interesting scenarios, like a realization of the
superweak idea without CP violation in the -meson system. In another
scenario the neutral scalars can be relatively light, and their contributions
to the -- transitions can alter the standard-model predictions
for CP violation in that system.Comment: 12 pages LATEX, no figure
Nuclear forces from chiral Lagrangians using the method of unitary transformation I: Formalism
We construct the two- and three-nucleon potential based on the most general
chiral effective pion-nucleon Lagrangian using the method of unitary
transformations. For that, we develop a power counting scheme consistent with
this projection formalism. In contrast to previous results obtained in
old-fashioned time-ordered perturbation theory, the method employed leads to
energy-independent potentials. We discuss in detail the similarities and
differences to the existing chiral nucleon-nucleon potentials. We also show
that to leading order in the power counting, the three-nucleon forces vanish
lending credit to the result obtained by Weinberg using old-fashioned
time-ordered perturbation theory.Comment: 27 pp, LaTeX file, 8 figures (uses epsf
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