1,763 research outputs found
Polarization and `Model Independent' Extraction of from and
We briefly discuss the predictions of the heavy quark effective theory for
the semileptonic decays of a heavy pseudoscalar to a light one, or to a light
vector meson. We point out that measurement of combinations of differential
helicity decay rates at Cleo-c and the factories can provide a model
independent means of extracting the ratio
. We briefly discuss the corrections to this prediction.Comment: 8 pages, LaTeX, 1 figur
Breakdown of scaling in neutrino and electron scattering
Observation of deviations from scaling in the structure functions for deep-inelastic inclusive lepton-hadron scattering may provide a test of the hypothesis that the strong interactions are described by an asymptotically free field theory. Tests not involving additional assumptions are obtained for the combinations of structure functions F2 (ep)-F2 (en), F2 (ν)-F2 (ν), and xF3(ν or ν). Neutrino and electron scattering experiments are compared as possible tests of asymptotic freedom
Higher Order Corrections at Zero Recoil
The general structure of the corrections at zero recoil is studied. The
relevant matrix elements are forward matrix elements of local higher
dimensional operators and their time ordered products with higher order terms
from the Lagrangian. These matrix elements may be classified in a simple way
and the analysis at the non recoil point for the form factor of heavy quark
currents simplifies drastically. The second order recoil corrections to the
form factor of the axial vector current, relevant for the
determination from decays, are estimated to be .Comment: LaTeX, 25 pages, one figure, appended after \end{document} as
uu-encoded and compressed eps file, uses epsf, CERN-TH.7162/9
Path Integrals, Density Matrices, and Information Flow with Closed Timelike Curves
Two formulations of quantum mechanics, inequivalent in the presence of closed
timelike curves, are studied in the context of a soluable system. It
illustrates how quantum field nonlinearities lead to a breakdown of unitarity,
causality, and superposition using a path integral. Deutsch's density matrix
approach is causal but typically destroys coherence. For each of these
formulations I demonstrate that there are yet further alternatives in
prescribing the handling of information flow (inequivalent to previous
analyses) that have implications for any system in which unitarity or coherence
are not preserved.Comment: 25 pages, phyzzx, CALT-68-188
Hadronic Transitions among Quarkonium States in a Soft-Exchange-Approximation. Chiral Breaking and Spin Symmetry Breaking Processes
Although no asymptotic heavy quark spin symmetry, and even more no flavor
symmetry, are expected for systems such as quarkonium, a numerical discussion
shows that for some processes and in a preasymptotic region which may roughly
include charmonium and bottomonium, the use of the spin-symmetry may be useful
in conjunction with chiral symmetry for light hadrons (soft-exchange-
approximation regime, SEA). We continue our discussion of hadronic transitions
in the SEA-regime by studying in particular chiral breaking transitions such as
, , level splittings and transitions which break
both chiral and spin symmetry, such as , , and .Comment: LaTeX (style article) 19 pages, UGVA-DPT 12-80
Estimates with an Effective Chiral Lagrangian for Heavy Mesons
On the basis of an effective lagrangian incorporating approximate chiral
symmetry and heavy-quark spin and flavor symmetries, and by use of information
on leptonic decays, we estimate the effective coupling.Comment: UGVA-DPT 1992/07-779, BARI-TH/92-117 Revised version, September 1992,
LaTeX (style article), 7 page
Reinstatement of "germinal epithelium" of the ovary
BACKGROUND: The existing dogma that the former term ovarian "germinal epithelium" resulted from a mistaken belief that it could give rise to new germ cells is now strongly challenged. DISCUSSION: Two years ago, a research group of the University of Tennessee led by Antonin Bukovsky successfully demonstrated the oogenic process from the human ovarian covering epithelium now commonly called the ovarian surface epithelium. They showed the new oocyte with zona pellucida and granulosa cells, both originated from the surface epithelium arising from mesenchymal cells in the tunica albuginea, and stressed that the human ovary could form primary follicles throughout the reproductive period. This gives a big impact not only to the field of reproductive medicine, but also to the oncologic area. The surface epithelium is regarded as the major source of ovarian cancers, and most of the neoplasms exhibit the histology resembling müllerian epithelia. Since the differentiating capability of the surface epithelium has now expanded, the histologic range of the neoplasms in this category may extend to include both germ cell tumors and sex cord-stromal cell tumors. SUMMARY: Since the oogenic capability of ovarian surface cells has been proven, it is now believed that the oocytes can originate from them. The term "germinal epithelium", hence, might reasonably be reinstated
Complete Renormalization Group Improvement-Avoiding Factorization and Renormalization Scale Dependence in QCD Predictions
For moments of leptoproduction structure functions we show that all
dependence on the renormalization and factorization scales disappears, provided
that all the ultraviolet logarithms involving the physical energy scale Q are
completely resummed. The approach is closely related to Grunberg's method of
Effective Charges. A direct and simple method for extracting the universal
dimensional transmutation parameter of QCD from experimental data is advocated.Comment: 16 pages, no figure
- …