2 research outputs found
The Complete |Delta S|=2 Hamiltonian in the Next-To-Leading Order
We present the complete next-to-leading order short-distance QCD corrections
to the effective \dstwo -hamiltonian in the Standard Model. The calculation of
the coefficient is described in great detail. It involves the two-loop
mixing of bilocal structures composed of two \dsone\ operators into \dstwo\
operators. The next-to-leading order corrections enhance by 27\% to
\eta_3=0.47 \errorpm{+0.03}{-0.04} thereby affecting the phenomenology of
sizeably. depends on the physical input parameters ,
and \laMSb only weakly. The quoted error stems from renormalization
scale dependences, which have reduced compared to the old leading log result.
The known calculation of and is repeated in order to compare
the structure of the three QCD coefficients. We further discuss some field
theoretical aspects of the calculation such as the renormalization group
equation for Green's functions with two operator insertions and the
renormalization scheme dependence caused by the presence of evanescent
operators.Comment: 68 pages, requires LaTeX2e and the standard LaTeX-packages epsf.sty,
rotate.sty, a4.sty, subeqn.sty, cite.sty, array.sty, dcolumn.sty; Figures are
submitted as a seperate tar.gz-file. A complete PostScript version may be
obtained from
ftp://feynman.t30.physik.tu-muenchen.de/pub/preprints/tum-86-96.ps.gz or
ftp://feynman.t30.physik.tu-muenchen.de/pub/preprints/tum-86-96.ps2.gz
(scaled down and rotated version to print two pages on one sheet of paper).
Source available at
ftp://feynman.t30.physik.tu-muenchen.de/pub/preprints/tum-86-96.tar.g
Cosmological implications of neutrinos
Massive neutrinos were the first proposed, and remain the most natural,
particle candidate for the dark matter. In the absence of firm laboratory
evidence for neutrino mass, considerations of the formation of large scale
structure in the universe provide a sensitive, albeit indirect, probe of this
possibility. Observations of galaxy clustering and large angle anisotropy in
the cosmic microwave background have been interpreted as requiring that
neutrinos provide about 20% of the critical density. However the need for such
`hot' dark matter is removed if the primordial spectrum of density fluctuations
is tilted below scale-invariance, as is often the case in physically realistic
inflationary models. This question will be resolved by forthcoming precision
measurements of microwave background anisotropy on small angular scales. This
data will also improve the nucleosynthesis bound on the number of neutrino
species and test whether decays of relic neutrinos could have ionized the
intergalactic medium.Comment: 13 pages (LaTeX, espcrc2.sty) including 9 figures (epsf); Plenary
talk at the XVI International Workshop on Weak Interactions and Neutrinos,
Capri, 22-28 June 1997; to appear in the Proceedings (eds. G. Fiorillo, V.
Palladino and P. Strolin) ; References [11,28,52] revise