56 research outputs found
The Mixed Vector Current Correlator <0|T(V^3_\mu V^8_\nu )|0> To Two Loops in Chiral Perturbation Theory
The isospin-breaking correlator of the product of flavor octet vector
currents, and , is computed to
next-to-next- to-leading (two-loop) order in Chiral Perturbation Theory. Large
corrections to both the magnitude and -dependence of the one-loop result
are found, and the reasons for the slow convergence of the chiral series for
the correlator given. The two-loop expression involves a single
counterterm, present also in the two-loop expressions for
and , which counterterm
contributes a constant to the scalar correlator . The
feasibility of extracting the value of this counterterm from other sources is
discussed. Analysis of the slope of the correlator with respect to using
QCD sum rules is shown to suggest that, even to two-loop order, the chiral
series for the correlator may not yet be well-converged.Comment: 32 pages, uses REVTEX and epsfig.sty with 7 uuencoded figures. Entire
manuscript available as a ps file at
http://www.physics.adelaide.edu.au/theory/home.html Also available via
anonymous ftp at ftp://adelphi.adelaide.edu.au/pub/theory/ADP-95-27.T181.p
Non-factorizable contributions in hadronic weak decays of charm mesons
Two body decays of charm mesons are studied by describing their amplitude in
terms of a sum of factorizable and non-factorizable ones. The former is
estimated by using a naive factorization while the latter is calculated by
using a hard pseudo-scalar-meson approximation. The hard pseudo-scalar-meson
amplitude is given by a sum of the so-called equal-time commutator term and
surface term which contains all possible pole contributions of various mesons,
not only the ordinary but also four-quark ,
hybrid and glue-balls.
Naively factorized amplitudes for the spectator decays which lead to too big
rates can interfere destructively with exotic meson pole amplitudes and the
total amplitudes can reproduce their observed rates. The non-factorizable
contributions can supply sufficiently large contributions to the color
suppressed decays which are strongly suppressed in the naive factorization. A
possible solution to the long standing puzzle that the ratio of decay rates for
to is around 2.5 is given by different
contributions of exotic meson poles.Comment: 22 pages, RevTe
decay within unitarized chiral perturbation theory
We improve the calculations of the decay
within the context of meson chiral lagrangians. We use a chiral unitary
approach for the meson-meson interaction, thus generating the
resonance and fixing the longstanding sign ambiguity on its contribution. This
also allows us to calculate the loops with one vector meson exchange, thus
removing a former source of uncertainty. In addition we ensure the consistency
of the approach with other processes. First, by using vector meson dominance
couplings normalized to agree with radiative vector meson decays. And, second,
by checking the consistency of the calculations with the related reaction. We find an decay width
of eV, in clear disagreement with published data but in
remarkable agreement with the most recent measurement.Comment: 15 pages, 10 figures, published versio
Study of 3-prong Hadronic Decays with Charged Kaons
Using a sample of 4.7/fb integrated luminosity accumulated with the CLEO-II
detector at the Cornell Electron Storage Ring (CESR), we have measured the
branching fractions of the tau lepton into and relative to and relative to . The relative branching fractions are: (5.16+-0.20+-0.50)*,
(1.52+-0.14+-0.29)*, (2.54+-0.44+-0.39)* and at 95%
C.L., respectively. Coupled with additional experimental information, we use
our results to extract information on the structure of three-prong tau decays
to charged kaons.Comment: 16 pages postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Antidiabetic effects of natural plant extracts via inhibition of carbohydrate hydrolysis enzymes with emphasis on pancreatic alpha amylase
Mortalità per cause tumorali e non tumorali nell’ex-USSL 37 - Breno (Brescia) nel periodo 1980-1991.
Conoscenze e atteggiamenti in tema di AIDS tra gli adolescenti di Brescia e della comunità montana della Vallecamonica (BS) (USSL 37- Breno)
Consumi di alcol e di tabacco tra i giovani di una comunità urbana e di una montana della Lombardia
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