1,999 research outputs found
Analytical results for O(\alpha_s) radiative corrections to e+ e- -> tbar t(pol.) up to a given gluon energy cut
We determine the O(\alpha_s) radiative corrections to polarized top quark
pair production in e+ e- -annihilations with a specified gluon energy cut. We
write down fully analytical results for the unpolarized and polarized
O(\alpha_s) cross sections e+ e- -> tbar t (G) and e+ e- -> tbar t(pol.) (G)
including their polar orientation dependence relative to the beam direction. In
the soft gluon limit we recover the usual factorizing form known from the soft
gluon approximation. In the limit when the gluon energy cut takes its maximum
value we recover the totally inclusive unpolarized and polarized cross sections
calculated previously. We provide some numerical results on the cut-off
dependence of the various polarized and unpolarized cross sections and discuss
how the exact results numerically differ from the approximate soft-gluon
results.Comment: 49 pages in LaTeX, including 17 encapsulated PostScript figure
A numerical test of differential equations for one- and two-loop sunrise diagrams using configuration space techniques
We use configuration space methods to write down one-dimensional integral
representations for one- and two-loop sunrise diagrams (also called Bessel
moments) which we use to numerically check on the correctness of the second
order differential equations for one- and two-loop sunrise diagrams that have
recently been discussed in the literature.Comment: 11 pages, no figures, published versio
Theory of Heavy Baryon Decay
We discuss various topics in the theory of heavy baryon decays. Among these
are recent applications of the Relativistic Three Quark Model to semileptonic,
nonleptonic, one-pion and one-photon transitions among heavy baryons, new
higher order perturbative results on the correlator of two heavy baryon
currents and on the semi-inclusive decay .Comment: 10 pages, invited talk given by J.G. K\"orner at the 3rd
International Conference on B Physics and CP Violation (BCONF99), Taipei,
Taiwan, 3-7 Dec 1999, to appear in the Proceedings, edited by H.Y. Cheng and
W.S. Hou (World Scientific, 2000
O(\alpha_s) Corrections to Longitudinal Spin-Spin Correlations in e+e- -> q qbar
We calculate the corrections to longitudinal spin-spin
correlations in . For top quark pair production the
corrections to the longitudinal spin-spin asymmetry amount to
less than 1% in the -range from above -treshold up to
. In the case the
corrections reduce the asymmetry value from its value of -1 to
approximately -0.96 for -values around the Z-peak. This reduction can be
traced to finite anomalous contributions from residual mass effects which
survive the limit. We discuss the role of the anomalous contributions
and the pattern of how they contribute to spin-flip and no-flip terms.Comment: 10 pages, 2 postscript figure
Resolving the SELEX--LHCb Double-Charm Baryon Conflict: The Impact of Intrinsic Heavy-Quark Hadroproduction and Supersymmetric Light-Front Holographic QCD
In this paper we show that the intrinsic heavy-quark QCD mechanism for the
hadroproduction of heavy hadrons at large can resolve the apparent
conflict between measurements of double-charm baryons by the SELEX fixed-target
experiment and the LHCb experiment at the LHC collider. We show that both
experiments are compatible, and that both results can be correct. The observed
spectroscopy of double-charm hadrons is in agreement with the predictions of
supersymmetric light front holographic QCD.Comment: 15 pages, no figur
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