705 research outputs found
Master integrals for the two-loop light fermion contributions to and
We give the analytic expressions of the eight master integrals entering our
previous computation of two-loop light fermion contributions to and
. The results are expressed in terms of generalized
harmonic polylogarithms with maximum weight four included.Comment: 9 pages, 6 figure
Threshold Resummed Spectra in B -> Xu l nu Decays in NLO (I)
We evaluate thresholds resummed spectra in B -> Xu l nu decays in
next-to-leading order. We present results for the distribution in E_X and in
m_X^2/E_X^2, for the distribution in E_X and E_l and for the distribution in
E_X, where E_X and m_X are the energy and the invariant mass of the final
hadronic state Xu respectively and E_l is the energy of the charged lepton. We
explicitly show that all these spectra (where there is no integration over the
hadronic energy) can be directly related to the photon spectrum in B -> Xs
gamma via short-distance coefficient functions.Comment: 33 pages, no figures. The section on the double distribution in the
hadron and electron energies has been largely rewritten with an improved
resummation scheme. Small stylistic changes in the remaining sections.
References adde
Inclusive Measure of |V_ub| with the Analytic Coupling Model
By analyzing B -> X_u l nu_l spectra with a model based on soft-gluon
resummation and an analytic time-like QCD coupling, we obtain |V_ub| = (3.76
+-0.13 +- 0.22)*10^(-3), where the first and the second error refers to
experimental and theoretical errors, respectively. The V_ub value is obtained
from the available measured semileptonic branching fractions in limited regions
of the phase-space. The distributions in the lepton energy E_l, the hadron
invariant mass m_X, the light-cone momentum P_+ = E_X - p_X, together with the
double distributions in (m_X,q^2) and (E_l,s_h^max), are used to select the
phase-space regions. The q^2 is the dilepton squared momentum and s_h^max is
the maximal m_X^2 at fixed q^2 and E_l. The V_ub value obtained is in complete
agreement with the value coming from exclusive B decays and from an over-all
fit to the Standard Model parameters. We show that the slight disagreement (up
to +2 sigma) with respect to previous inclusive measurements is not related to
different choices for the b (and c) masses but to a different modelling of the
threshold (Sudakov) region.Comment: 19 pages, 2 figures, revised version accepted in Eur.Phys.J.
Tests on A36 and A441 steel beam-columns
This describes an experimental study of 5 rolled 8WF31 steel beam columns which was performed in order to determine their strength and deformation behavior
Approximate NNLO Threshold Resummation in Heavy Flavour Decays
We present an approximate NNLO evaluation of the QCD form factor resumming
large logarithmic perturbative contributions in semi-inclusive heavy flavour
decays.Comment: 16 pages, 3 figures, Latex; minor changes; 2 figures adde
On the Generalized Harmonic Polylogarithms of One Complex Variable
We describe how to compute numerically in the complex plain a set of
Generalized Harmonic Polylogarithms (GHPLs) with square roots in the weights,
using the C++/GiNaC numerical routines of Vollinga and Weinzierl. As an
example, we provide the numerical values of the NLO electroweak light-fermion
corrections to the Higgs boson production in gluon fusion in the case of
complex W and Z masses.Comment: 25 pages, 1 figur
Renormalization of the Lattice HQET Isgur-Wise Function
We compute the perturbative renormalization factors required to match to the
continuum Isgur-Wise function, calculated using lattice Heavy Quark Effective
Theory. The velocity, mass, wavefunction and current renormalizations are
calculated for both the forward difference and backward difference actions for
a variety of velocities. Subtleties are clarified regarding tadpole
improvement, regulating divergences, and variations of techniques used in these
renormalizations.Comment: 28 pages, 0 figures, LaTeX. Final version accepted for publication in
Phys. Rev. D. (Minor changes.
Radiatively corrected shape function for inclusive heavy hadron decays
We discuss the non-perturbative and the radiative corrections to inclusive B
decays from the point of view known from QED corrections to high energy e^+ e^-
processes. Here the leading contributions can be implemented through the so
called ``radiator function'' which corresponds to the shape function known in
heavy hadron decays. In this way some new insight into the origin of the shape
function is obtained. As a byproduct, a parameterization of the radiatively
corrected shape function is suggested which can be implemented in Monte Carlo
studies of inclusive heavy hadron decays.Comment: LaTeX, uses a4, graphicx and psfrag, 10 pages. The complete paper is
also available at http://www-ttp.physik.uni-karlsruhe.de/Preprints
Bosonic corrections to the effective leptonic weak mixing angle at the two-loop level
Details of the recent calculation of the two-loop bosonic corrections to the
effective leptonic weak mixing angle are presented. In particular, the
expansion in the difference of the W and Z boson masses is studied and some of
the master integrals needed are given in analytic form.Comment: 5 pages, 4 figures, to appear in the proceedings of the 7th
International Symposium on Radiative Corrections (RADCOR05), Shonan Village,
Japan, 200
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