21 research outputs found
QCD and Yukawa corrections to single-top-quark production via q qbar -> t bbar
We calculate the O(alpha_s) and O(alpha_W m_t^2/M_W^2) corrections to the
production of a single top quark via the weak process q qbar -> t bbar at the
Fermilab Tevatron and the CERN Large Hadron Collider. An accurate calculation
of the cross section is necessary in order to extract |V_tb| from experiment.Comment: LaTeX, 13 pages, replaced with version to appear in Phys. Rev.
QCD Corrections to Spin Dependent Drell-Yan and a Global Subtraction Scheme
We present QCD corrections to the Drell-Yan process in the transversely
polarized, longitudinally polarized and unpolarized cases. The analytical
results are presented in a form valid for all -dimensional regularization
schemes. A universal mass factorization scheme is presented in which the
results reduce to those of dimensional reduction. The connection between the
parton distributions and fragmentation functions of dimensional reduction and
those of dimensional regularization is elucidated in a simple manner. Numerical
results are presented for proton-proton collisions at energies relevant to RHIC
(Relativistic Heavy Ion Collider). The perturbative stability of the transverse
and longitudinal asymmetries is investigated.Comment: 18 pages, 8 figures in 1 postscript fil
Predictions for Higgs production at the Tevatron and the associated uncertainties
We update the theoretical predictions for the production cross sections of
the Standard Model Higgs boson at the Fermilab Tevatron collider, focusing on
the two main search channels, the gluon-gluon fusion mechanism and
the Higgs-strahlung processes with , including all
relevant higher order QCD and electroweak corrections in perturbation theory.
We then estimate the various uncertainties affecting these predictions: the
scale uncertainties which are viewed as a measure of the unknown higher order
effects, the uncertainties from the parton distribution functions and the
related errors on the strong coupling constant, as well as the uncertainties
due to the use of an effective theory approach in the determination of the
radiative corrections in the process at next-to-next-to-leading
order. We find that while the cross sections are well under control in the
Higgs--strahlung processes, the theoretical uncertainties are rather large in
the case of the gluon-gluon fusion channel, possibly shifting the central
values of the next-to-next-to-leading order cross sections by more than
. These uncertainties are thus significantly larger than the
error assumed by the CDF and D0 experiments in their recent
analysis that has excluded the Higgs mass range 162-166 GeV at the 95%
confidence level. These exclusion limits should be, therefore, reconsidered in
the light of these large theoretical uncertainties.Comment: 40 pages, 12 figures. A few typos are corrected and some updated
numbers are provide
Electroweak Radiative Corrections to W Boson Production in Hadronic Collisions
The O(\alpha) electroweak radiative corrections to the process pp, ppbar\to W
\to\ell^\pm\nu (\ell=e,\mu) are calculated. The O(\alpha) corrections can be
decomposed into separately gauge invariant contributions to the W boson
production and decay processes. Factorizing the collinear singularity
associated with initial state photon radiation into the parton distribution
functions, we find that initial state corrections have a significantly smaller
effect than final state radiative corrections. We study in detail the effect of
electroweak radiative corrections on a number of interesting observables: the W
transverse mass distribution, the W to Z transverse mass ratio, the charge
asymmetry of leptons in W\to\ell\nu decays, as well as the W production cross
section and the W to Z cross section ratio. We also investigate how
experimental lepton identification requirements change the effect of the
electroweak corrections.Comment: 38 pages, Revtex, 13 embedded postscript figure