15 research outputs found
Two-loop electroweak corrections at high energies
We discuss two-loop leading and angular-dependent next-to-leading logarithmic
electroweak virtual corrections to arbitrary processes at energies above the
electroweak scale. The relevant Feynman diagrams involving soft-collinear gauge
bosons gamma, Z, W, have been evaluated in eikonal approximation. We present
results obtained from the analytic evaluation of massive loop integrals. To
isolate mass singularities we used the Sudakov method and alternatively the
sector decomposition method in the Feynman-parameter representation.Comment: 5 pages. Talk presented by S.P. at the International Symposium on
Radiative Corrections RADCOR 2002, September 8-13, Kloster Banz, Germany. To
appear in the proceeding
One-loop weak corrections to hadronic production of Z bosons at large transverse momenta
To match the precision of present and future measurements of Z-boson
production at hadron colliders, electroweak radiative corrections must be
included in the theory predictions. In this paper we consider their effect on
the transverse momentum () distribution of Z bosons, with emphasis on
large . We evaluate, analytically and numerically, the full one-loop
corrections for the parton scattering reaction and its
crossed variants. In addition we derive compact approximate expressions which
are valid in the high-energy region, where the weak corrections are strongly
enhanced by logarithms of . These expressions include quadratic
and single logarithms as well as those terms that are not logarithmically
enhanced. This approximation, which confirms and extends earlier results
obtained to next-to-leading logarithmic accuracy, permits to reproduce the
exact one-loop corrections with high precision. Numerical results are presented
for proton-proton and proton-antiproton collisions. The corrections are
negative and their size increases with . For the Tevatron they amount up
to -7% at 300 GeV. For the LHC, where transverse momenta of 2 TeV or more can
be reached, corrections up to -40% are observed. We also include the dominant
two-loop effects of up to 8% in our final LHC predictions.Comment: 32 pages, 7 figure
Two-loop electroweak angular-dependent logarithms at high energies
We present results on the two-loop leading and angular-dependent
next-to-leading logarithmic virtual corrections to arbitrary processes at
energies above the electroweak scale. In the `t Hooft-Feynman gauge the
relevant Feynman diagrams involving soft and collinear gauge bosons \gamma, Z,
W^\pm coupling to external legs are evaluated in the eikonal approximation in
the region where all kinematical invariants are much larger than the
electroweak scale. The logarithmic mass singularities are extracted from
massive multi-scale loop integrals using the Sudakov method and alternatively
the sector-decomposition method in the Feynman-parameter representation. The
derivations are performed within the spontaneously broken phase of the
electroweak theory, and the two-loop results are in agreement with the
exponentiation prescriptions that have been proposed in the literature based on
a symmetric SU(2) x U(1) theory matched with QED at the electroweak scale.Comment: 31 pages, LaTe
Electroweak Physics
The results of high precision weak neutral current (WNC), Z-pole, and high
energy collider electroweak experiments have been the primary prediction and
test of electroweak unification. The electroweak program is briefly reviewed
from a historical perspective. Current changes, anomalies, and things to watch
are summarized, and the implications for the standard model and beyond
discussed.Comment: 12 pages, invited talk presented at the Conference on the
Intersections of Particle and Nuclear Physics (CIPANP 2003), New York, May
200
Electroweak physics
Work on electroweak precision calculations and event generators for electroweak physics studies at current and future colliders is summarized
Electroweak corrections to W-boson pair production at the LHC
Vector-boson pair production ranks among the most important Standard-Model
benchmark processes at the LHC, not only in view of on-going Higgs analyses.
These processes may also help to gain a deeper understanding of the electroweak
interaction in general, and to test the validity of the Standard Model at
highest energies. In this work, the first calculation of the full one-loop
electroweak corrections to on-shell W-boson pair production at hadron colliders
is presented. We discuss the impact of the corrections on the total cross
section as well as on relevant differential distributions. We observe that
corrections due to photon-induced channels can be amazingly large at energies
accessible at the LHC, while radiation of additional massive vector bosons does
not influence the results significantly.Comment: 29 pages, 15 figures, 4 tables; some references and comments on
\gamma\gamma -> WW added; matches version published in JHE
Electroweak Corrections to Large Transverse Momentum Production of W Bosons at the LHC.
To match the precision of present and future measurements of W-boson
production at hadron colliders, electroweak radiative corrections must be
included in the theory predictions. In this paper we consider their effect on
the transverse momentum (p_T) distribution of W bosons, with emphasis on large
p_T. We evaluate the full electroweak O(\alpha) corrections to the process pp
-> Wj including virtual and real photonic contributions. We also provide
compact approximate expressions which are valid in the high-energy region,
where the electroweak corrections are strongly enhanced by logarithms of
\hat{s}/M_W^2. These expressions include quadratic and single logarithms at one
loop as well as quartic and triple logarithms at two loops. Numerical results
are presented for proton-proton collisions at 14 TeV. The corrections are
negative and their size increases with p_T. At the LHC, where transverse
momenta of 2 TeV or more can be reached, the one- and two-loop corrections
amount up to -40% and +10%, respectively.Comment: 11 pages, 3 figure
Electroweak Corrections to Hadronic Production of W Bosons at Large Transverse Momenta.
To match the precision of present and future measurements of W-boson
production at hadron colliders electroweak radiative corrections must be
included in the theory predictions. In this paper we consider their effect on
the transverse momentum (p_T) distribution of W bosons, with emphasis on large
p_T. We evaluate the full electroweak O(alpha) corrections to the processes pp
-> W+jet and p\bar p -> W+jet including virtual and real photonic
contributions. We present the explicit expressions in analytical form for the
virtual corrections and provide results for the real corrections, discussing in
detail the treatment of soft and collinear singularities. We also provide
compact approximate expressions which are valid in the high-energy region,
where the electroweak corrections are strongly enhanced by logarithms of
\hat{s}/M_W^2. These expressions describe the complete asymptotic behaviour at
one loop as well as the leading and next-to-leading logarithms at two loops.
Numerical results are presented for proton-proton collisions at 14 TeV and
proton-antiproton collisions at 2 TeV. The corrections are negative and their
size increases with p_T. At the LHC, where transverse momenta of 2 TeV or more
can be reached, the one- and two-loop corrections amount up to -40% and +10%,
respectively, and will be important for a precise analysis of W production. At
the Tevatron, transverse momenta up to 300 GeV are within reach. In this case
the electroweak corrections amount up to -10% and are thus larger than the
expected statistical error.Comment: 61 pages. Various modifications: detailed discussion of final-state
singularities and comments on NNLO, W/Z emission, QED effects in PDFs.
Results unchanged. To appear in Nucl. Phys.