1,436 research outputs found
A closed expression for the UV-divergent parts of one-loop tensor integrals in dimensional regularization
Starting from the general definition of a one-loop tensor N-point function,
we use its Feynman parametrization to calculate the UV-divergent part of an
arbitrary tensor coefficient in the framework of dimensional regularization. In
contrast to existing recursion schemes, we are able to present a general
analytic result in closed form that enables direct determination of the
UV-divergent part of any one-loop tensor N-point coefficient independent from
UV-divergent parts of other one-loop tensor N-point coefficients. Simplified
formulas and explicit expressions are presented for A-, B-, C-, D-, E-, and
F-functions.Comment: 19 pages (single column), the result of previous versions is further
evaluated leading to a closed analytic expression for the UV-divergent part
of an arbitrary one-loop tensor coefficient, title is modified accordingly, a
sign error in the appendix (C_{00000000}) has been corrected, a mathematica
notebook containing an implementation of the newly derived formula is
attache
Quadratic electroweak corrections for polarized Moller scattering
The paper discusses the two-loop (NNLO) electroweak radiative corrections to
the parity violating electron-electron scattering asymmetry induced by squaring
one-loop diagrams. The calculations are relevant for the ultra-precise 11 GeV
MOLLER experiment planned at Jefferson Laboratory and experiments at
high-energy future electron colliders. The imaginary parts of the amplitudes
are taken into consideration consistently in both the infrared-finite and
divergent terms. The size of the obtained partial correction is significant,
which indicates a need for a complete study of the two-loop electroweak
radiative corrections in order to meet the precision goals of future
experiments
Electroweak-correction effects in gauge-boson pair production at the LHC
We have studied the effect of one-loop logarithmic electroweak radiative
corrections on WZ and production processes at the LHC. We present
analytical results for the leading-logarithmic electroweak corrections to the
corresponding partonic processes du -> WZ, Wgamma. Using the leading-pole
approximation we implement these corrections into Monte Carlo programs for
. We find that electroweak corrections
lower the predictions by 5-20% in the physically interesting region of large
transverse momentum and small rapidity separation of the gauge bosons.Comment: 28 pages, LaTex, 13 eps figures included; references added and
corrected typo
Precision Predictions for (Un)Stable W+W- Pair Production At and Beyond LEP2 Energies Beyond LEP2 Energies
We present precision calculations of the processes e+e- -> 4-fermions in
which the double resonant W+W- intermediate state occurs. Referring to this
latter intermediate state as the 'signal process', we show that, by using the
YFS Monte Carlo event generators YFSWW3-1.14 and KORALW1.42 in an appropriate
combination, we achieve a physical precision on the signal process, as isolated
with LEP2 MC Workshop cuts, below 0.5 per cent. We stress the full gauge
invariance of our calculations and we compare our results with those of other
authors where appropriate. In particular, sample Monte Carlo data are
explicitly illustrated and compared with the results of the program RacoonWW of
Dittmaier {\it et al.}. In this way, we show that the total (physical plus
technical) precision tag for the WW signal process cross section is 0.4 per
cent for 200 GeV, for example. Results are also given for 500 GeV with an eye
toward the LC.Comment: 19 pages, 2 figs;corrected Tab. 3;improved refs.,figs.,text;improved
refs.,text;improved tex
Near-threshold boson pair production in the model of smeared-mass unstable particles
Near-threshold production of boson pairs is considered within the framework
of the model of unstable particles with smeared mass. We describe the principal
aspects of the model and consider the strategy of calculations including the
radiative corrections. The results of calculations are in good agreement with
LEP II data and Monte-Carlo simulations. Suggested approach significantly
simplifies calculations with respect to the standard perturbative one.Comment: 15 pages, 6 figures, minor corrections, references adde
Radiative Corrections to ZZ->ZZ in the Electroweak Standard Model
The cross-section for ZZ->ZZ with arbitrarily polarized Z bosons is
calculated within the electroweak Standard Model including the complete
O(alpha) corrections. We show the numerical importance of the radiative
corrections and elaborate its characteristic features. The treatment of the
Higgs-boson resonance is discussed in different schemes including the
S-matrix-motivated pole scheme and the background-field method. The numerical
accuracy of the equivalence theorem is investigated by comparing the
cross-sections for purely longitudinal Z bosons obtained from the equivalence
theorem and from the complete calculation. In this context the full O(alpha)
corrections are also confronted with the enhanced corrections of O(alpha
M_H^2/s_w^2 M_W^2), which were frequently used in the literature.Comment: 35 pages LaTeX, 19 postscript figures include
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