282 research outputs found
Subleading Logarithmic QED Initial State Corrections to to
Using the method of massive operator matrix elements, we calculate the
subleading QED initial state radiative corrections to the process for the first three logarithmic contributions from
to and compare their effects to the leading
contribution and one more subleading term .
The calculation is performed in the limit of large center of mass energies
squared . These terms supplement the known corrections to
, which were completed recently. Given the high precision at
future colliders operating at very large luminosity, these corrections are
important for concise theoretical predictions. The present calculation needs
the calculation of one more two--loop massive operator matrix element in QED.
The radiators are obtained as solutions of the associated Callen--Symanzik
equations in the massive case. The radiators can be expressed in terms of
harmonic polylogarithms to weight {\sf w = 6} of argument and and
in Mellin space by generalized harmonic sums. Numerical results are
presented on the position of the peak and corrections to the width,
. The corrections calculated result into a final theoretical accuracy
for and which is estimated to be of O(30 keV) at
an anticipated systematic accuracy at the FCC\_ee of \sim 100 keV. This
precision cannot be reached, however, by including only the corrections up to
.Comment: 58 pages, 3 Figure
Forfeiture of Attorney\u27s Fees Under RICO and CCE
We present the matching relations of the variable flavor number scheme at next-to-leading order, which are of importance to define heavy quark partonic distributions for the use at high energy colliders such as Tevatron and the LHC. The consideration of the two-mass effects due to both charm and bottom quarks, having rather similar masses, are important. These effects have not been considered in previous investigations. Numerical results are presented for a wide range of scales. We also present the corresponding contributions to the structure function
The Three Loop Two-Mass Contribution to the Gluon Vacuum Polarization
We calculate the two-mass contribution to the 3-loop vacuum polarization of
the gluon in Quantum Chromodynamics at virtuality for general masses
and also present the analogous result for the photon in Quantum
Electrodynamics.Comment: 5 pages Late
The unpolarized two-loop massive pure singlet Wilson coefficients for deep-inelastic scattering
We calculate the massive two--loop pure singlet Wilson coefficients for heavy
quark production in the unpolarized case analytically in the whole kinematic
region and derive the threshold and asymptotic expansions. We also recalculate
the corresponding massless two--loop Wilson coefficients. The complete
expressions contain iterated integrals with elliptic letters. The contributing
alphabets enlarge the Kummer-Poincar\'e letters by a series of square-root
valued letters. A new class of iterated integrals, the Kummer-elliptic
integrals, are introduced. For the structure functions and we also
derive improved asymptotic representations adding power corrections. Numerical
results are presented.Comment: 42, pages Latex, 8 Figure
The Initial State QED Corrections to Annihilation to a Neutral Vector Boson Revisited
We calculate the non-singlet, the pure singlet contribution, and their
interference term, at due to electron-pair initial state
radiation to annihilation into a neutral vector boson in a direct
analytic computation without any approximation. The correction is represented
in terms of iterated incomplete elliptic integrals. Performing the limit we find discrepancies with the earlier results of
Ref.~\cite{Berends:1987ab} and confirm results obtained in
Ref.~\cite{Blumlein:2011mi} where the effective method of massive operator
matrix elements has been used, which works for all but the power corrections in
. In this way, we also confirm the validity of the factorization of
massive partons in the Drell-Yan process. We also add non-logarithmic terms at
which have not been considered in \cite{Berends:1987ab}. The
corrections are of central importance for precision analyzes in
annihilation into at high luminosity.Comment: 4 pages Latex, 2 Figures, several style file
The Two-mass Contribution to the Three-Loop Gluonic Operator Matrix Element
We calculate the two-mass QCD contributions to the massive operator matrix
element at in analytic form in Mellin
- and -space, maintaining the complete dependence on the heavy quark mass
ratio. These terms are important ingredients for the matching relations of the
variable flavor number scheme in the presence of two heavy quark flavors, such
as charm and bottom. In Mellin -space the result is given in the form of
nested harmonic, generalized harmonic, cyclotomic and binomial sums, with
arguments depending on the mass ratio. The Mellin inversion of these quantities
to -space gives rise to generalized iterated integrals with square root
valued letters in the alphabet, depending on the mass ratio as well. Numerical
results are presented.Comment: 99 pages LATEX, 2 Figure
The two-mass contribution to the three-loop pure singlet operator matrix element
We present the two-mass QCD contributions to the pure singlet operator matrix
element at three loop order in x-space. These terms are relevant for
calculating the structure function at as well as
for the matching relations in the variable flavor number scheme and the heavy
quark distribution functions at the same order. The result for the operator
matrix element is given in terms of generalized iterated integrals that include
square root letters in the alphabet, depending also on the mass ratio through
the main argument. Numerical results are presented.Comment: 28 papges Latex, 3 figure
The massive 3-loop operator matrix elements with two masses and the generalized variable flavor number scheme
We report on our latest results in the calculation of the two--mass
contributions to 3--loop operator matrix elements (OMEs). These OMEs are needed
to compute the corresponding contributions to the deep-inealstic scattering
structure functions and to generalize the variable flavor number scheme by
including both charm and bottom quarks. We present the results for the
non-singlet and OMEs, and compare the size of their contribution
relative to the single mass case. Results for the gluonic OME are
given in the physical case, going beyond those presented in a previous
publication where scalar diagrams were computed. We also discuss our recently
published two--mass contribution to the pure singlet OME, and present an
alternative method of calculating the corresponding diagrams.Comment: 20 pages Latex, 5 Figures, different style file
The QED initial state corrections to the forward-backward asymmetry of e e → γ/Z to higher orders
The QED initial state corrections are calculated to the forward-backward asymmetry for e e → γ/Z in the leading logarithmic approximation to O(αL) extending the known corrections up to O(αL) in analytic form. We use the method of massive on-shell operator matrix elements and present the radiators both in Mellin-N and momentum fraction z-space. Numerical results are presented for various energies around the Z-peak by also including energy cuts. These corrections are of relevance for the precision measurements at the FCC_ee
The QED Initial State Corrections to the Forward-Backward Asymmetry of to Higher Orders
The QED initial state corrections are calculated to the forward-backward
asymmetry for in the leading
logarithmic approximation to extending the known corrections
up to in analytic form. We use the method of massive on-shell
operator matrix elements and present the radiators both in Mellin- and
momentum fraction -space. Numerical results are presented for various
energies around the -peak by also including energy cuts. These corrections
are of relevance for the precision measurements at the FCCee.Comment: Dedicated to the Memory of Tini Veltman, who made it possible to
probe the Standard Model at high precisio
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