234 research outputs found

    Forfeiture of Attorney\u27s Fees Under RICO and CCE

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    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 F2(x,Q2)F_2(x,Q^2)

    The unpolarized two-loop massive pure singlet Wilson coefficients for deep-inelastic scattering

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    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 F2F_2 and FLF_L we also derive improved asymptotic representations adding power corrections. Numerical results are presented.Comment: 42, pages Latex, 8 Figure

    The O(α2)O(\alpha^2) Initial State QED Corrections to e+e−e^+e^- Annihilation to a Neutral Vector Boson Revisited

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    We calculate the non-singlet, the pure singlet contribution, and their interference term, at O(α2)O(\alpha^2) due to electron-pair initial state radiation to e+e−e^+ e^- 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 s≫me2s \gg m_e^2 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 m2/sm^2/s. 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 O(α2)O(\alpha^2) which have not been considered in \cite{Berends:1987ab}. The corrections are of central importance for precision analyzes in e+e−e^+e^- annihilation into γ∗/Z∗\gamma^*/Z^* at high luminosity.Comment: 4 pages Latex, 2 Figures, several style file

    The Two-mass Contribution to the Three-Loop Gluonic Operator Matrix Element Agg,Q(3)A_{gg,Q}^{(3)}

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    We calculate the two-mass QCD contributions to the massive operator matrix element Agg,QA_{gg,Q} at O(αs3)\mathcal{O} (\alpha_s^3) in analytic form in Mellin NN- and zz-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 NN-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 zz-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

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    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 F2(x,Q2)F_2(x,Q^2) at O(αs3)O(\alpha_s^3) 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 QED Initial State Corrections to the Forward-Backward Asymmetry of e+e−→γ∗/Z0∗e^+e^- \to \gamma^*/Z^{0*} to Higher Orders

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    The QED initial state corrections are calculated to the forward-backward asymmetry for e+e−→γ∗/Z0∗e^+e^- \rightarrow \gamma^*/{Z^{0}}^* in the leading logarithmic approximation to O(α6L6)O(\alpha^6 L^6) extending the known corrections up to O(α2L2)O(\alpha^2 L^2) in analytic form. We use the method of massive on-shell operator matrix elements and present the radiators both in Mellin-NN and momentum fraction zz-space. Numerical results are presented for various energies around the ZZ-peak by also including energy cuts. These corrections are of relevance for the precision measurements at the FCC_\_ee.Comment: Dedicated to the Memory of Tini Veltman, who made it possible to probe the Standard Model at high precisio

    The O(α2^{2}) initial state QED corrections to e+^{+} e−^{-} →\rightarrow Îł\gamma∗^{*} / Z0∗_{0}^{*}

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    We calculate the complete O(α\alpha2^{2}) initial state radiation corrections to e+^{+} e−^{-} annihilation into a neutral vector boson in a direct analytic computation without any approximation. The corrections are represented in terms of iterated incomplete (elliptic) integrals over alphabets of square-root valued letters. Performing the limit s >> me2_{e}^{2}, we find discrepancies with the earlier results of Ref. [1] and confirm results obtained in Ref. [2] where the effective method of massive operator matrix elements has been used, which works for all but the power corrections in me2_{e}^{2}/s. In this way, we also confirm the validity of the factorization of massive partons in the Drell-Yan process to O(α\alpha2^{2}). We add non logarithmic terms at O(α\alpha2^{2}) which have not been considered in previous calculations. The final results in the limit s >> me2_{e}^{2} can be given in terms of Nielsen integrals
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